THE HEAD AND SECK 



"55 



The lachrymal nerve enters the orbit through the sphenoidal 

 fissure, above the muscles, and external to the frontal nerve. It 

 then passes forwards and outwards along the upper border of the 

 external rectus muscle, in company with the lachrymal arterj'. 

 On reaching the lachrymal gland it furnishes numerous branches 

 to its deep surface, and is then continued beneath it through the 

 superior palpebral ligament, to be distributed to the skin and con- 

 junctiva of the outer part of the upper eyelid, and the skin in the 

 region of the external angular process of the frontal bone. Near 

 the lachry-mal gland it sends downwards a small \\\ ig, which joins 

 the temporal branch of the orbital or temporo-malar nerve. 



Supia-orbital Nerve 

 (in two divisioDs) 



Supratrochlear Ner\ e 

 Infratrochlear of Naii. 



Olfactory Bulb. 

 Nasal Nerve. 



Optic Nerve. 



•Frontal Nerve on Levator 

 PalpebrjE Superioris 



Lachrymal Nerve passing 

 along External Rectus 



Ophthalmic Artery "' 



Third Nerve — — 



Foarth Nerve-' U v-^^r- 



/ VSF'v, '■ Gasserian Ganglion 

 Sixth Neni-e ' \ '■' ''■ Sensory Root of Fifth Nerve 



Motor Root of Fifth Nerve 



~-- Superior Maxillary Nerve 

 -.' '^^ ■" Ophthalmic Ne/v-e 

 ""•- Inferior Maxillary Nerve 



Fig. 470. — Dissection of the Orbit from above (Hirschfeld and 



Leveille). 



The nasal nerve is more deeply placed than the frontal and 

 lachr\Tnal. It enters the orbit through the sphenoidal fissure, and 

 passes bet\veen the two heads of the external rectus muscle, Ijong 

 between the upper and lower divisions of the third ner\'e. It then 

 passes obliquely inwards and forwards to the inner wall of the 

 orbit, lying beneath the superior rectus and above the optic nerve, 

 and subsequently betiveen the superior oblique and the internal 

 rectus. Having reached the inner wall of the orbit at the anterior 

 ethmoidal, or internal orbital, foramen it parts with its infratrochlear 

 branch, and then passes through that foramen, in company with the 

 anterior ethmoidal artery, and so enters the anterior fossa of the 

 base of the skull. It then passes forwards and inwards in a groove 

 on the upper surface of the cribriform plate of the ethmoid bone. 



