INVOLUNTARY EXTRAOCULAR MUSCLES(MULLER’S MUSCLES)

RANGEEN CHANDRAN R

SUPERIOR TARSAL MUSCLE

Origin-Undersurface of levator palpebrae superioris.

Insertion-superior tarsal plate of upper eyelid.

Nerve supply-postganglionic sympathetic fibres of superior cervical sympathetic ganglion.

Action-elevation of upper eyelid.

CLINICAL

Peripheral arterial arcade between levator aponeurosis and upper border of superior tarsal muscle.

So plane of dissection created between levator aponeurosis and superior tarsal muscle.

In thyroid eye disease,fibrosis and mast cell infiltration of muscle occurs.

Partial ptosis-in Horner’s syndrome(2mm ptosis)

INFERIOR TARSAL MUSCLE

Origin-Capsulopalpebral fascia.

Insertion-Inferior tarsal plate.

Nerve supply-Post ganglionic sympathetic fibres of superior cervical sympathetic ganglion

Action-lower lid retraction.

ORBITALIS MUSCLE

Vestigial muscle.

Orbital muscle of muller.

Crosses inferior orbital fissure and sphenomaxillary fissure.

Unites with periosteum of orbit.

Action-Forward protrusion of eyeball.

Nerve supply-post ganglionic sympathetic fibres from superior cervical sympathetic ganglion.

CLINICAL

Paralysis of orbitalis- enophthalmos

(Horner’s syndrome)

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