DISSECTION OF THE HEAD AND NECK 297 



CAROTID AND INFRAORBITAL CANALS (CANALIS 

 CAROTICUS ET CANALIS INFRAORBITALIS). 



Carotid Canal (Canalis caroticus). 



Remove the inferior wall of the carotid canal with strong 

 forceps. Do not disturb the position of the Eustachian tube. 

 Inside the carotid canal study the following : 



(a) Internal carotid artery (A. carotis internet). (Cf. Spalteholz, Fig. 



442.) 



(aa) Caroticotympanic ramus (ramus caroticotympanicus) (0. T. 

 tympanic branch). 



(b) Venous plexus of internal carotid (plexus venosus caroticus internus). 



(c) Internal carotid nerve of sympathetic system (N. caroticus internus). 



(Cf. Spalteholz, Figs. 773 and 779.) 

 (ca) Internal carotid plexus (plexus caroticus internus). 



(caa) Deep petrosal nerve (N. petrosus profundus) (0. T. 

 large, deep petrosal nerve), which runs to the 

 pterygoid canal (0. T. Vidian canal) and unites 

 with the N. petrosus superficialis major to form 

 the nerve of the pterygoid canal (N. canalis ptery- 

 goidei [Vidii]) (0. T. Vidian nerve). 



Infraorbital Canal (Canalis inf raorbitalis) . 



Remove the M. temporalis and the upper head of the M. 

 pterygoideus externus ; saw through the squama temporalis and 

 the ala magna oss. sphenoidalis, beginning on the cut margin of 

 the skull just above the meatus acusticus externus and passing 

 obliquely downward and forward towards the medial end of 

 the fissura orbitalis superior (0. T. sphenoidal fissure). The 

 saw-cut should enter the fissura orbitalis superior just lateral 

 from the foramen rotundum. Make a second saw-cut from 

 the cut margin of the cranial wall, just above the anterior 

 margin of the ala magna oss. sphenoidalis, downward into the 

 fissura orbitalis superior, to meet the first saw-cut. Remove 

 the bone thus freed and with bone-forceps remove what remains 

 of the ala magna lateral from the foramen rotundum, keeping 

 intact, however, the entire bony margin of this aperture. Next 

 open the canalis inf raorbitalis with bone-forceps (or chisel if 

 necessary). Study the following: 



(a) Maxillary nerve (N. maxillaris) (0. T. superior maxillary). (Fig. 

 115, p. 274.) 



Trace it from the ganglion semilunare [Gasseri] to its 

 termination. 



