490 CAROTID ARTERY. 



branches enter the orbit through the malar of the nose, sending its branches over the 



bone, and spread over the lachrymal gland, spongy bones and into the antrum maxillare : 



communicating with the lachrymal artery. these branches anastomose with the ethmoidal 



h. The alveolar artery descends forwards branches of the ophthalmic artery, 



over the superior maxillary bone, very tortuous THE INTERNAL CAROTID ARTERY, (carotisin- 



in its course ; it gives two or three twigs, which terna sen cerebralis, Scemm. ccrebrale anterieure, 



pass into the inferior and posterior dental fora- Chaussier.}Th\s artery is larger than the external 



mina to be distributed to the lining membrane carotid inthe foetus, but in the adultis only equal 



of the antrum maxillare and the molar teeth; in size to that vessel, aud sometimes even smaller, 



the other branches of the alveolar artery are At its origin it takes a curve outwards so as to 



distributed to the gums, to the buccinator, to get external to the commencement of the ex- 



the periosteum of the superior maxillary bone, ternal carotid ; it then mounts upwards and 



and to the cellular substance of the cheek : forwards in front of the three superior cervical 



they communicate with the infra-orbital, labial vertebrae, and making a few contortions along 



and buccal. the side of the pharynx, enters the foramen 



i. The infra-orbital artery arises from the caroticum of the temporal bone, traversing the 



internal maxillary at the superior part of the carotid canal of that bone internal to the ca- 



pterygo-maxillary space ; it enters the infra- vernous sinus, perforates the dura mater internal 



orbital canal, through which it passes forwards to the anterior clinoid process of the sphenoid 



and inwards, sending branches into the orbit bone, where it divides into two large branches, 



and maxillary sinus; passing out by the infra- the anterior and middle cerebral, 



orbital hole it comes forward on the face The internal carotid artery has the following 



behind the levator labii superioris, and termi- relations from its origin to the place where it 



nates in a number of branches, which pass into enters the foramen caroticum : anteriorly it has 



the muscles of the upper lip, and anastomose the external carotid and its branches in contact 



with the labial, alveolar, buccal, and nasal with it at its origin, also the hypoglossal or lin- 



branch of the ophthalmic. gual nerve, and as it passes under the digastric 



The remaining branches of the internal max- muscle it also slips beneath the following parts 



illary are given off in the pterygo-maxillary which lie between it and the external carotid, 



space; of these the first is the styloid process, with the muscles attached 



/. The superior palatine descends behind to it, part of the parotid gland, the glosso- 



the tuberosity of the superior maxillary bone pharyngeal and inferior pharyngeal nerves, 



in the palato-maxillary canal : it usually gives Posteriorly it lies on the rectus capitis anti- 



off two branches, which descend through holes cus major, having the par vagum and superior 



in the pterygoid process of the* palate bone, laryngeal nerve behind it, and higher up the 



and are distributed to the soft palate; while trunk of the hypo-glossal nerve coming from 



the trunk of the superior palatine passing out between it and the internal jugular vein, 



of the posterior palatine hole, directs itself for- The internal jugular vein bounds it externally 



wards and inwards in a groove on the surface at first, but passes to its posterior side above 



of the hard palate, and divides into numerous where it gets to the internal side of the root of 



branches, which are distributed to the mucous the styloid process. Internally the carotid ar- 



membrane and glands of the palate, to the tery lies on the side of the pharynx to which it 



gums, and to the superior maxillary bone ; one is more closely applied towards its upper part, 



of these branches sometimes passes up through lying on the stylo-glossus and the outer surface 



the foramen incisivum to the nasal fossae. of the superior constrictor muscles, which with 



m. The vidian artery is an insignificant some cellular membrane and a venous plexus 



branch which traverses the vidian canal from separate it from the tonsil, external and poste- 



before backwards, and coming out of its poste- rior to which it lies, at the distance of from six 



rior opening is distributed to the Eustachian to eight lines in the natural state of the parts; 



tube and the roof of the pharynx : it anasto- but when that gland is enlarged in consequence 



moses with the inferior pharyngeal. either of acute inflammation or chronic disease, 



n. The ptery go-palatine or superior pha- the distance between it and the artery is dimi- 



ryngeal is a small insignificant branch, which nished so much as to expose the latter to some 



passes through the pterygo-palatine hole, and risk of being wounded in opening abscesses in 



is distributed like the former to the roof of the the tonsil, an occurrence of which the records 



pharynx and Eustachian tube, sending some of experience are not without examples. In 



branches to the sphenoid bone and the mem- this stage of its course the internal carotid 



brane lining its sinuses. seldom gives any branches; occasionally, how- 



o. The spheno-palatine artery may be con- ever, the inferior pharyngeal or the occipital 



sidered the termination of the internal maxil- arises from it. Having entered the carotid 



lary ; it enters by the spheno-palatine hole into canal, the artery ascends vertically, then turns 



the posterior part of the nasal fossae, and divides forwards and inwards, and passing out of the 



into two principal branches ; an external and canal opposite the posterior clinoid process, it 



an internal; the internal branch passing across takes a second turn upwards, then forwards 



the roof of the nasal fossae arrives at the septum, along the side of the sella turcica, between the 



on which its branches are principally distri- layers of the dura mater which include the ca- 



buted ; it also supplies branches to the roof of vernous sinus, between which latter and the 



the pharynx and the posterior ethmoidal cells; bone the artery is situate. At the anterior 



the external branch descends on the lateral wall extremity of the side of the sella turcica it makes 



