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LATERAL MUSCLES OF NECK 233 



Action. — Acting together, to extend the neck; acting singly, 

 to flex and rotate the neck to the opposite side. 



Structure. — The muscle is composed of two sets of bundles. 

 The superficial bundles are, directed obliquely forward and 

 inward, each passing from an ■ articular process to the spine 

 of the preceding vertebra. The deep bundles are shorter and 

 run straight from an articular process to that of the preceding 

 vertebra. 



Relations. — Superficially, the complexus, longissimus, tra- 

 chelo-mastoideus, and great ol^lique muscles; deeply, the 

 spinalis muscle, the ligamentum nuchip, and the arches of the 



Blood-supply. — Deep cervical and vertebral arteries. 

 Nerve-supply. — Dorsal Ijranches of the last six cervical 

 nerves. 



8. Spinalis. — ^Deseribed with the longissimus on p. 237. 



9. Obliquus capitis posterior (s. caudalis) (great oblique 

 muscle of the head). — This is a strong, quadrilateral muscle, 



M •- 2. 



r: ^. ^ -f I which covers the dorso-lateral aspect of the atlas and axis 



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Origin. — The side of the spine and the posterior articular 

 ^ 5 ■= 2 . ^ g 2 process of the axis. 

 S lis53<^-^:5 Insertion. — Tlu^ dorsal surface of the wing of the atlas. 



s g'ltlt-n^ Action. — Chiefly to rotate the atlas, and with it the head, 



fa -c " .i||^"-3 to the same side; also to assist in extending and fixing the 

 S c ^. i "- f ^--< atlanto-axial joint. 



o s I I 71 a o 2 Structure. — ^The muscle is composed almost entirely of 



.» -s^s^l^ parallel fleshy fi})ers directed ol)liquely forward and outward. 



H « Relations. — Superficially, the skin, the splcnius, complexus, 



trachelo-mastoideus, and mastoido-humeralis muscles; deeply, 

 the arch and spine of the axis, the wing of the atlas, the 



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;a ^ "=;■ -^ I % "^ atlanto-axial joint, the multifidus cervicis, the posterior 



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straight muscles, the occipital and vertebral vessels, and the 

 first and second cervical nerves. The terminal part of the 

 vertebral artery joins the posterior branch of the occipital 

 artery under cover of the muscle. 



Blood-supply. — Occipital and vertebral arteries. 

 Nerve-supply. — Dorsal l)ranch of the second cervical nerve. 

 I oo" S I i 10. Obliquus capitis anterior (s. cranialis) (small oblique 



i >; I ^ c muscle of the head). — A short, thick, quadrilateral muscle which 

 lies on the side of the occipito-atlantal articulation. 



Origin. — The anterior edge of the wing of the atlas and the 

 - t -^ ;^ -i .2 p fossa atlantis. 



I - = ;§ I I J Insertion. — The styloid process and crest of the occipital 



^Z ^■'^,'s ^ 'i bone, and the mastoid process. 



iC i I ^. o I V,- Action. — Acting together, to extend the head on the atlas; 



I I =r 1 1 ^ I acting singly, to flex the head laterally. 



Structure. — The muscle contains a good deal of tendinous 

 tissue. The direction of its fibers is forward, upward, and inward. 

 gl's Relations. — Superficially, the posterior auricular muscles, 



■^ J S I J S3 artery, and nerve, the aponeurosis of the splenius, trachelo- 

 o "i I .| > 1^' 2 mastoideus and mastoido-humeralis, and the parotid gland; 

 deeply, the straight muscles, the complexus, the occipito- 

 hyoideus, the occipito-atlantal articulation, branches of the 

 occipital artery, and a branch of the occipital nerve. 



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