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5d. The Anterior Vertebral Muscles
FIG. 387 - The anterior vertebral muscles. The anterior vertebral muscles (Fig. 387). are: Longus colli. Rectus capitis anterior. Longus capitis. Rectus capitis lateralis. The Longus colli is situated on the anterior surface of the vertebral column, between the atlas and the third thoracic vertebra. It is broad in the middle, narrow and pointed at either end, and consists of three portions, a superior oblique, an inferior oblique, and a vertical. The superior oblique portion arises from the anterior tubercles of the transverse processes of the third, fourth, and fifth cervical vertebræ and, ascending obliquely with a medial inclination, is inserted by a narrow tendon into the tubercle on the anterior arch of the atlas. The inferior oblique portion, the smallest part of the muscle, arises from the front of the bodies of the first two or three thoracic vertebræ; and, ascending obliquely in a lateral direction, is inserted into the anterior tubercles of the transverse processes of the fifth and sixth cervical vertebræ. The vertical portion arises, below, from the front of the bodies of the upper three thoracic and lower three cervical vertebræ, and is inserted into the front of the bodies of the second, third, and fourth cervical vertebræ. The Longus capitis (Rectus capitis anticus major), broad and thick above, narrow below, arises by four tendinous slips, from the anterior tubercles of the transverse processes of the third, fourth, fifth, and sixth cervical vertebræ, and ascends, converging toward its fellow of the opposite side, to be inserted into the inferior surface of the basilar part of the occipital bone. The Rectus capitis anterior (Rectus capitis anticus minor) is a short, flat muscle, situated immediately behind the upper part of the Longus capitis. It arises from the anterior surface of the lateral mass of the atlas, and from the root of its transverse process, and passing obliquely upward and medialward, is inserted into the inferior surface of the basilar part of the occipital bone immediately in front of the foramen magnum. The Rectus capitis lateralis, a short, flat muscle, arises from the upper surface of the transverse process of the atlas, and is inserted into the under surface of the jugular process of the occipital bone. Nerves.—The Rectus capitis anterior and the Rectus capitis lateralis are supplied from the loop between the first and second cervical nerves; the Longus capitis, by branches from the first, second, and third cervical; the Longus colli, by branches from the second to the seventh cervical nerves. Actions.—The Longus capitis and Rectus capitis anterior are the direct antagonists of the muscles at the back of the neck, serving to restore the head to its natural position after it has been drawn backward. These muscles also flex the head, and from their obliquity, rotate it, so as to turn the face to one or the other side. The Rectus lateralis, acting on one side, bends the head laterally. The Longus colli flexes and slightly rotates the cervical portion of the vertebral column.
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