HEAD AND ANTERIOR CERVICAL STRUCTURES. 13 



The Cranial Nerves: 



Fourth, or trochlear nerve, 793. (775) 



Passes through the dura mater a little behind the posterior clinoid process. 

 It passes through the outer wall of the cavernous sinus, lying below the 

 third nerve and above the first division of the fifth, and then runs forward 

 through the sphenoidal fissure, passing above the third nerve. 



Fifth, or trigeminal nerve, 794. (776) 



The fifth nerve passes through an aperture in the dura mater under the free 

 border of the tentorium at the apex of the petrous portion of the temporal 

 bone. It consists of two parts a larger or sensory root, and a smaller or 

 motor. Upon its sensory root is developed a large ganglion, the Gasserian 

 ganglion ; the motor root passes below and is not connected with it. From 

 this ganglion proceed the three primary divisions of the nerve, the ophthal- 

 mic, maxillary, and mandibular. 

 Gasserian ganglion, 795. (777) 



Ophthalmic division of the fifth nerve, 795. (777) 

 Maxillary division of the fifth nerve, 797. (780) 

 Mandibular division, 801. (783) 



Sixth, or abducent nerve, 805. (787) 



The sixth nerve pierces the dura mater behind the body of the sphenoid 

 bone, which it grooves. It then passes along the inner wall of the caver- 

 nous sinus, external to the internal carotid artery, and enters the orbit 

 through the sphenoidal fissure. 



Seventh, or facial nerve, 806. (788) 



Passes outward through the meatus auditorius internus. 



Eighth, or auditory nerve, 811. (792) 



Passes outward through the internal auditory meatus with the facial. It is 

 the larger of the two nerves, and lies below the facial. 



Ninth, or glosso-pharyngeal nerve, 813. (794) 



Tenth, or pneumogastric nerve, 815. (796) 



Eleventh, or spinal accessory nerve, 819. (800) 



The three nerves pass through the jugular foramen, the ninth in front of the 

 pneumogastric, the eleventh behind it. 



Twelfth, or hypoglossal nerve, 820. (801) 



Passes through the anterior condyloid foramen. 



The sinuses should now be demonstrated. Trace each, laying it open with the point of the knife. 



Venous sinuses of the cranium, 656-7-8-9-60-1. (643-5-6-7-8) 

 Inferior longitudinal or inferior sagittal sinus. 

 Straight sinus, or sinus rectus. Torcular Herophili. 

 Occipital sinus, marginal sinuses. 

 Lateral sinus. Transverse sinus. Sinus jugularis. Sigmoid sinus. 



Right lateral sinus. Left. 

 Cavernous sinus : 



In front. Internally. Posteriorly. 

 Circular sinus, or intercavernous sinuses. 



Anterior, posterior, inferior, etc. 

 Superior petrosal sinus. 

 Inferior petrosal sinus. 

 Transverse or basilar sinus. 

 Spheno-parietal sinus, or sinus alae parvae. 

 Petro-sqtiamous sinus. 



The cranial sinuses, 711. (695) 

 Larger system : 



Superior longitudinal, inferior longitudinal, straight, occipital, petrosal. 



Torcular Herophili. Lateral sinuses. 

 Smaller system: 



Spheno-parietal, cavernous, circular, transverse, inferior petrosal sinuses. 

 Emissary veins, 711, 1116. (695, 1093) 



