Part 22

Origin.—From the apices of the hyapophyses of the second, the third, and the fourth cervical vertebræ.

Insertion.—To the triangular area on the basi-temporal of the base of the cranium.

Shape.—At first tendinous, becomes somewhat fleshy as it passes forward.

FIG. 19.—Muscles of the head and neck. 1, Masseter muscle. 2, Infraorbital sinus. 3, Biventer maxilla. 4, Temporalis. 5, Complexus. 6, Rectus capitis posticus major. 7, Flexor capitis inferior. 8, Rectus capitis anticus minor. 9, Biventer cervicis. 10, Longus colli posticus. 11, Obliquus colli. 12, Intertransversales. 13, Longus colli anterior. 14, Lateral temporo-maxillary ligament. 15, Lateral ligament of the jaw. 16, Trachelo-mastoideus. 17, Rectus capitis lateralis. 18, Scalenus medius. 19, Rhomboideus. 20, Trapezius. 21, Location of scapula. 22, Supraspinatus. 23, Teres et Infraspinatus. ]

Relations.—Antero-inferior portion of the neck close to the rectus capitis anticus minor.

Action.—Flexes the head upon the neck.

=Rectus Capitis Posticus Major= (Fig. 19, No. 6). (Synonym.—Rectus capitis dorsalis major.)

Location.—Supero-lateral area on the anterior portion of the neck.

Origin.—From the median anterior aspect of the second cervical vertebra, and the supero-anterior border of the neural canal.

Insertion.—To the crescent-shaped area at the back of the skull.

Shape.—Short, thick, fleshy bundle.

Relations.—Superiorly with the complexus; inferiorly with the trachelo-mastoideus and the vertebræ.

Action.—Singly, pulls the head to one side; acting with its fellow, extends the head.

=Biventer Cervicis= (Fig. 19, No. 9). Location.—Occupies the superior part of the neck.

Origin.—From the side of the neural spine of the first dorsal vertebra, and from the adjacent tendon of the longus colli posticus.

Insertion.—To the occiput.

Shape.—Tendinous in the middle with a more or less spindle-shaped belly at each end.

Relations.—Superior to the longus colli posticus. It lies next to the skin.

Action.—Extends the head on the neck and elevates the neck.

=Longus Colli Posticus= (Fig. 19, No. 10). (Synonym.—Longus colli dorsalis.)

Location.—Occupies the superior part of the neck.

Origin.—From the marginal edges of the summits of the neural spines of the first two dorsal vertebræ.

Insertion.—To the transverse process of the axis, and superior part of the cervical vertebræ.

Shape.—A long, somewhat narrow, flattened muscle, the inferior portion of which is divided into five or six fasciculi.

Relations.—Superiorly with the biventer cervicis and inferiorly with the vertebræ.

Action.—Raises the neck upward.

=Obliquus Colli= (Fig. 19, No. 11). Location.—On the lateral side of the neck.

Origin and Insertion.—The first of the seven fasciculi originates from the diapophysis of the eleventh cervical vertebra, winds obliquely over the tenth, and is inserted into the posterior margin of the postzygapophysis of the ninth vertebra. In its passage it receives the slip from the longus colli posticus. The next fasciculus originates from the transverse process of the tenth cervical vertebra, winds obliquely over the ninth vertebra, and is inserted to the postzygapophysis of the eighth vertebra. In its passage it also receives a fasciculus from the longus colli posticus. The next three fasciculi originate in a similar manner being attached to similar postzygapophyses and have slips extending forward which slips are inserted to the neural spines of the alternate vertebræ. The sixth fasciculus originates from the transverse process of the sixth vertebra, passing obliquely up the neck is inserted to the extremity of the diapophysis of the fourth vertebra, the outer extremity of the transverse process of the third vertebra. The seventh, or anterior, fasciculus originates from the transverse process of the fifth vertebra, and is inserted to the extremity of the diapophysis of the third vertebra.