5S ANATOMY IN A NUTSHELL. 



lower border tonus, in conjunction with the Latissimus dorsi, part of the pos- 

 terior boundary of the axilla. 



Origin. From the oval surface on the dorsal aspect of the inferior angle 

 of the scapula, and from the fibrous septa interposed between it and the Teres 

 minor and Infraspinatus. (Plate XX.) 



Insertion, [nner bicipital ridge of humerus. (Plate XXIII.) 



A.CTION. Assists Lattissimus dorsi in drawing humerus downward and 

 backward. 



Nerve Supply. — Fifth and sixth cervical through the lower subscapular. 



Blood Si pply. Subscapular artery. 



Coraco-brachialis. Description. — This is the smallest of the three mus- 

 cle- in the ant. hum< ral region, and is situated at the upper and inner part of 

 the arm. Its fibers pass downward, backward, and a little outward, and ter- 

 minate in a Hat tendon. This muscle is perforated l>y the musculo-cutaneous 

 nerve and its inner border forms a guide to the position of the brachial artery 

 in tying this vessel in the upper part of its course. The brachial vessels and 

 median nerve lie upon its anterior surface at its insertion. (Plate XVI.) 



Origin. Apex of coracoid process in common with short head of Biceps. 

 (Plate XX 1.) 



INSERTION.— Ridge on inner side of shaft of humerus about its middle, 

 between the origins of the Triceps and Brachialis anticus. (Plate XXIII.) 



Action. — Draws the humerus forward and inward and assits in elevating 

 the same. 



Nerve Supply.— Seventh cervical through the Musculo-cutaneous. 



Blood Supply. — Brachial, muscular branches. 



Biceps. — Description. — (Plates III-XY-XYI.) — The Biceps is a long 

 fusiform muscle, occupying the whole of the anterior surface of the arm, and 

 divided above into two portions or heads, from which circumstance it has re- 

 ceived its name. Each head is tendinous but is succeeded by an elongated 

 muscular belly, and the two bellies, although closely applied to each other, 

 may readily be separated until within about three inches of the elbow-joint. 

 Here they end in a flattened tendon, a synovial bursa being interposed between 

 it and the front of the tuberosity of the radius. As this tendon approaches the 

 radius it become.- twisted U] itself so that its anterior surface becomes ex- 

 ternal. ( >pposite the bend of the elbow it gives off. from its inner side, a broad 

 aponeurosis, the bicipital fascia (semilunar fascia,) which passes obliquely 

 downward and is continuous with the deep fascia of the forearm. The Biceps 

 muscle occasionally has a third head which may consist of two slips passing 

 down, one in front of the other behind the brachial artery, concealing this ves- 

 sel in the lower half of the arm. 



The inner border of the Biceps froms a guide to the position of the artery 

 in tying that vessel in the middle of the arm. 



ORIGIN.— (Plates XX-XXI.) The long head arises from the upper mar- 

 gin of the glenoid cavity and is continuous with the glenoid ligament. The 

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

 of synovial membrane, passes through an opening in the capsular ligament and 



