ANATOMY IN A NUTSHELL. 119 



The axilla is the anatomical space through which passes the brachial plexus 

 and the axillary vessels. It is filled with lymphatic vessels and nodes and areo- 

 lar tissue. It is pyramidal in shape,having four sides, a base. and an apex. The 

 apex corresponds to a point between the clavicle, the upper part of the scapula 

 and the first rib. The base is the arm-pit which is made by fascia passing from 

 the lower borders of the Latissimus dorsi behind and the Pectoraiis major in 

 front. The anterior margin of the base is higher than the posterior margin. 

 This space is narrow externally, but broad internally. 



Its boundaries are as follows: Plate XVI. 



In Front: — (1) Pectoraiis major. (2) Pectoraiis minor. 



Behind: — (1) Subscapulars (above,) (2) Teres major and (3) Latissimus 

 dorsi (below.) 



Outer Side: — (1) Humerus, 2) Biceps, (3) Coraco-brachialis. 



Ennek Side: — (1) First four ribs and their intercostal spaces. (2) a part of 

 the Serratus magnus. 



The axillary vessels, brachial plexus, branches of the intercostal nerves, 

 lymphatic nodes, all connected by areolar tissue and fat lie in this space. 



In finishing the arm it is well to review the cutaneous nerve supply of the 

 hand which is as follows: Plate XXXVI. 



All the integument on the ulnar side of the middle line of the ring finger on 

 both palmar and dorsal surfaces of the hand is supplied by the ulnar nerve. 

 This line on the dorsum of the hand may be drawn through the middle 



OF THE MIDDLE FINGER INSTEAD OF THE RING FINGER. All (ill the radial side of 



this line on palmar surface is supplied by the median, on the dorsal surface by 

 the radial. The radial nerve extends to the base of the thumb nail, to the distal 

 interphalangeal joint of index finger and not quite to the proximal interphal- 

 angeal joint of middle finger, and sends a few twigs to the skin of the metapha- 

 langeal articulation of ring finger. The parts of the dorsal of the thumb, index. 

 middle and ring fingers not supplied by the radial get the median. 



The synovial membrane of the wrist (Plate XLII.) This membrane con- 

 sists of five portions. First portion is called membrana sacciformis and is 

 between the interarticular fibro-cartilage and the ulna, also extending between 

 the radius and ulna. The second portiox is between the radius and inter- 

 articular fibro-cartilage proximally and the scaphoid, semilunar and cuneiform 

 distally. The third portion is between the trapezium and metacarpal nl the 

 thumb. The fourth portion is large and extends between the scaphoid, 

 semilunar and cuneiform proximally and after sending septa between the bones 

 of the second row of the wrist ends by separating this second row from the sec- 

 ond, third, fourth and fifth metacarpal bones distally. It also sends projec- 

 tions between the metacarpal bones just mentioned. Tim: fifth PORTION is 

 between the cuneiform and pisiform bones. 



