BONES OF THE THORACIC LIMB 199 
line (Crista interossea) laterally for the attachment of the interosseous ligament. 
The proximal end (Capitulum radii) is relatively small and is supported by a dis- 
tinct neck (Collum radii). It bears a concave surface (Fovea capituli) for articu- 
lation with the humerus, and a convex marginal area (Circumferentia articularis) 
behind for the ulna. The radial tuberosity is small. There is a large lateral tuber- 
osity and below this a rough eminence. The distal extremity is much wider. 
It has an extensive concave carpal articular surface. Its medial border projects 
downward, forming the styloid process of the radius. Laterally there is a concave 
facet (Incisura ulnaris radii) for articulation with the ulna. Dorsally are three 
distinct grooves for the extensor tendons. The ulna is well developed, but dimin- 
Lateral Medial Intertuberal 
tuberosity 
groove 
tuberosity 
Lateral tuber- 
osily 
Head 
Neck 
Teres emi- 
Neck 
vence 
Deltoid tuberosity : 
Musculo-spiral 
groove 
Coronoid fossa Lateral condyloid 
Metical crest 
condyle Olecranon fossa 
Lateral 
condyle Medial condyle 
Dateral epicondyle Medial epicondyle 
Fic. 218.—Lerr Humercs or Doc; LaTerat View. Fic. 219.—Lerr Humerus or Doc; Meprat View. 
1, Attachment of medial ligament of elbow joint; 2, 
attachment of flexor muscles to medial epicondyle. 
ishes in size distally. It crosses the volar surface of the radius medio-laterally. 
The shaft is large and three-sided in its proximal two-thirds, smaller and more 
rounded below. Its dorsal surface is in general rough. The nutrient foramen is 
near the proximal end. A vascular groove descends from it and indicates the course 
of the interosseous artery. The proximal end is relatively short. It is concave 
and smooth medially, convex and rough laterally. The olecranon is grooved and 
bears three prominences, of which the posterior one is large and rounded. The 
semilunar notch is wide below and completes the surface for articulation with the 
trochlea of the humerus. Below it is a concave surface (Incisura radialis), which 
articulates with the back of the head of the radius, and below this is a fossa, which 
receives a tuberosity of the radius. The distal end (Capitulum ulnz) is small and 
