ANTERIOR HUMERAL REGION. 303 



and affords attachment to the Triceps behind, and the Brachialis anticus in front. 

 It is perforated by the ulnar nerve, and the inferior profunda and anastomotic 

 arteries. At the elbow, the deep fascia takes attachment to all the prominent 

 points round this joint, and is continuous with the fascia of the forearm. On the 

 removal of this fascia, the muscles of the anterior humeral region are exposed. 



The Coraco-brachialis, the smallest of the three muscles in this region, is situated 

 at the upper and inner part of the arm. It arises by fleshy fibres from the apex 

 of the coracoid process, in common with the short head of the Biceps, and from 

 the intermuscular septum between the two muscles ; the fibres pass downwards, 

 backwards, and a little outwards, to be inserted by means of a flat tendon into a 

 rough ridge at the middle of the inner side of the shaft of the humerus. It is 

 perforated by the musculo-cutaneous. nerve. The inner border of the muscle 

 forms a guide to the performance of the operation of tying the brachial artery in 

 the upper part of its course. 



Relations. By its anterior surface, with the Deltoid and Pectoralis major above; 

 at its insertion it is crossed by the brachial vessels and median nerve. By its* 

 posterior surface, with the tendons of the Subscapularis, Latissimus dorsi, and 

 Teres major, the short head of the Triceps, the humerus, and the anterior circumflex 

 vessels. By its inner border, with the brachial artery, and the median and mus- 

 culo-cutaneous nerves. By its outer border, with the short head of the Biceps 

 and Brachialis anticus. 



The Biceps is a long fusiform muscle, situated along the anterior aspect of the 

 arm in its entire length, and divided above into two portions or heads, from which 

 circumstance it has received its name. The short head arises by a thick flattened 

 tendon from the apex of the coracoid process, in common with the Coraco- 

 brachialis. The long head arises from the upper margin of the glenoid cavity, 

 by a long rounded tendon, which is continuous with the glenoid ligament. This 

 tendon arches over the head of the humerus, being inclosed in a special sheath of 

 the synovial membrane of the shoulder-joint ; it then pierces the capsular ligament 

 at its attachment to the humerus, and descends in the bicipital groove in which 

 it is retained by a fibrous prolongation from the te'ndon of the Pectoralis major. 

 The fibres from this tendon form a rounded belly, and, about the middle of the 

 arm, join with the short portion of the muscle. The belly of the muscle, narrow 

 and somewhat flattened, terminates above the elbow in a flattened tendon, which 

 is inserted into the back part of the tuberosity of the radius, a synovial bursa 

 being interposed between the tendon and the front of the tuberosity. The tendon 

 of the muscle is thin and broad ; as it approaches the radius it becomes narrow 

 and twisted upon itself, being applied by a flat surface to the back part of the 

 tuberosity, and opposite the bend of the elbow gives off, from its inner side, a 

 broad aponeurosis, which passes obliquely downwards and inwards across the 

 brachial artery, and is continuous with the fascia of the forearm. The inner 

 border of this muscle forms a guide to the performance of the operation of tying 

 the brachial artery in the middle of the arm. 1 



Relations. Its anterior surface is overlapped above by the Fectoralis major and 

 Deltoid ; in the rest of its extent it is covered by the superficial and deep fasciae 

 and the integument. Its posterior surface rests on the shoulder-joint and humerus, 

 from which it is separated by the Subscapularis, Teres major, Latissimus dorsi, 

 Brachialis anticus, and the musculo-cutaneous nerve. Its inner border is in rela- 

 tion with the Coraco-brachialis, the brachial vessels, and median nerve. By its 

 outer border, with the Deltoid and Supinator longus. 



1 A third head to the Biceps is occasionally found (Theile says as often as once in eight or 

 nine subjects), arising at the upper and inner part of the Brachialis anticus with the fibres of 

 which it is continuous, and is inserted into the bicipital fascia, and inner side of the tendon of the 

 Biceps. In most cases this additional slip passes behind the brachial artery in its course down 

 the arm. Occasionally the third head consists of two slips, which pass down, one in front, the 

 other behind the artery, concealing this vessel in the lower half of the arm. 



