Humerus | Continuing Medical Education Continuing Medical Education The humerus is a long bone in the arm or forelimb that runs from the shoulder to the elbow. Anatomically, in modern humans, it connects the scapula and the lower arm (consisting of the radius and ulna), and consists of three sections. The upper extremity consists of a rounded head, a narrow neck, and two short processes (tubercles, sometimes called tuberosities.) Its body is cylindrical in its upper portion, and more prismatic below. The lower extremity consists of 2 epicondyles, 2 processes (trochlea & capitulum), and 3 fossae (radial fossa, coronoid fossa, andolecranon fossa). As well as its true anatomical neck, the constriction below the greater and lesser tubercles of the humerus is referred to as its surgical neck due to its tendency to commonly get fractured, thus often becoming the focus of surgeons.

humerus - 必应 humerus - 必应 © 2016 Microsoft 新的隐私声明和 Cookie 新的法律声明 广告 帮助 反馈 A condyle (/ˈkɒndəl/ or /ˈkɒndaɪl/; Latin: condylus, from Greek: kondylos; κόνδυλος knuckle) is the round prominence at the end of a bone, most often part of a joint - a… 2014-11-12 Do you call the humerus bone the funny bone? 答 heck yea! :D 来自 answers.yahoo.com 2005-06-01 问 Given a tetanus shot, but the nurse supposedly injected the bone? ... bone?mkt=zh-cn 2005-6-1 The lateral epicondyle of the humerus is a small, tuberculated eminence, curved a little forward, and giving attachment to the radial collateral ligament of the elbow ...

epicondyle of the humerus?mkt=zh-cn 2017-1-9 Trochlea of humerus (part of the elbow hinge joint with the ulna) Trochlea of femur (forming the knee hinge joint with the patella) The trochlea tali in the superior surface of ... 2014-1-27 Humerus (Upper Arm Bone) < Upper Extremity Anatomy << Upper Appendicular Skeleton <<< Appendicular Skeleton @ Wellness Advocate . com In our body's arms (upper arms) , each Humerus (Upper Arm Bone) consists of three sections. The upper extremity of the humerus (upper arm bone) consists of a rounded head, a narrow neck, and two short processes (tubercles, or tuberosities). The body of the Humerus is in its upper portion cylindrical, and below more prismatic. The lower extremity of humerus consists of 2 epicondyles , 2 processes ( trochlea & capitulum ), and 3 fossae ( radial fossa , coronoid fossa , and olecranon fossa).

[10434] ï¿½Humeral Headï¿½ In our body's humerus (upper arm bone) , the Humeral Head is the rounded upper or proximal extremity, fitting into the glenoid cavity of the scapula bone (shoulder blade) , consisting of the large rounded head joined to the body by the neck (constricted portion), with two eminences, the greater and lesser tubercles. [9758] In our body's arms at the shoulder , the Humerus (Upper Arm Bone) consists of a large rounded head joined to the body by a constricted portion (neck), and two the eminences, the greater and lesser tubercles. [10278] ï¿½Lateral Epicondyle of the Humerusï¿½ In and on our body's, Lateral Epicondyle of the Humerus is the common origin of the Extensor Carpi Ulnaris muscle, the Extensor Carpi Radialis, and gives attachment to the radial collateral ligament of the elbow-joint.

[5826] ï¿½Medial Epicondyle of the Humerusï¿½ In our body's upper extremities , Medial Epicondyle of the Humerus is a projection (eminence) on the humerus (upper arm bone) that gives attachment to the ulnar collateral ligament of the elbow joint, to the pronator teres , and to a common origin for the common flexor tendons and some of the forearm flexor muscles. [5827] humerus - definition - What is ? What is ? humerus definition : humerus The humerus (, Plural: humeri) is a long bone in the arm or forelimb that runs from the shoulder to the elbow. It connects the scapula and the two bones of the lower arm, the radius and ulna, and consists of three sections. The humeral upper extremity consists of a rounded head, a narrow neck, and two short processes (tubercles, sometimes called tuberosities). The body is cylindrical in its upper portion, and more prismatic below.

The lower extremity consists of 2 epicondyles, 2 processes (trochlea & capitulum), and 3 fossae (radial fossa, coronoid fossa, and olecranon fossa). As well as its true anatomical neck, the constriction below the greater and lesser tubercles of the humerus is referred to as its surgical neck due to its tendency to fracture, thus often becoming the focus of surgeons. ==Etymology== The word "humerus" is derived from meaning upper arm, shoulder, and is linguistically related to Gothic ams shoulder and Greek ōmos. ==Structure== === Articulations === At the shoulder, the head of the humerus articulates with the glenoid fossa of the scapula. More distally, at the elbow, the capitulum of the humerus articulates with the head of the radius, and the trochlea of the humerus articulates with the trochlear notch of the ulna. ===Nerves=== The axillary nerve is located at the proximal end, against the shoulder girdle.

Dislocation of the humerus's glenohumeral joint, has the potential to injure the axillary nerve or the axillary artery. Signs and symptoms of this dislocation include a loss of the normal shoulder contour and a palpable depression under the acromion. The radial nerve follows the humerus closely. At the midshaft of the humerus, the radial nerve travels from the posterior to the anterior aspect of the bone in the spiral groove. A fracture of the humerus in this region can result in radial nerve injury. The ulnar nerve at the distal end of the humerus near the elbow is sometimes referred to in popular culture as 'the funny bone'. Striking this nerve can cause a tingling sensation ("funny" feeling), and sometimes a significant amount of pain. It lies posterior to the medial epicondyle, and is easily damaged in elbow injuries. ==Function== ===Muscular attachment=== The deltoid originates on the lateral third of the clavicle, acromion and the crest of the spine of the scapula. It is inserted on the deltoid tuberosity of the humerus and has several actions including abduction, extension, and circumduction of the shoulder.

The supraspinatus also originates on the spine of the scapula. It inserts on the greater tubercle of the humerus, and assists in abduction of the shoulder. The pectoralis major, teres major, and latissimus dorsi insert at the intertubercular groove of the humerus. They work to adduct and medially, or internally, rotate the humerus. The infraspinatus and teres minor insert on the greater tubercle, and work to laterally, or externally, rotate the humerus. In contrast, the subscapularis muscle inserts onto the lesser tubercle and works to medially, or internally, rotate the humerus. The biceps brachii, brachialis, and brachioradialis (which attaches distally) act to flex the elbow. (The biceps do not attach to the humerus.) The triceps brachii and anconeus extend the elbow, and attach to the posterior side of the humerus. The four muscles of supraspinatus, infraspinatus, teres minor and subscapularis form a musculo-ligamentous girdle called the rotator cuff.

This cuff stabilizes the very mobile but inherently unstable glenohumeral joint. The other muscles are used as counterbalances for the actions of lifting/pulling and pressing/pushing. {| class="wikitable" align="left" |+ Left humerus. Posterior view. |- | 65px || 140px || 100px || 140px || 70px |} ==Other animals== Primitive fossils of amphibians had little, if any, shaft connecting the upper and lower extremities, making their limbs very short. In most living tetrapods, however, the humerus has a similar form to that of humans; connecting their extremities. In many reptiles and some primitive mammals, the lower extremity includes a large foramen, or opening, which allows nerves and blood vessels pass through. ==Additional images== File:Humerus animation.gif|Position of humerus (shown in red). Animation. File:Left humerus - close-up - animation.gif|Left humerus. Animation. File:Human arm bones diagram.svg|Human arm bones diagram. File:Inferior epiphysis of humerus.jpg|Humerus - inferior epiphysis. Anterior view.

File:Slide10DEN.JPG|Trochlea. Posterior view. File:LeftHumanPosteriorDistalHumerusFlexed.jpg|Humerus - inferior epiphysis. Posterior view. File:AnteroMedialHeadofLeftHumerus.jpg|Humerus - superior epiphysis. Anterior view. File:Superior epiphysis.jpg|Humerus - superior epiphysis. Posterior view. File:Elbow joint - deep dissection (anterior view, human cadaver).jpg|Elbow joint. Deep dissection. Anterior view. File:Slide1bgbg.JPG|Elbow joint. Deep dissection. Posterior view. File:Slide3bgbg.JPG|Elbow joint. Deep dissection. Posterior view. ==See also== * Humerus fracture Humerus - OrthopaedicsOne Articles - OrthopaedicsOne Injuries/Disorders Axillary nerve The most common type of shoulder dislocation is an anterior or inferior dislocation of the humerus of the glenohumeral joint. This dislocation has the potential to injure the axillary nerve or axillary artery.

Signs and symptoms of this dislocation include a loss of the normal shoulder contour and a palpable depression under the acromion. Ulnar nerve The ulnar nerve at the distal end of the humerus near the elbow is sometimes referred to in popular culture as the "funny bone." Striking this nerve can cause a tingling sensation ("funny" feeling), and sometimes a significant amount of pain. Peer Review OrthopaedicsOne Peer Review Workflow is an innovative platform that allows the process of peer review to occur right within an OrthopaedicsOne article in an open, transparent and flexible manner. Learn more Instructions for Authors Read our Instructions for Authors to learn about contributing or editing articles on OrthopaedicsOne. Content Partner Learn about becoming an OrthopaedicsOne Content Partner . Academic Resources Anatomy at Career Step - StudyBlue StudyBlue the study of the structure of the body chemical level molecules: proteins, carbohydrates, fats, and vitamins Advertisement ) molecules combine to form cells Tissue Level A tissue is a group of cells working together to perform one or more specific functions.

four types: covers body surfaces, lines body cavity, provides protection,protects from injury or fluid loss muscle tissue responsible for all the movements of the body 3 types of tissue: skeletal, smooth, cardiac made of long fibers; the tissue that allows for voluntary body movement; found and attached to bones subdivision of the four types of tissue in the body lines internal organs and carries out primary involuntary body movements that assist the organ function subdivision of the four types of tissue in the body -found only in the heart; specially designed to maintain heartbeat and blood flow subdivision of the four types of tissue in the body connective tissue tissue that binds the body together and supports posture and funtion. Has three subtypes: supporting, binding, fibrous with adipose included consists of bone and cartilage in the body binding connective tissue defined as the tendons & ligaments; strong, thick thissue that binds material connects muscles together and binds skin to the rest of the body fibrous connective tissue binding material instead of connecting other connective tissues. connects muscles together and binds the skin to the rest of the body nervous tissue composed of nerve cells. it is the communication system of the body; electronically passing messages to and from the brain.

allows motor function - voluntary and involuntary Organ Level Organs consist of two or more tissues each has a specific shape and function. ex: heart, lungs, liver, brain, and kidneys Advertisement organ systems consist of different organs that work together closely (Integument, nervous, digestive) organism level the largest structural level; all parts which make up the body and function with each other form the total organism -- one living individual disease deviation from the normal function of any part of the body acquired disease classification was not born with it congenital disease classification present at birth; not hereditary deficiency disease classification developmental disease classification short: abnormality in development of tissues or organ (that occurs as a result of some abnormality in the development of tissue, organ, or body part. sometimes characterized as a disorder either there before birth or during the growth stages) degenerative disease classification pertaining to deteriorating.

Going from normal to less than normal; dysfuntional essential disease classification short: of unknown cause or unknown cause or spontaneous origin (assigned to diseases for which the cause is unknown - assumed to spontaneously arise.) familial disease classification short: suggests a hereditary component (occuring or affecting more members of a family then expected; suggests hereditary) functional disease classification short: normal structure not working properly; no underlaying cause (one in which the structure is unaffected by it is not functioning properly) hereditary disease classification short: transmitted from parent to child (means genetically transmitted from parent to child. Should be a familiar term) idiopathic disease classification short: of unknown cause or spontaneous origin (also means of unknown causes, arising spontaneously) infectious disease classification (a disease caused by an infection) molecular disease classification short: abnormality of a single molecule (a disease caused by abnormality in the chemical structure or concentration of a single molecule - often congenital) neoplastic disease classification short: related to a tumor (pertaining to any new abdormal growth. Specifically a new growth of tissue which is progressive & uncontrolled.

growths are generally called tumors) nutritional disease classification short: caused by dietary intake (a disease caused by nutritional factors, such as insufficent or excessive dietary intake) organic disease classification short: abnormality of a bodily structure (a disease that is due to a demonstrable abnormality in a bodily structure or the composition of its fluids) traumatic disease classification resulting from some type of injury. fractures, burns, cuts, or war -- post-traumatic stress disorder acute disease classification are formed from red blood cells and certain white blood cells erythropoiesis (ur-ith-row-poi-ee-sis) formation of red blood cells; carry oxygen from the lungs to the reast of the body and return carbon dioxide and other waste products red blood cells carry oxygen from the lungs to the rest of the body and return carbon dioxide and other water products white blood cells; help fight infection and support the immune system ossification process of new bone formation osteoblasts bone forming cells that secrete a matrix which become calcified.

osteocytes former osteoblasts that are surrounded by bone matrix that is calcified large multinucleated cells that reabsorb bone matrix bone cells cells the body has programmed to create bones immature bones bone that has ossified and calcified cortical bone forms a protective outer layer around every bone in the body osteon structural unit of compact bone Center of an osteon, contains blood vessels and nerves. Concentric lamellae are formed.

"spongy"; refers to mostly bone tissue represents 20% of skeletal mass; 80% of surface trabecular network of bone tissue structural unit: does not contain osteon, less dense then cortical bone, very elastic, higher turnover rate than cortical bone maintains an intricate balance of bone cells, marrow, and other tissue vital for bone formation as hard as cortical bone comprises most of the bones in the axial skeleton canaliculi narrow channels through which osteocytes extend lacunae small cavities containg mature bone cells length is greater then width; extremities cube shaped bones found in the wrist and ankle made up of a layer of marrow sandwiched between to layers of compact bone; located in the cranial vault, sternum, shoulder blades, and ribs Come in a variety of odd shapes; do not fall into any other bone-type categories.

Found in the face, spinal column, and hips rounded masses embedded in certain tendons; usually related to the surface joints ususally where there is a lot of friction sesamoid = "seed-like" patella (kneecap) tiny rounded bones found between suture lines of the skull where the edges of the skull bones are joined together found between the major skull bones bone marking which looks "scooped-out", groove, or pit bone marking where a bone has an opening or hole in it bone markings along with the types, functions, and shapes of bones these helpe to differentiate bones sinuses bone markings constricted end of a long bone before the head or rounded end a long or deep hole in a bone; a passageway through the substance of a bone small, smooth, and flat areas large rounded projections spaces or "soft spots" in the skull --allow the fetal skull to be compressed slightly during birth --allow for brain growth during late fetal life the space where the frontal angles of the parietal bones meet the two halves of the frontal bone the space where the occipital angles of the parietal bones meet the occipital the interval on either side of the head between the mastoid angle of the parietal bone,

 the temporal bone, and the occiptal bone an interval on either side of the head where the frontal angle of the temporal bone and the greater wing of the sphenoid meet joins the frontal bone to the 2 parietal bones bone that closes the anterior part of the cranial cavity and forms the skeleton of the forehead joins the two parietal bones to the occipital bone bone situated at the posterior and inferior part of the cranium; articulating with the two parietal and two temporal bones bones forming part of the superior and lateral surfaces of the skull (forming top and sides of skull) and joining each other in the midline at the sagittal suture joins one parietal bone to the other down the middle of the skull joins parietal bone to the temporal bone bones forming part of the lateral surfaces and the base of the skull, and containing the organs of hearing.

long, narrow, and curled bone shelf that protudes into the breating passage; shaped like a long sea shell small bone located near the tear duct area in front of the ethmoid bone lacrimal meaning; tearducts largest of the facial bones; the nasal cavity to form the roof of the mouth Upper jaw bone; contain upper teeth two bones forming the bridge of the nose Each of two bones within the skull forming parts of the eye socket, the nasal cavity, and the hard palate. (pink) Makes up part of the cheek bones and outer part of the eye. Attaches to the temporal bone separates the nasal cavity from the brain, it is the most deeply situated bone of the skull.

bat shaped bone located at the base of the skull; deep; located behind the eye sockets The small thin bone separating the left and right nasal cavities The horseshoe-shaped bone at the bottom of the teeth process prominence or projection as of bone marking; elongated bony path located above the eye socket under the forehead; opening for nerve and blood vessels a conical projection on the temporal bone located behind the ear a slender (projection) piece of bone located on the temporal bone; extends down from the skull projection on the back of the mandible A flattened triangular projection above the angle of the jaw where the temporalis muscle is attached The middle of the three ossicles of the ear Transfer vibration to the next ossicles in the ear the incus Last of the three ossicles; smallest bone in the body small U- shaped in neck. Not attached to any other bone "floating"; only connected to cartilage.

7- Cervical 1 Sacrum (5 fused) 1 Coccyx (4 fused) A major support structure for the body; 26 bones; the spinal cord runs right through the center of the bony vertebral column protecting it from injury *C1 vertebra *lacks a body and has large flat articulating surfaces with occipital condyles of the skull (allows you to nod yes) C2 Acts as pivot(axle) for rotation b/t axis & atlas Rotate head "no" neck-- The cervical spine contains 7 vertebrae located in the neck area. In medical reports, abbreviated C1-C7. Concave. Raise head and stand erect includes the atlas and axis vertebraes Thoracic Spine chest area - connects to the ribs-- Below the cervical spine, made up of 12 vertebrae. A pair of ribs is connected to each pair of thoracic vertebrae. T1 - T12 Continues from the lumbar down to pelvis. Contains one vertebrae and the coccyx bone (tail bone) Helps with moving hips loosely connected or joined.

The 12 vertebra of the thoracic spine articulate to the 12 ribs to form protection for the thoracic cavity at the end of the vertebrae, 5 bones that have fused together as one, is also called tailbone Between L5 and S1 Important for movements of spine relative to pelvis composed of fibrous tissue & cartilage. found between the bodies of adjacent vertebrae from the C2-Sacrum. absorb spinal compression & shock Upper portion of the sternum (breastbone) the "handle" Looks like the knot of a tie, it articulates with the clavicle. The bony structure that forms the middle portion of the sternum The lowest portion of the sternum; smallest area of the sternum where manubruim and the body of the sternum meet The portion of the skeletal system that comprises the arms, legs, pelvis, and shoulder.

clavicle scapula humerus F.) superior angle / Inferior Angle process that helps form point of the shoulder helps form point of shoulder cavity where the humerous rests (round tear drop, articulates with humerous ) The humerus is a long bone in the arm or forelimb that runs from the shoulder to the elbow. Anatomically, it connects the scapula and the lower arm (consisting of the radius and ulna), and consists of three sections.

bone in forearm that is on the thumb side ID: head, neck, radial tuberosity, ulnar notch (where it meets ulna), styloid process pinky side of the forearm forms a margin for the tendons of two muscles to the thumb large bony process of the ulna which projects behind the articulation with the humerus and forms the boney prominence known as the elbow pulley-shaped structure of the elbow; on the ulna; articulates with the distal humerus depression on proximal end where the head of the radius articulates with ulna 8 bones in the wrist; "So Long to Pinky Here Comes The Thumb" Scaphoid - bottom, thumb portion of the hip bone between the "eyes" projection near neck of femur. provides muscle attachment on lateral side of femur boney prominence where muscle attach to femur. The socket of the hipbone, which articulates with the head of the femur.

protrusion which ligaments and tendons attach on the inferior end of the femur protrusion which ligaments and tendons attach on the inferior end of the femur kneecap is a thick, sesamoid bone which articulates with the femur and covers and protects the anterior articular surface of the knee joint.

larges of the two lower legs; weigh bearing; big toe side round bony projection on the tibia and fibula on each side of the ankle long, skinny lower leg bone; little toe side ankle bones; weight supporting & shock absorbers Talus (tay-lus) 5 - 7 1st, 2nd,& 3rd cuneiform (cue-nae-i-forms) foot bone starting from the big toe to the small pinky 1 - 5 metatarsal toe (phalanges); 14 total ea foot distal phalanx - tip middle phalanx - middle proximal phalanx - attaches to metatarsales formed at the base of the metatarsals, extending form the medial to the lateral sides of the foot, arch that runs horizontally prodominant arch, running from the base of the (2) calcaneus to the (1) talus, and down to the 3 medial metatarsals arches just enough to redistribute body weight to the (2) calcaneus and head of the 5th metatarsal heel bone; the strongest bone in the foot no joint cavity and, in general do not move -- ex: cranial sutures have no

 cavity & are somewhat moveable ex: intervertebral discs have joint cavities that are kept lubricated by synovial fluid ex: intercarpal joint (wrist) allow movement around 3 axes ex: ball & socket joint found in hip & shoulder bending; decrease the joint angle "flexing the biceps" unbending to inrease angle between 2 bones; extending - reaching your arm as far as you can.

Virtually eliminating the angle between humerus & radius/ulna Moving a body part away from the midline Movement towards the midline. bringing closer to body movement of a body part in a circle. which can include all the other joint movements as well circular movement around an axis (movement from side to side with lower body stationary) position of body when lying fae down - palms down & feet bent downward position of body when lying face down - palms down & feet bent downward movement of foot that brings top of foot closer to leg movement of foot that brings heel closer to posterior part of leg; toes pointed farther away from leg.

this is opposite of dorsiflexion ligaments band or tie; white, fibrous, slightly elastic tissue that binds ends of bones together movement allows human skeleton movement posture when certain muscles contract in order for the body to maintain and erect or sitting position stabilization of joints muscle and ligaments are vial to joint stabilization & allow smooth movement when bending or twisting body tempurature maintenance constant contracting produces heat which helps maintain body temperature skeletal muscle primary muscle used to allow voluntary movement smooth muscle muscle that lines walls of internal organs cardiac muscle found only in the heart origin less moveable attachment of a muscle insertion more moveable attachment of a muscle direct (fleshy) attachments short strands of connective tissue appear to attach directly to a bone indirect attachment long strands of connective tissue extending beyond the muscle tendon Chapter 9: THE ARM AND ELBOW Chapter 9: The arm and elbow Muscles of arm (table 9-1 ) The muscles of the anterior arm are the biceps, coracobrachialis, and brachialis. They are supplied by the musculocutaneous nerve. The triceps is the muscle of the posterior arm, and it is supplied by the radial nerve.

The anterior and posterior muscles are separated from each other by lateral and medial intermuscular septa (fig. 9-1 ). The biceps brachii arises from the scapula by two heads. The long, or lateral, head, arising from the supraglenoid tubercle, descends within the capsule of the shoulder joint and lies in the intertubercular groove. The short, or medial, head arises from the coracoid process in common with the coracobrachialis. The bicipital tendons give way to muscular bellies that unite and continue as a readily palpable tendon. The insertion is into the tuberosity of the radius (its posterior part; hence the biceps can act as a supinator) and the fascia of the forearm (and ultimately the ulna) by means of the bicipital aponeurosis (see fig. 9-4 ). The biceps and brachialis are the chief flexors of the forearm. The origin of the brachialis embraces the insertion of the deltoid. The coracobrachialis is generally pierced by the musculocutaneous nerve.

The flexion of the forearm (or the twitch of the muscle without movement) that follows tapping of the tendon of insertion of the biceps is known as the biceps reflex. The reflex center is in segments C5 and 6 of the spinal cord. The triceps brachii forms the bulk of the posterior arm. Its three heads are arranged in two planes (fig. 9-2 ): the long and lateral heads occupy a superficial plane, whereas the medial head is deeper. The radial nerve passes between the long and medial heads and then lies on the humerus under cover of the lateral head. The long head separates the triangular from the quadrangular space and the teres major from the teres minor. The triceps is the extensor of the forearm and takes part in pushing, throwing, hammering, and shoveling. A subcutaneous bursa over the olecranon and tendon of the triceps may become thickened ("miner's elbow"). The extension of the forearm (or the twitch without movement) that follows tapping of the tendon of insertion of the triceps is known as the triceps reflex. The reflex center is in segments C6 and 7 of the spinal cord.

Nerves of arm The muscles of the anterior arm are supplied by the musculocutaneous nerve; the triceps is supplied by the radial nerve (see fig. 9-1 ). The musculocutaneous nerve (from the lateral cord) usually pierces the coracobrachialis and descends between the biceps and brachialis (see fig. 9-1 ) to enter the lateral side of the arm. The musculocutaneous nerve supplies the biceps, coracobrachialis, brachialis, and elbow joint and terminates as the lateral antebrachial cutaneous nerve. The radial nerve (the continuation of the posterior cord) passes posteriorly with the profunda brachii artery, winds around the humerus (fig. 9-2 ) under cover of the long and lateral heads of the triceps, and descends anteriorly into the cubital fossa, where it lies in a deep groove between the brachioradialis and the brachialis (figs. 9-3 and 9-4 ). At, or just inferior to the level of the lateral epicondyle, the radial nerve divides into superficial and deep branches.

The nerve has several cutaneous branches (posterior brachial, lower lateral brachial, posterior antebrachial) and muscular twigs to the triceps, anconeus, brachioradialis, extensor carpi radialis longus and usually brevis, and branches to the elbow joint. The superficial branch is the direct continuation of the radial nerve into the forearm. * The deep branch winds laterally around the radius between the layers of the supinator and continues as the posterior interosseous nerve to the muscles of the posterior forearm. The median and ulnar nerves have no branches in the arm and are in transit to the forearm. The median nerve, which is originally on the lateral side of the brachial artery, crosses anterior to (occasionally behind) that vessel and then descends on its medial aspect. In the cubital fossa (fig. 9-4B ), it lies deep to the median cubital vein and the bicipital aponeurosis and gives a branch to the elbow joint. It enters the forearm between the heads of the pronator teres. The ulnar nerve, originally medial to the brachial artery, proceeds posteriorward to the posterior aspect of the medial epicondyle.

It enters the forearm between the heads of the flexor carpi ulnaris and under a tendonous arch formed between these heads (the cubital tunnel). Arteries of arm At the inferior border of the teres major, i.e., the distal limit of the posterior axillary fold, the axillary becomes the brachial artery (figs. 7-3 and 9-4 ). The brachial artery lies superficially on the medial side of the arm, at first medial to the humerus and then anterior to the bone. Hence the artery can be compressed against the humerus. The pulsations of the artery can be palpated where it is partly overlapped by the biceps and coracobrachialis. This vessel is used in sphygmomanometry. The brachial artery lies successively on the triceps and brachialis and is crossed (usually anteriorly) by the median nerve. At the elbow the artery lies in the middle of the cubital fossa, between the biceps tendon laterally and the median nerve medially (fig. 9-4B ). It is crossed by the bicipital aponeurosis, which separates it from the median cubital vein.

Opposite the neck of the radius, it divides into the radial and ulnar arteries, but variations, including high division (in the upper third of the arm), are common. In addition to muscular and nutrient branches, the brachial artery gives off the profunda brachii artery and one or more ulnar collateral arteries. The profunda brachii crosses posterior to the humerus with the radial nerve and divides into collateral branches on the radial side. These, together with those on the ulnar side, form an extensive anastomosis around the elbow joint, which is completed inferiorly by recurrent branches derived from the radial and ulnar arteries. The existence of the anastomosis is important; the details of the individual branches are not. Cubital fossa (fig. 9-4 ) The brachioradialis laterally and the pronator teres medially form a V-shaped interval known as the cubital fossa. These muscles, which belong to the forearm, arise from the lateral and medial supracondylar ridges of the humerus, respectively, and descend to the radius. The floor of the fossa is formed by the brachialis and by the supinator laterally.

The contents include the biceps tendon, brachial artery, and median nerve, from lateral to medial. The artery usually divides at the apex of the fossa. The radial nerve is in a deep groove between the brachioradialis and brachialis. The fossa is roofed by fascia, strengthened by the bicipital aponeurosis, and crossed by the superficial veins. The median cubital vein is frequently used for intravenous injections and blood transfusions. Its close relationship to the underlying brachial artery and median nerve should be kept in mind. Joints. Elbow joint. The humerus, radius, and ulna form a hinge joint, situated 2 or 3 cm inferior to the epicondyles (figs. 6-16 , 9-5 , and 9-6 ). The capitulum of the humerus articulates with the upper aspect of the head of the radius (humeroradial joint), and the trochlea of the humerus articulates with the trochlear notch of the ulna (humero-ulnar joint). These two parts of the elbow joint are continuous with each other and share a common cavity with the proximal radio-ulnar joint.

Effusions of the elbow joint generally occur posteriorly, as do dislocations, and it is from this aspect that the joint is most easily approached surgically. The capsule is weak ion the anterior and posterior sides but is strengthened on each side by ligaments. The radial collateral ligament extends fan wise from the lateral epicondyle to the annular ligament. The ulnar collateral ligament runs from the medial epicondyle to the coronoid process and the olecranon. The elbow joint is supplied by adjacent nerves. Proximal Radio-ulnar Joint. The circumference of the head of the radius fits into the radial notch of the ulna to form a pivot joint. It is surrounded by the strong anular ligament, which is attached to the anterior and posterior margins of the notch. In children, the head of the radius may be subluxated through the anular ligament by a sudden jerk on the limb. Some fibers extend from the lower margin of the notch to the neck of the radius (quadrate ligament). The synovial membrane is continuous with that of the elbow joint. Movements at Elbow and Proximal Radioulnar Joints.

The elbow is a hinge joint; hence movement is limited to flexion and extension. Owing to the shape of the medial part of the trochlea, however, the supinated forearm makes a "carrying angle" with the arm during extension. The term "supination" is used for the position of the forearm and hand when the palm faces anterior, as in the anatomical position. The term "pronation" is used when the palm faces posterior. These terms are used also for the movements that bring about these positions. Supination and pronation are considerably more complicated than a mere lateral and medial rotation. The axis of movement extends from the middle of the head of the radius to the lower end of the ulna. Although the head of the radius merely rotates within the annular ligament, its inferior end describes an arc around the lower end of the ulna and carries the hand with it. In pronation, the shafts of the radius and ulna cross each other (the main reason for selecting supination to be the anatomical position). The movements are usually accompanied by rotation of the humerus (minimal when the elbow is flexed), and the ulna does not remain fixed.

Supination has been thought to be generally stronger than pronation, and the threads of screws are arranged to take advantage of this (for right-handed people). Flexion is controlled by segments C5 and 6 of the spinal cord, pronation and supination by C6, and extension by C7 and 8. The flexors of the forearm are the brachialis, biceps, and brachioradialis. The extensor is the triceps, particularly the medial head. The pronators are the pronator quadratus and the pronator teres. The supinators are the supinator and the biceps. QUESTIONS 9-1 What are the two main compartments of the arm? 9-1 The compartments of the arm are the anterior, for the flexors (musculocutaneous nerve), and the posterior, for the extensor (radial nerve). 9-2 What are the chief actions of the biceps brachii? 9-2 The biceps is a flexor and powerful supinator of the forearm. It "puts a corkscrew in and pulls the cork out." 9-3 Which spinal segments are associated with (a) flexion and (b) extension at the elbow?

9-3 C5 and 6 nerves (biceps and brachialis) are involved in flexion, and chiefly C6 and 7 nerves (triceps) are concerned with extension at the elbow. See table 8-4 . 9-4 Where is the ulnar nerve in contact with the humerus? 9-4 The ulnar nerve is in contact with the posterior aspect of the medial epicondyle ("funny bone"). When the nerve is under tension in ulnar neuritis, it is possible surgically to transpose the nerve into the anterior elbow. 9-5 Between which muscles, or heads of muscles, do the radial, median, and ulnar nerves enter the forearm? 9-5 Near the elbow, the radial nerve lies between the brachioradialis and the brachialis. The median nerve enters the forearm between the heads of the pronator teres; the ulnar nerve enters between the heads of the flexor carpi ulnaris. 9-6 Which important structures lie medial to the biceps tendon in the cubital fossa? 9-6 The brachial artery and the median nerve lie medial to the biceps tendon in the cubital fossa.

Occasionally the artery and nerve pass under cover of a hook-shaped spur of bone, the supracondylar process, which may project from the humerus above the medial epicondyle and is visible radiographically. 9-7 Under which conditions is subluxation of the head of the radius found? 9-7 In children, a sudden jerk on the limb may cause the head of the radius to be subluxated through the anular ligament. 9-8 Look up the origin of the word cubital. 9-8 The word cubital comes from the Latin cubitus, elbow or forearm, on which the Romans rested in a position called "decubitus." A cubit, or ell, is the distance from the elbow to the fingertips. An L-shaped bow is an elbow. Cf. ankle, the part at an angle. Figure legends Figure 9-1 Horizontal section through the middle of the arm. In A, the nerves and vessels are identified. B, shows the flexor muscles (supplied by the musculocutaneous nerve) anterior and the extensors (supplied by the radial nerve) posterior. B.B., biceps brachii; Br., brachialis.

The three heads of the triceps are indicated. Figure 9-2 A, The triangular and quadrangular spaces, separated by the long head of the triceps. The subscapular and posterior circumflex humeral arteries, respectively, pass through these spaces, and the axillary nerve traverses the quadrangular space. The spine of the scapula has been cut. B and C show the superficial and deep planes of the triceps. Figure 9-3 Horizontal sections through the upper and lower parts of the arm. Figure 9-4 The cubital fossa. A, The superficial nerves and veins. B, The contents of the cubital fossa. Figure 9-5 Schematic sagittal section through the humero-ulnar part of the elbow joint. The width of the joint cavity is exaggerated. Figure 9-6 ligaments of right elbow joint. * There is a small and functionally insignificant branch to the brachialis muscle as well. Jump to:

Question: What long bone in the arm that runs from the shoulder to the elbow to connect the scapula and the lower arm consists of 3 sections?
Answer: Humerus