Head of radius - wikipedia Head of radius Head of radius The radius and ulna of the left forearm, posterior surface. The top is proximal ( elbow ) and bottom is distal ( wrist ). Details Identifiers Latin Caput radii TA A02. 4.05. 002 FMA 33773 Anatomical terms of bone ( edit on Wikidata ) The head of the radius has a cylindrical form, and on its upper surface is a shallow cup or fovea for articulation with the capitulum of the humerus. The circumference of the head is smooth ; it is broad medially where it articulates with the radial notch of the ulna, narrow in the rest of its extent, which is embraced by the annular ligament. Contents 1 Articular surfaces 1.1 Humeroradial joint 1.2 Proximal radioulnar joint 2 Additional images 3 See also 4 References Articular surfaces The head of the radius is shaped to articulate with a complex of articular surfaces during both flexion - extension at the elbow and supination - pronation in the forearm : Humeroradial joint Main article : Humeroradial joints The head 's proximal surface is concave and cup - shaped to correspond to the spherical surface of the capitulum of the humerus. The radius can thus glide on the capitulum during elbow flexion - extension while simultaneously rotate about its own main axis during supination - pronation. Between the capitulum and the trochlea of the humerus is the capitulotrochlear groove. A semi-lunar surface around the circumference of head is shaped to articulate continuously with this groove. The capitulum does not extend to the posterior side of the humerus and, consequently, during full elbow extension only the anterior half of the head articulates with the capitulum. In full flexion the head similarly reaches beyond the capitulum to enter the shallow radial fossa on the anterior side of the humerus. Proximal radioulnar joint Main article : Proximal radioulnar joint The head is cylindrical to allow axial rotation of the radius, thus to articulate with the annular ligament and the radial notch on the ulna. However, the head of the radius is not perfectly cylindrical but slightly oval. In anatomical position, its major axis ( 28 mm ( 1.1 in ) ) is directed antero - posteriorly and the shorter axis ( 24 mm ( 0.94 in ) ) lateralo - medially. Even though the annular ligament holds the head firmly in place, the ligament is still flexible enough to allow some stretching while the head rotates within it. During pronation the radius is rotated so that the head 's major axis reaches the radial notch on the ulna. This causes a small but significant lateral displacement of the radius ' main axis -- equal to half the difference between the two axes of the head ( 2 mm ( 0.079 in ) ) -- just enough space to accommodate the radial tuberosity as it being moved medially. Additional images Elbow joint. Deep dissection. Posterior view. Elbow joint. Deep dissection. Posterior view. Elbow joint. Deep dissection. Posterior view. See also Nursemaid 's elbow References This article incorporates text in the public domain from page 1 of the 20th edition of Gray 's Anatomy ( 1918 ) Jump up ^ Gray 's Anatomy ( 1918 ), see infobox ^ Jump up to : Kapandji, Ibrahim Adalbert ( 1982 ). The Physiology of the Joints : Volume One Upper Limb ( 5th ed. ). New York : Churchill Livingstone. p. 82. ^ Jump up to : Kapandji, Ibrahim Adalbert ( 1982 ). The Physiology of the Joints : Volume One Upper Limb ( 5th ed. ). New York : Churchill Livingstone. p. 112. Bones of the arm Shoulder girdle, clavicle conoid tubercle trapezoid line costal tuberosity subclavian groove Scapula fossae ( subscapular, supraspinatous, infraspinatous ) notches ( suprascapular, great scapular ) glenoid cavity tubercles ( infraglenoid, supraglenoid ) spine of scapula acromion coracoid process angles ( superior, inferior, lateral ) Humerus upper extremity : necks ( anatomical, surgical ) tubercles ( greater, lesser ) bicipital groove body : radial sulcus deltoid tuberosity lower extremity : capitulum trochlea epicondyles ( lateral, medial ) supracondylar ridges ( lateral, medial ) fossae ( radial, coronoid, olecranon ) Forearm Radius near elbow ( head, tuberosity ) near wrist ( ulnar notch, styloid process, Lister 's tubercle ) Ulna near elbow ( tuberosity, olecranon, coronoid process, radial notch, trochlear notch ) near wrist ( styloid process ) Hand Carpal bones scaphoid lunate triquetral pisiform trapezium trapezoid capitate hamate hamulus Metacarpal bones 1st 2nd 3rd 4th 5th Phalanges proximal intermediate distal Anatomy portal Retrieved from `` https://en.wikipedia.org/w/index.php?title=Head_of_radius&oldid=825178884 '' Categories : Wikipedia articles incorporating text from the 20th edition of Gray 's Anatomy ( 1918 ) Radius ( bone ) Hidden categories : Pages with unresolved properties Talk Contents About Wikipedia Galego ไทย Edit links This page was last edited on 11 February 2018, at 22 : 58. 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Question: the head of the radius articulates with which structure and bone
Answer: the capitulum of the humerus