270 



MUSCLES AND FASCIAE. 



Fig. 159. Dissection of the Muscles of the Back. 



length of the upper border of the spine of the scapula; the inferior fibres converge 

 near the scapula, and are attached to a triangular aponeurosis, which glides over 



a smooth surface at the inner extremity of 

 the spine, and is inserted into a tubercle 

 in immediate connection with its outer 

 part. The Trapezius is fleshy in the 

 greater part of its extent, but tendinous 

 at its origin and insertion. At its occipital 

 origin, it is connected to the bone by a 

 thin fibrous lamina, firmly adherent to the 

 skin, and wanting the lustrous, shining 

 appearance of aponeurosis. At its origin 

 from the spines of the vertebrae, it is 

 connected by means of a broad semi- 

 elliptical aponeurosis, which occupies the 

 space between the sixth cervical and the 

 third dorsal vertebras, and forms, with 

 the aponeurosis of the opposite muscle, a 

 tendinous ellipse. The remaining part of 

 the origin is effected by numerous short 

 tendinous fibres. If the Trapezius is dis- 

 sected on both sides, the two muscles 

 resemble a trapezium, or diamond-shaped 

 quadrangle ; two angles, corresponding to 

 the shoulders; a third, to the occipital 

 protuberance; and the fourth, to the 

 spinous process of the last dorsal ver- 

 tebra. 



The clavicular insertion of this muscle 

 varies as to the extent; of its attachment; 

 it sometimes advances as far as the middle 



of the clavicle, and may even become blended with the posterior edge of the 

 Sterno-mastoid, or overlap it. This should be borne in mind in the operation for 

 tying the third part of the subclavian artery. 



Relations. By its superficial surface, with the integument to which it is closely 

 adherent above, but separated below by an aponeurotic lamina. By its deep sur- 

 face, in the neck, with the Complexus, Splenius, Levator anguli scapulas, and 

 Khomboideus minor ; in the back, with the Rhomboideus major, Supra-spinatus, 

 Infra-spinatus, a small portion of the Serratus posticus superior, the intervertebral 

 aponeurosis which separates it from the Erector spinse, and with the Latissimus 

 dorsi. The spinal accessory nerve passes beneath the anterior border of this 

 muscle, near the clavicle. The outer margin of its cervical portion forms the 

 posterior boundary of the posterior triangle of the neck, the other boundaries 

 being the Sterno-mastoid in front, and the clavicle below. 



The ligamentum nuchse (fig. 160) is a thin band of condensed cellulo-fibrous 

 membrane, placed in the line of union between the two Trapezii in the neck. It 

 extends from the external occipital protuberance to the spinous process of the 

 seventh cervical vertebra, where it is continuous with the supra-spinous ligament. 

 From its anterior surface a fibrous slip is given off to the spinous process of 

 each of the cervical vertebras, excepting the atlas, so as to form a septum between 

 the muscles on each side of the neck. In man, it is merely the rudiment of an 

 important elastic ligament, which, in some of the lower animals, serves to sustain 

 the weight of the head. 



The Latissimus Dorsi is a broad flat muscle, which covers the lumbar and 

 lower half of the dorsal regions, and is gradually contracted into a narrow fasci- 

 culus at its insertion into the humerus. It arises by an aponeurosis from the 

 spinous processes of the sixth inferior dorsal, from those of the lumbar and sacral 



