144 



MUSCLES OF THE HEAD AND NECK. 



intestinal canal, bladder, and internal organs of generation. At the 

 commencement of the alimentary canal in the resophagus, and 

 near its termination in the rectum, the muscular coat is formed by 

 a blending of the fibres of both classes. The heart is developed 

 from the middle, or vascular layer of the germinal membrane ; and 

 although involuntary in its action, is composed of ultimate fibres 

 having the transverse striae of the muscle of animal life. 



The muscles, may be arranged in conformity with the general 

 division of the body into, 1. Those of the head and neck. 2. 

 Those of the trunk. 3. Those of the upper extremity. 4. Those 

 of the lower extremity. 



1. MUSCLES OF THE HEAD AND NECK. 



The muscles of the head and neck admit of a subdivision into 

 those of the head and face, and those of the neck. 



Muscles of the Head and Face. These muscles may be divided 

 into groups corresponding with the natural regions of the head and 

 face ; the groups are eight in number, viz. 



1. Cranial group. 5. Superior labial group. 



2. Orbital group. 6. Inferior labial group. 



3. Ocular group. 7. Maxillary group. 



4. Nasal group. 8. Auricular group. 



The muscles of each of these groups may be thus arranged 



1. Cranial group. 

 Occipito-frontalis. 



2. Orbital group. 



Orbicularis palpebrarum, 

 Corrugator supercilii, 

 Tensor tarsi. 



3. Ocular group. 



Levator palpebrse, 

 Rectus superior, 

 Rectus inferior, 

 Rectus internus, 

 Rectus externus, 

 Obliquus superior, 

 Obliquus inferior. 



4. Nasal group. 



Pyramidalis nasi, 

 Compressor nasi. 



5. Superior labial group. 

 (Orbicularis oris), 



Levator labii superioris aleeque 

 nasi, 



Levator labii superioris pro- 



prius, 



Levator anguli oris, 

 Zygomaticus major, 

 Zygomaticus minor, 

 Depressor labii superioris alse- 



que nasi. 



6. Inferior labial group. 



(Orbicularis oris),* 

 Depressor labii inferioris, 

 Depressor anguli oris, 

 Levator labii inferioris. 



7. Maxillary group. 



Masseter, 

 Temporalis, 

 Buccinator, 

 Pterygoideus externus, 

 Pterygoideus internus. 



8. Auricular group. 

 Attolens aurem, 

 Attrahens aurem, 

 Retrahens aurem. 



* The orbicularis ori?, from encircling the mouth, belongs necessarily to both the 

 superior and inferior labial regions ; it is therefore enclosed within brackets in both. 



