343 MUSCLES AND FASCIAE. 



fibres into the upper margin of the acromion process, and into the whole 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 at the outer part of the surface. 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 aponeu- 

 rosis. At its origin from the spines of the vertebrse, it is connected to the 

 bones by means of a broad semi-elliptical aponeurosis, which occupies the space 

 between the sixth cervical and the third dorsal vertebrse, and forms, with the 

 aponeurosis of the opposite muscle, a tendinous ellipse. The rest of the muscle 

 arises by numerous short tendinous fibres. If the Trapezius is dissected on 

 both sides, the two muscles resemble a trapezium, or diamond-shaped quad- 

 rangle; two angles corresponding to the shoulders; a third to the occipital 

 protuberance; and the fourth to the spinous process of the last dorsal vertebra. 



The clavicular insertion of this muscle varies as to the extent of its attach- 

 ment ; 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 surface, in the neck, with the Complexus, Splenius, Levator Anguli Sca- 

 pulae, and Rhomboideus Minor; in the back, with the Rhomboideus Major, 

 Supraspinatus, Infraspinatus, a small portion of the Serratus Posticus Superior, 

 the vertebral aponeurosis (which separates it from the Erector Spinas) and 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. 227) 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 supraspinous 

 ligament. From its anterior surface a fibrous slip is given off to the spinous 

 process of each of the cervical, vertebrae, 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 

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

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

 the spinous processes of the six inferior dorsal, from those of the lumbar and 

 sacral vertebrae, and from the supraspinous ligament. Over the sacrum, the 

 aponeuroses of this muscle blends with the tendon of the Erector Spinae. It 

 also arises from the external lip of the crest of the ilium, behind the origin of 

 the External Oblique, and by fleshy digitations from the three or four lower 

 ribs, which are interposed between similar processes of the External Oblique 

 muscle (Fig. 230). From this extensive origin the fibres pass in different 

 directions, the upper ones horizontally, the middle obliquely upwards, and the 

 lower vertically upwards, so as to converge and form a thick fasciculus, which 

 crosses the inferior angle of the scapula, and occasionally receives a few fibres 

 from it. The muscle then curves around the lower border of the Teres Major, 

 and is twisted upon itself, so that the superior fibres become at first posterior 

 and then inferior, and the vertical fibres at first anterior and then superior. It 



