_Shape._—A long, rather thick fasciculus. _Relations._—With the stylo-hyoideus and cerato-hyoideus. _Action._—Protrudes the tongue from the mouth. =Cerato-hyoideus= (Fig. 9, No. 8). (Synonym.—Kerato-hyoideus.) _Location._—Inferior to the hyoid apparatus. _Origin._—By a delicate tendinous slip from the under side of the shaft of the basi-hyal element of the hyoid apparatus. _Insertion._—To a small elevation on the under side of the anterior end of the glosso-hyal. _Shape._—A small round muscular fasciculus becoming tendinous in its anterior half. _Relations._—Superiorly with the hyoid apparatus. _Action._—Singly, pulls the tongue to one side; acting with its fellow, depresses the tongue. =Sterno-hyoideus.= _Location._—Inferior to the hyoid apparatus. _Origin._—From the outer anterior surface of the thyroid bone of the superior larynx. _Insertion._—To the anterior part of the basi-hyal. _Shape._—At first broad and rather fleshy, becomes contracted and somewhat tendinous. _Relations._—Inferior to the hyoid apparatus and superior larynx. _Action._—When the larynx is fixed, acting alone deflects the tongue laterally; acting with its fellow, depresses the tongue. If the base of the tongue is fixed the two pull the larynx forward. Hence muscles of deglutition. =Depressor-glossus.= _Location._—Superior to the basi-hyal. _Origin._—From the under portion of the basi-hyal. _Insertion._—To under part of the glosso-hyal. _Shape._—Small, short. _Relations._—Superiorly with the basi-hyal and glosso-hyal bones. _Action._—Depresses the tip of the tongue and elevates the base. =Cerato-glossus.= _Location._—On the upper portion of the cornu of the hyoid. _Origin._—One-half of the surface of the first basi-branchial. _Insertion._—To the upper side of the shaft of the cerato-branchial element of the hyoid apparatus. _Shape._—A small muscular fasciculus. _Relations._—Supero-laterally to the cerato-branchial element. _Action._—Elevates the cornua of the hyoid arches and presses them against the skull. =Hyoideus Transversus= (Fig. 9, No. 9 and 10). _Location._—Envelops the spur process of the euro-hyal. _Origin and Insertion._—It extends from the inner side of one cornu to the spur process. _Shape._—Thin, flat. _Relations._—Posterior to the euro-hyal, which it envelops, and between the cornua of the os hyoides. _Action._—Approximates the cornua of the os hyoides. THE CERVICAL MUSCLES