(b) Radius-Ulna (Figure 20.17). (1) These are the bones of the lower arm. The radius is on the thumb side, and the ulna is on the side of the little finger. (2) The radius is shorter than the ulna and consists of a head, shaft and lower end, with a tuberosity below the neck, a nutrient foramen in the shaft and a styloid process at the lower end. (3) The ulna is longer than the radius and possesses an olecranon and coronoid processes, with trochlear and radial notches at the upper end. (4) The shaft of the ulna is long, with a nutrient foramen, supinator fossa and a crest-like interosseous border. (5) The lower end of the ulna is slightly expanded and consists of head and styloid process.

(c) Carpal Bones. (1) These are eight bones of the wrist, arranged into two rows of four bones each and held together by a series of ligaments. (2) Proximal row- (a) Scaphoid (b) Lunate (c) Triquetral (d) Pisiformes. (3) Distal row - (a) Trapezium, (b) Trapezoid (c) Capitate (d) Hamate.

(d) Metacarpals and Phalanges. The hand consist of five bones of the palm called metacarpals and 14 phalanges - two for the thumb and three each for the four fingers.