THE MUSCLES OF THE ORBIT 171 



the orbicularis) rises from the glabella, and passes up and 

 out to end at the middle of the orbital arch in the orbicularis 

 and skin of the eyebrow. 



The levator palpebrce superior will be described with the 

 orbital muscles. 



Actions. Palpebral part closes the lids; upper half of the 

 orbital part depresses the eyebrow and opposes the frontalis, 

 used in forcible closure of the lids; in common winking the 

 palpebral part carries forward the internal palpebral ligament 

 and anterior wall of the lacrymal sac, and sucks in tears; the 

 pars lacrymalis (tensor tarsi) probably alternates with the 

 palpebral part, draws back the palpebral ligament, and com- 

 presses the sac. The corrugator produces vertical wrinkles at 

 the inner end of the eyebrow. 



THE MUSCLES OF THE FACE 



Only one of these, the buccinator, will be described. All 

 the others are unimportant. 



M. buccinator (trumpet muscle), a flat layer forming a large 

 part of the wall of the mouth; attached at the upper and lower 

 margins to the alveoli of the maxillary bones opposite the 

 molar teeth, posteriorly to the pterygomaxillary ligament, 

 separating it from the superior constrictor of the pharynx, 

 fibers become thickened at the angle of the mouth and join 

 the orbicularis; higher and lower fibers are directed to corre- 

 sponding lips, middle ones decussate, the upper to the lower 

 lip, the lower to the upper lip. 



Nerve supply is from the facial. 



Action is to flatten the cheek, keep food between the teeth, 

 and to expel air from the mouth. 



THE MUSCLES OF THE ORBIT 



There are seven for description. The M. levator palpebrce 

 superioris (origin, above the optic foramen and superior rectus) 

 ends in a membranous expansion; inserted into the fibrous 

 tarsus of the upper eyelid. 



The four straight muscles have a continuous tendinous origin 



