Anatomy of the Eye

Extrinsic Skeletal Muscles

• The eye is controlled by six extrinsic skeletal muscles.
• These muscles are governed by the somatic nervous system.

Muscle Groups

1. Rectus Muscles

   • Superior Rectus: Located on top of the eye, runs parallel with the midline.
   • Inferior Rectus: Positioned underneath, harder to see.
   • Medial Rectus: Runs medially.
   • Lateral Rectus: Runs laterally.

2. Oblique Muscles

   • Superior Oblique: Runs at an angle medially before looping back.
   • Inferior Oblique: Starts on the lateral side and runs at an angle.

Cranial Nerve Control

• Three cranial nerves control the six muscles.

Mnemonic

• LR6: Lateral Rectus is controlled by the Abducens (Cranial Nerve VI).
• SO4: Superior Oblique is controlled by the Trochlear (Cranial Nerve IV).
• O3: All other muscles (Superior Rectus, Medial Rectus, Inferior Rectus, Inferior Oblique) are controlled by the Oculomotor (Cranial Nerve III).

This lecture covers the arrangement and control of eye muscles by cranial nerves, providing a mnemonic to facilitate learning.