OCR Text |
Show 1883.] ANATOMY OF PHOXNICOPTERUS. 643 internal deltoid and biceps, to be inserted into the inner side of the humerus ; and to this aponeurosis are attached the remaining fibres of the pectoralis. 15. The second pectoral occupies about three quarters of the ventral face of the sternum ; it also arises from the proximal half of the coracoid, and from nearly the whole of the coraco-clavicular membrane. Its tendon passes as usual over the scapula to go to the lesser tuberosity of the humerus, at the top of the deltoid ridge. 16. The third pectoral is relatively small; it arises from the lower third of the posterior margin of the coracoid, and passes to the tip of the great tuberosity of the humerus. 1 7. The biceps arises by two heads-a long tendon from the head of the coracoid, and a fleshy head from the lower surface of the pectoral aponeurosis. 18. The supraspinatus arises from the anterior half of the ventral border of the scapula, and is attached to the great tuberosity of the humerus, just anteriorly to the tendon of the pectoralis tertius. 19. The subscapularis arises from the anterior half of the deep surface of the scapula, being inserted into the great tuberosity of the humerus below the tendons of the third pectoral and supraspinatus. 20. The extensor carpi radialis longus arises by fleshy fibres from the ridge above the outer condyle of the humerus, and forms a short fleshy belly, which joins a long tendon, passing first over a groove in the distal head of the radius, and then over the middle of three grooves on the face of the radial carpal, to be finally inserted into the tuberosity of the thumb metacarpal. 21. The extensor carpi radialis brevis arises by a short tendon from the outer condyle of the humerus ; its short belly is attached to the aponeurosis covering the preceding muscle, and its tendon runs below the long extensor tendon to the thumb metacarpal. 22. The abductor poliicis arises by three slips-the first from the interosseous border of the radius for about a third of its length, beginning near the bicipital tuberosity ; the second from the upper surface of the ulna, just beneath the head of the radius; and the third from a ridge on the ulna, just distal to the ulnar tendon of the biceps. The second and third slips unite before joining the first. The tendon curves round to the outer side of the radius, and passes through the outer of three grooves on the radial carpal bone, to be inserted on the great tuberosity of the thumb metacarpal, below and external to the radial extensor of the carpus. 23. The extensor carpi ulnaris arises from the outer surface of the outer condyle of the humerus, superficially to all the other murcles which arise there; it is also attached to the outer side of the ulna. The belly is small, and the long tendon passes through a separate groove in the outer side of the ulna to the outer side of the second metacarpal. 24. The adductor manus arises from the fascia on the outer side of the head of the ulna, and passes to the inner edge of the third metarcarpal. 25. The pronator quadratus arises from the inner (palmar) surface |