• There are 7 extraocular skeletal muscles
• They can be divided into groups:
  • Recti and oblique muscles - responsible for eye movement
  • Levator palpebrae superioris - responsible for superior eyelid movement

Recti muscles

• 'Straight' - direct path from origin to attachment
• Superior rectus, inferior rectus, medial rectus, lateral rectus
• Origin: all originate from common tendinous ring
• Insertion: all insert onto sclera

Oblique muscles

• Insert onto the eyeball at an oblique angle
• Inferior oblique and superior oblique
• Origin: superior oblique originates from sphenoid bone, inferior oblique originates from orbital plate of maxilla
• Insertion: both insert onto sclera
• The tendon of the superior oblique passes through a trochlea (loop of connective tissue) before inserting onto the eyeball

Levator palpebrae superioris muscle (LPS)

• The only muscle involved in raising the superior eyelid
• Origin: lesser wing of sphenoid
• Insertion: skin and tarsus of superior eyelid

Superior tarsal muscle

• A small portion of this muscle contains a collection of smooth muscle fibres, known as the superior tarsal muscle or Mueller's muscle, which assists the levator palpebrae superioris in opening the eyelid