THE MUSCLES OF THE HYOID BONE. 



459 



thyreoid cartilage ; (2) supra-hyoid muscles, connecting it to the mandible, cranium, 

 and tongue ; and (3) the middle constrictor muscle of the pharynx (p. 464). 



The infra-hyoid muscles, comprise the omo-hyoid, sterno-hyoid, sterno- thyreoid, 

 and thyreo-hyoid muscles. 



M. Omohyoideus. The omo-hyoid is a muscle with two bellies, anterior and 

 posterior. The posterior belly arises from the superior margin of the scapula and 

 the superior transverse scapular ligament (Fig. 333, p. 372). It forms a narrow 

 muscular band, which passes obliquely forwards and upwards, and ends in an 

 intermediate tendon beneath the sterno-mastoid muscle. 



From this tendon the anterior belly proceeds upwards, to be inserted into the 

 lateral part of the inferior border of the body of the hyoid bone. 



The posterior belly of the muscle separates the posterior .triangle into occipital 

 and subclavian parts ; the anterior belly crosses the common carotid artery at the 



STYLOGLOSSUS 



V \ GEN 10- 

 GLOSSUS 



-A- HYOGLOSSUS 

 GENIO-HYOID 



MYLO-HYOID 

 ' DIGASTRIC (anterior belly) 



.STERNO-THYREOID 

 STERNO-HYOID 



FIG. 408. THE MUSCLES OF THE TONGUE AND HYOID BONE (right side). 



level of the cricoid cartilage, and in the anterior triangle forms the boundary 

 between the muscular and carotid triangles. A process of the deep cervical fascia 

 binds down the tendon and the posterior belly to the clavicle and the first rib. 



M. Sternohyoideus. The sterno-hyoid muscle arises from the posterior 

 surface of the manubrium, from the back of the first costal cartilage, and from the 

 clavicle (Fig. 327, p. 366). 



It passes vertically upwards in the neck, medial to the omo-hyoid and anterior 



the sterno-thyreoid muscle, to be inserted into the medial part of the body of 

 the hyoid bone. " Except near its origin, which is covered by the sternum, clavicle, 

 and sternal head of the sterno-mastoid, the muscle is superficially placed. 



M. Sternothyreoideus. The sterno-thyreoid muscle arises beneath the 

 sterno-hyoid from the back of the manubrium and first costal cartilage. 



Broader than the preceding muscle, it passes upwards, and slightly in a lateral 

 .rection in the neck, in front of the trachea and thyreoid gland, and deep to the 

 rno-mastoid, omo-hyoid, and sterno-hyoid muscles. It is inserted into the oblique 



sterno 



