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INTERNAL CAROTID ARTERY. 



are sometimes seen in the cervical portion of the vessel near the base 

 of the skull ; and by the side of the sella turcica it resembles the italic 

 letter s, placed horizontally. 



Relations. In consideration of its connections, the artery is divi- 

 sible into a cervical, petrous, cavernous, and cerebral portion. The 

 Cervical portion is in relation posteriorly with the rectus anticus 

 major, sympathetic nerve, pharyngeal and laryngeal nerves which 

 cross behind it, and near the carotid foramen with the glosso-pharyn- 

 geal, pneumogastric and lingual nerves, and partially with the internal 

 jugular vein. Internally it is in relation with the side of the pharynx, 

 the tonsil, and the ascending pharyngeal artery. Externally with the 

 internal jugular vein, glosso-pharyngeal, pneumogastric, and hypoglossal 

 nerves ; and in front with the stylo-glossus, and stylo-pharyngeus 

 muscle, glosso-pharyngeal nerve, and parotid gland. 



Plan of the relations of the cervical portion of the internal carotid 

 artery. 



In Front. 

 Parotid gland, 

 Stylo-glossus muscle, 

 Stylo-pharyngeus muscle, 

 Glosso-pharyngeal nerve. 



Behind. 



Superior cervical ganglion, 

 Pneumogastric nerve, 

 Glosso-pharyngeal, 

 Pharyngeal nerve, 

 Superior laryngeal nerve, 

 Sympathetic nerve, 

 Rectus anticus major. 



The Petrous portion is separated from the bony wall of the carotid 

 canal by a lining of dura mater ; it is in relation with the carotid 

 plexus, and is covered in by the Casserian ganglion. 



The Cavernous portion is situated in the inner wall of the cavernous 

 sinus, and is in relation by its outer side with the lining membrane of 

 the sinus, the sixth nerve, and the ascending branches of the carotid 

 plexus. The third, fourth, and ophthalmic nerves are placed in the 

 outer wall of the cavernous sinus, and are separated from the artery 

 by the lining membrane of the sinus. 



The Cerebral portion of the artery is enclosed in a sheath of the 

 arachnoid, and is in relation with the optic nerve. At its point of 

 division it is situated in the fissure of Sylvius. 



