DISSECTION OF THE BACK. 



Parts 

 beneath 



latissimus. 



Second 



muscular 



layer. 



Levator 

 anguli 

 scapuhe : 



relations 



and use 



on scapula, 



on the neck 



Rhomboid 

 muscles. 



Small 

 muscle. 



Large 

 muscle : 



origin ; 

 insertion ; 



relations. 



In the interval between the last rib and the iliac crest the 

 latissimus is adherent to the aponeurosis of the transversal is 

 abdominis muscle, and should not be detached from it. 



Parts covered by the latissimus. The latissimus dorsi lies on the 

 erector spinse, the serratus posticus inferior, the lower ribs with 

 their intercostal muscles, and the lower angle of the scapula, with 

 parts of the rhomboideus major, infraspinatus, and teres major 

 muscles. Nearer the humerus it turns round the teres major, and 

 is placed in front of that muscle at its insertion. In passing from 

 the chest to the arm, the latissimus forms part of the posterior 

 boundary of the axilla. 



The SECOND LAYER OP MUSCLES (fig. 3, c, D, E), comprising 

 the elevator of the angle of the scapula, and the large and small 

 rhomboid muscles are now to be examined, as well as the posterior 

 belly of the omohyoid muscle, the suprascapular artery and nerve, 

 and the transverse cervical artery and its branches, already referred 

 to (p. 7). 



The LEVATOR ANGULI SCAPULA (fig. 3, c) arises by tendinous 

 slips from the posterior tubercles of the transverse processes of the 

 upper four cervical vertebrae. The fibres form an elongated muscle, 

 which is inserted into the base of the scapula between the spine and 

 the superior angle (fig. 12, p. 32). 



At its origin the levator lies beneath the sterno-mastoid, and, at its 

 insertion, beneath the trapezius, where it meets the serratus magnus 

 muscle ; the rest of the muscle appears in the posterior triangular 

 space of the neck. Beneath it are some of the other cervical muscles, 

 viz., splenius colli and cervicalis ascendens. 



Action. The muscle raises the angle and hinder part of the 

 scapula, and depresses the acromion ; but in combination with the 

 upper fibres of the trapezius, which prevent the rotation down of 

 the acromion, it shrugs the shoulder. 



When the shoulder is fixed, the neck can be bent to the side by 

 the levator. 



RHOMBOIDEI MUSCLES. The muscular layer of the rhomboidei 

 is attached to the base of the scapula, and consists of two pieces, 

 large and small, which are usually separated by a slight interval. 



The RHOMBOIDEUS MINOR (fig. 3, D) is a thin narrow band, which 

 arises from the spines of the seventh cervical and first dorsal vertebrae, 

 and the ligamentum nuchee, and is inserted into the base of the 

 scapula, opposite the smooth surface at the root of the spine (fig. 12). 



The RHOMBOIDEUS MAJOR (fig. 3, E) is much larger than the 

 preceding muscle. It arises from the spines of four or five dorsal 

 vertebrae below the rhomboideus minor, and from the supraspinous 

 ligaments ; and its fibres are directed outwards and downwards to be 

 inserted into the base of the scapula between the spine and the lower 

 angle (fig. 12). Sometimes the upper fibres are not fixed to the 

 scapula directly, but end on a tendinous arch passing down the bone. 



The rhomboidei are for the most part covered by the trapezius 

 and latissimus ; but a portion of the larger muscle is subcutaneous 

 near the scapula. 



