278 INTERNAL CAROTID ARTERY. 



The Vidian branch passes backwards along the pterygoid canal, 

 and is distributed to the sheath of the Vidian nerve, and to the Eus- 

 tachian tube. 



INTERNAL CAROTID ARTERY. 



The internal carotid artery curves slightly outwards from the 

 bifurcation of the common carotid, and then ascends nearly perpen- 

 dicularly through the maxillo-pharyngeal space* to the carotid fora- 

 men in the petrous bone. It next passes inicards along the carotid 

 canal, forwards by the side of the sella turcica, and upwards by the 

 anterior clinoid process, where it pierces the dura mater and divides 

 into three terminal branches. The course of this artery is remark- 

 able from the number of angular curves which it forms ; one or two 

 of these flexures are sometimes seen in the cervical portion of the 

 vessel near to the base of the skull ; and by the side of the sella tur- 

 cica 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 inter- 

 nal 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 lingual 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. 



Internally. 

 Pharynx, 

 Tonsil, 



Ascending pharyn- 

 geal artery. 



Internal 

 Carotid Artery. 



Externally. 

 Jugular vein, 

 Glosso-pharyngeal, 

 Pneumogastric, 

 Lingual 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. 



* For the boundaries of this space see page 166. 



