Mnemonic Monday: Major Actions of Extraocular Muscles

By Haley Masterson

Have you ever struggled to remember the important actions of the trochlear, abducens, and oculomotor nerves? If so, struggle no longer – here’s a mnemonic to make your Monday a little easier.

SALT ME DOWN: Six Abducts Laterally, Trochlear acts Medially Down. The oculomotor nerve is responsible for everything else.

To review: the abducens nerve (CN VI) will abduct the eye through its innervation of the lateral rectus muscle. Meanwhile, the trochlear nerve (CN IV) innervates the superior oblique muscle, which has one major action: depression – though it’s important to recognize that its effect is only clinically significant when the eye is medially adducted. Thus, the mnemonic: trochlear acts medially down.

Finally, the oculomotor nerve (CN III) innervates the medial rectus (adduction), inferior rectus (depression when not medially adducted), inferior oblique (elevation, abduction), and superior rectus muscles (elevation), as well as the levator palpebrae superioris – which does not act directly on the eye, but does function to elevate the eyelid.

 

Bibliography

1. Agarwal, Sunita. “Extraocular Muscles.” Textbook of Ophthalmology. New Delhi: Jaypee Bros., 2002.

2. Orient, Jane M., and Joseph D. Sapira. “The Neurologic Examination.” Sapira’s Art & Science of Bedside Diagnosis. Philadelphia: Lippincott Williams & Wilkins, 2005.

Discussion

25 thoughts on “Mnemonic Monday: Major Actions of Extraocular Muscles”

  1. According to First Aid for Step 1 – 2011, p. 421, the superior oblique abducts the eye (moves it laterally), not medially. I agree that the Sup. Oblique depresses the eye only when the eye is adducted, but it doesn’t actually adduct the eye, does it?

  2. @molly; the superior oblique muscle actually does adduct the eye. { Superior Oblique & Superior Rectus}. The converse is also true ( The Inferior Oblique & Inferior Rectus abduct the eye}.

  3. LR6 and SO4 is the best one i learnt from my school, Lateral rectus by 6(abducens) and Superior Oblique by 4(trochlear) and the rest by 3.

  4. The mnemonic is very good and accurate
    Great job Haley !

    Only one extra word to integrate the knowledge . In case of a lesion of the brain affecting CN4 or CN 6 the eye affected will show diplopia on clinical examination while CN3 will show diplopia , ptosis , mydriasis ,loss of accommodation .

  5. ??Hermes???????????20????????200????????????????????????????????????????????????????????????????????????????????????????——????????????????????????????????????????????????????HOUSE365????????????????????????????????????——80???????8????????????hermes?? ?“????”????????????????

  6. Actually, for vertical movement testing, the correct way is:
    – To test the rectus (sup. and inf): move the tested eye AWAY (abduct) to nullify the effect of the oblique muscles and then test elevation or depression.
    – To test the oblique (sup. and inf): move the tested eye INWARD (adduct) to nullify the effect of the rectus muscles and then test elevation or depression.
    The article has a mistake on the last paragraph “inferior oblique (elevation, abduction)”. It should be ADduction since it’s elevate the adducted eye.
    More details can be explained here:
    http://cim.ucdavis.edu/Eyes/eyeText.htm

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