740 HUMAN ANATOMY. 



nal to the neck of the mandible ; the second, or pterygoid portion, is that which traverses the 

 zygomatic fossa, and is in relation with the pterygoid muscles ; and the third, or spheno-maxil- 

 lary portion, extends from where it passes between the two heads of the external pterygoid mus- 

 cle to its entrance into the spheno-palatine foramen. Of the sixteen named branches arising from 

 the internal maxillary artery, five arise from the first portion, five from the second, and six from 

 the third. 



From the first or mandibular portion arise ( i ) the deep auricular, ( 2 ) the tympanic, ( 3 ) 

 the 7niddle meningeal, (4) Xhe^ small meningeal, and (5) th& inferior dental arten&s. 



{a) The deep auricular (a. auricularis profunda) is a small branch which passes behind the 

 temporo-mandibular articulation, to which it sends branches, and perforates the anterior wall of 

 the external auditory meatus to supply the skin lining that passage and the outer surface of the 

 tympanic membrane. 



{b) The tympanic (a. lympanica anterior), also a small branch, passes upward, giving off 

 branches to the temporo-mandibular articulation, and enters the Glaserian fissure. Thence it 

 traverses the iter chordae anterius along with the chorda tympani, and reaches the middle ear, to 

 whose mucous membrane it is distributed, anastomosing with the tympanic branches of the stylo- 

 mastoid artery. 



[c) The middle meningeal (a. meningea media) is the largest of all the branches. It as- 

 cends vertically towards the base of the skull and enters the cranium by the foramen spinosum, 

 and, after passing outward and upward for a short distance upon the great wing of the sphenoid, 

 divides into an anterior and a posterior terminal branch, which ramify over the surface of the 

 dura and supply nearly the whole of its lateral and superior surfaces, making abundant anasto- 

 moses with the vessel of the opposite side. The anterior branch, the larger of the two terminal 

 branches, passes obliquely forward over the greater wing of the sphenoid, crosses the anterior 

 inferior angle of the parietal, and then ascends along the anterior border of that bone almost to 

 the superior longitudinal sinus, sending off numerous branches. The posterior brajich passes 

 backward and upward over the squamous portion of the temporal bone, and then over the pos- 

 terior part of the parietal bone, giving off numerous branches which pass upward as far as the 

 superior longitudinal sinus and backward as far as the lateral sinus. In addition to these ter- 

 minal branches, the main stem within the cranium also gives origin to {aa) a. petrosal branch 

 (a. petrosus superficialis) which enters the hiatus Fallopii and anastomoses with the terminal por- 

 tion of the stylo-mastoid arteries ; to [bb) Gasserian branches, minute twigs which pass to the 

 Gasserian ganglion and the fifth nerve ; to {cc) a tympanic branch (a. tympanica superior) which 

 descends through the petro-squamous suture to the mucous membrane of the middle ear and the 

 mastoid cells ; and, finally, to {dd) an orbital branch, a small vessel that passes into the orbit 

 through the outermost portion of the sphenoidal fissure and anastomoses with the lachrymal 

 branch of the ophthalmic. 



{d) The small meningeal (r. meningeus accessorius) is an inconstant branch, sometimes 

 arising from the middle meningeal. It passes upward along the mandibular division of the fifth 

 nerve, and enters the cranium through the foramen ovale to be distributed to the Gasserian 

 ganglion and the dura mater in its neighborhood. 



{e) The inferior dental (a. alveolaris inferior) is given off from the lower surface of the artery 

 and descends along with the inferior dental nerve to the mandibular foramen. Before reaching 

 the foramen it gives off {aa) a lingual branch, which accompanies the lingual nerve to the 

 tongue, and {bb) a inylo-hyoid branch (ramus mylohyoideus), accompanying the mylo-hyoid 

 nerve to the muscle of that name. Entering the mandibular foramen, it traverses the man- 

 dibular canal, giving off branches to the roots of the lower teeth as it passes them, and finally 

 emerges at the mental foramen as (cr) the mental artery (a. mentalis), supplying the neighboring 

 muscles and integument and anastomosing with the submental and inferior labial branches of the 

 facial. Just before issuing from the mental foramen it gives off {dd) an incisive branch which 

 distributes twigs to the incisor teeth. 



From the second, or pterygoid portion, arise branches distributed chiefly to the adjacent 

 muscles ; they are ( i ) the masseteric, (2) the deep temporal, (3 and 4) the internal and exter- 

 nal pterygoid, and (5) the buccal axXj&xy. 



(/) The masseteric branch (a. masseterica) passes with the corresponding nerve through 

 the sigmoid notch of the mandible to enter the deep surface of the masseter. 



{g) The deep temporal branches are two in number, the anterior and the posterior. The 

 posterior branch (a. temporalis profunda posterior) arises close to or in common with the mas- 

 seteric, while the anterior or\& (a. temporalis profunda anterior) is given off near the termination 

 of the pterygoid portion of the artery. They both pass upward between the temporal muscle 

 and the bone, supplying the muscle and anastomosing with the middle temporal branch of the 

 temporal artery. 



(/? and /) The internal and external pterygoid branches ( rami pterj-goidei) are short and 

 variable in number. They pass directly into the muscles of the same names. 



