NERVES OF THE SHOULDER. 



583 



and beneath the levator anguli scapula. It is distributed to the deep surface of 

 the rhomboid muscles, and gives sometimes a branch to the levator scapula? 



Thenevxeof the guljclavius wvscb'.oi small sizG, arisen from the front of the 

 cord which results from the union of the fifth and sixth cervical nerves. It is 

 directed over the outer part of the subclavian artery to ^he deep surface of the 

 subclavius muscle. This small nerve is commonly connected with the plu-enic 

 nerve in the neck or in the chest, by means of a slender filament. 



Branch to join tlie pfirenic nerve— This small and short branch is an offset 

 from the fifth cervical nerve ; it joins tlie phrenic nerve on the anterior scalenus 

 muscle. 



Fig. 357. — DiSTKiBUTioN OP Fig- 357. 



THE Suprascapular axd 

 Circumflex Nerves (from 

 HirscLfeld and Levielle). s 



«, the scalenus raeilius and 

 posticus muscles ; 6, levator 

 angidi scapuhe ; c, acromion ; 

 d, deltoid muscle, of which 

 tlie back part has been de- 

 taclied from the scapida and 

 in part removed ; c, rhomboid 

 muscle ; /, teres major ; [/, la- 

 tissimus dorsi ; 1, the brachial 

 plexus of nerves as seen from 

 behind ; 1', the nerve of the 

 levator scapuke and rhomboid 

 muscles ; 2, placed on the 

 clavicle, marks the supra- 

 scapular nerve ; 3, its branch 

 to the supraspinixtus muscle ; 



4, branch to the infr.ispinatus ; 



5, placed on the back of the 

 humerus below the insertion 



of the teres minor, marks the circumflex nerve passing out of the quadrangular interval ; 



6, its branch to the teres minor muscle : 7, branches to the deep surface of the deltoid ; 

 S, cutaneous branch to the back of the shoulder. 



Posterior thoracic nerve. — The posterior thoracic nerve (nerve of the serra- 

 tus magnus; external respiratory of Bell) is fonned m the substance of the middle 

 scalenus muscle by two roots, one from the fifth and another from the sixth 

 nerve, and reaches the sui'face of the scalenus lower than the nerve of the rhom- 

 l)oid muscles, with which it is often connected. It descends behind the brachial 

 plexus on the outer surface of the serratus magnus, nearly to the lower border of 

 that muscle, supplying it with numerous branches. 



Suprascapular nerve. —The suprascapular nerve arises from the back of the 

 cord formed by the union of the fifth and sixth nerves, and bends beneath the 

 trapezius to the upper border of the scapula, whete it passes between the muscles 

 and the bone. Entering the supraspinous fossa of the .scapula, through the 

 suprascapular notch (beneath the ligament which crosses the notch), the supra- 

 scapular nerve supplies two branches to the supraspinatus, one near the upper, 

 the other near the lower part of the muscle, and it then descends through the 

 great scapular notch into the lower fossa, where it ends in the infraspinatus 

 muscle. 



Articular branches. — In the upper fossa of the scapula, a slender articular 

 filniii'-nt is given to the shoulder-joint, and in the lower fossa other twigs of the 

 nerve enter the same joint and the substance of the scapula. 



Varieties. — The communicating branch to the phrenic nerve has been seen 

 to pass down into the thorax over the subclavian artery and even over the vein 

 before joining with the phrenic. The posterior thoracic nerve sometimes gets an 

 additional branch from the seventh 'cervical, and Lucas has recorded three 



