28 THE POCKET ANATOMY 



INFRA-HYOID REGION. 



Sterno-hyoid : posterior surface of sternum, clavicle and 

 intervening ligament (F) lower border of body of hyoid bone 

 (A) (ist, 2nd and 3rd cervical through ansa hypoglossi). 

 [Depresses hyoid bone.] 



Sterno-thyroid : posterior surface of sternum, cartilage of 

 ist rib(F) oblique line on side of thyroid cartilage(p) (ist, 

 2nd and 3rd cervical through ansa hypoglossi). [Depresses 

 thyroid cartilage.] 



Thyro-hyoid : oblique line on side of thyroid cartilage(p) 

 internal half of greater cornu and outer part of body of 

 hyoid bone(p) (ist and 2nd cervical). [Depresses hyoid on 

 thyroid.] 



Omo-hyoid: upper border of scapula behind notch, and 

 transverse ligament(A) lower part of body of hyoid bonefp) 

 (ist, 2nd and 3rd cervical through ansa hypoglossi). [A de- 

 presses hyoid, B very feebly raises shoulder.] 



Consists of two bellies united by an intervening tendon. The 

 tendon and posterior belly is bound down to clavicle and cartilage of 

 ist rib by a process of deep cervical fascia. 



SUPRA-HYO1D REGION. 



Digastric : Posterior belly. Groove on internal surface of 

 mastoid process(p). Anterior belly. Posterior surface of in- 

 ferior maxilla, by side of symphysis(p) intervening tendon 

 (T), which is bound down to hyoid bone by process of deep 

 cervical fascia (anterior, Mylo-hyoid of inferior dental ; 

 posterior, Facial). [With posterior belly fixed and hyoid 

 bone depressed, it depresses mandible; with the lower jaw 

 fixed, it raises hyoid.] 



Stylo-hyoid : posterior aspect of styloid process near root(x) 

 body of hyoid bone at union of great cornu and body(x) 

 (Facial) . [Raises and draws back hyoid bone, and so tongue.] 

 Perforated by tendon of digastric. 



Mylo-hyoid : mylo-hyoid ridge on inner surface of inferior 

 maxilla(F) middle of body of hyoid bone(T), and joins fellow 

 in median line(A) (Mylo-hyoid of inferior dental). [A raises 

 and draws forwards hyoid under mandible ; B depresses jaw.] 



Parts beneath the mylo-hyoid: sublingual and part of sub- 

 maxillary gland, with Wharton's duct; genio-hyoid, genio- 

 hyo-glossus, hyo-glossus, stylo-glossus muscles, sublingual and 

 ranine arteries ; gustatory, and hypoglossal nerves ; sub- 

 maxillary ganglion . 



