Henry Gray (18251861). Anatomy of the Human Body. 1918.
to its tendon of insertion becomes prominent as a sharp ridge running downward and medialward.
On either side of the Biceps brachii at the lower part of the arm the Brachialis is discernible. Laterally it forms a narrow eminence extending some distance up the arm; medially it exhibits only a little fulness above the elbow.
On the back of the arm the long head of the Triceps brachii may be seen as a longitudinal eminence, emerging from under cover of Deltoideus and gradually passing into the flattened plane of the tendon of the muscle at the lower part of the back of the arm. When the muscle is in action the medial and lateral heads become prominent.
On the front of the elbow are two muscular elevations, one on either side, separate above but converging below so as to form the medial and lateral boundaries of the anticubital fossa. The medial elevation consists of the Pronator teres and the Flexors, and forms a fusiform mass, pointed above at the medial epicondyle and gradually tapering off below. The Pronator teres is the most lateral of the group, while the Flexor carpi radialis, lying to its medial side, is the most prominent and may be traced downward to its tendon, which is situated nearer to the radial than to the ulnar border of the front of the wrist and medial to the radial artery. The Palmaris longus presents no surface marking above, but below, its tendon stands out when the muscle is in action as a sharp, tense cord in front of the middle of the wrist. The Flexor digitorum sublimis does not directly influence surface form; the position of its four tendons on the front of the lower part of the forearm is indicated by an elongated depression between the tendons of Palmaris longus and Flexor carpi ulnaris. The Flexor carpi ulnaris determines the contour of the medial border of the forearm, and is separated from the Extensor group of muscles by the ulnar furrow produced by the subcutaneous dorsal border of the ulna; its tendon is evident along the ulnar border of the lower part of the forearm, and is most marked when the hand is flexed and adducted.
The elevation forming the lateral side of the anticubital fossa consists of the Brachioradialis, the Extensors and the Supinator; it occupies the lateral and a considerable part of the dorsal surface of the forearm in the region of the elbow, and forms a fusiform mass which is altogether on a higher level than that produced by the medial elevation. Its apex is between the Triceps brachii and Brachialis some distance above the elbow-joint; it acquires its greatest breadth opposite the lateral epicondyle, and below this shades off into a flattened surface. About the middle of the forearm it divides into two diverging longitudinal eminences. The lateral eminence consists of the Brachioradialis and the Extensores carpi radiales longus and brevis, and descends from the lateral supracondylar ridge in the direction of the styloid process of the radius. The medial eminence comprises the Extensor digitorum communis, Extensor digiti quinti proprius, and the Extensor carpi ulnaris; it begins at the lateral epicondyle of the humerus as a tapering mass which is separated above from the Anconæus by a well-marked furrow, and below from the Pronator teres and Flexor group by the ulnar furrow. The medial border of the Brachioradialis starts as a rounded elevation above the lateral epicondyle; lower down the muscle forms a prominent mass on the radial side of the upper part of the forearm; below it tapers to its tendon, which may be traced to the styloid process of the radius. The Anconæus presents as a triangular slightly elevated area, immediately lateral to the subcutaneous surface of the olecranon and differentiated from the Extensor group by an oblique depression; the upper angle of the triangle is at the dimple over the lateral epicondyle.
At the lower part of the back of the forearm in the interval between the two diverging eminences is an oblique elongated swelling; full above but flattened and partially subdivided below; it is caused by the Abductor pollicis longus and the Extensor pollicis brevis. It crosses the dorsal and lateral surfaces of