BRAXCHE* O/ THE EXTERXAL CAROTID. 561 



bone divides into branches which supply the posterior part of the dura mater and 

 cranium. The branches of this vessel are distributed partly to the dura mater, 

 but chiefly to the bones ; they anastomose with the arteries "of the opposite side, 

 and with the anterior and posterior meningeal. 



The middle meningeal on entering the cranium gives off the following collat- 

 eral branches : 1. Numerous small vessels to the ganglion of the fifth nerve and 

 to the dura mater in this situation : 2. A branch (petrosal branch), which enters 

 the hiatus Fallopii. supplies the facial nerve, and anastomoses with the stvlo- 

 mastoid branch of the posterior auricular artery ; 3. Orbital branches, which pass 

 through the sphenoidal fissure or through separate canals in the great win of the 

 sphenoid to anastomose with the lachrymal or other branches of the ophthalmic 

 artery : 4. Temporal branches, which pass through foramina in the great win of 

 the sphenoid, and anastomose in the temporal fossa with the deep temporal arteries. 



Surgical Anatomy. The middle meoingeal is an artery of considerable surgical import- 

 ance, as it may be injured in fractures of the temporal region of the skull, and the injury may 

 be followed by considerable haemorrhage between the bone and dura mater, which niay" cause 

 compression of the brain and require the operation of trephining for its relief. This artery 

 crosses the anterior inferior angle of the parietal bone at a point li inches behind the external 

 angular process of the frontal bone, and If inches above the zygoma. From this point the ante- 

 rior branch passes upward and sliehtly backward to the sagittal suture, lying about i inch to 

 f inch behind the coronal suture. The posterior branch passes upward and backward over the 

 squamous portion of the temporal bone. In order to expose the artery as it lies in the canal in 

 the parietal bone, a semilnnar incision, with its convexity upward, should be made, commencing 

 an inch behind the external angular process, and carried backward for 2 inches. The structures 

 cut through are : 1 1 ) skin : (2) superficial fascia, with branches of the superficial temporal vessels 

 and nerves: )3) the fascia continued down from the aponenrosis of the Oeeipito-frontali- 

 the two layers of the temporal fascia: (5) the temporal muscle: (6) die deep temporal vessels; 



'..e pericranium ; and (8; the bone. 



The small meningeal is sometimes derived from the preceding. It enters the 

 skull through the foramen ovale. and supplies the Gasserian ganglion and dura 

 mater. Before entering the cranium it gives off a branch to the nasal fossa, soft 

 palate, and tonsil. 



The inferior dental descends with the dental nerve to the foramen on the inner 

 side of the ram us of the jaw. It runs along the dental canal in the substance 

 of the bone, accompanied by the nerve, and opposite the first bicuspid tooth divides 

 into rwo branches, incisor and mental ; the former is continued forward beneath 

 the incisor teeth as far as the symphysis. where it anastomoses with the arterv of 

 the opposite side : the mental branch escapes with the nerve at the mental foramen, 

 supplies the structures com; -sing the chin, and anastomoses with the submental. 

 inferior labial, and inferior coronary arteries. As the dental artery enters the 

 foramen it gives off a mylo-hyoid branch, which runs in the mylo-hyoid groove, 

 and ramifies on the under surface of the Mylo-hyoid muscle. " The dental and 

 incisor arteries during their course through the substance of the bone give off a 

 few twigs which are lost in the cancellous tissue, and a series of branches which 

 correspond in number to the roots of the teeth : these enter the minute apertures 

 at the extremities of the fangs and supply the pulp of the teeth. 



BRANCHES OF TH - \D OR PTERTGOID PORTION OF INTERNAL MAXILLARY. 

 Deep Temporal. Masseteric. 



Pterygoid. Buccal. 



These branches are distributed, as their names imply, to the muscles in the 

 maxillary region. 



The deep temporal arteries, two in number, anterior and posterior, each occupy 

 that part of the temporal fossa indicated by its name. Ascending between 

 the Temporal muscle and pericranium, they supply that muscle and anastomose 

 with the other temporal arteries, the anterior branch communicating with the 

 lachrymal through small branches which perforate the malar bone and great win<* 

 of the sphenoid. 



