Image Based Question-67493

The muscle which is not supplied by the nerve (Arrow) near the overlying organ as shown in the picture below is ?

A. Thyroarytenoid.

B. Posterior cricoarytenoid.

C. Cricothyroid.

D. Lateral cricoarytenoid.

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Correct Answer » C Explanation

Ans:C. Cricothyroid.

The nerve marked by an arrow near the thyroid is recurrent laryngeal nerve.

Adductor of vocal cords

Thyroarytenoid muscle:

• R and L muscles; attached to thyroid and arytenoid cartilages on each side.

• Action shortens and relaxes vocal ligament.

Note: deeper inner fibers referred to as “vocalis muscle”.

Lateral cricoarytenoid muscle: (R and L muscles):

• Attached to cricoid and arytenoid cartilage on each side.
• Closes or adducts vocal folds.
• Supplied by Recurrent laryngeal nerve.

Cricothyroid muscle:

• Attached to cricoid and thyroid cartilages.
• Tilts the thyroid cartilage, thus increasing tension of vocal folds
• Supplied by external laryngeal nerve

Inter-arytenoid muscle (transverse and oblique)

• Attached between right and left arytenoid cartilages
• Closes inlet of larynx
• Supplied by Recurrent laryngeal nerve Abductor of vocal cords

Posterior cricoarytenoid muscle

• Attached to cricoid and arytenoid cartilages

• Move arytenoid cartilages so as to move both vocal folds apart, “open” of abduct vocal folds

• Supplied by Recurrent laryngeal nerve

Vocalis muscle (derived from inner and deeper fibers of thyroarytenoid msucle)

Supplied by Recurrent laryngeal nerve

All intrinsic muscles of the larynx are supplied by the recurrent laryngeal nerve except for cricothyroid which is supplied by external laryngeal nerve.