The _insertion_ is onto the transverse processes of all the cervical
vertebræ, including the axis and atlas. According to Strauss-Durckheim
the fibres from any given transverse process are inserted into the
transverse processes of all the vertebræ craniad of it.
The muscle is partly continuous craniad with the longus capitis (_e_).
The cervical nerves pass out between the bundles of the cervical
portion.
_Relations._--Outer (lateral) surface in the thoracic region with the
external oblique (Fig. 68, _p_), the pectoralis minor (Fig. 65, _o_),
and in part with the serratus anterior (Fig. 73, _i_); in the cervical
region with the sternomastoid (Fig. 65, _g_). Inner (medial) surface
with the serratus anterior (Fig. 73, _i_), the levator scapulæ (Fig. 73,
_h_), the longus atlantis, the transverse processes of the cervical
vertebræ, and the longus capitis (Fig. 73, _e_).
_Action._--Flexes the neck and draws the ribs craniad.
=M. longus capitis= (or =rectus capitis anterior major=) (Fig. 72, _a_;
Fig. 73, _e_).--This is a long muscle lying on the ventral aspect of the
cervical vertebræ. With the muscle of the opposite side and the
underlying longus colli (Fig. 72, _g′_) it forms a trough in which lie
the œsophagus, pharynx, and trachea.
_Origin_ by five (or six) heads from the ventral margins of the
transverse processes of the cervical vertebræ from the second to the
sixth inclusive. The heads unite into a common belly, the lateral border
of which is united with the levator scapulæ ventralis (Fig. 72, _c_)
near its insertion.
_Insertion_ into the body of the sphenoid bone between the bulla and the
middle line. The insertion extends craniad onto the basisphenoid.
_Relations._--Ventral surface with the sternomastoid (Fig. 65, _g_) and
the large lymphatic gland ventrad of the external ear. Lateral surface
with the scalenus (Fig. 72, _h_) and craniad with the levator scapulæ
ventralis (Fig. 72, _c_-_c″_). Medial surface with the carotid artery,
the trachea, œsophagus, and pharynx. Dorsal edge with the vertebræ, the
longus colli (Fig. 72, _g′_), and the rectus capitis anterior minor
(Fig. 72, _b_).
_Action._--Lowers the snout.
=M. rectus capitis anterior minor= (Fig. 72, _b_).--This is a flat band
beneath (dorsad of) the longus capitis (_a_).
_Origin_ from the ventral surface of the inferior arch (body) of the
atlas (3) for about five millimeters laterad of the middle line.
_Insertion_ into a deep depression on the basioccipital caudad of the
insertion of the longus capitis (_a_) and between the caudal end of the
bulla (1) and the median line.
_Relations._--Ventral surface with the longus capitis (_a_). Dorsal
surface with the anterior (ventral) atlanto-occipital membrane (2).
_Action._--Depresses the snout.
[Illustration: FIG. 72.--MUSCLES ON THE VENTRAL SURFACE OF THE
CERVICAL VERTEBRÆ.
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