Which of the following is NOT a long bone?

Appeared in: AIIMS Raipur - 2017 (Shift-3)

Explanation

The Sternum, or breastbone, is classified as a flat bone due to its thin, flattened shape.
The primary functions of flat bones like the sternum are to protect vital organs (such as the heart and lungs) and to provide a broad surface for muscle attachment.
Unlike long bones, which are characterized by a shaft and two ends and facilitate movement, the sternum's structure is adapted for protection and anchorage.

Option A: The Humerus is the bone of the upper arm and is a classic example of a long bone.
Option C: The Femur, or thigh bone, is the longest and strongest bone in the body and is classified as a long bone.
Option D: The Ulna is one of the two long bones in the forearm, located on the side of the little finger.

Visual 1: Diagram - Classification of bones. This diagram would show examples of long, short, flat, irregular, and sesamoid bones, helping to visually differentiate their shapes.
Visual 2: Illustration - The human skeleton. An illustration highlighting the sternum, humerus, femur, and ulna would clearly show their respective shapes and positions in the body.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Classification of bones by shape as background academic context rather than a clinical decision trigger.
The sternum is a critical anatomical landmark for performing effective cardiopulmonary resuscitation (CPR), as chest compressions are applied to its lower half.
A sternal puncture is a procedure where a needle is inserted into the sternum to aspirate bone marrow for diagnosing various hematological disorders like leukemia.
What if? If the question asked for an 'irregular bone', a correct answer would be a vertebra or a hip bone, as their complex shapes do not fit into the long, short, or flat categories.

How to Approach the Question

First, carefully read the question and identify the negative keyword 'NOT'. This signals that you must find the option that does not belong to the specified category.
Recall the main classifications of bones based on shape: long, short, flat, and irregular.
Systematically evaluate each option against the definition of a 'long bone' (a bone that is longer than it is wide).
Classify each bone: Humerus is a long bone. Sternum is a flat bone. Femur is a long bone. Ulna is a long bone.
Identify the outlier. The Sternum is the only bone in the list that is not a long bone.
Select Sternum as the correct answer because the question asks which one is NOT a long bone.

Concept Tested & Keywords

Concept Tested: Classification of bones by shape
Stem keywords: bone, long bone
Lead-in keywords: NOT
Negative lead-in flag: The question asks to identify the option that is NOT a long bone.

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