428 



THE MUSCLES AND FASCIAE 



Trachelo-mastoid. 

 Complexus. 

 Biventer cervicis. 

 Spinalis colli. 



FIFTH LAYER. 



Semispinalis dorsi. 

 Semispinalis colli. 

 Multifidus spinse. 



Rotatores spinae. 



Supraspinales. 



Interspinales. 



Extensor coccygis. 



Intertransversales. 



Rectus capitis posticus major. 



Rectus capitis posticus minor. 



Obliquus capitis superior. 



Obliquus capitis inferior. 



First Layer. 



Trapezius. j Latissimus dorsi. 



Dissection (Fig. 286). Place the body in a prone position, with the arms extended 

 over the sides of the table, and the chest and abdomen supported by several blocks, so as 



to render the muscles tense. Then make an incision 

 along the middle line of the back from the occipital 

 protuberance to the coccyx. Make a transverse incision 

 from the upper end of this to the mastoid process, and 

 a third incision from its lower end, along the crest of 

 the ilium to about its middle. This large intervening 

 space should, for convenience of dissection, be sub- 

 divided by a fourth incision, extending obliquely from 

 the spinous process of the last dorsal vertebra, upward 

 and outward, to the acromion process. This incision 

 corresponds with the lower border of the Trapezius 

 muscle. The flaps of integument are then to be re- 

 moved in the direction shown in the figure. 



The superficial fascia is exposed upon re- 

 moving the skin from the back. It forms a 

 layer of considerable thickness and strength, 

 in Avhich a quantity of granular pinkish fat is 

 contained. It is continuous with the super- 

 ficial fascia in other parts of the body. The 

 deep fascia is a dense fibrous layer attached to 

 the occipital bone, the spines of the vertebrae, 

 the crest of the ilium, and the spine of the 

 scapula. It covers over the superficial muscles, 

 forming sheaths for them, and is continuous, 

 in the neck at the anterior border of the Tra- 

 pezius, with the deep cervical fascia ; on the 

 thorax, with the deep fascia of the axilla and 

 chest, and on the abdomen with the fascia 

 covering the abdominal muscles. 



The Trapezius (Fig. 287) is a broad, flat, 

 triangular muscle, placed immediately be- 

 neath the skin and fascia, and covering the upper and back part of the neck and 

 shoulders. It arises from the inner third of the superior curved line of the occipital 

 bone ; from the ligamentum nuchse, the spinous process of the seventh cervical, 

 and those of all the dorsal vertebras ; and fr am the corresponding portion of the 

 supraspinous ligament. From this origin the superior fibres proceed downward 

 and outward, the inferior ones upward and outward, and the middle fibres 

 horizontally, and are inserted, the superior ones into the outer third of the 

 posterior border of the clavicle ; the middle fibres into the inner margin of the 

 acromion process, and into the superior lip. of the posterior border or crest of the 

 spine of the scapula ; the inferior fibres converge near the scapula, and terminate 

 in a triangular aponeurosis, which glides over a smooth surface at the inner extremity 

 of the spine, to be inserted into a tubercle at the outer part of this smooth surface. 

 The Trapezius is fleshy in the greater part of its extent, but tendinous at its origin 



FIG. 286. Dissection of the muscles of the 

 back. 



