extraocular muscles dr.gosai
DESCRIPTION
Extraocular musclesTRANSCRIPT
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ORBIT
EXTRAOCCULAR MUSCLES
Dr.B.B.Gosai
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Bony Orbit
Seven bones make up the bony orbit: Frontal Zygomatic Maxillary Ethmoidal Sphenoid Lacrimal Palatine
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Bony Orbit
ROOF:The orbital roof
formed from both the orbital plate of the frontal bone and the lesser wing of the sphenoid bone. Above the roof is cranial cavity.
Contains: Lacrimal fossa for lacrimal gland
FLOOR:The floor of the orbit
is formed from three bones and related to maxillary sinus:
Maxillary Palatine Orbital plate of the
zygomatic
It contains:Infraorbital grooveAttachment of Inferior
oblique muscle
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Bony Orbit
MEDIAL WALL of the orbit is formed from four bones and related to lateral wall of nose: Frontal process of the
maxillary Lacrimal Orbital plate of the
ethmoidal Lesser wing of the
sphenoidLacrimal fossa for
lacrimal sac.
LATERAL WALL: Formed from two bones: Zygomatic Greater wing of the
sphenoidThickest and strongestLateral orbital
tubercle (Whitnall’s tubercle) for attachment of lateral check ligament
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Orbital Foramina
The optic foramen: Transmit Optic nerve and Ophthalmic artery
The supraorbital foramen, or notch: transmit supraorbital nerve and vessels
The zygomatic foramen: Transmit Zygomatic nerve
Infraorbital canal: Transmit Infraorbital nerve and vessels
Superior orbital fissure: Transmit occulomotor nerve, trochlear nerve, abducent nerve, Branches of Ophthalmic nerve, Ophthalmic veins
Inferior orbital fissure: Maxillary nerve
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Structures passing through superior orbital fissure
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Extra ocular Muscles in the orbit
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Extraocular Muscles
The four recti and two oblique muscles
All are supplied by oculomotor nerve III except superior oblique (Trochlear N) and lateral rectus (Abducent N)
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Voluntary Muscles:1. Four Recti – Superior, inferior, medial and
lateral.2. Two Oblique – Superior & inferior.3. Elevator of upper eyelid – Levator palpebrae
superioris.Involuntary Muscles:1. Superior tarsal muscle – Deeper part of levator
palpebrae superioris2. Inferior tarsal muscle3. Orbitalis muscle
Extra ocular Muscles in the Orbit
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Extra ocular Muscles
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Extra ocular Muscles:Origin
Common annular tendinous ring
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Extra ocular Muscles:Origin
Superior ObliqueLevator palpebrae superioris
Medial Rectus
Lateral Rectus
Superior Rectus
Inferior RectusInferior Oblique
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Levator Palpebrae Superioris Origin: Orbital surface of lesser
wing of sphenoid bone, anterosuperior to optic canal.
Insertion: Splits in two lamina Superior lamina (voluntary) to Skin
of upper eyelid & anterior surface of superior tarsal plate
Inferior lamina (Muller’s muscle)(involuntary) to upper margin of superior tarsus (superior tarsal or muller’s muscle) & superior conjunctival fornix
Nerve Supply: Oculomotor nerve (voluntary part); Sympathetic (involuntary part)
Action: Elevation of upper eyelid. Damage to oculomotor nerve lead
to paralysis of this muscle and leads to ptosis.
Even damage to sympathetic fibers in Horner’s syndrome leads to partial ptosis due to paralysis of Muller’s muscle.
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Extra ocular MusclesInsertion: on the sclera
Recti – on sclera in front of equator; distance from cornea – SR = 7.7mm, LR = 6.9mm. IR = 6.5mm; MR = 5.5mm.Superior Oblique – Behind the equator on sclera in superolateral posterior quadrant, between the recti superior and lateralis.Inferior Oblique: - Behind the equator on sclera in inferolateral posterior quadrant, between the recti superior and lateralis.
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Nerve Supply:
Abducent (VI cranial) nerve supplies lateral rectus
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Nerve Supply:
Trochlear (IV cranial) nerve supplies superior oblique
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Nerve Supply Superior, Inferior & Medial Recti; Levator
palpebrae superioris and Inferior Oblique Muscles are supplied by Oculomotor ( III cranial) Nerve
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Movements of Eyeball Along vertical axis : Lateral rotation (Abduction) & Medial
rotation (Adduction) Along Transverse axis: Elevation & Depression Along anteroposterior axis: Intortion (cornea moves
medially from 12 O'clock position) & Extortion (cornea moves laterally from 12 O'clock position)
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Actions of Recti Muscles
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Actions of Recti Muscles
Superior rectus: Elevation; Adduction; Intortion
Inferior rectus: Depression; Adduction; Extortion
Medial rectus: Adduction;
Lateral rectus: Abduction;
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Actions of Oblique Muscles
Superior Oblique: : Depression,Abduction,Intortion
Inferior Oblique : Elevation,Abduction,Extortion
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Actions of Oblique Muscles
Superior Oblique: : Intortion
Inferior Oblique : Extortion
Anteroposterior axis
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Actions of Oblique Muscles
Both oblique muscles pulls posterolateral quadrant anteromedially; thus abduct the eyeball.
Vertical axis
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Recti muscles: straight muscles•Superior rectus: oculomotor nerve
•Adduction, elevation, intorsion
•Inferior rectus: oculomotor nerve•Adduction, depression, extorsion
•Medial rectus: oculomotor nerve•Adduction
•Lateral rectus: abducent nerve•Abduction
•Superior oblique: trochlear nerve•Abduction, depression, intorsion
•Inferior oblique: oculomotor nerve•Abduction, elevation, extorsion
Movements of Eyeball
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Applied AnatomyAbnormal deviation of eyeball is known as
Squint (Strabismus).
Paralysis of Lateral rectus due to damage to Abducent nerve leads to Medial Squint.
Damage to Occulomotor nerve leads to paralysis of all muscles of eye except Superior oblique and lateral rectus leading to Lateral Squint and Ptosis-Dropping of Eyelid.
Damage to Trochlear nerve cause paralysis of superior oblique muscle causing diplopia while looking downwards.
Medial Squint
Lateral Squint and Ptosis -Dropping of Eyelid.
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Superior Oblique
Inferior Oblique
Superior rectus
Inferior rectus
Medial rectus
Lateral rectus
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• Causes: interruption of sympathetic pathway like multiple sclerosis, syringomyelia, traction of stellate ganglion by cervical rib, ganglion metastatic lesion.
• Signs:• Constriction of pupil (miosis) due to paralysis of dilator
pupillae• Slight drooping of eyelid (ptosis) due to paralysis of
Muller’s muscle (Part of Levator palpebrae superioris)• Enophthalmos (Retraction of eyeball) due to paralysis of
Orbitalis muscle which support the eyeball• Loss of sweating (anhydrosis) damage to sympathetic
fibers to sweat glands• Loss of ciliospinal reflex
Horner’s syndrome
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