DISSECTION OF THE UPPER EXTREMITY 51 



Broad Muscles of the Back (Second Layer). 



Make the rhomboid muscles tense and clean their surfaces 

 carefully. Find the trunk of the dorsal nerve of the scapula 

 (A 7 , dor sails scapulae] (O. T.. nerve to the rhomboids) and the 

 descending ramus of the transverse artery of the neck (A. trans- 

 versa colli) in the interval between the M. levator scapulae and 

 the M. rhomboideus minor. 



(a) Greater rhomboid muscle (M. rhomboideus major). 



(b) Lesser rhomboid muscle (M. rhomboideus minor). 



(c) Levator muscle of scapula (M. levator scapulae) (0. T. levator anguli 



scapulae). 



Establish the form, position, origin, insertion, action, and 

 innervation of each. Find the two rami of the cervical nerve on 

 the surface of the M. levator scapulae and then cut the muscle in 

 two in the middle. Eeflect the lower portion lateralward. Cut 

 through the attachments of the Mm. rhomboidei near the median 

 plane and reflect the muscles lateralward. Dissect out care- 

 fully- 



(a) Dorsal nerve of scapula (N. dorsalis scapulae). 



(b) Descending ramus of transverse artery of neck (ramus descendens 



A. transversae colli) (0. T. posterior scapular artery). 



Near the superior margin of the scapula expose the inferior 

 belly of the omohyoid muscle (venter inferior M. omoliyoidei}. 

 Define its exact attachment to the scapula. Note the relations 

 of the A. transversa scapulae (0. T. suprascapular artery) and 

 of the N. suprascapularis to the Lig. transversum scapulae 

 superius. 



The dissector of the arm may next assist the dissector of the 

 head in making out the muscles of the back. Study the form, 

 position, origin, insertion, action, and innervation of each. 



ANTERIOR THORACIC REGION AND AXILLARY 



FOSSA. 



Surface Anatomy. 

 Examine 



(a) Outline of clavicle. 



(aa) Shaft of clavicle. 



(ab) Sternal extremity (extremitas sternalis). 



(ac) Acromial extremity (extremitas acromialis). 



