328 THE MUSCULATURE 



of the first three cervical myotomes and are innervated by the first three cervical nerves through 

 the ansa hypoglossi. The primitive segmental origin of these muscles is frequently indicated 

 by transverse tendons (inscriptiones tendineae). They correspond morphologically with the 

 rectus abdominis musculature. 



The scalene group (fig. 352) lies at the side of the neck and extends to the first and 

 second ribs from the transverse processes of the lower six cervical vertebrae. The muscles of this 

 group bend the neck toward the side, or if the neck be fixed, elevate the thorax. They come 

 from the lateral parts of the ventro-lateral divisions of the lower five cervical myotomes and are 

 innervated by the lower five cervical nerves. They correspond morphologically with the 

 intercostal and with the lateral abdominal musculature. 



The prevertebral group hes back of the pharynx and oesophagus and in front of the bodies 

 and transverse processes of the cervical veitebrse. The muscles of this group arise not only 

 from the transverse processes and bodies of the cervical vertebrae, but also in part from the 

 bodies of the first three thoracic vertebrae, and are inserted in part into the cervical vertebrae 

 (/ongus coZii) and in part into the base of the occipital bone {longus capitis). This musculature 

 flexes the neck and the head. When acting on one side it rotates the head toward the same 

 side. It is innervated by the first six cervical nerves. 



The deep shoulder -girdle musculature. — This becomes differentiated from the ven- 

 tro-lateral divisions of the lowei five or six cervical myotomes. Like the muscles of the 

 superficial layer those of the deeper layer spread out widely from their origin. There are four 

 muscles in the deeper group, all of which become attached to the dorsal border of the scapula. 

 Of these, one, the levator scapuloe (fig. 353), remains in the cervical region, extending from 

 the upper cervical transverse processes to the medial angle of the scapula. Two, the rhomboids 

 (fig. 353), extend over the intrinsic dorsal musculature and are attached to the upper thoracic 

 and lower cervical vertebral spines; while the fourth, the serratus anterior (fig. 354), extends 

 over the side of the upper part of the thorax beneath the scapula and is attached to the first 

 nine ribs. These muscles all, however, through their innervation, reveal in the adult their 

 primitive cervical origin. They are supplied by branches from the third to the seventh cervical 

 nerves. The levator scapulae elevates the scapula, the rhomboid muscles retract it and the serratus 

 anterior draws it forward. The levator and rhomboid muscles rotate the shoulder girdle so 

 as to depress the shoulder, the serratus anterior, like the trapezius, rotates it so as to raise 

 the shoulder. The two former muscles are an aid in extending the arm, the latter in flexing 

 and abducting it. When the group, as a whole, contracts action is exerted on the ribs so that 

 the group is of use in forced inspiration. 



The intrinsic dorsal musculature of the neck, innervated by the dorsal divisions of the 

 cervical nerves, is separated from the scalene muscles by the levator scapulae. Dorsally it is 

 covered by the trapezius and the rhomboid muscles. It is to be looked upon as a specialized 

 portion of the system of intrinsic dorsal muscles which extend from the sacrum to the base of 

 the skull on each side of the vertebral column. The primary function of this muscle system 

 is to extend and to rotate the spine and the skull. In the thoracic region three main subdivi- 

 sions may be recogni.^ed, a lateral, the ilio-costal; an intermediate, the longissimus; and a medial, 

 the transverse-spinal gi'oup (fig. 381). In the cervical region these three groups may likewise 

 be recogni,-ed and, in addition, there is a superficial group, the splenius (fig. 380), not represented 

 in the lower thoracic region. The splenius arises from the upper thoracic and lower cervicla 

 spines and is inserted into the transverse processes of the upper cervical vertebrae and into the 

 mastoid processes of the temporal bone and the neighbouring part of the occipital. It acts with 

 the sterno-cleido-mastoid, by which it is crossed r.ear the head, in extending the head, bending 

 it toward the side, but tends to rotate it toward the same side instead of toward the opposite 

 side. Laterally beneath the splenius the ilio-costalis cervicis extends from the upper part 

 of the thorax to the transverse processes of the sixth to the fourth cervical vertebrae, and the 

 longissimus cervicis and capitis extend from the same region to the transverse processes of the 

 mid-cervical vertebrae and to the mastoid process of the temporal bone (fig. 381). These 

 muscles likewise extend and bend the head and neck laterally and rotate it toward the same 

 side. Medially on each side the strong semispinalis capitis (fig. 381), arises from the upper 

 thoracic and the lower cervical vertebrae, spreads out and is inserted into the squamous portion 

 of the occipital bone. It is a powerful extensor of the head. Beneath it numerous fasciculi 

 extend from the transverse proces-es to the spines of the cervical vertebrae. These fasciculi, 

 the more superficial of which are the longest, constitute the St.mispinales cervicis, multifidus, 

 and rotatores muscles. They extend and rotate the neck. 



Between the successive spines and the transverse process there are short muscles (inter- 

 spinales, interlransversares) . The rectus capitis anterior and the rectus capitis lateralis between 

 the transverse process of the atlas and the lateral part of the occipital belong with the latter 

 series. 



Between the base of the skull behind and the first two vertebrae there are four deep-seated 

 specialized muscles which constitute the suboccipital group (fig. 382). The rectus capitis 

 posterior major and minor sjiread out respectively frf)ni the spines of the atlas and epistroj)heu8 

 and are inserted beneath the inferior nuchal line of the occipital. The obliquus capitis inferior 

 arises from the spine of the epistropheus and is inserted into the transverse process of the 

 atlas; the ol)li</uvs cnpilis superior ari.ses from this and is inserted into the lateral part of the 

 inferior nuchal line of t he occijiital. These muscles extend and rotate the head. A detailed de- 

 scription of the intrinsic muscles of the back is given on page 410. 



The muscle fasciae in the head and neck are well developed in connection with most of 

 the grouj)8 of inu.sclcs except the facialis group and are described in detail in connection with 

 each of these groups. In the head we may here call attention merely to the dense temporal 

 fascia which covers over the temyjoral fossa and hides from view the temporal muscle. In 

 the neck the fascia; are of ronsideral)lc practical importance. It is convenient to think of them 

 as divisible into several layers althougli the various layers fu.se to some extent. The external 

 layer (fig. 350) maybe looked upon as completely ensheathing the neck and as dividing on each 



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