Orbit, Extraocular Muscles And CN 3 4 6 Flashcards
Thinnest wall of Orbit
Medial Wall
Medial wall of the orbit is formed by
u
S ~ body of Sphenoid
M ~ Maxilla
L ~ Lacrimal
E ~ Ethmoid
Fracture is seen in the which wall of the orbit
Floor of the Orbit
Lateral wall of Orbit Formed by
Zygomatic Bone
Greater Wing of Sphenoid
Roof of the orbit is formed by
Frontal Bone
Lesser wing of Sphenoid
Floor of the Orbit is Formed by
Maxilla Bone
Zygomatic Bone
Palatine Bone
Optic Canal Transmit and Present in Which Bonw
In the Lesser Wing of Sphenoid
Ophthalmic Artery
Optic nerve with Meninges
Superior Orbital Fissure Is divided into
Superolateral Part
Intermediate Part
Inferomedial Part
Structures Passing Through Superolateral Compartment of Superior Orbital Fissure
L ~ Lacrimal nerve
F ~ Frontal nerve
T ~ Trochlear nerve
Superior Ophthalmic Vein
Structures Passing Through Intermediate Compartment of Superior Orbital Fissure
SO ~ Superior division of Oculomotor nerve
N ~ Nasociliary nerve
I ~ Inferior division of oculomotor nerve
A ~ Abducent nerve
Structures passing through Inferomedial Compartment of Superior Orbital Fissure
Inferior Ophthalmic Vein
Inferior Orbital Fissure transmitting
Infraorbital Nerve (continuation of Maxillary Nerve)
Zygomatic Branch (of Maxillary Nerve)
Recti ~ means
Straight
Origin of 4 Rectus Muscles
Common Tendinous Ring
Origin of Inferior Oblique Muscle
Floor of The Orbit (Maxilla Bone)
Angle of Superior Rectus and Medial Rectus on which side to Visual Axis
Lateral to Visual Axis
Main Action of Superior Rectus Muscle
Elevation on abducted eye
Other Actions;
Adduction
Intorsion
Main action of Inferior Rectus Muscle
Depression on abducted eye
Other Actions;
Adduction
Extortion
Intorsion of the eye ball refers to
Inward movement of the eyeward
Intorsion is done by ____________ muscles
Extorsion done by __________
muscles
Superior muscles ~ intorsion
Inferior muscles ~ extorsion
Superior and Inferior Oblique Muscles are attached behind the _____________
Equator of eye ball
Angle of Superior and Inferior oblique is on which side of the Visual Axis
Medial to Visual Axis
Main Action of Superior Oblique Muscle is
And other actions
Depression on adducted eye
Other Actions;
Abduction
Intorsion
Main Action of Inferior oblique muscle
And other actions
Elevation on adducted eye
Other Actions;
Abduction
Extorsion
Elevation on Abducted Eye is done by __________ Muscle
Superior Rectus Muscle
Elevation on Adducted Eye is done by __________ Muscle
Inferior Oblique Muscle
Depression on abducted eye is done by ___________ Muscle
Inferior Rectus Muscle
Depression of adducted eye is done by _________ Muscle
Superior Oblique Muscle
Adduction is done by
Main Muscle -
Other Muscle -
Main Muscle - Medial Rectus
Other Muscle - Superior and Inferior Rectus
Abduction is done by
Main Muscle -
Other Muscle -
Main Muscle - Lateral Rectus
Other Muscle - Superior and Inferior Obliue
Nerve Supply To Extra Ocular Muscles ~ mnemonic
SO4 LR6 Remaining3
Functional columns of 3rd nerve
GSE - to supply Extraocular Muscle
GVE - to supply Sphincter Pupillae and Ciliaris Muscle
Parasympathetic column from Edinger Westfall Nucles
3rd and 4th Nerve is passing b/w _________ Arteries
Posterior Cerebral Artery
and
Superior Cerebellar Artery
Before entering the Orbital Cavity 3rd Nerve is divided into
Superior and Inferior Division
Then both enters through superior orbital fissure in the common Tendinous ring
Superior Division of Oculomotor nerve is supplying
Levator Palpebrae Superioris
Superior Rectus Muscle
Medial Rectus
Inferior Rectus
Inferior Oblique
Muscles supplied by
Inferior division on Oculomotor nerve
GVE ~ Parasympathetic Component of Oculomotor Nerve reach Ciliary Ganglion via
Nerve To Inferior Oblique
Parasympathetic Fibres from Ciliary Ganglion via ___________ Nerve, Supplies _______ and ________ Muscle
Via Short Ciliary Nerves
Ciliaris Muscle (95% fibres)
and
Sphincter Pupillae (5%)
Oculomotor Nucleus is located in the Midbrain at the level of
Superior Colliculus
Fibres Supplying the ___________ Muscle,
is crossing to the opposite side within the nucleus and joins with the oculomotor Nerve
Fibres coming to Superior Rectus Muscle
Lesion to the Right Oculomotor Nucleus
Which side of the Superior Rectus Muscle will be affected?
Both side Superior Rectus Muscles will be affected
Lesion in one nucleus will affect crossing of opposite side fibres too
Changes In Accommodation Reflex
- Medial Convergence of eyeball ~ by medial Rectus
- Construction of Pupil ~ Sphincter Pupillae
- Increase in Thickness of Lens ~ Ciliary Muscle
The sole Property of 3rd Cranial Nerve
Accommodation Reflex
Features of 3rd Nerve Palsy
P
P D
p D O
Reflexes ~
P ~ Ptosis (LPS)
P D ~ Pupils Dilated
p D O ~ Down d/t Superior Oblique
Out d/t Lateral Rectus
Loss of Light Reflex
Loss of Accommodation
Cranial Nerve with
Dorsal Exit
Internal Decussation ~ Supply contralateral side
Longest IntraCranial Course
Slender/Smallest Nerve
Trochlear Nerve
Exit of Trochlear Nerve from the midbrain at the level of
Inferior Colliculus
Nerves Passing between Superior Cerebellar Artery and Posterior Cerebral Artery
3rd and 4th Cranial Nerves
Features of 4th Nerve Injury
Loss of Intorsion
Extorted Eye Ball
To correct extorsion Head Tilt ~ to Opposite side
Location of Abducens Nucleus
Lying under Facial Colliculus
Nerve with longest Intradural course
Abducens Nerve
Dorello’s Canal is situated Between
And is formed by
Between Apex of the
Petrous Temporal Bone and Clivus
Formed by Petrosphenoid Ligament
Under Raised Intracranial Pressure the Abducent Nerve is irritated by
Apex of the Petrous-Temporal Bone
Most Common Nerve to get affected in the Raised Intracranial Pressure
6th Cranial Nerve
Nerve passing through (space) the cavernous sinus
6th Cranial Nerve
