Extraocular Muscle

Extraocular muscles are the six skeletal muscles that control eye movement and one muscle that controls eyelid elevation. These muscles allow the eye to move in multiple directions with precision and speed.

• Medial rectus – adducts the eye (moves it toward the nose)
• Lateral rectus – abducts the eye (moves it away from the nose)
• Superior rectus – elevates, adducts, and intorts the eye
• Inferior rectus – depresses, adducts, and extorts the eye
• Superior oblique – intorts, depresses, and abducts the eye
• Inferior oblique – extorts, elevates, and abducts the eye
• Levator palpebrae superioris – elevates the upper eyelid (not involved in eye movement)

• Oculomotor nerve (CN III):
  • Superior division → superior rectus, levator palpebrae superioris
  • Inferior division → medial rectus, inferior rectus, inferior oblique
• Trochlear nerve (CN IV): superior oblique
• Abducens nerve (CN VI): lateral rectus

These muscles coordinate to allow:

• Horizontal gaze (medial + lateral rectus)
• Vertical gaze (superior/inferior rectus and oblique synergy)
• Torsional (rotational) movements of the eyeball
• Binocular alignment and smooth pursuit of targets

• Lesions of the nerves innervating these muscles cause:
  • Diplopia (double vision)
  • Ophthalmoplegia (paralysis of eye movements)
  • Ptosis (drooping eyelid) if levator palpebrae superioris is affected

• oculomotor_nerve
• trochlear_nerve
• abducens_nerve
• cranial_nerve_palsies