Osteology |
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| Bone | Structure | Description |
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| frontal | orbital plate | forms the roof of the orbit |
| superior orbital margin | contains supraorbital notch or foramen |
| superciliary arches | above orbtial margins |
| supraorbital notch (foramen occasionally) | in superior orbital margin, for supraorbital neurovascular bundle |
| ethmoid | cribriform plate | perforated for olfactory nerves (Latin, cribiform = sieve-like) |
| crista galli | superior projection into anterior cranial fossa which anchors falx cerebri anteriorly (Latin, crista galli = cock's comb) |
| anterior ethmoidal foramen | opening in the medial wall of the orbit; transmits anterior ethmoidal vessels and nerve (Greek, ethmoid = sieve-like) |
| posterior ethmoidal foramen | opening in the medial wall of the orbit; transmits posterior ethmoidal vessels and nerve (Greek, ethmoid = sieve-like) |
| lacrimal | | forms part of the medial wall of the orbit; articulates: anteriorly with frontal process of maxilla; superiorly with frontal bone; posteriorly with ethmoid; inferiorly with orbital process of maxilla (Latin, lacrima = a tear) |
| sphenoid | optic canal | foramen at lateral end of chiasmatic sulcus, medial to anterior clinoid process; transmits optic nerve and ophthalmic artery (Greek, sphenoid = wedge-shaped) |
| lesser wing of sphenoid | forms posterior margin of anterior cranial fossa; articulates anteriorly with orbital plate of frontal bone (Greek, sphenoid = wedge-shaped) |
| greater wing of sphenoid | forms medial part of floor of middle cranial fossa, part of temporal fossa laterally, and posterior part of lateral wall of orbit; articulates anteriorly with zygomatic, superiorly with frontal & parietal bone (at pterion), posteriorly with squamous & petrous temporal bone (Greek, sphenoid = wedge-shaped) |
| superior orbital fissure | between lesser & greater wings of sphenoid; transmits oculomotor nerve, trochlear nerve, abducens nerve, branches of ophthalmic division of trigeminal nerve, superior ophthalmic vein, lymphatics |
| maxilla | frontal process | forms part of medial orbital wall & margin |
| orbital process | forms floor of orbit |
| infraorbital groove & canal | in orbital process, for infraorbital neurovascular bundle |
| infraorbital foramen | anterior opening of infraorbital canal, for infraorbital neurovascular bundle |
| palatine | perpendicular plate | articulates anteriorly with maxilla; posteriorly it forms medial wall of pterygopalatine fossa |
| orbital process | projects superiorly from perpendicular plate; forms a small part of the floor of the orbit posteriorly |
Muscles |
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| Muscle | Origin | Insertion | Action | Innervation | Notes |
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| orbicularis oculi | orbital part: medial orbital margin & medial palpebral ligament; palpebral part: medial palpebral ligament | orbital part: lateral cheek skin; palpebral part: lateral palpebral raphe | closes the eyelids | temporal & zygomatic branches of facial nerve (VII) | activated involuntarily in the blink reflex |
| levator palpebrae superioris | apex of orbit above optic canal | skin and fascia of upper eyelid and superior tarsal plate | elevates upper eyelid | oculomotor nerve (III) and sympathetics (to superior tarsal portion) | fibers inserting into superior tarsal plate are called superior tarsal muscle and are smooth muscle; lesion of the sympathetic supply causes slight ptosis (drooping eyelid) (Latin, levator = to lift + palpebrae = eyelid) |
| rectus, superior | common tendinous ring at apex of orbit | sclera on superior surface of eyeball | elevates and adducts the eyeball; rotates superior pole of iris medially | oculomotor nerve (III), superior division | none |
| rectus, inferior | common tendinous ring at apex of orbit | sclera on inferior surface of eyeball | depresses and adducts eyeball; rotates superior pole of iris laterally | oculomotor nerve (III), inferior division | none |
| rectus, medial | common tendinous ring at apex of orbit | sclera on medial surface of eyeball | adducts eyeball | oculomotor nerve (III) (inferior division) | none |
| rectus, lateral | common tendinous ring at apex of orbit | sclera on lateral surface of eyeball | abducts eyeball | abducens nerve (VI) | none |
| superior oblique | apex of orbit above optic canal | sclera on superior surface of eyeball, posteriorly | depresses and abducts the eyeball; rotates the superior pole of the iris medially | trochlear nerve (IV) | passes through fibrocartilagenous pulley known as trochlea |
| inferior oblique | floor of orbit lateral to lacrimal groove | sclera on inferior surface of eyeball, beneath the lateral rectus m. | elevates and abducts eyeball; rotates superior pole of iris laterally | oculomotor nerve (III), inferior division | none |
| pupillae, sphincter | encircles iris | encircles iris | constricts pupil | parasympathetic fibers of oculomotor nerve (III), synapsing in ciliary ganglion | none |
| ciliary | meridional fibers: scleral spur; circular fibers: encircle root of iris | meridional fibers: ciliary process; circular fibers: encircle root of iris | relaxes suspensory ligament of lens for accommodation (near vision) | parasympathetic fibers in oculomotor nerve (III), synapsing in ciliary ganglion | none |
| pupillae, dilator | outer margin of iris | inner margin of iris | dilates pupil | sympathetic fibers via short ciliary nerves, synapsing in superior cervical sympathetic ganglion | none |
Nerves |
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| Nerve | Source | Branches | Motor | Sensory | Notes |
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| trochlear | trochlear nucleus of midbrain | | superior oblique (GSE) | | also known as: CN IV, 4th cranial nerve; passes through superior orbital fissure; smallest cranial nerve, only cranial nerve to arise from dorsum of brainstem (Latin, trochlea = a pulley) |
| ophthalmic | trigeminal ganglion | meningeal br., lacrimal, frontal, nasociliary | | skin of forehead, upper eyelid & nose, upper nasal cavity & frontal, ethmoid & sphenoid sinuses (GSA) | also known as: V1, ophthalmic division of trigeminal; passes through superior orbital fissure; lacrimal n. receives postgang. parasymp. to lacrimal gland from zygomaticotemporal br. of zygomatic n. |
| lacrimal | ophthalmic division of trigeminal (V1) | | carries secretomotor (postganglionic parasympathetic) to lacrimal gland from zygomaticotemporal br. of maxillary n. (synapse occurs in pterygopalatine ganglion) | skin of upper eye lid laterally & associated conjunctiva |
(Latin, lacrima = a tear) |
| frontal | ophthalmic division of trigeminal | supraorbital, supratrochlear | | skin of forehead & medial part of upper eyelid, frontal sinus | the most superior content of the orbit |
| supraorbital | frontal | medial & lateral brs. | |
skin of forehead, frontal sinus |
| supratrochlear | frontal | | | skin of forehead medially & upper eyelid medially & associated conjunctiva |
(Latin, trochlea = a pulley) |
| infratrochlear | nasociliary br. of V1 | | | skin & conjunctiva of eyelids medially, skin of nose laterally |
(Latin, trochlea = a pulley) |
| nasociliary | ophthalmic division of trigeminal | communicating br. to ciliary gang., long ciliary, ant. & post. ethmoidal, infratrochlear | |
eyeball, skin of nose & eyelids medially & associated conjunctiva, upper nasal cavity, ethmoid & sphenoid sinuses |
| ciliary, long | nasociliary | | | eyeball (GSA) | these nerves bypass the ciliary ganglion |
| ethmoidal, anterior | nasociliary | internal & external nasal brs. | | mucous lining of anterior ethmoid air cells, upper anterior part of nasal cavity, skin of nose | passes from orbit into anterior ethmoidal foramen, anteriorly lying on cribriform plate, through ethmoid fissure into nasal cavity (Greek, ethmoid = sieve-like) |
| ethmoidal, posterior | nasociliary | | | mucous lining of posterior ethmoid air cells, sphenoid sinus | passes from orbit through posterior ethmoid foramen (Greek, ethmoid = sieve-like) |
| abducens | pons: abducens nucleus | | GSE: lateral rectus m. | | also known as: CN VI, 6th cranial nerve; passes through the superior orbital fissure (Latin, abducens = to draw away) |
| oculomotor | GSE: oculomotor nuclei of midbrain; GVE: accessory (Edinger-Westphal) nucleus (preganglionic parasympathetic) | superior br., inferior br. | superior br.: levator palpebrae superioris, superior rectus; inferior br: medial rectus, inferior rectus, inferior oblique; ciliary muscle & sphincter pupillae (GVE preganglionic parasympathetic to ciliary ganglion via parasympathetic root, postganglionic parasympathetic via short ciliary nn.) | | also known as: CN III, 3rd cranial nerve; passes through superior orbital fissure |
| nerve to inferior oblique | inf. br. of oculomotor | parasympathetic root of ciliary gang. | sphincter pupillae & ciliary m. (parasymp.), inf. oblique | | parasymp. root carries GVE pregang. parasymp. to ciliary gang., short ciliary ns. carry postgang. parasymp. into eyeball |
| ganglion, ciliary | preganglionic parasympathetic via inferior division of oculomotor n. (III) | postganglionic parasympathetic via short ciliary nn. | sphincter pupillae & ciliary mm. | | a parasympathetic ganglion; it does NOT contain cell bodies of sensory neurons; located on lateral side of optic n. near apex of orbit |
| ciliary, short | ciliary ganglion: sensory root - from nasociliary n.(V1); sympathetic root - from internal carotid plexus; parasympathetic root - from oculomotor n. (III) | multiple short ciliary ns. leave ciliary ganglion anteriorly | sphincter pupillae & ciliary mm. (parasympathetic), dilator pupillae (sympathetic) | eyeball | mixed nerves which contain sensory and 2 types of motor nerve fibers; postganglionic parasympathetic neurons whose axons are located in these nerves have their cell bodies in the ciliary ganglion |
| optic | ganglion layer of retina to forebrain | | | vision (SSA) | also known as: CN II, 2nd cranial nerve; course of optic nerve - through optic canal to optic chiasma, then optic tract to lateral geniculate body & optic radiation |
| zygomatic | maxillary division of trigeminal (V2) | zygomaticofacial & zygomaticotemporal | secretomotor (postgang. parasymp.) to lacrimal gland (via fibers from pterygopalatine gang. that reach lacrimal n. by communicating br. of zygomaticotemporal) | skin of face lateral & superior to orbit | carries postganglionic parasympathetic axons to the lacrimal gland that have synapsed in the pterygopalatine ganglion |
| sympathetic chain ganglia, cervical | preganglionic sympathetic via ascending fibers from T1-T5 | postganglionic sympathetic via gray rami communicans to cervical spinal nn.; internal & external carotid nn.; cervical cardiac brs. | dilator pupillae m.; vascular smooth muscle; arrector pili muscles & sweat glands of head and neck; heart & lungs | pain from viscera | located parallel & lateral to vertebral bodies in neck; there are no white rami communicans at cervical levels |
Arteries |
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| Artery | Source | Branches | Supply | Notes |
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| ophthalmic | internal carotid | central retinal, lacrimal, muscular brs., ant. & post. ethmoid, medial palpebral, supraorbital, supratrochlear, dorsal nasal | optic nerve & retina, extraocular muscles, eyelids, forehead, ethmoid air cells & lateral nasal wall, dorsum of nose | provides the only artery to the retina (central retinal a.) |
| central, of retina | ophthalmic | sup. & inf. nasal, sup. & inf. temporal brs. | retina | only blood supply to the retina; viewed in funduscopic exam |
| ethmoidal, anterior | ophthalmic | anterior menigeal a., ant. septal br., ant. lat. nasal br. | ethmoid & frontal sinuses, dura anteriorly, nasal mucosa | leaves orbit through anterior ethmoid foramen, then runs forward on cribriform plate |
| ethmoidal, posterior | ophthalmic | | post. ethmoid sinuses | (Greek, ethmoid = sieve-like) |
| lacrimal | ophthalmic | lateral palpebral | lacrimal gland, eyelids laterally | (Latin, lacrima = a tear |
| supraorbital | ophthalmic | | muscles, skin & fascia of forehead | |
| supratrochlear | ophthalmic | | muscles, skin & fascia of forehead medially | (Latin, trochlea = a pulley) |
Clinical Terms
|
|
Term
|
Definition
|
| ptosis |
paralytic drooping of the upper eyelid usually described in
reference to damage of the sympathetic nerves found in the cervical
sympathetic trunk or internal carotid nerves that ultimately supply the
superior tarsal muscle, but may also involve the levator palpebrae
superioris muscle innervated by the oculomotor nerve |
| orbital cellulitis |
inflammation or infection of the soft tissues of the orbit such as the
periocular fat and connective tissue
|
| cavernous sinus thrombosis/thrombophlebitis |
a blood clot within the cavernous sinus (a sinus cavity which is bordered by the sphenoid bone and the temporal bone). This condition produces a syndrome called cavernous sinus syndrome-characterized by edema of the eyelids and conjunctivae and paralysis of the third, fourth and sixth cranial nerves. Thrombophlebitis is the inflammation of the thrombosed vein |
| myopia |
that error of refraction in which rays of light entering the eye parallel to the
optic axis are brought to a focus in front of the retina, as a result of the eyeball
being too long from front to back (axial myopia) or of an increased strength in
refractive power of the media of the eye (index myopia). Also called
nearsightedness, because the near point is less distant than it is in emmetropia
with an equal amplitude of accommodation |
| presbyopia |
a defect of vision consequent upon advancing age. It is due to rigidity of the crystalline lens, which produce difficulty of accommodation and recession of the near point of vision, so that objects very near the eyes can not be seen distinctly without the use of convex glasses. Called also presbytia |
| diplopia |
(double vision) the perception of two images of a single object |
| blowout fracture |
fracture of the orbital floor due to increased orbital pressure from trauma. Orbital contents may herniate into the maxillary sinus and the inferior oblique and rectus muscles be entrapped, causing diplopia |
| sty |
an inflamed swelling or boil on the edge of the eyelid |
| conjunctivitis |
inflammation of the conjunctiva, generally consisting of conjunctival
hyperemia associated with a discharge |
| pink eye |
acute epidemic conjunctivitis (generally viral in nature) |
| papilledema |
edema of the optic disk (papilla), most commonly due to increased intracranial pressure, malignant hypertension or thrombosis of the central retinal vein |
| hyperopia |
that error of refraction in which rays of light entering the eye parallel to the
optic axis are brought to a focus behind the retina, as a result of the eyeball
being too short from front to back. This is referred to as farsightedness, as it
is easier to see distant objects than near ones. |
