Basic anatomy of extra ocular muscles

1. EXTRAOCULAR MUSCLES
ANATOMY(BASIC)
Steffy Johnson M.optom

3. INTRODUCTION
• The extraocular muscles are located within the orbit.
• There are seven extraocular muscles –
1. Levator Palpebrae Superioris
2. Superior Rectus
3. Inferior Rectus
4. Medial Rectus
5. Lateral Rectus
6. Inferior Oblique
7. Superior Oblique

5. MUSCLES OF EYE MOVEMENT
• There are six muscles involved in the control of the eyeball itself.
They can be divided into two groups:
• The Four Recti Muscles,
• The Two Oblique Muscles.

6. RECTI MUSCLES
• There are four recti muscles;
1. Superior Rectus
2. Inferior Rectus
3. Medial Rectus
4. Lateral Rectus

7. ANNULUS OF ZINN
• The four recti muscles arise from a short funnel-shaped tendinous
ring called the annulus of Zinn.

8. SPIRAL OF TILLAUX
• Describes the insertion of the rectus muscles in relation to the limbus.

10. SUPERIOR RECTUS
• Origin – The superior rectus arises from the upper part of the annulus
of Zinn
• Insertion - 7.7 mm from limbus.
• Blood supply – Superior muscular branch of ophthalmic artery
• Size – 41.8 mm long
• Innervation – oculomotor nerve

12. INFERIOR RECTUS
• It is shortest of the recti muscles.
• Origin–It arises below common tendinous ring
• Insertion– 6.5 mm from the limbus.
• Blood supply – the inferior muscular branch of ophthalmic artery
• Size – 40 mm long
• Innervation – inferior division of the 3rd nerve(oculomotor nerve)

13. MEDIAL RECTUS
• It is largest of the ocular muscles
• Origin- medial side of common tendinous ring
• Insertion- 5.5 mm from the limbus.
• Blood supply – the inferior muscular branch of ophthalmic artery
• Size – 40.8 mm long
• Innervation– The inferior division of the 3rd nerve

14. LATERAL RECTUS
• Origin – arises from the annulus of Zinn
• Insertion – 6.9 mm from the limbus
• Blood supply – the lacrimal artery
• Size – 40.6 mm long
• Innervation– The 6th nerve (abducens)

15. OBLIQUE MUSCLES
• There are two oblique muscles:
1. Superior Oblique
2. Inferior Oblique
• Unlike the recti group of muscles, they do not originate from the
common tendinous ring.

16. SUPERIOR OBLIQUE
• It is longest and thinnest eye muscle.
• Origin – arises above and medial to the optic foramen.
• Blood supply – the superior muscular branch of ophthalmic artery.
• Size – 40 mm long
• Innervation – is supplied by the 4th or trochlear nerve

17. INFERIOR OBLIQUE
• Origin – front of the orbit.
• Insertion – inserted posterior inferior temporal quadrant at level of
macula
• Blood supply – the inferior branch of ophthalmic artery
• Size – 37 mm long
• Innervation– the inferior division of the oculomotor nerve

18. LEVATOR PALPEBRAE SUPERIORIS
• The levator palpebrae superioris (LPS) is the only muscle involved in
raising the superior eyelid.