, .MM/. FOREARM, HAND. POSTERIOR 1'ART. 361 



lip of the scapular spine and acromioii, and into the posterior OUter one-third 

 of the clavicle. (Fig. 252.) 



3. Describe tlie circiunjlex nerve. 



It is a branch of the posterior cord of the brachial plexus. (Fig. 42.) It 

 passes through the circumflex quadrangular space, to the back of the shoulder. 

 It gives muscular branches to the deltoid and teres minor muscles, anil cutaneous 

 branches to the skin covering tin- insertion of these muscles and articular 

 bran, lies to the shoulder-joint. (Hilton's la\\ . ) 



Suprn-eplnatua 



i'H- A-citgiitl'ir artery 



Hhomboldcus minor 

 Levator auguli scapula 



Deltoid, innertlon 

 Deltoid 



Deltoid muBdo 



\ I 



Trapeclua \ Triceps 



Rhomboldeua major 



Terea major muscles 



Terea major, insertion 



Dorsalu icapulte artery Posterior circitmjti-j: artery 



FIG. 254. THE DORSAL SCAPULAR ARTERY. 

 (From a dissection in the Museum of the Royal College of Surgeons.) 



4. Describe the suproscafmlar nerve. 



A branch of the upper trunk of the brachial plexus. (Fig. 42.) It passes 

 through the constant suprascapular foramen. It gives muscular branches to 

 (i) the supraspinatus, (2) the infraspinatus, and articular branches from each 

 muscular branch, to the shoulder-joint. (Hilton's law.) 



5. Describe the intisciilo-spiral nerve. 



It is a branch of the posterior cord of the brachial plexus. (Fig. 42.) It 

 may be found on the floor of the second triangular space. (Fig. 249.) It passes 

 between the two humeral heads of the triceps in the musculo-spiral groove of the 

 humerus. It lies between the brachialis anticus and brachio-radialis muscles in the 

 lower third of the arm. It gives muscular branches to the triceps and anconeus 

 24 



