136' Anatomy of The Rabbit. 



(e) The rhomboideus minor. Origin : Ligamentum nuchae. 

 Insertion : Anterior two-thirds of the vertebral border of the 

 scapula. 



(f) The rhomboideus major. Origin: Spinous processes of the 

 first seven thoracic vertebrae. Insertion: Posterior third of 

 vertebral border. 



By dividing the rhomboidei the scapula may be displaced laterad. • 

 The operation is facilitated by dividing the latissimus dorsi, the re- 

 lations of which should, however, first be noted (2, a.). 



(g) The levator scapulae minor. Origin: Mastoid and supra- 

 occipital portions of the skull. Insertion : Medial surface of 

 the inferior angle of the scapula. 



(h) The serratus anterior. Origin in two portions : 



Cervical portion: Transverse processes of the posterior five 



cervical vertebrae and the anterior two ribs. 

 Thoracic portion: Third to ninth ribs by separate slips alter- 

 nating with those of the external oblique. 

 Common insertion : Medial surface of the vertebral border of the 

 scapula. 



The transverse artery of the neck (a. transversa colli) lies on the 

 medial side of the cervical portion. 



2. Muscles arising from the axial skeleton and the pectoral girdle and 

 inserted on the humerus, for the most part at its proximal extremity. 



(a) The latissimus dorsi. Origin: Lumbodorsal fascia and four 

 posterior ribs. Insertion: Humeral spine. A long flat 

 triangular muscle, covering a considerable portion of the 

 lateral surface of the thorax ; having its dorsal angle covered 

 by the thoracic portion of the trapezius. Its insertion end 

 passes to the medial side of the humerus. 



(b) The pectoralis primus (p. tenuis). Origin: Manubrium 

 sterni. Insertion: Humeral spine. 



A branch of the thoracoacromial artery appears between this muscle 

 and the deltoidens. 



(c) The pectoralis secundus (p. major). Origin: Entire lateral 

 portion of the sternum. Insertion : Anteromedial surface of 

 the humerus, beginning below the head, and extending to the 

 boundary between the middle and distal thirds. The anterior 

 fibres are covered by those of (b). Some of the posterior 

 fibres are inserted highest on the humerus. 



The two muscles should be separated and cut across. 



(d) The pectoralis tertius (p. minor). Origin consisting of two 

 portions.: 



First portion : Middle line of the sternum between the attach- 

 ments of the second to fourth ribs. 



Second portion : Manubrium sterni, extending to the level of 

 the first rib. 



Insertion : The superficial fibres of the first portion are attached 

 to the clavicle. The remaining fibres, combined with those 



