The inner or prevertebral group consists of the greater and lesser rectus capitis anticus and the longus colli.

Longus capitis muscle (Rectus capitis anticus major muscle)

The rectus capitis anticus major — named from its direction, position, and size — is a thick, irregular, quadrilateral sheet.

Origin

The front of the anterior tubercles of the third, fourth, fifth, and sixth cervical vertebrae.

Insertion

A transverse impression upon the under surface of the basilar process of the occipital bone, extending from just behind the pharyngeal tubercle outwards and somewhat forwards.

Structure

Arising by four tendinous teeth, the parallel fleshy fibres run pwards and inwards to be inserted directly upon the occipital bone. An incomplete tendinous intersection crosses its anterior surface.

Nerve-supply

Internal branches from the first and second cervical nerves enter the upper part of its front surface.

Action

To flex the head, and slightly to rotate it to the same side.

Relations

In front, the internal and common carotid artery, the internal jugular vein, the pneumogastric and sympathetic nerves, and the upper part of the pharynx; behind, the rectus capitis anticus minor and part of the longus colli.

Rectus capitis anterior muscle (Rectus capitis anticus minor)

The rectus capitis anticus minor — named from its direction, position, and size — is thick and ribbon-shaped and continues the series of the anterior intertransversales.

Origin

The upper surface of the lateral mass of the atlas in front of the articular process.

Insertion

The under surface of the basilar portion of the occipital bone in out of the foramen magnum, but not as far inwards as the preceding muscle.

Structure

Parallel or slightly divergent fleshy fibres which run upwards and wards.

Nerve-supply

The first cervical nerve, which sends a filament to its front surface.

Action

To flex the head.

Relations

In front, the rectus capitis amicus major; behind, the anterior occipitoaxial ligament.

Longus colli muscle

The longus colli — named from its length and the region in which it lies — is a compound muscle, and forms an elongated triangular sheet with the base running vertically along the outer border of the anterior common ligament, and the obtuse apex directed outwards. It consists of three portions: one mesial, the vertical; and two lateral, the upper and lower oblique portions.

Vertical portion

Origin

Lateral part of the front of the bodies of the last two cervical and first three thoracic vertebra, external to the anterior common ligament.

Insertion

Lateral part of front of the bodies of the second, third, and fourth cervical vertebrae.

Lower oblique portion:

Origin

The side of the front of the bodies of the first three thoracic vertebrae.

Insertion

The front of the anterior tubercles of the transverse processes of the fifth and sixth cervical vertebrae.

Upper oblique portion

Origin

The front of the anterior tubercles of the transverse processes of the third, fourth, and fifth cervical vertebrae.

Insertion

The under surface and front of one side of the anterior tubercle of the atlas.

Structure

All three portions arise by short tendons, then become fleshy, and are inserted by short tendons, with the exception of the superior oblique portion, which has a fleshy attachment to the tubercle of the atlas.

Nerve-supply

The anterior branches from the cervical nerves soon after their emergence.

Action

To flex the neck; and also by its oblique portions slightly to rotate and laterally flex it.

Relations

In front, the pharynx, oesophagus, great vessels of the neck, the inferior thyroid artery, the sympathetic cord, the pneumogastric nerve, and the current laryngeal nerve; behind, the vertebral column, and, under cover of the lower oblique portion, the vertebral artery.

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