CHAPTER 21 : The Orbit and Eyeball

21.4.2 Muscles of the eyeball :

Muscle
Origin
Insertion

The recti

  • Superior rectus
  • Inferior rectus
  • Medial rectus
  • Lateral rectus
 Common tendinous ring Front portion of the sclera
Superior oblique Sphenoid bone, passes through a cartilaginous pulley (the trochlear) Back of the scleras
Inferior oblique Maxilla Back of the sclera.

 
Actions of the muscles of the eyeball

Movement may be considered to be around a vertical axis (abduction and adduction) , a lateromedial axis ( elevation and depression ) and an anteroposterior axis ( extorsion and intorsion )

Muscle
Action
Lateral rectus Abduction
Medial rectus Adduction
Superior recti Elevation
Inferior recti Depression
Superior oblique Turns cornea downwards and outwards
Inferior oblique Turns cornea upwards and inwards