EXTRAOCULAR MUSCLES
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WHAT IS EXTRAOCULAR MUSCLE------
HUMAN EYE THERE ARE SIX EXTRAOCULAR MUSCLES. WHICH ARE HELPS TO MOVEMENTS OF THE EYE IN THE DIFFERENT DIRECTION AND THE SUPERIOR EYELID.
THE EXTRAOCULAR MUSCLES ARE LOCATED WITHIN THE ORBIT.
EXTRAOCULAR MUSCLES ARE--
1. SUPERIOR RECTUS MUSCLE
2. INFERIOR RECTUS MUSCLE
3. MEDIAL RECTUS MUSCLE
4. LATERAL RECTUS MUSCLE
5. SUPERIOR OBLIQUE MUSCLE
6. INFERIOR OBLIQUE MUSCLE.
THERE IS ANOTHER ONE MUSCLE WHICH IS RESPONSIBLE FOR SUPERIOR EYELID MOVEMENT - LEVATOR PALPEBRAE MUSCLE.
MUSCLES OF EYE MOVEMENTS------
THERE ARE SIX MUSCLES INVOLVE IN THE CONTROL OF THE EYEBALL MOVEMENT.
THEY ARE DIVIDED INTO TWO PARTS ---------
A. FOUR RECTI MUSCLE
B. TWO OBLIQUE MUSCLE
RECTI MUSCLE----
THERE IS FOUR RECTI MUSCLE. THEY ARE- SUPERIOR RECTUS, INFERIOR RECTUS, MEDIAL RECTUS & LATERAL RECTUS.
ORIGIN--
THE FOUR RECTUS MUSCLES ARE ORIGINATES FROM COMMON TENDINOUS RING(THE ANNULUS OF ZINN) WHICH IS ATTACH OF THE APEX OF THE ORBIT.
INSERTION--
ALL FOUR RECTUS MUSCLES ARE INSERTED INTO THE SCLERA AT THE DIFFERENT DISTANCE FROM THE LIMBUS.
1. SUPERIOR RECTUS------
ORIGIN--
ORIGINATES FROM THE SUPERIOR PART OF THE COMMON TENDINOUS RING.
INSERTION--
ATTACHES TO THE INFERIOR & ANTERIOR ASPECT OF THE SCLERA.
DISTANCE- 7.9 mm
NERVE SUPPLY--- 3rd CRANIAL NERVE.
ACTION-----
PRIMARY-- ELEVATION
SECONDARY--- INTORTION OR MEDIAL ROTATION OF THE EYEBALL.
TERTIARY-- ADDUCTION
2. INFERIOR RECTUS--------
ORIGIN-----
ORIGINATES FROM THE SUPERIOR PART OF THE COMMON TENDINOUS RING.
INSERTION--
ATTACHES TO THE INFERIOR & ANTERIOR ASPECT OF THE SCLERA.
DISTANCE- 6.8mm
NERVE SUPPLY--- 3rd CRANIAL NERVE.
ACTION-----
PRIMARY-- DEPRESSION
SECONDARY--- EXTORTION OR LATERAL ROTATION OF THE EYEBALL.
TERTIARY-- ADDUCTION
3. MEDIAL RECTUS----
ORIGIN-----
ORIGINATES FROM THE SUPERIOR PART OF THE COMMON TENDINOUS RING.INSERTION--
ATTACHES TO THE INFERIOR & ANTERIOR ASPECT OF THE SCLERA.
DISTANCE- 5.3mm (CLOSEST MUSCLE FROM THE LIMBUS)
NERVE SUPPLY--- 3rd CRANIAL NERVE.
ACTION-----
PRIMARY-- ADDUCTION
4. LATERAL RECTUS-------
ORIGIN-----
ORIGINATES FROM THE SUPERIOR PART OF THE COMMON TENDINOUS RING.INSERTION--
ATTACHES TO THE INFERIOR & ANTERIOR ASPECT OF THE SCLERA.
DISTANCE- 6.9mm
NERVE SUPPLY--- 6th CRANIAL NERVE.
ACTION-----
PRIMARY-- ABDUCTION
OBLIQUE MUSCLE--------
5.SUPERIOR OBLIQUE MUSCLE
ORIGIN--
ORIGINATES FROM THE BODY OF THE SPHENOID.
INSERTION---
UPPER PORTION OF THE SCLERA.
NERVE SUPPLY- 4th CRANIAL NERVE
ACTION--
PRIMARY-- INTORTION OR MEDIAL ROTATION OF THE EYEBALL.
SECONDARY-- DEPRESSION
TERTIARY-- ABDUCTION
6.INFERIOR OBLIQUE MUSCLE
ORIGIN--
ORIGINATES FROM THE ANTERIOR ASPECTS OF THE ORBITAL FLOOR.
INSERTION---
LOWER AND OUTER PART OF THE SCLERA.
NERVE SUPPLY- 3rd CRANIAL NERVE
ACTION--
PRIMARY-- EXTORTION OR LATERAL ROTATION OF THE EYEBALL.
SECONDARY-- ELEVATION
TERTIARY-- ABDUCTION
** ELEVATION----- UPWARD MOVEMENT
** DEPRESSION-- DOWNWARD MOVEMENT
**INTORTION--- MEDIAL ROTATION OF THE EYEBALL.
**EXTORTION-- LATERAL ROTATION OF THE EYEBALL.
**** (LR)6(SO)4--- LATERAL RECTUS SUPPLIED BY 6th CRANIAL NERVE & SUPERIOR OBLIQUE MUSCLE SUPPLIED BY 4th CRANIAL NERVE, OTHERS ARE SUPPLIED BY 3rd CRANIAL NERVE.
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