.",44 ANATOMY IX A XUTSHELL. 



intermaxillary region, Platysma myoides of the superficial cervical region, and 

 Buccinator of the intermaxillary region. 



Blood Supply. — Branches from the internal maxillary. 



LESSON CLXXXIV. 



1. Masseter muscle which has been described on page o'20. 



2. Internal pterygoid which has been described on page 529. 

 .!. External pterygoid which has been described on pane 529. 

 4. Temporal muscle which has been described on page 508. 



."). Genio-hyo-glossus. — Description. — This muscle is fan-shaped and 

 placed vertically on either side of the middle line of the jaw. The apex of this 

 muscle is at its point of attachment to the lower jaw and its base is its insertion 

 into the tongue and the hyoid hone. This muscle is more or less blended with 

 its fellow in front but separated from it behind. 



Origin. — From the superior genial tubercle on the inner side of the sym- 

 physis of the jaw. 



1 NSERTK in. Into the upper part of the body of the hyoid bone and median 

 line of the tongue, the side of the pharynx, and the entire length of the under 

 surface of the tongue. 



Action.— To retract and protrude the tongue. 



Xki;\ e Supply. — Hypoglossal. 



Blood Si pply. — Lingual. 



(>. Genio-hyoideus. — Description. — This muscle increases in breadth as 

 it pa>ses towards its insertion and lies close to its fellow. It is situated be- 

 neath the inner border of the Mylo-hyoid. 



Origin.— From the inferior genial tubercle of the lower jaw. 



Insertion. — Into the anterior surface of the body of the hyoid bone. 



A' tion. To lift and draw forward the hyoid bone. 



Nerve Supply. — Hypoglossal. 



Blood Supply. — Lingual. 



7. Mylo-hyoid. — 



Origin. — From the mylo-hyoid ridge of the lower jaw. 

 Insertion. Into the body of the hyoid bone and a median fibrous raphe 

 running in mid-line of the hyoid bone to the chin. 



V ii"\. Lift- the hyoid and draws it forward. 



N i i:\ i. Si pply.- -Mylo-hyoid branch of the inferior dental of the fifth. 



Blood Supply. Submental and mylo-hyoid arteries. 



8. Digastric muscle which has been described on page 521. 



9. Superior constrictor which has been described on page 515. 

 in. Depressor labii int'erioris, also called Quadratus menti. 



Origin. From the external oblique line of the inferior maxillary bone 

 below and internal to the mental foramen. 



Insertion. — Into the lower lip (facial pari of the Orbicularis oris). 



Action. To draw the lower lip down. 



Nerve Si pply. Supramaxillary branch of facial nerve. 





