DISSECTION OF THE HEAD AND NECK 275 



(aca) Frontal nerve (N. frontalis). 



(acb) Lacrimal nerve (N. lacrimalis) . 

 (ace) Nasociliary nerve (N. nasociliaris) . 



Through what openings does the N. maxillaris 

 leave the skull? Find the meningeal branch (N. 

 meningeus (medius)). Through what openings 

 does the N. mandibularis leave the skull? Observe 

 its relation to the ramus meningeus accessorius of 

 the A. meningea media. 



(b) Oculomotor nerve (N. oculomotorius) (0. T. N. cerebralis III.). 



(ba) Superior branch (ramus superior). 



(bb) Inferior branch (ramus inferior). 



(c) Trochlear nerve (N. trochlearis) (0. T. nervus patheticus; N. cere- 



bralis IV.). 



(d) Abducent nerve (N. abducens) (0. T. N. cerebralis VI.). 



(e) Cavernous plexus of sympathetic (plexus cavernosus). 



(f) Larger superficial petrosal nerve (N. petrosus superficialis major). 



(g) Smaller superficial petrosal nerve (N. petrosus superficialis minor). 



ORBIT. 



Removal of Roof of Orbit (Facies superior orbitae). 



Chisel away the thick bone forming the cranial wall above 

 the aditus orbitae, but leave unbroken the supraorbital margin 

 (mar go supraorbitalis). Remove carefully the whole of the thin 

 roof of the orbit (paries superior). With bone-forceps cut away 

 that part of the ala parva of the sphenoid bone which forms the 

 superior orbital fissure (fissura orbitalis superior) (0. T. sphe- 

 noidal fissure). Cut away the processus clinoideus anterior. 

 The periosteum of the paries superior is now exposed ; note its 

 continuity with the dura mater through the superior orbital 

 fissure. Cut through it sagittally midway between the lateral 

 and medial walls of the orbit and also transversely near the 

 anterior margin of the paries superior. Reflect the two halves 

 medialward and lateral ward respectively. Grasp the front of 

 the bulbus oculi with forceps, pull it forward, and fasten to the 

 nose by means of needle and thread passed through the tunica 

 conjunctiva bulbi. Avoid perforation of the eyeball proper. 



Frontal Nerve (N. frontalis). 



Find it lying upon the upper surface of the M. levator pal- 

 pebrae superioris. Clean it and the upper surface of the muscle, 

 avoiding, in front, the A. supraorbitalis. Study the following 

 branches of the N. frontalis : 



