MUSCLES OF THE HEAD. 



accompanied by a lateral movement, during which the extremity of the jaw 

 is earned to the opposite side. 



5. Difjastricuf. 



KII/HW. Iloiinrelat lias made two distinct muscles of this the dignstriens ami 

 : laxillari-. (iinnl has described it as the fctylo-maxillaris. (IVrchall has 

 evidently followed Uoiir-relat's example. and divided the muscle into digiulricut and 

 Leyh adopts the same course.) 



Form Sti-iK-tur,' Situation Din-rtion. Composed of two fleshy bodies 



more or less divided by intersections, and united at their extremities by a 



median tendon, this muscle is situated in the intermaxillary space, and 



Is from the occiput to near the symphysis of the chin, describing a 



curve upwards. 



Aftm-lnni'iit*. It takes its origin from the styloid process of the occipital 

 Ixiiii , by its superior fleshy body. It terminates : 1, On the curved portion 

 of thr posterior border of the lower jaw by a considerable fasciculus, which 

 is detueheil from the superior fleshy body; 1 2, On the internal face of the 

 s:uue !>< me and the straight portion of its posterior border, by aponeurotic 

 digitations which succeed the muscular fibres of the inferior fleshy body. 



Relations. The superior belly of the muscle responds, superficially, to 

 the piirotid gland and the tendon of insertion of the sterno-maxillaris ; 

 deeply, to the guttural pouch, the submaxillary gland, and the larynx and 

 pharynx. The median tendon passes through the ring of the hyoideus 

 maguus. The lower belly is in contact, outwards, with the ramus of the 

 inferior maxilla ; inwards, with the mylo-hyoideus muscle. 



Action. When this muscle contracts, it acts at the same time on the 

 hyoid bone, which it raises in becoming straight, and on the lower jaw, 

 which it pulls backwards and depresses at the same time. 



C. Hyoideal Region. 



This region includes six muscles grouped around the os hyoides, which 

 tin v move. Five of these are pairs : the mi/Io-liyoideus, genio-Jtyoi<1>'>ix, xti/t<>- 

 ]ii/;<lmx, L-I i-nto li/nideiis, and the occipito styloideus. The single one is the 

 twmteerxuli* ]ti/iili i. 



1'rrparatinn. Sejarate the head from the trunk, and remove the muscles of the 



eh,-.!. '!e, with the parotid gland. 2. The branch of the. inferior maxilla In-ing 



i. it i- .-:I\MI through in two places; at first behind the last molar, then in 



:i. Ait- r having separated the pterygoids and the .siylo-maxillaris 



fpim tin- nppi r fragment or c-ondyle, and tin- coroiioid process, it is torn off by pulling 



it hark wards; then thcpterygnids and tin- digastricusare excised. 1. The inferior frairment 



nf tin- jaw In-aniii: the molar teeth in tunnel down by isolating the niyln-hyiden> I'nim the 



nun-Mil- iiieinbr.inc. ">. Carefully remove the tminue by sepnrating its extrinsic ninsoles 



from tin- ^eiiio-hyol 'ens, the anterior appendix of tlie hyuid Ixine, the trannvert-e muM-le, 



and the -mall hyoidi-n-. 



Th having leen |x-rformed in this manm r.the liru'e hy.. ideal branch may 



be K|'uriited from tin .-null, by sawing throu-Ji the hea.1 lon^itnd'inally, leuvinir tlii' 

 ymphyBifl menti intact, and turning down the oorreqpooding IHJf to the side ali-i ail\ 

 te<l, a- \vell a- th.- irn-at byoid branch, the pharynx, larynx, and .-...ft pal.,te. 



Situation Structure. A membranous muscle situated in the 

 intermaxillary space, flattened from side to side, elongated in the ilin i timi 



1 Ti.is is the fasciculus which Ilourgelat has described as a dit-tinct mncle. 



