BICEPS MUSCLE. 43 



The INTERNAL CUTANEOUS BRANCH OF THE MUSCULO-SPIRAL one from 



NERVE, becoming subcutaneous in the upper third, winds to the ~ 



back of the arm, and reaches nearly as far as the olecranon. 



The INTERCOSTO-HUMERAL NERVE, a branch of the second inter- and inter- 

 costal (p. 13, and fig. 4), perforates the fascia near the axilla, and humeral. 

 ramifies on the inner side and posterior surface of the arm in the 

 upper half. The size and distribution of this nerve depend upon 

 the development of the small internal cutaneous and the offset of 

 the inusculo-spiral. 



The DEEP FASCIA of the arm is a white shining membrane, which Aponeurosis 

 surrounds the limb, and sends processes between the muscles. of 

 Over the biceps muscle it is thinner than elsewhere. At certain 

 points it receives accessory fibres from the subjacent tendons : thus, receives ac- 

 in front of the elbow an offset from the tendon of the biceps joins it ; from 

 and near the axilla the tendons of the pectoralis major, latissimus tendons ; 

 dorsi, and teres major send prolongations to it. 



At the upper part of the limb the fascia is continuous with that disposition 

 of the axilla, and is prolonged over the deltoid and pectoral muscles 

 to the scapula, clavicle, and chest. Below, it is continued to the and below ; 

 forearm, and is connected to the prominences of bone around the 

 elbow-joint, especially to the supracondylar ridges of the humerus, forms inter- 

 b > as to give rise to the intermuscular septa of the arm. 



Dissection. The muscles and vessels of the arm will next be 



red ; the limb is still to lie on the back, but the shoulder is 



to be raised by means of a small block ; and the scapula is to be 



fixed in such a position as to render tense the muscles. The inner 



surface of the arm is to be placed towards the dissector. 



The aponeurosis is to be reflected from the front of the arm by Dissection 

 an incision along the centre, like that through the skin ; and it is of ;Ies> 

 to be removed on the outer side as far as the outer supracondylar 

 ridge of the humerus, but on the inner side rather farther back 

 than the corresponding line, so as to lay bare part of the triceps of vessels, 

 muscle. In raising the fascia the knife must be carried in the 

 direction of the fibres of the biceps muscle ; and, to prevent the 

 displacement of the brachial artery and its companion nerves, 

 fasten them here and there with stitches. 



In front of the elbow is a hollow containing the brachial vessels ; J" J of 

 and into this the artery should be followed, to show its ending in elbow. 

 the radial and ulnar trunks. 



MUSCLES ON THE FRONT OF THE ARM. There are only three Position of 

 muscles on the front of the arm. The one along the centre of the O f the arm. 

 limb is the biceps ; and that along its inner side, reaching about 

 half-way down, is the coraco-brachialis. The brachialis anticus lies 

 beneath the biceps. Some muscles of the forearm are connected to 

 the inner and outer condyles of the humerus, and to the ridge above 

 the outer condyle. 



The BICEPS MUSCLE (fig. 18, p. 45, and fig. 7, p. 23) forms the gceps 

 prominence seen on the front of the arm. It is wider at the brachii: 

 middle than at either end ; and the upper end consists of two 

 tendinous pieces of different lengths, which are attached to the 



