Ulna Bone Anatomy, Diagram & Function | Body Maps Your message has been sent. OK We're sorry, an error occurred. We are unable to collect your feedback at this time. However, your feedback is important to us. Please try again later. Close Ulna The ulna is one of two bones that give structure to the forearm. The ulna is located on the opposite side of the forearm from the thumb. It joins with the humerus on its larger end to make the elbow joint, and joins with the carpal bones of the hand at its smaller end. Together with the radius, the ulna enables the wrist joint to rotate. The ulna is 50 percent larger in diameter than the radius at 4 to 5 months of age. During adult life, when remodeling and resorption are complete, the ulnar diameter becomes half that of the radius. The ulna is found, and has similar function, in both humans and four-footed animals, such as dogs and cats. If the ulna breaks, it will most commonly occur at either the point where the radius and ulna form a joint or where the ulna forms a joint with the hand's carpal bones.

Ulnar fractures cause severe pain, difficulty in moving the joint affected, and even deformity of the arm if the fracture is compound. Ulna Anatomy 2D Interactive 3D Rotate & Zoom Change Anatomical System Change View Angle Full Ulna Description [Continued from above] . . . The olecranon fits into a small recess in the humerus known as the olecranon fossa, preventing the elbow’s extension beyond around 180 degrees. Just distal to the olecranon is the concave trochlear notch that surrounds the trochlea of the humerus to form the hinge of the elbow joint. The distal lip of the trochlear notch protrudes anteriorly to form the coronoid process that helps to lock the ulna in place with the humerus at the elbow and fits into the coronoid fossa of the humerus. On the lateral edge of the coronoid process is the small radial notch that forms the proximal radioulnar joint with the radius and permits the radius to rotate around the ulna at the elbow. A long ridge on the anterior side of the coronoid process known as the ulnar tuberosity extends down the shaft of the ulna as a muscle attachment point.

Moving distally from the elbow, the ulna begins to taper slightly in diameter along its entire length while curving medially. At its distal end, the ulna forms a small part of the wrist with the radius and the carpals of the hand. A rounded process known as the head of the ulna forms the distal radioulnar joint with the concave ulnar notch of the radius. The alignment of these joint-forming processes allows the radius to rotate around the ulna at the wrist. A small bony extension known as the styloid process protrudes from the posterior and medial corner of the ulna and provides an attachment point for the ulnar collateral ligament of the wrist. Functionally, the ulna provides muscle attachment sites for over a dozen muscles in the upper arm and forearm. In the upper arm, the triceps brachii and anconeus muscles form insertions at the olecranon to extend the forearm at the elbow. The brachialis muscle has its insertion on the coronoid process to flex the arm at the elbow. Many muscles that act on the hand and wrist have their origins on the ulna, including the pronators, supinators, flexors and extensors.

Like its neighbors the humerus and radius, the ulna is classified as a long bone because of its long, narrow shape. All long bones have a similar structure, with a hollow shaft surrounded by compact bone and reinforced at the ends with spongy bone. The hollow medullary cavity at the center of the ulna is filled with a soft, greasy substance known as yellow bone marrow. Yellow bone marrow contains many adipocytes and stores energy for the body in the form of triglycerides, or fats. Surrounding the medullary cavity is the hard, dense compact bone made of mineral matrix and collagen fibers. The mix of collagen and minerals, including calcium, gives the ulna its great strength and flexibility. The ends of the ulna are reinforced by spongy bone that increases the strength of the compact bone near the joints without significantly increasing the mass of the bone. Each region of spongy bone is made of many thin columns known as trabeculae that act like the steel girders of a bridge to withstand the stresses placed on the bone. Red bone marrow is found in the spaces between the trabeculae and contains many stem cells that produce the body’s blood cells.

On the joint-forming ends of the ulna are thin layers of hyaline cartilage that cover the compact bone and protect it from the stresses at the joints. Hyaline is as smooth as ice to help bones glide past each other at the joints. It is also rubbery to absorb the shocks of impacts at the joints. The outer surface of the ulna (except at the joints) is covered in a thin fibrous layer known as the periosteum. Periosteum is made of a dense weave of collagen fibers that extend into the tendons and ligaments that attach the ulna to the muscles and bones of the arm. The ulna begins at birth as a long bony shaft, known as the diaphysis, capped with hyaline cartilage at both ends. At around 4 years of age, the hyaline at the distal end by the wrist begins to ossify and forms a small bony cap known as the distal epiphysis. A thin layer of hyaline, known as the epiphyseal plate or growth plate, remains between the diaphysis and the newly formed epiphysis.

The ulna grows lengthwise into the growth plate, which in turn grows to prevent the fusion of the diaphysis and epiphysis. At around age 10, the proximal tip of the olecranon begins to ossify and forms the proximal epiphysis. These three bones continue to grow and remain separated by the epiphyseal plates until the end of puberty and the beginning of adulthood, when they fuse together to form a single, unified ulna. The site of the epiphyseal plate becomes known as the metaphysis in the mature bone. Prepared by Tim Taylor, Anatomy and Physiology Instructor The Ulna - Human Anatomy (Elbow Bone) (* 56 The ulna (Figs. 212, 213) is a long bone, prismatic in form, placed at the medial side of the forearm, parallel with the radius. It is divisible into a body and two extremities. Its upper extremity, of great thickness and strength, forms a large part of the elbow-joint; the bone diminishes in size from above downward, its lower extremity being very small, and excluded from the wrist-joint by the interposition of an articular disk.

The Upper Extremity (proximal extremity) (Fig. 212).The upper extremity presents two curved processes, the olecranon and the coronoid process; and two concave, articular cavities, the semilunar and radial notches. The Olecranon (olecranon process).The olecranon is a large, thick, curved eminence, situated at the upper and back part of the ulna. It is bent forward at the summit so as to present a prominent lip which is received into the olecranon fossa of the humerus in extension of the forearm. Its base is contracted where it joins the body and the narrowest part of the upper end of the ulna. Its posterior surface, directed backward, is triangular, smooth, subcutaneous, and covered by a bursa. Its superior surface is of quadrilateral form, marked behind by a rough impression for the insertion of the Triceps brachii; and in front, near the margin, by a slight transverse groove for the attachment of part of the posterior ligament of the elbow-joint. Its anterior surface is smooth, concave, and forms the upper part of the semilunar notch.

Its borders present continuations of the groove on the margin of the superior surface; they serve for the attachment of ligaments, viz., the back part of the ulnar collateral ligament medially, and the posterior ligament laterally. From the medial border a part of the Flexor carpi ulnaris arises; while to the lateral border the Anconæus is attached. The Coronoid Process (processus coronoideus).The coronoid process is a triangular eminence projecting forward from the upper and front part of the ulna. Its base is continuous with the body of the bone, and of considerable strength. Its apex is pointed, slightly curved upward, and in flexion of the forearm is received into the coronoid fossa of the humerus. Its upper surface is smooth, concave, and forms the lower part of the semilunar notch. Its antero-inferior surface is concave, and marked by a rough impression for the insertion of the Brachialis.

At the junction of this surface with the front of the body is a rough eminence, the tuberosity of the ulna, which gives insertion to a part of the Brachialis; to the lateral border of this tuberosity the oblique cord is attached. Its lateral surface presents a narrow, oblong, articular depression, the radial notch. Its medial surface, by its prominent, free margin, serves for the attachment of part of the ulnar collateral ligament. At the front part of this surface is a small rounded eminence for the origin of one head of the Flexor digitorum sublimis; behind the eminence is a depression for part of the origin of the Flexor digitorum profundus; descending from the eminence is a ridge which gives origin to one head of the Pronator teres. Frequently, the Flexor pollicis longus arises from the lower part of the coronoid process by a rounded bundle of muscular fibers.

The Semilunar Notch (incisura semilunaris; greater sigmoid cavity).The semilunar notch is a large depression, formed by the olecranon and the coronoid process, and serving for articulation with the trochlea of the humerus. About the middle of either side of this notch is an indentation, which contracts it somewhat, and indicates the junction of the olecranon and the coronoid process. The notch is concave from above downward, and divided into a medial and a lateral portion by a smooth ridge running from the summit of the olecranon to the tip of the coronoid process. The medial portion is the larger, and is slightly concave transversely; the lateral is convex above, slightly concave below. The Radial Notch (incisura radialis; lesser sigmoid cavity).The radial notch is a narrow, oblong, articular depression on the lateral side of the coronoid process; it receives the circumferential articular surface of the head of the radius. It is concave from before backward, and its prominent extremities serve for the attachment of the annular ligament.

The Body or Shaft (corpus ulnæ).The body at its upper part is prismatic in form, and curved so as to be convex behind and lateralward; its central part is straight; its lower part is rounded, smooth, and bent a little lateralward. It tapers gradually from above downward, and has three borders and three surfaces. Borders.The volar border (margo volaris; anterior border) begins above at the prominent medial angle of the coronoid process, and ends below in front of the styloid process. Its upper part, well-defined, and its middle portion, smooth and rounded, give origin to the Flexor digitorum profundus; its lower fourth serves for the origin of the Pronator quadratus. This border separates the volar from the medial surface.

The dorsal border (margo dorsalis; posterior border) begins above at the apex of the triangular subcutaneous surface at the back part of the olecranon, and ends below at the back of the styloid process; it is well-marked in the upper three-fourths, and gives attachment to an aponeurosis which affords a common origin to the Flexor carpi ulnaris, the Extensor carpi ulnaris, and the Flexor digitorum profundus; its lower fourth is smooth and rounded. This border separates the medial from the dorsal surface. The interosseous crest (crista interossea; external or interosseous border) begins above by the union of two lines, which converge from the extremities of the radial notch and enclose between them a triangular space for the origin of part of the Supinator; it ends below at the head of the ulna. Its upper part is sharp, its lower fourth smooth and rounded. This crest gives attachment to the interosseous membrane, and separates the volar from the dorsal surface.

Surfaces.The volar surface (facies volaris; anterior surface), much broader above than below, is concave in its upper three-fourths, and gives origin to the Flexor digitorum profundus; its lower fourth, also concave, is covered by the Pronator quadratus. The lower fourth is separated from the remaining portion by a ridge, directed obliquely downward and medialward, which marks the extent of origin of the Pronator quadratus. At the junction of the upper with the middle third of the bone is the nutrient canal, directed obliquely upward. FIG. 213 Bones of left forearm. Anterior aspect. FIG. 214 Bones of left forearm. Posterior aspect. The dorsal surface (facies dorsalis; posterior surface) directed backward and lateralward, is broad and concave above; convex and somewhat narrower in the middle; narrow, smooth, and rounded below. On its upper part is an oblique ridge, which runs from the dorsal end of the radial notch, downward to the dorsal border; the triangular surface above this ridge receives the insertion of the Anconæus, while the upper part of the ridge affords attachment to the Supinator.

Below this the surface is subdivided by a longitudinal ridge, sometimes called the perpendicular line, into two parts: the medial part is smooth, and covered by the Extensor carpi ulnaris; the lateral portion, wider and rougher, gives origin from above downward to the Supinator, the Abductor pollicis longus, the Extensor pollicis longus, and the Extensor indicis proprius. The medial surface (facies medialis; internal surface) is broad and concave above, narrow and convex below. Its upper three-fourths give origin to the Flexor digitorum profundus; its lower fourth is subcutaneous. FIG. 215 Plan of ossification of the ulna. From three centers. FIG. 216 Epiphysial lines of ulna in a young adult. Lateral aspect. The lines of attachment of the articular capsules are in blue.

The Lower Extremity (distal extremity).The lower extremity of the ulna is small, and presents two eminences; the lateral and larger is a rounded, articular eminence, termed the head of the ulna; the medial, narrower and more projecting, is a non-articular eminence, the styloid process. The head presents an articular surface, part of which, of an oval or semilunar form, is directed downward, and articulates with the upper surface of the triangular articular disk which separates it from the wrist-joint; the remaining portion, directed lateralward, is narrow, convex, and received into the ulnar notch of the radius. The styloid process projects from the medial and back part of the bone; it descends a little lower than the head, and its rounded end affords attachment to the ulnar collateral ligament of the wrist-joint. The head is separated from the styloid process by a depression for the attachment of the apex of the triangular articular disk, and behind, by a shallow groove for the tendon of the Extensor carpi ulnaris.

Structure.The long, narrow medullary cavity is enclosed in a strong wall of compact tissue which is thickest along the interosseous border and dorsal surface. At the extremities the compact layer thins. The compact layer is continued onto the back of the olecranon as a plate of close spongy bone with lamellæ parallel. From the inner surface of this plate and the compact layer below it trabeculæ arch forward toward the olecranon and coronoid and cross other trabeculæ, passing backward over the medullary cavity from the upper part of the shaft below the coronoid. Below the coronoid process there is a small area of compact bone from which trabeculæ curve upward to end obliquely to the surface of the semilunar notch which is coated with a thin layer of compact bone. The trabeculæ at the lower end have a more longitudinal direction. Ossification (Figs. 215, 216).The ulna is ossified from three centers: one each for the body, the inferior extremity, and the top of the olecranon.

Ossification begins near the middle of the body, about the eighth week of fetal life, and soon extends through the greater part of the bone. At birth the ends are cartilaginous. About the fourth year, a center appears in the middle of the head, and soon extends into the styloid process. About the tenth year, a center appears in the olecranon near its extremity, the chief part of this process being formed by an upward extension of the body. The upper epiphysis joins the body about the sixteenth, the lower about the twentieth year. Articulations.The ulna articulates with the humerus and radius. Note 56. In the anatomical position, the forearm is placed in extension and supination with the palm looking forward and the thumb on the outer side. [ back ] BBC Science & Nature - Human Body and Mind - Skeleton Layer Shoulder socket: Is made by your collarbone and shoulder blade Ulna: You often rest your ulna on the table Shoulder Your shoulder is made up of a collarbone (clavicle) and a shoulder blade (scapula). These bones project out from your body forming a scaffold for your arm to hang from.

Your collarbone is a thin bone that bridges the top of your sternum, in the front of your ribcage, to your shoulder socket at the end of your shoulder blade. It is the only bone in your shoulder that connects directly to your ribcage. Your collarbone supports the weight of your entire arm. When someone has a broken shoulder, they usually hae damaged their collarbone. If the bone has snapped completely, the whole shoulder sags. Your shoulder blade is a large flat bone. It's not connected to your ribcage, but is held in place by your shoulder muscles. The ends of your collarbone and shoulder blade meet, forming a shoulder socket that your arm fits into. This 'ball and socket' joint is loosely held in place by ligaments. This makes your shoulder joint incredibly flexible, but means it can be dislocated more easily than other joints in your body. Arm Your arm is made up of three long bones: your humerus in your upper arm and your ulna and radius in your lower arm. Your upper and lower arms are connected at your elbow by a hinge joint between your humerus and ulna.

Your radius and ulna are linked at your elbow in a way that allows you to rotate your hand and forearm by more than 180 degrees. Your ulna bone forms the point of your elbow. Your shoulder and arm bones have roughened patches on their surfaces where muscles are attached. When the muscles contract, this pulls the bone the muscles are attached to, making your arm move. Ulna Ulna Human Anatomy » Body Systems » Skeletal System » Ulna Introduction: Of the two bones of the forearm, the ulna is the longer one and is placed medially. It consists of a large proximal end supporting the olecranon and the coronoid processes, a body or shaft tapering distally, and a small rounded distal end called the head. Ulna med.jpg ( Proximal End of Ulna The olecranon process lies in line with the body. Its dorsal surface is more or less triangular in form, smooth, subcutaneous and covered by a bursa. The coronoid process is a bracket-like process, which projects forwards from the anterior and proximal part of the shaft, and is fused with the olecranon proximally.

Of the lateral margins of the coronoid process, the medial is usually the better defined. The smooth medial surface of the coronoid process merges with the olecranon dorsally, and with the medial surface of the body distally. Body (Shaft) of Ulna: The body of ulna is nearly straight, or slightly curved, stout and thick proximally, gradually tapering towards its distal extremity. It has three borders and three surfaces. Surfaces are anterior, posterior, and medial while the borders are; interosseous, posterior and anterior. The interosseous border is crisp and sharp in the proximal three-fourths of the body, but becomes faint and ill-defined in the distal fourth The posterior border curves laterally above and slightly medially below. It is continuous proximally with the triangular subcutaneous area on the back of the olecranon process. It is well marked above but becomes faint and more rounded below, although it may still be traced distally to the dorsal surface of the base of the styloid process. The anterior surface corresponds to the front and medial side of the body. Sometimes the anterior and medial surfaces are regarded as two parts of the same surface separated by rounded anterior margin.

The posterior surface of the body lies between the posterior border and the interosseous crest. At its proximal part it is extends on to the lateral side of the olecranon. Distal End of Ulna: The distal end of the ulna presents a rounded head, from which, on its medial and posterior aspect, there projects a cylindrical pointed process called the styloid process. The dorsal and medial surface of the styloid process is channeled by a groove which separates it from the dorsal surface of the head. Nutrient Foramina of Ulna: A foramen, having a proximal direction, for the nutrient artery of the body opens on the anterior surface of the bone. Vascular canals of large size are seen proximal and posterior to the radial notch. At the distal end of the bone similar openings are seen in the groove between the styloid process and the distal articular surface of the head. Ossification of Ulna: The ulna is ossified from one primary and two or more secondary centers. The center for the body appears early in the second month of fetal life.

At birth the body and a considerable part of the proximal extremity, including the coronoid process, are ossified, as well as part of the distal extremity. The olecranon and the distal surface of the head and the styloid process are cartilaginous. At About ten years of age a secondary centre appears in the cartilage at the proximal end of the bone, and forms an epiphysis which unites with the body at about sixteen. A scale-like center appears in the cartilage of the head at about the sixth year, from which the distal surface of that part of the bone is developed, and by the extension of which the styloid process is also ossified; this epiphysis does not unite with the shaft till the twentieth or twenty-third years. Share this page: II. Osteology. 6a. 4. The Ulna. Gray, Henry. 1918. Anatomy of the Human Body. (Elbow Bone) 56 The ulna ( Figs. 212, 213 ) is a long bone, prismatic in form, placed at the medial side of the forearm, parallel with the radius.

It is divisible into a body and two extremities. Its upper extremity, of great thickness and strength, forms a large part of the elbow-joint; the bone diminishes in size from above downward, its lower extremity being very small, and excluded from the wrist-joint by the interposition of an articular disk. 1 The Upper Extremity (proximal extremity) (Fig. 212 ).The upper extremity presents two curved processes, the olecranon and the coronoid process; and two concave, articular cavities, the semilunar and radial notches. 2 The Olecranon (olecranon process).The olecranon is a large, thick, curved eminence, situated at the upper and back part of the ulna. It is bent forward at the summit so as to present a prominent lip which is received into the olecranon fossa of the humerus in extension of the forearm. Its base is contracted where it joins the body and the narrowest part of the upper end of the ulna. Its posterior surface, directed backward, is triangular, smooth, subcutaneous, and covered by a bursa.

Its superior surface is of quadrilateral form, marked behind by a rough impression for the insertion of the Triceps brachii; and in front, near the margin, by a slight transverse groove for the attachment of part of the posterior ligament of the elbow-joint. Its anterior surface is smooth, concave, and forms the upper part of the semilunar notch. Its borders present continuations of the groove on the margin of the superior surface; they serve for the attachment of ligaments, viz., the back part of the ulnar collateral ligament medially, and the posterior ligament laterally. From the medial border a part of the Flexor carpi ulnaris arises; while to the lateral border the Anconæus is attached. FIG. 212 Upper extremity of left ulna. Lateral aspect. ( See enlarged image ) The Coronoid Process (processus coronoideus).The coronoid process is a triangular eminence projecting forward from the upper and front part of the ulna. Its base is continuous with the body of the bone, and of considerable strength.

Its apex is pointed, slightly curved upward, and in flexion of the forearm is received into the coronoid fossa of the humerus. Its upper surface is smooth, concave, and forms the lower part of the semilunar notch. Its antero-inferior surface is concave, and marked by a rough impression for the insertion of the Brachialis. At the junction of this surface with the front of the body is a rough eminence, the tuberosity of the ulna, which gives insertion to a part of the Brachialis; to the lateral border of this tuberosity the oblique cord is attached. Its lateral surface presents a narrow, oblong, articular depression, the radial notch. Its medial surface, by its prominent, free margin, serves for the attachment of part of the ulnar collateral ligament. At the front part of this surface is a small rounded eminence for the origin of one head of the Flexor digitorum sublimis; behind the eminence is a depression for part of the origin of the Flexor digitorum profundus; descending from the eminence is a ridge which gives origin to one head of the Pronator teres.

Frequently, the Flexor pollicis longus arises from the lower part of the coronoid process by a rounded bundle of muscular fibers. 4 The Semilunar Notch (incisura semilunaris; greater sigmoid cavity).The semilunar notch is a large depression, formed by the olecranon and the coronoid process, and serving for articulation with the trochlea of the humerus. About the middle of either side of this notch is an indentation, which contracts it somewhat, and indicates the junction of the olecranon and the coronoid process. The notch is concave from above downward, and divided into a medial and a lateral portion by a smooth ridge running from the summit of the olecranon to the tip of the coronoid process. The medial portion is the larger, and is slightly concave transversely; the lateral is convex above, slightly concave below. 5 The Radial Notch (incisura radialis; lesser sigmoid cavity).The radial notch is a narrow, oblong, articular depression on the lateral side of the coronoid process; it receives the circumferential articular surface of the head of the radius.

It is concave from before backward, and its prominent extremities serve for the attachment of the annular ligament. 6 The Body or Shaft (corpus ulnæ).The body at its upper part is prismatic in form, and curved so as to be convex behind and lateralward; its central part is straight; its lower part is rounded, smooth, and bent a little lateralward. It tapers gradually from above downward, and has three borders and three surfaces. 7 Borders.The volar border (margo volaris; anterior border) begins above at the prominent medial angle of the coronoid process, and ends below in front of the styloid process. Its upper part, well-defined, and its middle portion, smooth and rounded, give origin to the Flexor digitorum profundus; its lower fourth serves for the origin of the Pronator quadratus. This border separates the volar from the medial surface.

8 The dorsal border (margo dorsalis; posterior border) begins above at the apex of the triangular subcutaneous surface at the back part of the olecranon, and ends below at the back of the styloid process; it is well-marked in the upper three-fourths, and gives attachment to an aponeurosis which affords a common origin to the Flexor carpi ulnaris, the Extensor carpi ulnaris, and the Flexor digitorum profundus; its lower fourth is smooth and rounded. This border separates the medial from the dorsal surface. 9 The interosseous crest (crista interossea; external or interosseous border) begins above by the union of two lines, which converge from the extremities of the radial notch and enclose between them a triangular space for the origin of part of the Supinator; it ends below at the head of the ulna. Its upper part is sharp, its lower fourth smooth and rounded. This crest gives attachment to the interosseous membrane, and separates the volar from the dorsal surface.

Surfaces.The volar surface (facies volaris; anterior surface), much broader above than below, is concave in its upper three-fourths, and gives origin to the Flexor digitorum profundus; its lower fourth, also concave, is covered by the Pronator quadratus. The lower fourth is separated from the remaining portion by a ridge, directed obliquely downward and medialward, which marks the extent of origin of the Pronator quadratus. At the junction of the upper with the middle third of the bone is the nutrient canal, directed obliquely upward. FIG. 213 Bones of left forearm. Anterior aspect. ( See enlarged image ) FIG. 214 Bones of left forearm. Posterior aspect. ( See enlarged image ) The dorsal surface (facies dorsalis; posterior surface) directed backward and lateralward, is broad and concave above; convex and somewhat narrower in the middle; narrow, smooth, and rounded below.

On its upper part is an oblique ridge, which runs from the dorsal end of the radial notch, downward to the dorsal border; the triangular surface above this ridge receives the insertion of the Anconæus, while the upper part of the ridge affords attachment to the Supinator. Below this the surface is subdivided by a longitudinal ridge, sometimes called the perpendicular line, into two parts: the medial part is smooth, and covered by the Extensor carpi ulnaris; the lateral portion, wider and rougher, gives origin from above downward to the Supinator, the Abductor pollicis longus, the Extensor pollicis longus, and the Extensor indicis proprius. FIG. 215 Plan of ossification of the ulna. From three centers. ( See enlarged image ) FIG. 216 Epiphysial lines of ulna in a young adult. Lateral aspect. The lines of attachment of the articular capsules are in blue.

( See enlarged image ) The Lower Extremity (distal extremity).The lower extremity of the ulna is small, and presents two eminences; the lateral and larger is a rounded, articular eminence, termed the head of the ulna; the medial, narrower and more projecting, is a non-articular eminence, the styloid process. The head presents an articular surface, part of which, of an oval or semilunar form, is directed downward, and articulates with the upper surface of the triangular articular disk which separates it from the wrist-joint; the remaining portion, directed lateralward, is narrow, convex, and received into the ulnar notch of the radius. The styloid process projects from the medial and back part of the bone; it descends a little lower than the head, and its rounded end affords attachment to the ulnar collateral ligament of the wrist-joint. The head is separated from the styloid process by a depression for the attachment of the apex of the triangular articular disk, and behind, by a shallow groove for the tendon of the Extensor carpi ulnaris.

14 Structure.The long, narrow medullary cavity is enclosed in a strong wall of compact tissue which is thickest along the interosseous border and dorsal surface. At the extremities the compact layer thins. The compact layer is continued onto the back of the olecranon as a plate of close spongy bone with lamellæ parallel. From the inner surface of this plate and the compact layer below it trabeculæ arch forward toward the olecranon and coronoid and cross other trabeculæ, passing backward over the medullary cavity from the upper part of the shaft below the coronoid. Below the coronoid process there is a small area of compact bone from which trabeculæ curve upward to end obliquely to the surface of the semilunar notch which is coated with a thin layer of compact bone. The trabeculæ at the lower end have a more longitudinal direction. 15 Ossification ( Figs. 215, 216 ).The ulna is ossified from three centers: one each for the body, the inferior extremity, and the top of the olecranon.

Ossification begins near the middle of the body, about the eighth week of fetal life, and soon extends through the greater part of the bone. At birth the ends are cartilaginous. About the fourth year, a center appears in the middle of the head, and soon extends into the styloid process. About the tenth year, a center appears in the olecranon near its extremity, the chief part of this process being formed by an upward extension of the body. The upper epiphysis joins the body about the sixteenth, the lower about the twentieth year. Radius Bone Definition, Diagram & Anatomy | Body Maps Your message has been sent. OK We're sorry, an error occurred. We are unable to collect your feedback at this time. However, your feedback is important to us. Please try again later. Close Radius The forearm contains two major bones. One is the ulna, and the other is the radius. In concert with each other, the two bones play a vital role in how the forearm rotates. The ulna primarily connects with the humerus at the elbow joint, while the radius primarily junctions with the carpal bones of the hand at the wrist joint. The two bones play only secondary roles at their opposing joints.

The radius is the home for a few muscles' insertion points. The biceps originate near the shoulder joint and insert into the radial tuberosity on the upper part of the radius, near the elbow joint. Other muscle attachments include the supinator, the flexor digitorum superficialis, the flexor pollicis longus, the pronator quadratus, and many more tendons and ligaments. Due to the human instinct to break a fall by outstretching the arms, the radius is one of the more frequently fractured bones in the body. Also, dislocation issues with both the wrist and the elbow may arise. Radius Radius Human Anatomy » Body Systems » Skeletal System » Radius Introduction: The forearm contains two bones namely; radius and ulna. Radius is shorter in size and lateral in position. Proximally it articulates with the humerus, and distally it supports the carpus. It consists of a proximal end, a body, and an expanded distal end. The body is narrow proximally, but increases in all its diameters distally. Radius ant.jpg ( Proximal End of Radius: Proximal end of radius consists of head, neck and tuberosity.

The head of radius is disc-shaped and provided with a shallow concave surface proximally for articulation with the capitulum of the humerus. The circumference of the head is smooth and is embraced by the annular ligament. The neck is the constricted part of the body which supports the head. Distal to the neck, on the medial side, there is an outstanding oval prominence, the radial tuberosity. Body of Radius: The body is narrow proximally and broad distally. It has a lateral curve and is wedge-shaped in cross section. The edge of the wedge forms the sharp medial interosseous border of the bone while its base corresponds to the thick and rounded lateral border over which the anterior surface becomes confluent with the posterior surface. The interosseous border is faint proximally where it lies in line with the dorsal margin of the tuberosity. It becomes sharp and prominent in the middle third of the bone. Distal to this it splits into two faint lines, which lead to either side of the ulnar notch on the distal end of the bone, thus including between them a narrow triangular area.

To this crest, as well as to the dorsal of the two divergent lines, the interosseous membrane is attached. The lateral surface is thick and rounded proximally, but becomes thinner and more prominent distally, where it merges with the base of the styloid process. The anterior surface is crossed obliquely by a line which runs from the tuberosity distally and laterally towards the middle of the lateral surface of the body. This is often called the anterior oblique line. The posterior surface is also crossed by an oblique line, less distinct than the anterior. Distal end of Radius: The distal end, which tends to be turned slightly forwards, has a somewhat triangular form. Its distal carpal articular surface, concave from before backwards, and slightly so from side to side, is divided into two facets by a slight antero- posterior ridge. The anterior border, prominent and turned forwards, is rough at its edge, where it serves for the attachment of the anterior part of the capsule of the wrist-joint. The posterior border is rough, rounded, and tubercular, and is grooved by many tendons.

The styloid process lies to the lateral side of the distal end; broad at its base, it becomes narrow and pointed distally where by its medial cartilage-covered surface it forms the summit of the distal triangular articular area On the medial side of the distal extremity is placed the ulnar notch for the reception of the head of the ulna. It is concave from before backwards, and plane proximo-distally. It forms a rectangular edge, by its inferior margins, which separates it from the distal carpal surface. Nutrient Foramina of Radius: The openings of several small nutrient canals may be seen in the region of the neck. That for the body, which has a proximal direction, is usually placed on the anterior surface of the bone, medial to the anterior oblique line, and about two inches distal to the tuberosity. The dorsal surface of the distal extremity of the bone is pierced by many small vascular foramina. Ossification of Radius: The center for the body makes its appearance early in the second month of intra-uterine life. A secondary center appears in the cartilage of the distal extremity about the second or third year.

This does not unite with the body until the twentieth or twenty-fifth years, somewhat earlier in the female. From this the carpal and ulnar articular surfaces are formed. The center for the head appears from the fifth to the seventh year, and fuses with the neck about the age of eighteen or twenty. It forms the capitular articular surface and combines with the neck to form the area for articulation with the radial notch of the ulna. A scale-like epiphysis capping the summit of the tuberosity has been described; this appears about the fourteenth or fifteenth year, and rapidly fuses with that process.

Share this page: Notes anterior longitudinal ligament a ligament that courses from superior to inferior along the anterior surfacesa of all vertebral bodies it lies directly posterior to the thoracic and abdominal viscera interspinous ligament a ligament that connects the spinous processes of two adjacent vertebra a syndesmosis intervertebral disc a fibrocartilaginous disk between adjacent vertebral bodies a symphysis; it is composed of two parts: an outer anulus fibrosus and an inner nucleus pulposus; the nucleus pulposus is the remnant of the notochord; the intervertebral disks are important shock absorbers between vertebrae ligamenta flava a ligament formed predominantly by elastic fibers which joins the laminae of adjacent vertebrae a syndesmosis; paired; the ligamentum flavum is penetrated by the needle during spinal tap; the word flavum is derived from the Latin word flavus, which means "yellow" - a reference to the predominance of yellow elastic fibers which gives this ligament its grossly visible color nuchal ligament a midline ligament that extends posteriorly from the spinous processes of cervical vertebrae and extends from the base of the skull to

 the 7th cervical vertebra a syndesmosis; it provides muscle attachments to the cervical spinous processes without the necessity of long spinous processes that would hinder extension of the neck posterior longitudinal ligament a ligament that courses from superior to inferior along the posterior surfaces of all vertebral bodies it is broader at the intervertebral disks and narrow at the vertebral bodies which gives it a scalloped edge; it is located in the vertebral canal; it is NOT penetrated by the needle during spinal tap supraspinous ligament a ligament that connects the tips of the spinous processes of thoracic and lumbar vertebrae a syndesmosis; the supraspinous ligament begins at the C7 vertebra and ends at the mid-sacral segmental level; it serves as a muscle attachment site zygapophyseal joint a small joint between the articular processes of adjacent vertebrae a synovial plane joint acromioclavicular joint the joint between the distal end of the clavicle and the acromion of the scapula a plane synovial joint; the shape of the articulation encourages the acromion to slide inferior to the clavicle during dislocation (

shoulder separation) a condition that occurs when the coracoclavicular ligament is torn; a small articular disk occurs within this joint capsule annular ligament the ligament that encircles the head of the radius it forms 4/5 of a circle - the radial notch of the ulna forms the other 1/5; it attaches to the margins of the radial notch; it holds the head of the radius against the ulna and cups in distal to the head to provide restraint against distal dislocation of the radius carpometacarpal joint, finger the articulation between the distal carpal bones and the proximal ends of the metacarpal bones of the hand a synovial plane joint; limited motion is permitted at the carpometacarpal joint; the carpometacarpal joint is reinforced by dorsal and palmar ligaments carpometacarpal joint, thumb the articulation between the trapezium and the proximal end of the metacarpal bone of the thumb a synovial saddle (sellar) joint; this articulation permits two planes of motion: flexion/extension and abduction/adduction which may be combined to produce circumduction coracoacromial ligament the lig

ament that connects the coracoid process to the acromion of the scapula it passes superior to both the head of the humerus and the supraspinatus tendon; it provides support for the head of the humerus that prevents superior dislocation coracoclavicular joint the joint between the coracoid process of the scapula and the inferior surface of the lateral portion of the clavicle a syndesmosis; this joint provides stability to the acromioclavicular joint coracoclavicular ligament the ligament that connects the upper surface of the coracoid process to the under surface of the clavicle it has two parts: conoid ligament (posteromedial part) and trapezoid ligament; tearing of the coracoclavicular ligament permits the acromion to move inferior to the distal end of the clavicle (shoulder separation), a condition which could result from a fall on the point of the shoulder costoclavicular ligament a ligament that attaches the clavicle to the first rib it resists superior displacement of the proximal end of the clavicle; the combined effect of this ligament, the sternoclavicular ligament and the inter

clavicular ligament is to produce a very strong sternoclavicular joint that seldom dislocates elbow joint the joint between the distal humerus and the proximal radius and ulna a synovial hinge joint; the elbow joint is a complex joint consisting of humeroradial, humeroulnar and proximal radioulnar articulations all within a common articular capsule; it is strengthened by the ulnar and radial collateral ligaments glenohumeral ligament, inferior a ligament reinforcing the anterior wall of the capsule of the glenohumeral joint it connects the humerus to the scapula; a thickening of the anteroinferior shoulder joint capsule glenohumeral ligament, middle a ligament reinforcing the anterior wall of the capsule of the glenohumeral joint it connects the humerus to the scapula; a thickening of the anterior shoulder joint capsule glenohumeral ligament, superior a ligament reinforcing the anterior wall of the capsule of the glenohumeral joint it connects the humerus to the scapula; a thickening of the anterosuperior shoulder joint capsule intercarpal ligaments, dorsal a series of short ligaments

 that connect adjacent carpal bones on their dorsal aspects intercarpal ligaments reinforce the articular capsule of the intercarpal joints; they prevent excessive movement of these synovial plane joints intercarpal ligaments, palmar a series of short ligaments that connect adjacent carpal bones on their ventral aspects intercarpal ligaments reinforce the articular capsule of the intercarpal joints; they prevent excessive movement of these synovial plane joints interclavicular ligament a ligament that reinforces the capsule of the sternoclavicular joint it spans the superior surface of the sternoclavicular joint and manubrium of the sternum; the combined effect of this ligament, the sternoclavicular ligament and the costoclavicular ligament is to produce a very strong sternoclavicular joint that seldom dislocates intermetacarpal joint the articulation between the adjacent sides of the proximal ends of metacarpal bones 2-5 a synovial plane joint; limited motion is possible between at the carpometacarpal joints or between adjacent metacarpal bones interosseous membrane, forearm a fibrous membrane that connects the interosseous borders located on the shafts of the radius and the

 ulna a syndesmosis; its fibers are oriented obliquely downward from the radius toward the ulna; the interosseous membrane is the classic example of a syndesmosis; proximally directed forces from the hand pass through the radius and are transferred to the ulna through the interosseous membrane; marked proximally by the oblique cord interphalangeal joints the articulations between the proximal and middle phalanges (proximal interphalangeal joint, abbreviated PIP) or the middle and distal phalanges (distal interphalangeal joint, abbreviated DIP) a synovial hinge joint; these joints are strengthened by medial and lateral collateral ligaments metacarpophalangeal joint the articulation between the head of a metacarpal and the base of a proximal phalanx a synovial condyloid (or ellipsoid) joint; it is strengthened by medial and lateral collateral ligaments; the joint has two planes of motion: flexion/extension and abduction/adduction which may be combined to yield circumduction midcarpal joint the joint which connects the proximal and distal rows of carpal bones a series of synovial plane joints

; small ranges of motion are permitted between carpal bones which take on an additive effect because there are several articulations in a proximodistal row (wrist, midcarpal and carpometacarpal joints); the midcarpal and intercarpal joints are reinforced by numerous ligaments oblique cord a thickening of connective tissue fibers at the proximal end of the interosseous membrane it connects the proximal end of the shaft of the radius to the proximal end of the shaft of the ulna radial collateral ligament, elbow a ligament spanning the lateral side of the elbow joint it connects the lateral epicondyle of the humerus with the radius and the annular ligament; it reinforces the lateral side of the elbow articular capsule; it is smaller and less distinct than the ulnar collateral ligament radial collateral ligament, wrist it connects the styloid process of the radius with the scaphoid and trapezium it reinforces the articular capsule on the lateral side of the wrist radiocarpal (wrist) joint characterized by an intracapsular articular disk; radius articulates with the proximal row of carpals radioulnar joint, distal the articulation between the head of

 the ulna and the ulnar notch of the radius a synovial pivot joint; this joint has a fibrocartilaginous articular disk that attaches to the styloid process of the ulna and the medial side of the distal radius radioulnar joint, intermediate the articulation formed by the interosseous membrane a syndesmosis; it connects the interosseous border of the ulna to the interosseous border of the radius; proximally directed forces from the hand pass through the radius and are transferred to the ulna through the interosseous membrane radioulnar joint, proximal the proximal articulation between the radius and ulna that is contained within the capsule of the elbow joint a synovial pivot joint; it is the articulation between the head of the radius and the radial notch of the ulna which is completed by the annular ligament shoulder joint the articulation between the head of the humerus and the glenoid fossa of the scapula a synovial ball and socket joint; the glenoid labrum deepens the socket; glenohumeral ligaments reinforce the joint capsule anteriorly; the tendon of the long head of the biceps

 brachii m.

passes through the shoulder joint cavity; the shoulder joint is supported by the muscles of the rotator cuff group (supraspinatus, infraspinatus, teres minor and subscapularis); also known as the glenohumeral joint; it is frequently dislocated sternoclavicular joint the joint what connects the clavicle with the sternum a synovial joint; its joint capsule is subdivided by a fibrous articular disc; it is strengthened by the sternoclavicular, interclavicular and costoclavicular ligaments; the sternoclavicular joint has the range of movement, but not the form, of a ball and socket joint sternoclavicular ligament a ligament that reinforces the capsule of the sternoclavicular joint the sternoclavicular ligament has two parts: anterior and posterior; it is a very strong ligament; the combined effect of this ligament, the costoclavicular ligament and the interclavicular ligament is to produce a very strong sternoclavicular joint that seldom dislocates transverse humeral ligament the ligament that spans the intertubercular sulcus of the humerus it connects the greater tubercle of the humerus

 to the lesser tubercle of the humerus and acts to retain the tendon of the long head of the biceps brachii m.

in the intertubercular sulcus transverse metacarpal ligament, deep a ligament that connects the metacarpophalangeal joints 2-5 on their palmar surface limited motion is permitted between the distal ends of adjacent metacarpal bones due to the presence of the deep transverse metacarpal ligaments; the metacarpal bones are bound together to form a solid foundation for finger movements transverse scapular ligament, superior a ligament that spans the suprascapular notch of the scapula it converts the suprascapular notch into a foramen; the suprascapular a. passes superior to the ligament and the suprascapular n.

passes inferior to the ligament (Army over the bridge, Navy under the bridge) ulnar collateral ligament, elbow a strong ligament spanning the medial side of the elbow joint it connects the medial epicondyle of the humerus with the ulna; it reinforces the medial side of the elbow articular capsule ulnar collateral ligament, wrist it connects the styloid process of the ulna to the pisiform and triquetrum it reinforces the articular capsule on the medial side of the wrist wrist joint the articulation between the distal end of the radius and the proximal row of carpal bones a synovial ellipsoid joint; two primary degrees of motion are permitted: abduction/adduction and flexion/extension - these motions are combined to produce circumduction; the radius actually articulates with the articular disk which in turn articulates with the proximal row of carpal bones (scaphoid, lunate and triquetrum) the articulation between the frontal bone and the two parietal bones a suture intermaxillary suture the articulation between the palatine processes of the right and left maxillae a suture; it is a midline feature of the hard palate and marks the line of fusion of the two

 palatine shelves (secondary palate) during development lambdoidal suture the articulation between the occipital bone and the parietal bone a suture metopic suture the articulation between the two ossification centers of the frontal bone a suture; a midline structure, it usually disappears during development but is occasionally present in adults pterion the articulation between four bones: the greater wing of the sphenoid bone, the frontal bone, the parietal bone, the squamous part of the temporal bone a suture; this is a site of relatively thin bone that is frequently fractured in blows to the side of the head; the middle meningeal a.

is located deep to this site and may be injured in skull fractures at this location, leading to epidural hematoma sagittal suture the articulation between the two parietal bones a suture; it is a midline structure that lies superficial to the superior sagittal venous sinus sphenomandibular ligament the ligament that attaches to the spine of the sphenoid bone superiorly and the lingula of the mandible inferiorly paired; it is a specialization of the pterygoid fascia and is a remnant of the mesenchymal core of the first pharyngeal arch (Meckel's cartilage) squamosal suture the articulation between the parietal bone and the squamous portion of the temporal bone a suture; the greater wing of the sphenoid bone participates in the formation of the anterior end of the squamosal suture stylohyoid ligament the ligament that connects the styloid process with the lesser horn of the hyoid bone a syndesmosis; paired; a remnant of the mesenchymal core of the second pharyngeal arch (Reichert's cartilage) stylomandibular ligament the ligament that connects the sty

loid process with the angle of the mandible paired; a thickening of the parotid fascia temporomandibular joint the articulation between the head of the condylar process of the mandible and the mandibular fossa of the temporal bone a synovial hinge joint; it is separated into two joint spaces by an intracapsular fibrous articular disc; gliding action occurs superior to the articular disc and hinge action occurs inferior to the disc costal cartilage the cartilage that caps the medial end of the rib costal cartilages of ribs 1-7 connect to the sternum; costal cartilages of ribs 8-10 connect to the costal cartilage of rib 7; costal cartilages of ribs 11 & 12 do not articulate anteriorly but end in the muscles of the abdominal wall radiate sternocostal ligaments ligaments that reinforce the sternocostal joint capsule these ligaments connect the costal cartilages of ribs 1-7 with the sternum on both the anterior and posterior surfaces of the sternocostal articulation sternal angle the angle formed by the articulation between the manubrium and the body of the

 sternum a synchondrosis; the cartilage within this joint usually does not become ossified until old age; the angle formed by this articulation is also called the angle of Louis; the sternal angle marks the level of the second costal cartilage from which all other ribs are counted sternocostal joints the articulations that connect the costal cartilages with the sternum a synchondrosis (rib 1) or synovial joints (ribs 2-10); sternocostal synovial joints involving ribs 2-7 contain thin joint capsules; interchondral joints involving ribs 8-10 have simple gliding synovial articulations; radiate sternocostal ligaments reinforce the sternocostal articulations xiphisternal joint the articulation that connects the xiphoid process with the body of the sternum a synchondrosis; the cartilage within this joint usually becomes ossified in old age; the xiphisternal joint marks the inferior extent of the thoracic cavity inguinal ligament the ligament that connects the anterior superior iliac spine with the pubic tubercle the inguinal ligament is a specialization of the inferior border of the

 external abdominal oblique aponeurosis; it is the site of origin for a part of the internal abdominal oblique muscle and for a part of the transversus abdominis muscle; also known as: Poupart's ligament lacunar ligament an extension of the medial end of the inguinal ligament which connects the pubic tubercle with the pecten of the pubis the lacunar ligament is a flattened portion of the aponeurosis of the external abdominal oblique m.

that projects posteriorly from the pubic tubercle; it forms the medial border of the femoral ring and the floor of the inguinal canal at the superficial inguinal ring pectineal ligament a thickening of fascia on the pecten of the pubis the pectineal ligament looks like an extension of the lacunar ligament along the surface of the pectineal line; also known as: Cooper's ligament (note: Cooper's ligaments are also found in the breast) a ligament that connects the transverse process of the L5 vertebra to the iliac crest the iliolumbar ligament stabilizes the lumbosacral joint lumbosacral joint the articulation between the L5 vertebral body and the body of the first sacral segment a symphysis; this articulation is characterized by all of the features of a typical intervertebral articulation which include: an intervertebral disk, anterior and posterior longitudinal ligaments, synovial joints between articular processes, ligamenta flava, interspinal and supraspinal ligaments; a strong iliolumbar ligament strengthens this joint pubic symphysis the midline joint uniting the

 superior rami of the two pubic bones a symphysis; a fibrocartilage interpubic disk unites the bones; the subpubic angle in the female is greater than the subpubic angle in the male sacroiliac joint the articulation between the ala of the sacrum and the auricular surface of the ilium a synovial joint; the fibrous articular capsule is thickened dorsally and ventrally to form the sacroiliac ligaments; because of the interlocking nature of the joint surfaces and the strong sacroiliac ligaments, only limited movement is permitted at the sacroiliac joint sacrospinous ligament the ligament that connects the ischial spine to the lateral surface of the sacrum and coccyx together with the sacrotuberous ligament, it converts the greater and lesser sciatic notches into greater and lesser sciatic foramina sacrotuberous ligament the ligament that connects the ischial tuberosity to the lateral surface of the sacrum and coccyx together with sacrospinous ligament, it converts the greater and lesser sciatic notches into greater and lesser sciatic foramina acetabular labrum a fibro

cartilage rim around the acetabulum the acetabular labrum deepens the acetabulum; it cups around the head of the femur and holds it firmly in the acetabulum ankle joint the articulation between the distal tibia, the medial malleolus of the tibia, the lateral malleolus of the fibula and the talus a synovial hinge joint; the ankle is reinforced by the deltoid ligament (anterior tibiotalar, tibionavicular, tibiocalcaneal, posterior tibiotalar parts), the anterior talofibular lig., the calcaneofibular lig.

and the posterior talofibular lig.; because of the shape of the talus, the ankle is most stable when the foot is dorsiflexed; the ankle is often injured when the foot is plantar flexed anterior cruciate ligament a ligament connecting the anterior aspect of the intercondylar eminence of the tibia with the medial surface of the lateral femoral condyle an intracapsular ligament located within the fibrous joint capsule of the knee but external to the synovial cavity of the knee; the anterior cruciate ligament limits the anterior movement of the tibia relative to the femur in all positions of joint movement; clipping-type injuries tear the anterior cruciate ligament because the leg is forced anteriorly relative to the femur which places great stress on the anterior cruciate ligament anterior talofibular ligament a ligament that connects the lateral malleolus of the fibula with the anterolateral surface of the talus it is a ligament that reinforces the ankle joint anterior tibiofibular ligament the ligament that connects the distal ends of the tibia and the fibula anteriorly this ligament reinforces the tibiofibular syndesmosis (at the

 distal ends of these bones) anterior tibiotalar ligament part of the deltoid ligament connecting the medial malleolus of the tibia with the talus it is a ligament that reinforces the ankle joint calcaneofibular ligament a ligament that connects the lateral malleolus of the fibula with the calcaneus it is a ligament that reinforces the ankle joint deltoid ligament the ligament that connects the medial malleolus of the tibia with the talus, navicular and calcaneus the deltoid ligament reinforces the ankle joint; it has the shape of the Greek letter delta, hence its name; it has four parts (from anterior to posterior): anterior tibiotalar lig., tibionavicular lig., tibiocalcaneal lig., posterior tibiotalar lig.

fibular collateral ligament the collateral ligament of the knee that connects the lateral epicondyle of the femur with the head of the fibula an extracapsular ligament, not part of the fibrous capsule of the knee; the fibular collateral ligament passes superficial to the tendon of origin of the popliteus m.

hip joint the articulation between the os coxae and the head of the femur a synovial ball and socket joint; it is reinforced by capsular ligaments (iliofemoral, pubofemoral, ischiofemoral, zona orbicularis); the fibers of the articular capsule become taut on hip extension and lax on hip flexion; dislocation injuries of the hip are most common when the hip is flexed (sitting in a car seat during an impact that causes the knees to strike the dash board, for example) iliofemoral ligament the ligament reinforcing the anterior surface of the articular capsule of the hip joint the iliofemoral ligament is shaped like an inverted "Y"; it connects the anterior inferior iliac spine to the anterior surface of the intertrochanteric line of the femur; also known as: ligament of Bigelow infrapatellar bursa, deep the bursa lying between the patellar ligament and the tibia synovial membrane, the deep infrapatellar bursa reduces friction between the patellar ligament and the tibia infrapatellar bursa, superficial a subcutaneous bursa overlying the patellar lig

ament synovial membrane interosseous ligaments of the foot ligaments that reinforce intertarsal (gliding) synovial joints they connect adjacent tarsal bones; they are named for the two bones that they connect and whether they are located on the dorsal or plantar surface of those bones interosseous membrane of the leg the membrane that connects the interosseous borders of the shafts of the tibia and fibula a syndesmosis interphalangeal joints the articulations between the proximal and middle phalanges (proximal interphalangeal joint, abbreviated PIP) or the middle and distal phalanges (distal interphalangeal joint, abbreviated DIP) a synovial hinge joint; these joints are strengthened by medial and lateral collateral ligaments ischiofemoral ligament the ligament reinforcing the posterior surface of the articular capsule of the hip joint the ischiofemoral ligament connects the body of the ischium to the posterior portion of the femoral neck knee joint the articulation between the femoral condyles and the tibial condyles a synovial hinge joint; it is reinforced by intracapsular ligaments (anterior

 & posterior cruciate ligaments) and two types of collateral ligaments (capsular - tibial collateral ligament, and extracapsular - fibular collateral ligament); the medial and lateral menisci are contained within the joint capsule lateral meniscus an intra-articular disc within the knee joint located between the lateral femoral condyle and the lateral tibial condyle fibrocartilage; it is attached to the coronary ligament and the intercondylar eminence of the tibia ligament of the head of the femur an intracapsular ligament that attaches to the fovea of the head of the femur and to the acetabular fossa the ligament of the head of the femur contains a small artery (the a.

of the ligament of the head of the femur) which supplies the femoral head; in fractures of the neck of the femur the retinacular aa. that course along the neck may be damaged, so that the artery to the head may be the only blood supply to the head and proximal neck long plantar ligament a ligament that connects the plantar surface of the calcaneus, cuboid and the bases of the lateral 3 metatarsal bones a ligament that reinforces a complex set of intertarsal (gliding) synovial joints; the long plantar ligament supports the longitudinal arch of the foot longitudinal arch of the foot the arch that passes from the calcaneus to the talus to the navicular to the cuneiforms to the metatarsal a series of plane synovial joints; the longitudinal arch of the foot is formed by the shapes of the metatarsal bones and is supported by the plantar calcaneonavicular (spring) ligament and many other small interosseous ligaments; the tendons of the tibialis anterior and tibialis posterior mm.

also play a supporting role in maintaining the longitudinal arch of the foot medial meniscus an intra-articular disc within the knee joint located between the medial femoral condyle and the medial tibial condyle fibrocartilage; it is attached to the tibial collateral ligament, coronary ligament and intercondylar eminence of the tibia; its attachment fo the tibial collateral ligament results in injury to the medial meniscus whenever the medial collateral ligament is injured metatarsophalangeal joint the articulation between the head of a metatarsal and the base of a proximal phalanx a synovial condyloid (or ellipsoid) joint; it is strengthened by medial and lateral collateral ligaments; the joint has two planes of motion: flexion/extension and abduction/adduction which may be combined to yield circumduction patellar ligament the tendon of insertion of the quadriceps femoris muscle the quadriceps femoris tendon connects the quadriceps femoris muscle group to the patella and the patellar ligament connects the patella to the tibial tuberosity; the patella is a sesamoid bone within the quadriceps femoris tendon plantar calcaneocuboid ligament

 a ligament that connects the calcaneus with the cuboid on their plantar surfaces a ligament that reinforces a complex set of intertarsal (gliding) synovial joints; it supports the longitudinal arch of the foot; also known as: short plantar ligament plantar calcaneonavicular ligament a ligament that connects the sustentaculum tali with the plantar surface of the navicular bone a ligament that reinforces a complex set of intertarsal (gliding) synovial joints; it supports the longitudinal arch of the foot; also known as: spring ligament posterior cruciate ligament a ligament connecting the posterior aspect of the intercondylar eminence with the lateral surface of the medial femoral condyle an intracapsular ligament located within the fibrous joint capsule of the knee but external to the synovial cavity of the knee; the posterior cruciate ligament limits the posterior movement of the tibia relative to the femur in all positions of joint movement posterior meniscofemoral ligament an intracapsular ligament that connects the posterior part of the lateral meniscus with the lateral surface of the medial femoral condyle may be absent posterior talof

ibular ligament a ligament that connects the lateral malleolus of the fibula with the posterolateral surface of the talus it is a ligament that reinforces the ankle joint posterior tibiofibular ligament the ligament that connects the distal ends of the tibia and the fibula posteriorly this ligament reinforces the tibiofibular syndesmosis (at the distal ends of these bones) posterior tibiotalar ligament part of the deltoid ligament connecting the medial malleolus of the tibia with the talus posteriorly it is a ligament that reinforces the ankle joint prepatellar bursa a subcutaneous bursa overlying the patella synovial membrane; inflammation of this bursa leads to the condition known as "housemaid's knee" (prepatellar bursitis), so named because housemaids at one time traumatized this bursa while scrubbing floors on their hands and knees pubofemoral ligament the ligament reinforcing the medial surface of the articular capsule of the hip joint the pubofemoral ligament connects the pubic portion of the rim of the bony acetabulum to the medial surface of the femoral neck

 suprapatellar bursa the superior extension of the synovial membrane of the knee joint it passes deep to the quadriceps femoris tendon; the suprapatellar bursa reduces friction between the quadriceps femoris tendon and the femur tarsometatarsal joints the articulations between the distal row of tarsal bones and the proximal ends of the metatarsal bones gliding synovial joints; they are reinforced by dorsal and plantar ligaments which limit the motion between adjacent bones tibial collateral ligament the collateral ligament of the knee joint connecting the medial epicondyle of the femur with the medial surface of the medial condyle of the tibia the tibial collateral ligament reinforces the medial surface of the articular capsule of the knee; it is attached to the medial meniscus which has clinical relevance - when the tibial collateral ligament tears in a clipping-type injury (knee abduction), the medial meniscus also tears tibiocalcaneal ligament part of the deltoid ligament connecting the medial malleolus of the tibia with the sustentaculum tali it is a ligament that reinforces the ankle joint tibionavicular ligament Radius

 and Ulna Radius and Ulna Science Main Index The arm consists of three large bones.

The humerus bone forms the upper arm. The radius and ulna are the two bones forming the lower arm. You have one radius and one ulna in each arm. The radius and ulna bones connect between the elbow joint and the wrist. One easy way to remember which bone is the radius, and which is the ulna, is that the radius connects to the thumb side of the wrist. Keep reading to learn more about the radius and ulna, and how your lower arm works. On this page: Top of Page The lower arm consists of two bones extending from the elbow to the wrist, running parallel to each other. The radius is on the outside, or lateral side, of the elbow. It connects to the thumb side of the wrist. The radius is bigger and longer than the ulna which is on the inside, or medial side, of the forearm closest to the body. The bony point of the elbow, that most people think of as the elbow, is actually the tip the ulna bone. The radius and ulna connect to the humerus bone of the upper arm at the elbow joint . Thehe elbow joint consists of a series of muscles or ligaments acting like a hinge so you can bend and straighten your arm.

This is bending and straighten is called flexing and extending the arm, respectively. The elbow also provides for rotation of the lower arm through twisting of the radius and ulna. This twisting allows you to turn your hand palm up or palm down. The rotation of the lower arm is called pronation or supination depending on the direction of movement. Normally, the radius and ulna are parallel to each other. During pronation, the radius rolls around the ulna at both the wrist and the elbow. In this position, the radius and ulna appear crossed. Here is an experiment. You can actually feel the radius and ulna rotating. Hold your right forearm with your left hand. Then rotate your right wrist palm up and then palm down. You will feel the radius and ulna bones in your right arm twisting and rotating.

Question: Where in the human body is the ulna?
Answer: Forearm