II30 



A MANUAL OF ANATOMY 



ment, platysma myoides, and deep cervical fascia. It rests upon 

 the mylo-hyoid muscle, and forms the lateral boundary of the sub- 

 mental triangle. Its inner border is connected with that of its 

 fellow by a fascial expansion. 



The posterior belly of the digastric, along with the stylo-hyoid muscle, like 

 the stapedius muscle, is associated with the posterior end of the second visceral, 

 or hyoid, arch. The nerve of this arch is the facial nerve, and this explains 

 the nerve-supply of the posterior belly. 



The anterior belly is associated with the anterior or mesial end of the first 

 visceral, or mandibular, arch. The nerve of this arch is the inferior maxillary 

 division of the fifth cranial, or trigeminal, nerve, and this explains the nerve - 

 supply of the anterior belly. 



Stylo-hyoid — Origin. — The posterior and outer aspect of the 

 styloid process of the temporal bone near its base. 



Mandible 



^:P-^ 



Mylo-hyoid 

 Muscle •-- 



Lingual Nerve 



.— Raph« 



Deep Part of Sub- _ 

 maxillary Gland 

 Post. Belly of Digastric — ' 

 Hypoglossal Nerve -- 

 Stylo-hyoid 



Body of Hyoid Bone ' i 



Depressor Muscles of Hyoid Bone 



Fig. 461B.— The Mylo-hyoid Region. 



Insertion. — The anterior surface of the hyoid bone at the junction 

 of the body and great comu. 



Nerve-supply. — The stylo - hyoid branch of the facial nerve, 

 which arises in common with the digastric branch. 



The muscle is directed downwards and forwards. 



Action. — To draw the hyoid bone upwards and backwards. 



The muscle Hes close above the posterior belly of the digastric, 

 and, before taking insertion, it usually spUts into two bundles, 

 which embrace the intervening tendon of the digastric. 



The stylo-hyoid muscle, along with the posterior belly of the digastric, like 

 the stapedius muscle, is associated with the posterior end of the second 

 visceral, or hyoid, arch. The nerve of this arch is the facial nerve, and this 

 explains the nerve-supply of this muscle. 



Mylo-hyoid — Origin. — The mylo-hyoid ridge, or internal oblique 

 line, of the infm^r^iiia'Xini.^r^'v^,, 



