490 



CAROTID ARTERY. 



branches enter the orbit through the malar 

 bone, and spread over the lachrymal gland, 

 communicating with the lachrymal artery. 



h. The alveolar artery descends forwards 

 over the superior maxillary bone, very tortuous 

 in its course ; it gives two or three twigs, which 

 pass into the inferior and posterior dental fora- 

 mina to be distributed to the lining membrane 

 of the antrum maxillare and the molar teeth ; 

 the other branches of the alveolar artery are 

 distributed to the gums, to the buccinator, to 

 the periosteum of the superior maxillary bone, 

 and to the cellular substance of the cheek: 

 they communicate with the infra-orbital, labial 

 and buccal. 



i. The infra-orbital artery arises from the 

 internal maxillary at the superior part of the 

 pterygo-maxillary space ; it enters the infra- 

 orbital canal, through which it passes forwards 

 and inwards, sending branches into the orbit 

 and maxillary sinus ; passing out by the infra- 

 orbital hole it comes forward on the face 

 behind the levator labii superioris, and termi- 

 nates in a number of branches, which pass into 

 the muscles of the upper lip, and anastomose 

 with the labial, alveolar, buccal, and nasal 

 branch of the ophthalmic. 



The remaining branches of the internal max- 

 illary are given off in the pterygo-maxillary 

 space; of these the first is 



/. The superior palatine descends behind 

 the tuberosity of the superior maxillary bone 

 in the palato-maxillary canal : it usually gives 

 off two branches, which descend through holes 

 in the pterygoid process of the palate bone, 

 and are distributed to the soft palate; while 

 the trunk of the superior palatine passing out 

 of the posterior palatine hole, directs itself for- 

 wards and inwards in a groove on the surface 

 of the hard palate, and divides into numerous 

 branches, which are distributed to the mucous 

 membrane and glands of the palate, to the 

 gums, and to the superior maxillary bone ; one 

 of these branches sometimes passes up through 

 the foramen incisivum to the nasal fossae. 



m. The vidian artery is an insignificant 

 branch which traverses the vidian canal from 

 before backwards, and coming out of its poste- 

 rior opening is distnbuted to the Eustachian 

 tube and the roof of the pharynx: it anasto- 

 moses with the inferior pharyngeal. 



n. The ptery go-palatine or superior pha- 

 ryngeal is a small insignificant branch, which 

 passes through the ptery go-palatine hole, and 

 is distributed like the former to the roof of the 

 pharynx and Eustachian tube, sending some 

 branches to the sphenoid bone and the mem- 

 brane lining its sinuses. 



o. The spheno-palatine artery may be con- 

 sidered the termination of the internal maxil- 

 lary ; it enters by the spheno-palatine hole into 

 the posterior part of the nasal fossae, and divides 

 into two principal branches ; an external and 

 an internal; the internal branch passing across 

 the roof of the nasal fossae arrives at the septum, 

 on which its branches are principally distri- 

 buted ; it also supplies branches to the roof of 

 the pharynx and the posterior ethmoidal cells; 

 the external branch descends on the lateral wall 



of the nose, sending its branches over the 

 spongy bones and into the antrum maxillare : 

 these branches anastomose with the ethmoidal 

 branches of the ophthalmic artery. 



THE INTERNAL CAROTID ARTERY, (carotisin- 



terna sen cerebralis, Soemm. cerebrate anterieure, 

 Chaussier.^This artery is larger than the external 

 carotid in the foetus, but in the adult is only equal 

 in size to that vessel, aud sometimes even smaller. 

 At its origin it takes a curve outwards so as to 

 get external to the commencement of the ex- 

 ternal carotid; it then mounts upwards and 

 forwards in front of the three superior cervical 

 vertebrae, and making a few contortions along 

 the side of the pharynx, enters the foramen 

 caroticum of the temporal bone, traversing the 

 carotid canal of that bone internal to the ca- 

 vernous sinus, perforates the dura mater internal 

 to the anterior clinoid process of the sphenoid 

 bone, where it divides into two large branches, 

 the anterior and middle cerebral. 



The internal carotid artery has the following 

 relations from its origin to the place where it 

 enters the foramen caroticum : anteriorly it has 

 the external carotid and its branches in contact 

 with it at its origin, also the hypoglossal or lin- 

 gual nerve, and as it passes under the digastric 

 muscle it also slips beneath the following parts 

 which lie between it and the external carotid, 

 the styloid process, with the muscles attached 

 to it, part of the parotid gland, the glosso- 

 pharyngeal and inferior pharyngeal nerves. 



Posteriorly it lies on the rectus capitis anti- 

 cus major, having the par vagum and superior 

 laryngeal nerve behind it, and higher up the 

 trunk of the hypo-glossal nerve coming from 

 between it and the internal jugular vein. 



The internal jugular vein bounds it externally 

 at first, but passes to its posterior side above 

 where it gets to the internal side of the root of 

 the styloid process. Internally the carotid ar- 

 tery lies on the side of the pharynx to which it 

 is more closely applied towards its upper part, 

 lying on the stylo-glossus and the outer surface 

 of the superior constrictor muscles, which with 

 some cellular membrane and a venous plexus 

 separate it from the tonsil, external and poste- 

 rior to which it lies, at the distance of from six 

 to eight lines in the natural state of the parts; 

 but when that gland is enlarged in consequence 

 either of acute inflammation or chronic disease, 

 the distance between it and the artery is dimi- 

 nished so much as to expose the latter to some 

 risk of being wounded in opening abscesses in 

 the tonsil, an occurrence of which the records 

 of experience are not without examples. In 

 this stage of its course the internal carotid 

 seldom gives any branches ; occasionally, how- 

 ever, the inferior pharyngeal or the occipital 

 arises from it. Having entered the carotid 

 canal, the artery ascends vertically, then turns 

 forwards and inwards, and passing out of the 

 canal opposite the posterior clinoid process, it 

 takes a second turn upwards, then forwards 

 along the side of the sella turcica, between the 

 layers of the dura mater which include the ca- 

 vernous sinus, between which latter and the 

 bone the artery is situate. At the anterior 

 extremity of the side of the sella turcica it makes 



