Orbit And Eyeball

Question 1

Name the extraocular muscles of the eyeball. Origin and insertion.

Answer 1

Involuntary :
superior tarsal , inferior tarsal, orbitalis muscles

Voluntary
1) four recti
•Origin: all arise from the common tendinous ring of Zinn. Lateral rectus arises by an additional head from the anterior surface of Greater wing of sphenoid.
•Insertion: Into the sclera, little behind the limbus.

2) Superior and Infetior oblique
•SO arises from the body of sphenoid, superomedial to optic canal, passes through fibrous pulley to turn downwards, backwards and laterally & inserted into posterosuperior quadrant of eyeball.
•IO arises from the anteromedial part of orbital surface of maxilla. Inserted into posterosuperior quadrant is eyeball.

3) Levator palpebrae sup -origin from undersurface of lesser wing. Insertion by 3 lamella. Sup lamella of skeletal muscle inserted into skin of upper eyelid, middle lamella into superior tarsus, lower one into Sup. Conjunctival fornix.

Question 2

What is the fascia Bulbi? What are it’s mofofications?

Answer 2

Also known as Tenons capsule.
Forms a lose, thin, membranous covering around the eyeball.

Pierced by

• Ant ciliary vessels
• Tendons is extraocular muscles
• Forms a sheath around each muscles
• Medical check ligament - extends from the sheath of medial rectus, attached to lacrimal bone.
• Lateral check ligament - from sheath of lateral rectus, attached to Whitnall’s tubercle on zygomatic bone.