Which is the smallest bone in the human body?

Appeared in: Bihar CHO -2019

Explanation

The stapes, located in the middle ear, is the smallest and lightest bone in the human body.
It measures approximately 3 x 2.5 mm and is shaped like a stirrup.
Its primary function is to transmit sound vibrations from the incus to the oval window of the inner ear, a critical step in the process of hearing.

Option A: The incus (anvil) is one of the three middle ear ossicles, but it is larger than the stapes.
Option B: The malleus (hammer) is the largest of the three middle ear ossicles.
Option C: The scapula, or shoulder blade, is a large, flat, triangular bone. It is one of the larger bones in the body, not the smallest.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Human Anatomy - Skeletal System as background academic context rather than a clinical decision trigger.
Understanding the anatomy of the ear ossicles is crucial for nurses caring for patients with hearing loss, particularly conductive hearing loss, which can be caused by problems with these bones.
A common condition affecting the stapes is otosclerosis, where the bone becomes immobile, causing hearing loss. Nurses may care for patients undergoing stapedectomy (surgical replacement of the stapes).
What if? If a patient has otosclerosis, the stapes is fixed and cannot vibrate, leading to conductive hearing loss. The treatment is a stapedectomy. The nurse's role is critical in providing post-operative care, including teaching the patient to avoid activities that increase ear pressure (like forceful nose blowing) and to keep the ear canal dry to prevent infection.

How to Approach the Question

This is a factual recall question from the subject of Human Anatomy.
First, read the question carefully to identify the key concept being tested: the 'smallest bone' in the human body.
Next, evaluate the given options. You have Incus, Malleus, Scapula, and Stapes.
Recognize that Malleus, Incus, and Stapes are the three ossicles of the middle ear, which are known to be very small. The Scapula (shoulder blade) is a large bone and can be immediately eliminated.
From the remaining three options, recall the relative sizes of the ear ossicles. The stapes is the smallest, followed by the incus, and then the malleus is the largest.
Therefore, select Stapes as the correct answer.

Concept Tested & Keywords

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E6 Physiology Review Sembulingam 5e p. 186-188

E6 Anatomy Applied Ashalatha 4e p. 237-239

Practise the full Bihar CHO -2019

Attempt every question from this paper in a timed mock, then review the full solution for each one.