THE HEAD AND NECK H65 



Muscles of the Face. 



Orbicularis Palpebrarum^Orbital Portion — Origin. — (i) The inner 

 part of the internal tarsal ligament ; (2) the outer surface of the 

 nasal process of the superior maxilla ; and (3) the internal angular 

 process of the frontal bone. 



Insertion. — ^This corresponds to the origin, there being no attach- 

 ment to the outer part of the orbit. 



Palpebral Portion — Origin. — ^The upper and lower surfaces of the 

 internal tarsal ligament. 



Insertion. — ^The upper and lower surfaces of the external tarsal 

 ligament. 



Nerve-supply. — ^The facial nerve. 



Action — Orbital Portion. — (i) The upper half depresses the 

 eyebrow, and antagonizes the frontalis muscle ; (2) the lower 

 half elevates the skin of the infra-orbital region. Palpebral 

 Portion. — ^This closes the eyelids, as in winking, the upper lid 

 being depressed and the lower raised, the former movement 

 being more free than the latter. Through means of its con- 

 nection with the internal tarsal ligament the palpebral portion 

 draws forwards the front part of the lachrymal sac, and so con- 

 tributes to the removal of the tears. When the entire muscle con- 

 tracts the lids are forcibly closed, and drawn slightly inwards. 



The upper part of the muscle is related by its deep surface to the 

 frontalis, the supra-orbital vessels and nerve, and the supratrochlear 

 nerve. The chief deep relations of the lower part are the levator 

 labii superioris, and, beneath that, the infra-orbital nerve. 



Internal Tarsal Ligament. — ^This is also called the tendo ociili, or 

 tendo palpebrarum. It is attached internally to the outer surface 

 of the nasal process of the superior maxilla, immediately in front 

 of the lachrymal groove. Its direction is outwards in front of the 

 lachrymal sac, and it bifurcates at the inner canthus, the divisions 

 diverging, and taking attachment to the inner extremities of the 

 tarsal plates. As the ligament passes in front of the lachrymal 

 sac it is in intimate contact with that sac, and it gives origin to 

 the palpebral portion of the orbicularis palpebrarum, which ex- 

 plains the action of that portion of the muscle upon the lachrymal sac. 



External Tarsal Ligament. — ^This is attached externally to the 

 frontal process of the malar bone. Its direction is inwards, and it 

 bifurcates at the outer canthus, the divisions taking attachment 

 to the outer extremities of the tarsal plates. 



Tensor Tarsi {Muscle of Horner) — Origin. — ^The crest of the 

 lachrymal bone, behind the lachrymal sac. 



Insertion. — By means of two slips into the inner extremities of 

 the tarsal plates, where the fibres become continuous with the 

 ciliary ftbres of the orbicularis palpebrarum. 



Nerve-supply. — ^The facial nerve. 



The direction of the muscle is outwards and forwards, and its 

 (two slips pass behind the lachrymal canals. 



