936 



THE NERVOUS SYSTEM 



region, and the parietal region almost as far as the lambdoid suture (fig. 740). One branch 

 running at the upper margin of the orbital cavity unites with a branch of the facial nerve. 



The frontal branch, given off at a variable point, lies medial to the supra-orbital, passes 

 through the frontal foramen, and is distributed to the skin of the forehead and upper eyehd 

 (fig. 734). 



The supratrochlear branch runs forward and medialward toward the upper and medial 

 angle of the orbit, where it passes above the pulley of the superior obUque muscle, pierces the 

 palpebral fascia, and ascends to the lower and middle part of the forehead, accompanied by 

 the frontal arterj^ (fig. 734). Before it leaves the orbit it sends a branch downward behind or 

 in front of the pulley of the obliquus superior which joins with the infratrochlear nerve, and as 

 it leaves the orbit it gives off filaments to supply the skin and conjunctiva of the medial third 

 of the upper eyelid. Its terminal branches pierce the orbicularis and frontalis, and, as they pass 

 to the skin of the forehead, they communicate with branches of the facial nerve. 



(6) The lacrimal nerve [n. lacrimalis] is the smallest of the three branches of the 

 ophthalmic division. It passes through the superior orbital (sphenoidal) fissure 

 lateral to and slightly below the frontal nerve, and is directed forward and lateral- 



FiG. 734. — Nerves of the Orbit from 



Above and Behind. (Schematic.) 



Infratrochlear 

 1 Supratrochlear 

 j I Frontal branch of frontal 

 ! I i Supraorbital 



3^ 



Anterior 

 ethmoidal ^--~ 



Superior ob-^ 

 lique muscle^ 



Medial rectus— 



Posterior 

 ethmoidal 



Trochlear 

 Naso-ciliary_2" 

 (nasal) 

 Annular com- _ 

 mon tendon 

 of Zinn 

 Optic nerve — 



Levator palpebrae 



superioris 

 Superior rectus 

 Lacrimal gland 

 Frontal 



Short ciliary nerves 

 Anastomosing branch 



with zygomatic 

 Lacrimal 



Long ciliary nerves 

 Inferior rectus 

 Branch to internal 



oblique 

 Lateral rectus 

 Ciliary ganglion 

 Sympathetic 1 Roots of 

 Short \ ciliary 



Long J ganglion 



Abducens 

 Inferior branch of 



oculo-motor 

 Superior branch of 



oculo-motor 

 Lateral rectus (lat. 



head) 

 Ophthalmic 

 Mazillaiy 



TOy^n^'-— Mandibular 

 ^ v^Vffi — Foramen spinosum 



Dura mater 



ward, along the upper border of the rectus lateralis to the lacrimal gland (fig. 734). 

 On the lateral wall of the or])it it receives a small ])ranch from the zygomatic 

 nerve (the orbital branch of the maxillary nerve). This ])ranch brings to the 

 lacrimal nerve secretory fibres for the lacrimal gland. A small twig passes beyond 

 the gland, pierces the palpebral fascia, supi)lies filaments to the conjunctiva, and 

 is then distributed to the integument at the lateral angle of the eye and to the skin 

 over the zygoniatic i)ro('o.'^s of the frontal l)one. 



(c) The naso-ciliary (nasal) nerve enters the orbit between the two heads of the 

 rectus lateralis and between the superior and inferior ])ranches of the oculo-motor 

 nerve. In the orbit it lies at first lateral to the optic nerve, but, as it runs obliquely 

 forward and medialward to the medial wall of tlu^ orbital cavity, it crosses aV)Ove 

 the optic nerve and between it and the rectus superior, and near the ])order of the 

 rectus medialis it divides into its terminal branches, the chief of which are the 

 infratrochlear and anterior ethmoidal nerves (fig. 734). In addition to those 

 received from the cavernous plexus before the division of the ophthalmic nerve, 



