_Blood-supply._—Occipital artery. _Nerve-supply._—Facial nerve. 4. =Genio-hyoideus.=—This is a long, spindle-shaped muscle, which lies under the tongue in contact with its fellow of the opposite side (Fig. 243). _Origin._—The angle of union of the rami of the mandible. _Insertion._—The extremity of the lingual process of the hyoid bone. _Action._—It draws the hyoid bone and tongue forward. _Structure._—The muscle arises by a short tendon, which is succeeded by the belly, composed of long bundles of parallel fibers. _Relations._—Below, the mylo-hyoideus; above, the hyo-glossus, stylo-glossus, genio-glossus, the sublingual gland, submaxillary duct, and the lingual nerve. _Blood-supply._—Sublingual artery. _Nerve-supply._—Hypoglossal nerve. 5. =Kerato-hyoideus.=—This small triangular muscle lies in the space between the thyroid and small cornu, under cover of the hyo-glossus (Fig. 243). _Origin._—The posterior edge of the small cornu and the adjacent part of the ventral border of the great cornu. _Insertion._—The dorsal edge of the thyroid cornu. _Action._—It raises the thyroid cornu and the larynx. _Relations._—The muscle is crossed outwardly by the lingual artery. _Blood-supply._—Lingual artery. _Nerve-supply._—Glosso-pharyngeal nerve. 6. =Hyoideus Transversus.=—This is a thin, unpaired muscle, which extends transversely between the two small cornua of the hyoid bone. _Attachments._—The small cornua close to the junction with the great cornua. _Action._—When relaxed, its upper surface is concave; when it contracts, it elevates the root of the tongue. _Structure._—Fleshy, composed of parallel transverse bundles. _Blood-supply._—Lingual artery. _Nerve-supply._—Glosso-pharyngeal nerve. 7. =Sterno-thyro-hyoideus=, and 8. =Omo-hyoideus.=—These are described with the muscles on the ventral surface of the neck. THE FASCIÆ AND MUSCLES OF THE NECK It is convenient to divide the muscles of the neck into ventral and lateral groups, the two lateral groups being separated from each other by the ligamentum nuchæ. THE FASCIÆ OF THE NECK The =superficial fascia= is in part two-layered, and contains the cervical portion of the panniculus. The fasciæ of the right and left sides are attached along the dorsal line of the neck to the ligamentum nuchæ, while along the ventral line they meet in a fibrous raphé. A deep layer is detached which passes underneath the panniculus, bridges over the jugular furrow, and crosses over the deep face of the mastoido-humeralis and omo-hyoideus to join the superficial layer. It again separates to pass under the cervical trapezius, and become attached to the ligamentum nuchæ. Along the ventral line a septum is detached which separates the sterno-cephalici. Two other layers in front of the shoulder inclose the prescapular lymph glands.