430 THE MUSCLES AND FASCIAE 



of aponeuroses. At its origin from the spines of the vertebrae 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 vertebrae, 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 quadrangle ; 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; by its deep 

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

 Rhomboideus minor ; in the back, with the Rhomboideus major, Supraspinatus, 

 Infraspinatus, and Vertebral aponeurosis (which separates it from the prolongations- 

 of the Erector spinae), and the Latissimus dorsi. The spinal accessory nerve and 

 the superficial cervical artery pass beneath the anterior border of this muscle, 

 near the clavicle. The anterior 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 nuchae (Fig. 287) 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 lamina is given off, which is attached 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 aponeurosis 

 of this muscle blends with the posterior layer of the lumbar fascia. 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. 292, 

 page 449). From this extensive origin the fibres pass in different directions, the 

 upper ones horizontally, the middle obliquely upward, and the lower vertically 

 upward, 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 then terminates in a short 

 quadrilateral tendon, about three inches in length, which, passing in front of the 

 tendon of the Teres major, is inserted into the bottom of the bicipital groove of 

 the humerus, its insertion extending higher on the humerus than that of the 

 tendon of the Pectoralis major. The lower border of the tendon of this muscle is 

 united with that of the Teres major, the surfaces of the two being separated by a 

 bursa ; another bursa is sometimes interposed between the muscle and the inferior 

 angle of the scapula. This muscle at its insertion gives off an expansion to the 

 deep fascia of the arm. 



A muscular slip, varying from 3 to 4 inches in length, and from \ to of an inch in breadth, 

 occasionally arises from the upper edge of the Latissimus dorsi about the middle of the posterior 



