2. Orbit
(Vessels & Nerves)
Dr. Zeenat Zaidi

3. Nerves of the Orbit Sensory nerves Optic nerve
Branches from the ophthalmic division of trigeminal nerve
Motor nerves
Occulomotor nerve
Trochlear nerve
Abducent nerve
(The maxillary nerve passes through the inferior orbital fissure, enters into the groove in floor of the orbit, continues as infraorbital nerve, exits through infraorbital foramen and supplies the skin of the face. Does not supply orbital contents)

4. Optic Nerve Enters through optic canal
Accompanied by opthalmic artery that lies below it
Surrounded by meninges & the subarachnoid space containing CSF
Runs forward & laterally within the cone of the recti muscles
Pierces the sclera at a point medial to the posterior pole of the eyeball. Here the meninges fuse with the sclera
A rise in the CSF pressure within the cranial cavity is transmitted to the back of the eye

5. Ophthalmic Nerve Smallest of the three divisions of trigeminal nerve
Arises from the superomedial part of the trigeminal ganglion
Runs forward in the lateral wall of the cavernous sinus and divides into:
Nasociliary nerve
Frontal nerve
Lacrimal nerve
which enter the orbit through the superior orbital fissure

6. Lacrimal Nerve
Enters orbit through the upper part of the superior orbital fissure, outside the tendinous ring
Runs forward along the upper border of lateral rectus muscle
Joined by a branch of the zygomaticotemporal nerve, which later leaves it to enter lacrimal gland
Supplies the lacrimal gland, and the skin of the lateral part of the upper eyelid

7. Frontal Nerve
Enters orbit through the upper part of the superior orbital fissure, outside the tendinous ring
Runs forward over the superior surface of levator palpebrae superioris muscle
Just before the orbital margin, divides into:
Supratrochlear nerve: Smaller branch, winds round the superior orbital margin, supplies skin of forehead & scalp
Supraorbital nerve: Larger branch, passes through supraorbital notch, supplies skin of forehead & scalp lateral to the area supplied by supratrochlear nerve

8. Nasociliary Nerve
Enters the orbit through the lower part of the superior orbital fissure, within the tendinous ring
Crosses above the optic nerve with the opthalmic artery, to reach the medial wall of the orbital cavity
Then runs forward along the upper margin of the medial rectus, and ends by dividing into the anterior ethmoidal & infratrochlear nerves

9. Nasociliary Nerve: Branches
Communicating branch to the ciliary ganglion: sensory fibers from the eyeball pass to the ciliary ganglion via short ciliary nerves, pass through the ganglion without interruption, and then join the nasociliary nerve
Long ciliary nerves: 2-3 in number, pass forward with the short ciliary nerves, contain sympathetic fibers for the dilator pupillae muscle
Posterior ethmoidal nerve: passes through the posterior ethmoidal foramen, supplies the ethmoidal & sphenoidal air sinus

10. Infratrochlear nerve: passes forward and supplies skin of medial part of upper lid & adjacent part of the nose
Anterior ethmoidal nerve: passes through anterior ethmoidal foramen, enters anterior cranial fossa, runs on the upper surface of the cribriform plate of ethmoid bone, enters nasal cavity through a slit on the side of the crista gali, supplies the nasal mucosa, and then appears on the face as external nasal nerve to supply the skin of the nose as far as the tip

11. Occulomotor Nerve
Divides into superior and inferior rami before entering the orbit.
Both rami enter the orbit through the lower part of the superior orbital fissure, within the tendinous ring
Superior ramus:
Supplies the superior rectus, pierces it and then supplies the overlying levator palpebrae superioris

12. Inferior ramus:
Gives branches to inferior & medial recti, and inferior oblique
Nerve to inferior oblique gives off a branch, carrying the preganglionic parasympathetic fibers to the ciliary ganglion

13. Lesion of Occulomotor Nerve
Leads to:
Diplopia
Lateral squint (paralysis of medial rectus)
Ptosis (paralysis of levator palpebrae superioris)
Dilatation of pupil (paralysis of constrictor pupillae muscle)
Loss of accomodation

14. Trochlear Nerve Lesion of nerve results in diplopia on looking down
Enters orbit through the upper part of the superior orbital fissure, outside the tendinous ring
Runs forward and medially across the origin of levator palpebrae superioris
Enters superior oblique muscle & supplies it
Lesion of nerve results in diplopia on looking down

15. Abducent Nerve Lesion of nerve leads to diplopia & medial squint
Enters orbit through the lower part of the superior orbital fissure, within the tendinous ring
Runs forward on the deeper surface of the lateral rectus muscle and supplies it
Lesion of nerve leads to diplopia & medial squint

16. Both divisions of occulomotor n. Nasociliary nerve Abducent nerve
Strutures passing through the tendinous ring:
Ophthalmic artery
Optic nerve
Both divisions of occulomotor n.
Nasociliary nerve
Abducent nerve
Strutures passing outside the tendinous ring:
Trochlear nerve
Lacrimal nerve
Frontal nerve
Maxillary nerve
Superior & inferior ophthalmic v.

17. Ciliary Ganglion
A parasympathetic ganglion located in the upper part of the orbit, lateral to the optic nerve
Afferent (preganglionic) fibers: Carried by the occulomotor nerve, reach the ganglion via the nerve to the inferior oblique
Efferent (postganglionic) fibers: Carried by the short ciliary nerves to the back of the eyeball to supply the constrictor pupillae and ciliary muscle

18. Gives passage to the:
Sympathetic fibers from the plexus around the internal carotid artery pass through the ganglion without interruption
Sensory fibers from the eyeball reach the ganglion through short ciliary nerves and pass through it without interruption, to join the nasociliary nerve

19. Vessels of the Orbit
Arterial supply: Ophthalmic artery, branch of internal carotid artery
Venous drainage: Superior & inferior ophthalmic veins, drain into the cavernous sinus

20. Ophthalmic Artery Branch of internal carotid artery
Passes through the optic canal below & lateral to the optic nerve
Crosses the optic nerve with the nasociliary nerve, obliquely to reach the medial wall of the orbit
Gives off numerous branches to supply orbital contents

21. Branches: Central artery of retina Muscular branches
Posterior ciliary arteries
Lacrimal artery
Supraorbital artery
Supratrochlear artery
Anterior & posterior ethmoidal arteries 6 5 7 3 1 7 2 4

22. Veins of the Orbit Superior & inferior ophthalmic veins:
Drain the orbital contents
Pass through the superior orbital fissure
Drain into the cavernous sinus
Communicates in front with facial vein
Inferior ophthalmic vein communicates, through the inferior orbital fissure with the pterygoid venous plexus

23. There are NO lymph vessels or lymph nodes in the orbital cavity

24. Thank u & Good Luck