ri48 



A MANUAL OF ANATOMY 



Nerve-supply. — ^The upper division of the third cranial nerve, the 

 branch from which enters the deep or ocular surface of the muscle 

 near its origin. 



The muscle is flattened from above downwards, and its direction 

 is forwards and slightly outwards. 



Action. — ^To elevate the eyeball, so as to direct the cornea up- 

 wards. The muscle imparts a certain amount of inward move- 

 ment to the eyeball, accompanied by slight rotation. 



Relations. — Superiorly, the levator palpebrae superioris, which is 

 the narrower of the two muscles. Inferiorly, the soft fat of the orbit. 



Internal Rectus — Origin. — ^The upper and lower parts of the 

 fibrous ring in relation to the optic foramen, the origin being wide, 



Supra-orbital Nerve 

 (in two divisions-) 



Supratrochlear Nerve 



Infratrochlear of Nasal^" 



Olfactory Bulb.^ 

 Nasal Nerve<rJ 



Optic Nerve — '. 



Ophthalmic Artery —'' 

 Third Nerve — 

 Fourth Nerve- 

 Sixth Nerve 



Frontal Nerve on Levator 

 , \'v\ Palpebrae Superiorjs 



^ — „ V... Lachrymal Nerve passing 



along External Rectus 



^----Superior Maxillary Nerve 

 ... ._'--■ ---.Ophthalmic Nerve 

 ;;•■" ""--.Inferior Maxillary Nerve 



'-•Gasserian Ganglion 

 ' Sensory Root of Fifth Nerve 

 Motor Root of Fifth Nerve 



Fig. 467. — Dissection of the Orbit from above (Hirschfeld and 



Leveille). 



and being situated partly on the inner side of, and partly below, the 

 optic foramen. 



Insertion. — By a thin expanded tendon into the inner surface of 

 the sclerotic about three or four lines from the margin of the cornea. 



Nerve-supply. — ^The lower division of the third cranial nerve, the 

 branch from which enters the deep or ocular surface of the muscle. 



The muscle is flattened from within outwards, and its borders are 

 superior and inferior. Its direction is almost straight forwards. 



Action. — To adduct the eyeball, so as to direct the cornea inwards. 



Relations. — Above the upper border of the muscle is the superior 

 oblique, and between the two the nasal nerve and the anterior and 

 posterior ethmoidal vessels pass. 



