THE UPPER LIMB 321 



clavian. Having coursed transversely outwards behind the clavicle, 

 it reaches the upper border of the scapula in company with the 

 suprascapular nerve. The artery then passes backwards over the 

 suprascapular ligament, whilst the nerve passes beneath it, and it 

 descends into the supraspinous fossa beneath the supraspinatus, 

 where it parts with several branches. Thereafter it passes 

 behind the neck of the scapula through the great scapular notch, 

 beneath the spino-glenoid ligament, into the upper and outer 

 part of the infraspinous fossa under cover of the infraspinatus, 

 where it anastomoses with the dorsalis scapulae and posterior 

 scapular. 



Branches. — ^These are as follows : muscular, in the neck, to the 

 sterno-cleido-mastoid and subclavius ; suprasternal, over the inner 

 end of the clavicle, to the integument over the presternum ; 

 medullary to the clavicle ; supra-acromial, which pierces the 

 trapezius to reach the upper surface of the acromion process, where 

 it anastomoses with branches of the acromio- thoracic and posterior 

 circimiflex ; articular to the acromio-clavicular and shoulder- 

 joints ; ventral to the belly of the scapula, given off as it passes 

 backwards over the suprascapular ligament, this branch anasto- 

 mosing with the ventral branches of the dorsalis scapulae and 

 posterior scapular ; supraspinous to the fossa and its muscle ; and 

 infraspinous to the fossa and its muscle. 



Suprascapular Nerve. — ^This nerve passes backwards beneath the 

 suprascapular ligament into the supraspinous fossa, where it gives 

 branches to the supraspinatus, and articular branches to the acromio- 

 clavicular and shoulder- joints. It then accompanies the artery 

 through the great scapular notch, beneath the spino-glenoid ligament, 

 to the infraspinous fossa, where it ends in branches to the infra- 

 spinatus. 



Teres Minor — Origin. — (i) The dorsimi of the scapula close to the 

 axillary border for its upper two-thirds, and (2) the septa between 

 it and the infraspinatus and teres major. 



Insertion. — ^The lower impression on the great tuberosity of the 

 humerus, and the surgical neck of the bone for a short distance 

 below, its tendon being closely connected with the back part of the 

 capsular ligament. 



Nerve-supply. — ^The circumflex nerve, the branch of which has a 

 reddish enlargement presenting the appearance of a ganglion, but 

 being in reality a fibrous thickening. 



The direction of the muscle is outwards and slightly upwards. 



Action. — ^The muscle is an external rotator of the arm when it is 

 abducted, and it also helps in depressing the arm. 



The muscle is pierced by the dorsalis scapulae artery. 



Teres Major — Origin. — (i) From an oval impression at the lower 

 and outer part of the infraspinous fossa, which extends on to the 

 lower angle, and reaches upwards on the axillary border for about 

 its lower third ; and (2) the septa between it and the teres minor, 

 infraspinatus, and subscapularis. 



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