552 THE BLOOD-VASCULAR SYSTEM 



foramen lacerum the arteiy is crossed on its lateral side by the great superficial petrosal nerve 

 as the latter goes to join the great deep petrosal from the carotid plexus to form the nerve of 

 the pterygoid canal (Vidian). 



Branches of the Internal Carotid Artery 



The cervical portion gives off no branch. The petrosal portion gives off the 

 caroticotympanic. The branches of the intracranial portion are : — (2) ophthalmic ; 

 (3) posterior communicating; (4) chorioid; (5) anterior cerebral; (6) middle 

 erebral. 



As the internal carotid artery lies on the medial side of the cavernois sinus, it also gives off 

 the following small branches — branches to the walls of the cavernous inus; to the pituitary body; 

 to the semilunar (Gasserian) ganglion; to the dura mater. These anastomose with anterior 

 branches of the middle meningeal. 



1. THE CAROTICOTYMPANIC ARTERY 



The caroticotympanic enters the tympanum through a small foramen in the 

 posterior wall of the carotid canal, and contributes its quota to the blood-supply of 

 that cavity. It anastomoses with the tympanic branches of the stylo-mastoid, 

 internal maxillary, and middle meningeal arteries. 



2. THE OPHTHALMIC ARTERY 



The ophthalmic artery (fig. 455) comes off from the internal carotid immedi- 

 ately below the anterior clinoid process just as the latter vessel is passing through 

 the dura matter. Entering the orbit through the optic foramen below and lateral 

 to theo ptic nerve, it at once perforates the sheath of dura mater which is prolonged 

 through the optic foramen on both artery and nerve. It then runs in a gentle 

 curve with a lateral convexity below the optic nerve and lateral rectus, being here 

 crossed by the naso-ciliary (nasal) nerve. Turning forward and upward, it 

 passes over the optic nerve, to its medial side. Thence it runs obliquely beneath 

 the superior rectus in front of the naso-ciliary (nasal) nerve under the lower border 

 of the superior oblique, but above the medial rectus, and continues its course under 

 the pulley for the superior oblique and reflected tendon of that muscle to the 

 medial i^alpcbral region, where it divides into the frontal and nasal branches. 



Branches of the Ophthalmic Artery 



The branches of the ophthalmic artery are: — (1) the lacrimal; (2) the supra- 

 orbital; (3) the central artery of the retina; (4) the muscular; (5) the ciliary; 

 (6) the posterior ethmoidal; (7) the anterior ethmoidal; (8) the medial palpe- 

 bral; (9) the frontal; and (10) the dorsal nasal. 



(1) Tlif lacrimal artery [a. lacrimalis], is usually the first and often the largest branch of 

 the ophthalinic. It arises between the superior and lateral rectus on the lateral side of the optic 

 nerve from the oplithulmic, soon after that vessel has entered the orbit. At times it is gjven 

 olT from the ophthalmic outside the orbit, and then usually passes into that cavity through the 

 8ui)erior (jrbital (sphenoidal^ fissure. It runs forward along the lateral wall of the orbit with 

 the lacrimal nerve, above the ujjper border of the lateral rectus, to the lacrimal gland, which 

 it supplies. In this course it furnishes the following branches:— (a) Recurrent, one or more 

 branches whicli ])ass backward tln-ough the superior orbital (sj)henoidal) fissure, and anasto- 

 mose with the lacrimal branch of the middle meningeal artery. The anastomosis is sometimes 

 of large size, and then takes the chief share in the formation of the lacrimal artery, (h) Mus- 

 cular branches, distributed chiefly to the lateral re(^tus. {<■) Zygomatic branches — small twigs, 

 which i)ass through tlie zygoinatico-orbital (malar) canals, and anastomose with the orbital 

 br.iiich of tli(! middle lcm])oral, and with the transverse facial on the cheek, {d) Lateral 

 palpebral arteries [iia. palpeln-ales lateralesj which are distributed to tiie upper and lower 

 eyelids and to the conjunct iva. {(') Ciliary. Hee Ciliary Ahtkiuks, page Fifhi. 



(2) Th(! supraorbital artery [a. sujjraorbitalis] usually ari.ses from the ophthalmic as the latter 

 ve.ssel is about to cro.ss over the optic nerve. Passing upward to the medial side of the superior 

 rectus and levator palpebra', it runs along the upj)er surface of the latter muscle with the 

 frontal nerve in the orbital fat, but beneath the periosteum, to the supraorbital notch. On 

 emerging on the forehead beneath the orbicularis oculi, it divides into a superficial and deep 

 branch, the former ramifies l)etween the skin and ei)icranius (occipito-frontalis), the latter 



