1154 



SURGICAL AXD TOPOGRAPHICAL ANATOMY 



should be made Imckwards. The superior piofunda comes off from the liighest 

 part of the artery and courses with tlie musculo-sj)iral nerve (tig. 714); the 

 nutrient artery arises opposite the middle of the humerus; the inferior ]>rofunda 

 below the middle, and courses with the ulnar nerve through the intermuscular 

 septum to the l)ack of the internal condyle. The anastomotica is given from 

 one to two inches above the bend of the ellM)W. 



The centre of the arm is a landmark for many anatomical structures. On the 

 outer side is the insertion of the deltoid; on the inner that of the coraco-brachialis. 

 The basilic vein and the nerve of Wrisberg here perforate the deep fascia, going in 

 reverse directions. The inferior profunda is here given off from the Ijrachial; the 

 median nerve also crosses the artery, and the ulnar nerve leaves the inner side of 

 the vessel to pass to the inner aspect of the limb. 



The brachialis anticus can be mai3i)ed out by two pointed processes which 

 surround the insertion of the deltoid, and which pass downwards into lines corre- 

 sponding to the two intermuscular septa, and then converge over the front of the 

 elbow to their insertion into the coronoid process. 



The median nerve can be traced by a line drawn from the outer side of the third 

 part of the axillary and first part of the brachial artery, across this latter vessel 

 about its centre, and then along its inner border to the forearm, where it passes 

 between the two heads of the pronator radii teres. 



The ulnar nerve lies to the inner side of the above arteries as far as the middle 

 of the arm, where it leaves the brachial to course more inwards and perforate the 

 internal intermuscular septum and get to tlie l)ack of the internal condyle. 



Fig. 717.— Vertical Sectiox of the Elbow. (One-half.) (Braune. 



Tendon of biceps -- 



Brachio-radialiB _ 

 RADIAL SERVE - 

 Brachialis anticus -- 



Extensor carpi radialis longior - 



Pronator teres 

 MEDIAN NERVE 



— — Flexor carpi radialis 



-' Internal lateral ligament 



' — ULNAR NERVE 



OLECRANON 



Tendon of triceps 



I 



The musculo-spiral nerve can be traced by a line beginning behind the third 

 part of the axillary artery, then carried vertically down behind the uppermost part 

 of the brachial, and then, just below the posterior border of the axilla, curving 

 backwards behind the humerus and slightly downwards, just below the insertion of 

 the deltoid. Thus, passing from within outwards and from before backwards in its 

 groove Avith the superior profunda vessels, it again comes to the front by perforating 

 the external intermuscular septum at a point about opposite to the junction of the 

 middle and lower thirds of the arm, and passes down in front of the external supra- 

 condyloid ridge, lying here between the brachio-radialis and brachialis anticus. to 

 the level of the external condyle, where it divides into radial and posterior inter- 

 osseous. The former of these accompanies the radial artery to the front of the arm, 

 the latter travels l)ackwards to the back of the forearm. 



On the back of the arm is the triceps muscle, with its three heads and tendon 

 of insertion, all ])rought into relief in a muscular subject when the forearm is 

 strongly extended. Of the three heads, the inner is the least distinct, arising below 

 the musculo-si)iral groove, reaching to each intermuscular septum, and tapering 

 away above as higli as the teres major. The outer head, arising above the groove 

 as high as the great tuberosity, appears in strong relief just below the deltoid; 

 while the middle or long head, arising from the scajiula just below the glenoid 

 cavity, appears between the teres muscles. The tendon of insertion, passing into 

 the upper and back part of the olecranon over a deep bursa, is shown by a some- 

 what depressed area. 



