500 



THE ARTERIES 



times of lavfre sizo, and takes the chief share in the formation of the lachrymal 

 artery, (ii ) Muscular branches, distributed chiell}' to the external rectus, (iii) 

 Malar branches — small twiiis, which ])ass through the malar canals, and anasto- 

 mose with the orltital Itranch (tf the middle tem})oral, and with the transverse facial 

 on the cheek, (iv; Palpebral branches, whidi arc distributed to the U])per and 

 lower eyelids and to the conjmutiva. {v) Ciliary. See Ciliary Akteeies, 

 page 501. 



(h) The Supraorbital Artery 



The supraorbital artery usually arises from the ophthalmic as the latter vessel 

 is about to cross over the optic nerve. Passing upwards to the inner side of the 

 superior rectus and levator palpebra?, it runs along the upper 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 orlncularis palpe- 



FiG. 339.— The Left Ophthalmic Aeteey and Vein. 



Supraorbital artery 



LACHRVMAL GLAND 



Superior rectus, cut 



EYEBALL 



External rectus 



Lachrymal artu y 



Superior rectus, cut 



Inferior ophthalmic it. in 

 Superior ophthalmic ^ein 



OPTIC NER VE - 

 Common ophthalmic vei 



'"''"''SS Commencement of sii/ie/iiir 

 ojihthalinic icin 



Reflected tendon of superior 

 oblique 



S — ophthalmic artery 



Anterior ethmoidal artery 



Posterior ethmoidal artery 

 Ciliary arteries 



Levator palpebrae, cut 

 Ligament of Zinn 



Ojdithalmic artery 



OPTIC COMMISSURE 



Internal carotid artery 



])rarmii, it divides into a superficial and deep branch; the former ramifies between 

 the skin and occipito-frontalis, the latter between the occii>ito-frontalis and the 

 pericranium. Both l)ranches anastomose with the anterior l)ranches of the superficial 

 temporal, the angular branch of the facial, and the transverse facial artery. The 

 branches of the supraorbital are: — (i) Periosteal, to the periosteum of the roof of 

 theorV)it; (ii) muscular, to the levator palpebnc and superior rectus; (iii) diploic, 

 given off as the artery is passing through the supraorbital notch and entering a 

 minute foramen at the bottom of the notch is distributed to the diploe and frontal 

 sinuses; (iv) trochlear, to the pulley of the sui)eri(>r olilique; (v) palpebral, to 

 the upper eyelid. 



(c) The Central Artery of the Retina 



The arteria centralis retinae, a small but constant branch, comes oflf from 

 the ophthalmic close to the optic foramen, and, perforating the optic nei've about a 

 (piarter of an inch behind the globe, runs forwards in the substance of the nerve to 

 the eyeball, supplying the retina. The fact that this artery penetrates the substance 

 of the optic nerve is of developmental interest, as it indicates the spot where the 



