522 ANATOMY IN A NUTSHELL. 



Origin. — The origin of the posterior belly is from the digastric groove of 

 the mastoid process of the temporal bone. The origin of the anterior holly is 

 from the fossa on the inner surface of the inferior maxillary bone near the 

 symphysis. 



Insertion.- Into its central tendon, which is held to the body of the hyoid 

 bone by the supra-hyoid aponeurosis. 



Action. — To raise the hyoid bone and tongue, to depress the lower jaw 

 and assist in opening the mouth. 



Nerve Supply. — The posterior belly receives the facial nerve, while the 

 anterior belly receives the mylo-hyoid branch of the inferior dental nerve. 



Blood Supply. — Facial artery, occipital artery, and posterior auricular 

 artery. 



8. Retrahens aurem, — 



Origin.- From the mastoid process of the temporal hone. 



1 nsertk in.- Into concha of ear. and Lower part of cranial surface. 



Action. To km rad the pinna. 



Nerve Supply.— Posterior auricular branch of die facial nerve. 



Blood Supply. — Branches from posterior auricular. 



9. Stylo-pharyngeus. — Description. — This muscle, which extends from 

 the styloid process of the temporal hone to die pharynx, is a long slender mus- 

 cle, rounded above and broad and thin below. The stylo-pharyngeus nerve in 

 passing to the tongue lies on die outer side of this muscle. 



Origin.- From the inner side and base of styloid process. 



Insertion.- Into the Consl ictor muscles, Palato-pharyngeus muscle, and 

 the posterior border of die thyroid cartilage. 



Action. - To elevate and widen die pharynx. 



Nerve Si pply. Glosso-pharyngeal. 



Blood Supply, ts same as die blood supply to die pharynx, which is 

 found mi page 315. 



K). Stylo-hyoid. — Description. — This muscle is perforated near its in- 

 sertion by the tendon of die Digastric muscle. It is situated in front of and 

 above die posterior belly of die Digastric. 



Origin.- From the styloid process of the temporal hone near its base. 



Insertion, tnto the body of die hyoid b ■. 



Action. Ii elevates and retracts the hyoid hone. 



Nerve Supply.- facial. 



Blood Si pply. Same a- Digastric muscle. 



11. Stylo-glossus. Im -i ription.- This is the shortesl and smallest of the 

 Styloid muscles. 



Origin, from the anterior and external surface of the styloid process 

 near its apex, and from the stylo-hyoid ligament by a thin aponeurosis. 



Insertion, into the sides of the tongue, and entering the dorsum of the 

 tongue blends with the Lingualis muscle in front of the Hyo-glossus muscle, 

 and its oblique portion passes over the Hyo-glossus muscle and decussates with 

 its fibers. 



