THE INTERNAL CAEOTID AETEEY. 



901 



carotid artery for a short distance below, and afterwards the wall of the pharynx, the 



areolar tissue posterior to the wall of the pharynx, the ascending pharyngeal artery, the 



pharyngeal plexus of veins, and the external and internal laryngeal nerves. Just before 



it enters the temporal bone the levator palati muscle is to its medial side. Lateral or 



, superficial to it are the sterno-mastoid, skin, and fasciae, and it is crossed under cover 



of the sterno-mastoid, from below upwards, by the hypoglossal nerve, the occipital artery, 



, and the posterior auricular artery. It is also crossed superficially, between the last- 



: mentioned arteries, by the digastric and stylo-hyoid muscles, which separate it from the 



parotid gland, and below the digastric it is covered by the lower part of the postero-medial 



surface of the gland. Passing obliquely across its anterior lateral surface, and separating 



Vertebral arteries 



Internal carotid artery-. 



Ascending pharyngeal 



artery 



Ascending palatine artery 



Styloglossus muscle-. 

 Stylopharyngeus muscle 

 Posterior auricular artery. 



Occipital artery. 

 External maxillary artery- 

 Lingual arter; 

 External carotid artery 

 Superior thyreoid artery 



Frontal artery 

 Nasal artery 

 Ciliary arteries 



,1 max- 

 illary artery 



W 



Common carotid 

 artery 



'ertebral artery 



Deep 

 cervical artery 



Superior inter- / 

 costal artery_/L_ 



Anastomosis / 



with first 

 aortic inter- 

 :ostal artery 



communicating arteries 

 "-* cerebral arteries 



Thyreo-cervical trunk 

 Subclavian artery 

 Internal mammary artery 



Innominate artery 

 FIG. 761. THE CAROTID, SUBCLAVIAN, AND VERTEBRAL ARTERIES AND THEIR MAIN BRANCHES. 



it from the external carotid artery, are the following structures, viz., the stylo-pharyngeus, 

 the styloid process, or the styloglossus muscle, and the glossopharyngeal nerve, the 

 pharyngeal branch of the vagus, and some sympathetic twigs. 



In the Carotid Canal. The artery, as it passes upwards, is an tero -inferior to the cochlea 

 and the tympanum; postero-medial to the auditory (Eustachian) tube and the canal for 

 the tensor tympani ; and below the semilunar ganglion. The thin lamina of bone which 

 separates it from the tympanum is frequently perforated, and that between it and the 

 semilunar ganglion is frequently absent. In its course through the canal it is accom- 

 panied by small veins and sympathetic nerves. The veins receive tributaries from 

 the tympanum, and communicate above with the cavernous sinus and below with the 

 internal jugular vein. The nerves are branches of the nervus caroticus internus, which 

 is the upward continuation of the sympathetic trunk ; they form a plexus around the 

 artery, called the internal carotid plexus. 



As it enters the cavity of the cranium the internal carotid artery pierces the external 

 layer of the dura mater and passes between the lingula and the sixth cerebral nerve 

 laterally, and the posterior petrosal process of the body of the sphenoid medially. 



In the Cranial Cavity. The artery runs forwards, in the lateral wall of the cavernous 



* 58 & 



