Anatomy Of Orbit

Dr. Azza Zaki

Dr. Azza Zaki

It is pyramidal in shape, having a base, an apex & 4 walls. Base: has 4 margins. Apex: Optic canal. 4 Walls: Roof 1- Orbital plate of frontal b. 2-Lesser wing of sphenoid b. Floor

1- Orbital surface of maxilla 2-Zygomatic bone Orbital process of palatine b. Medial

wall 1- Lacrimal bone 2-Orbital plate of ethmoid b.Body of sphenoid b. Lateral

wall Dr. Azza Zaki of sphenoid b 1- Zygomatic b. 2-Greater wing

The orbital cavity communicates with the:  Anterior cranial fossa via ant. and post. ethmoidal foramina  Middle cranial fossa via optic canal and the superior orbital fissure  Infratemporal fossa via inferior orbital fissure  Nasal cavity via nasolacrimal canal At the meeting of the medial wall &the roof, there are:  Optic canal (optic nerve, ophthalmic artery & meninges)  Posterior ethmoidal foramen  Anterior ethmoidal foramen  There are 2 fissures related to lateral wall:  Superior orbital fissure (between lesser & greater wing of sphenoid, pass through it: lacrimal, frontal, trochlear, superior division of oculomotor, nasociliary, inferior division of oculomotor , abducent nerves & ophthalmic veins)  Inferior orbital fissure (between greater wing of sphenoid and maxilla, passes through it: infra-orbital artery, maxillary nerve , zygomatic nerve & emissary vein between inf. ophthalmic v. & pterygoid plexus of veins. Dr. Azza Zaki

The eyeball.  The extra-ocular m.  Vessels:  Ophthalmic artery &veins.  Nerves:  Sensory:  optic , Ophthalmic & its branches( lacrimal,frontal & nasociliary) and zygomatic  Motor: 3,4,6  Ciliary ganglion  Lacrimal apparatus  Orbital fat 

Dr. Azza Zaki

There are 4 recti ,2 obloquies & the levator palpebrae superioris. 1-Levator palpebrae superioris 2- Superior rectus 3- Inferior rectus 4-Lateral rectus 5-Medial rectus 6- Superior oblique 7-Inferior oblique Intra-ocular:  Dilator pupillae  Constrictor pupillae  Ciliary muscle Dr. Azza Zaki

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6 2

5 3

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Origin: roof of the orbit in front of the optic canal Insertion : superficial lamella: front of superior tarsus & skin of upper eyelid &deep lamella: upper border of superior tarsus & superior fornix of conjunctiva Action: elevation of upper eyelid and sup. fornix of conjunctiva Nerve supply: sup division of oculomotor n.& smooth muscle by sympathetic fibers from ( SCSG). Dr. Azza Zaki

Recti Muscles Origin: common tendinous ring, according to their position (the lateral rectus m. arises by 2 heads) Insertion: into the sclera, 6mm from the limbus (corneo-scleral junction) Dr. Azza Zaki

Superior Rectus Action:  Elevation , adduction & intortion of eye.  Nerve supply:  Superior division of oculomotor. 

Dr. Azza Zaki

Inferior Rectus Action: depress, adduct & extort the eye Nerve supply: inferior division of oculomotor nerve. Lateral rectus : Abduct the eye & supplied by abducent nerve Medial rectus: Adduct the eye & supplied by inferior division of oculomotor

Dr. Azza Zaki

Superior Oblique origin:  Body of the sphenoid  Insertion:  its tendon passes through the trochlea, inserted into the sclera behind the equator of eyeball  Action:  directs the cornea downwards and laterally (depression. abduction and intortion)  Nerve Supply: Trochlear n. 

Dr. Azza Zaki

Inferior Oblique Origin: anterior part of the floor of the orbit Insertion: runs laterally and upwards, inserted into the sclera behind the equator of the eyeball Action: directs the cornea upwards and laterally (depress, abduct & extort the eye). Nerve Supply: inferior division of oculomotor n. Dr. Azza Zaki

S O

L

M R

S R

R

Dr. Azza Zaki

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Action of the extra- ocular muscles About the vertical (X) axis the eye moves from side-to-side Temporal displacements =  Abduction Nasal displacements =  Adduction   About the horizontal (Y) axis the eye moves up and down

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Downward displacements:  Depression Upward displacements:  Elevation   About the anterior-posterior, or sagittal (Z) axis the eye rotates

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Temporal rotations of the superior cornea:  Extorsions Dr. Azza Zaki

The rod going through the cornea represents the visual axis. The horizontal rod with the arrow represents the horizontal axis. As the eye turns around the horizontal axis, the visual axis sweeps along the vertical plane.

The horizontal rod going through the cornea represents the visual axis. The vertical rod with the arrow at the top represents the vertical axis. As the eye turns around the vertical axis, the visual axis sweeps along the horizontal .

Elevation& depression

Adduction & abduction Dr. Azza Zaki

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The third plane of action are  Intortion and extortion refer to rotation around the visual axis, as illustrated below.  Intortion refers to a nasal rotation from the 12 o'clock position.  Extortion refers to a temporal rotation from the 12 o'clock position. intortion or Dr. Azza Zaki

Anterior view Posterior view Dr. Azza Zaki

Dr. Azza Zaki

Dr. Azza Zaki

Dr. Azza Zaki

Direct elevation: Superior rectus & inferior oblique. Direct depression: Inferior rectus & superior oblique Abduction or medial rotation: Medial rectus, superior and inferior recti. Abduction or lateral rotation: Lateral rectus, superior & inferior oblique

Dr. Azza Zaki

Actions of Extra-Ocular M. Assuming That Each one Acting Alone L

M

L

M

Dr. Azza Zaki

Muscl action e LR abductio n MR adductio n SR elevatio IR depressi n on IO extortio SO intortion n

action

action

testing position abduction adduction

intortion adducti on adducti extortion on abducti elevatio on abducti n depressi on on Dr. Azza Zaki

up and out down and out up and in down and in

Anatomical Action

Clinical Testing

Dr. Azza Zaki

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Innervation of the Extraocular Muscles Medial, Inferior & Superior Rectus; Inferior Oblique:   Oculomotor nerve (III) Superior Oblique: Trochlear nerve (IV)  N.B.:  tendon of superior oblique passes through the trochlea Lateral Rectus: Abducent nerve (VI)  N.B.:  action of lateral rectus is abduction (abducent) Dr. Azza Zaki

Dr. Azza Zaki

Intra-Ocular Muscles

The muscles of the iris: 1- sphincter pupillae: circular in shape and are arranged around the margin of the pupil.  Action: constrict the pupil in the presence of bright light.& during accomodation.  Nerve supply : parasympathetic fibers from the oculomotor nerve (short ciliary branches of ciliary ganglion. 2- dilator pupillae:  Radial fibers  Action:  Dilate the pupil in the presence of light of low intensity & excessive sympathetic stimuli as in fear.  Nerve supply : sympathetic Dr. Azza Zaki fibers along long 

The Ciliary Muscle  

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Action: Pulls the ciliary body forward. Relax the suspensory ligament and lens becomes more convex. This increases the refractive power of the lens. Nerve supply: Parasympathetic fibers from the oculomotor after synaping in the ciluiary ganglion. Dr. Azza Zaki

Ophthalmic artery: Branches:  Central a. of the retina  Muscular  Posterior ciliary  Anterior ciliary  Lacrimal  Supratrochlear  Supraorbital  Dorsal nasal Dr. Azza Zaki

It is an end artery, so thrombus of it leads to blindness. Branches:  Sup.&inf. Nasal  & sup.&inf. Temporal. 

Dr. Azza Zaki

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Superior ophthalmic vein Inferior ophthalmic vein. The 2 veins communicate with facial vein anteriorly & end posteriorly in the cavernous sinus. The inf. Ophthalmic vein communicate with pterygoid plexus of veins by emissary vein Dr. Azza Zaki

Sensory : Optic nerve: for vision. Ophthalmic n.: for general sensation. Zygomatic n. Motor: 3,4,6 nerves Ciliary ganglion. Sympathetic fibers: from sup. Cervical

Dr. Azza Zaki

Dr. Azza Zaki

Formed of axons of ganglion cells of the retina & pierces the sclera medial to the center of the eyeball  Runs backwards and medially and leaves the orbital cavity through the optic canal.  Ends in the optic chiasma, medial to the termination of ICA • The intraorbital part is sinuous, to allow free movement of the eyeball Structures crossing optic n. from lateral to medial:  Ophthalmic artery  Nasociliary nerve  Superior ophthalmic vein 

Dr. Azza Zaki

the opthalmic artery runs below and lateral to the optic nerve (and within its meningeal sheath)  The nerve is pierced by the central artery and vein of the retina, 12 mm behind the eyeball  The nerve surrounded by meninges &subarachnoid space contains CSF ,  So rise in CSF pressure will compress the retinal veins & cause bulging of the optic disc (papilledema).  section of optic nerve leads to Dr. Azza Zaki total blindness of one eye. 

Branches: Lacrimal:

Enters the orbit through the sup orbital fissure (outside the common tendinous ring) Runs forwards and lateral, above the lateral rectus receives a communication from the zygomatico-temporal nerve (which carries secretory fibers to the lacrimal gland) Supplies the lacrimal gland Gives palpebral branches to the lateral part of upper eyelid

Frontal:

Runs forwards beneath the roof, above the levator palpabrae superioris & has 2 branches:

Supratrochlear & supraorbital

Dr. Azza Zaki

Nasociliary Nerve Branches: Communicating branch to the ciliary ganglion Long ciliary n. to dilator pupillae m. Posterior ethmoidal n. Infratrochlear n. Anterior ethmoidal n.

Dr. Azza Zaki

Position: In the posterior part of the orbit on the lateral side of the optic n. Suspended from the nasociliary n Roots: 1- parasympathetic: Preganglionic parasympathetic via the nerve of the inf. oblique (oculomotor) postganglionic short ciliary nerves supply sphincter pupillae & ciliary muscles. 2-Sympathetic: postganglionic from the Dr. Azza Zaki plexus around the int.

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Divides into superior and inferior divisions Both divisions enter the orbit through the superior orbital fissure (inside the common tendinous ring) The superior division supplies:  

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superior rectus levator palpebrae superioris

The inferior division supplies: 

Medial rectus

Dr. Azza Zaki

The nerve to inferior oblique carries the parasympathetic root to the ciliary ganglion These parasympathetic fibers arise from the Edinger Westphal nucleus in the midbrain The postganglionic fibers supply the constrictor pupillae and the ciliary muscle

In complete paralysis: The eye cannot be moved downward, upward or inward. External ( lateral) strabismus (squint).  Diplopia . Drooping of the upper eyelid (ptosis).  dilated fixed pupil non reactive to light. Dr. Azza Zaki loss of accomadation.

Trochlear nerve 

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Arising from posterior surface of the lower level mid brain. Supply superior oblique muscle.

Dr. Azza Zaki

Abducent Nerve 

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Enter the eye inside the common tendinous ring. Supply lateral rectus muscle. Responsible for turning the eye laterally. If cut leads to medial squint (strabismus)

Dr. Azza Zaki

Lacrimal gland Lacrimal ducts Conjunctival sac Lacrimal puncta Lacrimal canaliculi Lacrimal sac Nasolacrimal duct: open into inferior meatus of the

Dr. Azza Zaki

Divided into orbital & palpebral parts by tendone of levator palpebrae superioris muscle. Dr. Azza Zaki

Lacrimal sac: •It lies in the lacrimal groove behind the medial palpebral ligament. •Its upper end is blind •Its lower end is continuous with the nasolacrimal duct. Nasolacrimal duct: It end in the inferior meatus of the nose. Dr. Azza Zaki

parasympathetic supply: Originates from: nucleus lacrimalis of facial nerve in pons Then along nervus intermedius. Preganglionic parasympathetic: Greater superficial petrosal branch of facial nerve Greater petrosal nerve unit with deep petrosal nerve to form nerve of pterygoid canal, which relay in pterygopalatine ganglion then along zygomatic branch of maxillary nerve.  postganglionic parasympathetic: zygomaticotemporal branch, then along lacrimal nerve to the gland. Postganglionic sympathetic via deep petrosal from internal carotid plexus. Dr. Azza Zaki

Dr. Azza Zaki

Dr. Azza Zaki

Dr. Azza Zaki

Dr. Azza Zaki

Orbital Fascia Medial & lateral check ligaments & suspensor y

Dr. Azza Zaki

Dr. Azza Zaki

References 

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Gray_s_Anatomy_Student_edition.par t2. Color_Netter_Atlas_of_Human_Anatomy . Snell clinical anatomy for medical students 7th ed. Clinically oriented anatomy 5th ed Keith Moore Dr. Azza Zaki