_Relations._—Laterally with the vertebræ. Inferiorly with the intertransversales. Superiorly with the longus colli posticus, and externally with the skin. _Action._—Flexes one vertebra on the other laterally. =Longus Colli Anterior= (Fig. 19, No. 13). (Synonym.—Longus colli ventralis.) _Location._—Occupies the anterior portion of the neck. _Origin and Insertion._—This muscle is divided into a vertical portion, and a superior and an inferior oblique portion. The vertical portion originates from the hypophyses of the tenth to the fifteenth vertebra and is inserted by a tendon to the tubercle on the inferior portion of the atlas. Small, slender tendons are given off and insert to the apices of the parapophyses of the fourth to the tenth cervical vertebræ. There is more or less attachment to the bodies of the cervical vertebræ mentioned. The superior oblique portion originates from the diapophyses of the third, the fourth, the fifth cervical vertebræ and becoming tendinous is inserted to the tubercle on the inferior portion of the body of the atlas. The inferior oblique portion originates from the transverse processes of the fourth, the fifth, and the sixth cervical vertebræ. It is inserted by a slender tendon to the apex of the parapophysis of the third cervical vertebra. _Shape._—A long fleshy muscle extending the entire length of the neck. _Relations._—Inferiorly with the skin and superiorly with the cervical vertebræ. _Action._—Pulls the neck downward. =Rectus Capitis Lateralis= (Fig. 19, No. 17). _Location._—The infero-lateral anterior portion of the neck. _Origin._—Originates tendinous from the diapophysis of the third, the fourth, and the fifth cervical vertebræ. _Insertion._—Passes obliquely upward in front of the spinal column to the inner tubercle on the basal ridge of the basi-temporal bone, by a subcompressed tendon. _Shape._—A somewhat thick fasciculus. _Relations._—Superiorly with the trachelo-mastoideus, inferiorly with the longus colli anterior, and externally with the skin. _Action._—Singly, pulls the head down and to one side; acting with its fellow, pulls the head downward. =Trachelo-mastoideus= (Fig. 19, No. 16). (Synonym.—Longissimus capitis et atlantis.) _Location._—Laterally on the anterior portion of the neck. _Origin._—Semitendinous from the diapophyses of the second, the third, the fourth, and the fifth cervical vertebræ. _Insertion._—By subcompressed tendon to the base of the cranium, at the outer tubercle of the basal ridge of the basi-temporal. _Shape._—Flattened from side to side; broad at the posterior portion, becomes angular at the anterior portion. _Action._—Singly, pulls the head down and to one side; acting with its fellow, pulls the head downward. =Interspinales= (Fig. 17, _A_, No. 2). _Location._—Superior to the vertebra. _Origin and Insertion._—A series of muscles connecting the superior neural spines of the cervical vertebræ. _Shape._—Thin, flat.