252 ZOOTOMY. 



325. The tensor patagii brevis, a oroad sheet of 

 muscle covering the shoulder on its dorsal aspect ; it arises 

 from the dorsal ends of the coracoid and furcula, passes 

 backwards, parallel to the humerus and partly covering the 

 triceps, contributes fibres to the tensor longus, and is in- 

 serted by a broad tendon into the fascia of the extensor 

 metacarpi radialis longus. 



326. The insertion of the subclavius (§ 166) : the 

 muscle passes anteriorly into a tendon which proceeds for- 

 wards and outwards to the foramen triosseum : by cutting 

 through and reflecting the tensor brevis, the tendon is seen 

 to emerge from the foramen on its dorsal side and to be 

 inserted into the dorsal surface of the humerus, near the 

 greater tuberosity (§ 95) : by pulling upon the muscle, the 

 wing is raised ; the subclavius is the chief elevator of the 

 upper arm. 



327. The insertion of the pectoralis major (§ 153), 

 by cutting through and reflecting the biceps : its fibres 

 are gathered into a broad fiat tendon which is attached 

 along the whole extent of the greater tuberosity : the pec- 

 toralis major is the principal depressor of the wing. 



LIV. Remove the skin from the leg, and, by carefully 

 dissecting away the fascia, clear the muscles and 

 their tendons sufficiently to show : 



328. The extensor tendons of the digits, on the 

 anterior (dorsal) side of the tarso-metatarsus : those of the 

 second, third, and fourth, or forwardly-directed digits, are 

 formed by the trifurcation of a single tendon, which, traced 

 into the shank, is found to be the tendon of insertion of a 

 small muscle, the extensor longus digitorum, which 

 arises from the anterior face of the proximal end of the tibia : 

 the extensor tendon of the first digit, or hallux, springs from 

 a small distinct muscle, the extensor hallucis brevis. 



