_a_, Obliquus capitis anterior; _b_, obliquus capitis posterior; _c_,
rectus capitis lateralis; _d_, rectus capitis anterior minor; _e_,
rectus capitis anterior major; _f_, longus colli; _g_, _g′_,
scalenus; _h_, transversalis costarum; _i_, longissimus dorsi; _k_,
spinalis et semispinalis; _l_, multifidus dorsi; _m_, multifidus
cervicis; _n_, intertransversales; _o_, _o′_, rectus capitis
posterior major; _p_, rectus capitis posterior minor; _q_, tendon of
insertion of complexus; _1_, lamellar part, _1′_, funicular part of
ligamentum nuchæ; _2_, occipital crest; _3_, paramastoid process;
_4_, edge of wing of atlas; _5_, transverse, and _6_, articular,
processes of cervical vertebræ; _7_, nerves of brachial plexus
(cut); _8_, first rib. (Ellenberger-Baum, Anat. d. Haustiere.)
]
_Structure._—The muscle is fleshy and may be divided into two parallel
portions, superficial and deep. The former blends somewhat with the
terminal part of the complexus. The deep portion may be termed the
rectus capitis posterior medius.
_Relations._—Superficially, the anterior oblique, splenius, and
complexus; internally, the ligamentum nuchæ; deeply, the atlas, the
occipito-atlantal articulation, and the rectus capitis posterior minor.
The dorsal branch of the first cervical nerve appears between this
muscle and the small oblique.
_Blood-supply._—Occipital artery.
_Nerve-supply._—Dorsal branch of the first cervical nerve.
12. =Rectus capitis posterior minor= (s. dorsalis minor) (small
posterior straight muscle of the head).—This small muscle lies under
cover of the preceding.
_Origin._—The dorsal surface of the atlas.
_Insertion._—The occipital bone beneath the preceding muscle.
_Action._—To assist the preceding muscle.
_Structure._—It is fleshy and varies a good deal in volume, being
sometimes small and difficult to recognize.[44] On the other hand, it is
sometimes double.
_Relations._—Superficially, the preceding muscle and the small oblique;
deeply, the atlas and the occipito-atlantal articulation.
_Blood-supply._—Occipital artery.
_Nerve-supply._—Dorsal branch of the first cervical nerve.