THE BRACHIAL ARTERY. 593 



The circumflex arteries wind round the neck of the humerus. The posterior 

 cif 'I'm ilex (Fig. 361), the larger of the two, arises from the back part of the axillary 

 opposite the lower border of the Subscapularis muscle, and, passing backward with 

 the circumflex veins and nerve through the quadrangular space bounded by the 

 Teres major and minor, the scapular head of the Triceps and the humerus. winds 

 round the neck of that bone and is distributed to the Deltoid muscle and shoulder- 

 joint, anastomosing with the anterior circumflex and acromial thoracic arteries, and 

 with the superior profunda branch of the brachial artery. The anterior circumflex 

 (Figs. 361, 362), considerably smaller than the preceding, arises just below that 



I from the outer side of the axillary artery. It passes horizontally outward 

 beneath the Coraco-brachialis and short head of the Biceps, lying upon the fore part 

 of the neck of the humerus, and, on reaching the bicipital groove, gives oft" an 

 ascending branch which passes upward along the groove to supply the head of the 

 bone and the shoulder-joint. The trunk of the vessel is then continued outward 

 beneath the Deltoid, which it supplies, and anastomoses with the posterior circum- 

 flex artery. The axillary cutaneous branch, long and slender, is often found 

 ramifying in the superficial fascia of the floor of the axilla. 



THE BRACHIAL ARTERY (Fig. 363). 



The Brachial Artery commences at the lower margin of the tendon of the Teres 

 major, and, passing down the inner and anterior aspect of the arm, terminates about 

 half an inch below the bend of the elbow, where it divides into the radial and 



ulnar arteries. 



PLAN OF THE RELATIONS OF THE BRACHIAL ARTERY. 



In front. 



Integument and fasciae. 

 Bicipital fascia, median basilic vein. 

 Median nerve. 



Outer side. /^ ^\ Inner side. 



Vt-na comes. / Brac i,iai | Vena comes. 



Median nerve (above). Artery. Internal cutaneous and Ulnar nerves. 



Coraco-brachialis. V J Median nerve (below). 



Biceps. Basilic vein (upper half). 



Behind. 

 Triceps. 



Musculo-spiral nerve. 

 Superior profunda artery. 

 Coraco-brachialis (insertion). 

 Brachialis anticus. 



Relations. This artery is superficial throughout its entire extent, being covered, 

 in front, by the integument, the superficial and deep fascia; the bicipital fascia 

 separates it opposite the elbow from the median basilic vein ; the median nerve 

 crosses it at its middle. Behind, it is separated from the inner side of the 

 humerus. above, by the long and inner heads of the Triceps, the musculo-spiral 

 nerve and superior profunda artery intervening, and from the front of the bone, 

 below, by the insertion of the Coraco-brachialis muscle and by the Brachialis 

 anticus. By its outer side it is in relation with the commencement of the 

 median nerve and the Coraco-brachialis and Biceps muscles, which slightly 

 overlap the artery. By its inner side its upper half is in relation with the inter- 

 nal cutaneous and ulnar nerves, its lower half with the median nerve. The 

 basilic vein lies on the inner side of the artery, but is separated from it in the 

 lower part of the arm by the deep fascia. It is accompanied by two vense comites, 

 which lie in close contact with the artery, being connected together at inter- 

 vals bv short transverse communicating branches. 



V '._ 



SURGICAL ANATOMY OF THE BEND OF THE ELBOW. 

 At the bend of the elbow the brachial artery sinks deeply into a trian- 

 gular interval, the base of which is directed upward toward the humerus, 



38 



