The longest bone in human body is?

Appeared in: MNS 2015

Explanation

The femur, commonly known as the thigh bone, is the longest, strongest, and heaviest bone in the human body.
It extends from the hip joint (articulating with the acetabulum) to the knee joint (articulating with the tibia).
Its primary functions are to support the body's entire weight during activities like standing and walking, and to act as a lever for the powerful muscles of the thigh.

Option B: The fibula is the thinner and more lateral of the two bones in the lower leg; it is significantly shorter and less massive than the femur.
Option C: The tibia, or shin bone, is the second longest bone in the body, but it is shorter than the femur.
Option D: The humerus is the bone of the upper arm and is considerably shorter than the femur.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Anatomy of the human skeletal system, specifically the long bones as background academic context rather than a clinical decision trigger.
Femur fractures are considered medical emergencies. Due to the bone's size and vascularity, a fracture can lead to severe hemorrhage (1-1.5 liters of blood loss) into the thigh compartment and increase the risk of life-threatening complications like fat embolism syndrome.
The neck of the femur is a common site for fractures in elderly individuals, particularly those with osteoporosis. These 'hip fractures' often require surgical intervention and are associated with high rates of morbidity and mortality.
What if? If the question asked for the longest bone of the upper body, the correct answer would be the Humerus.

How to Approach the Question

This is a factual recall question based on fundamental knowledge of human anatomy.
First, identify the key term in the question, which is 'longest bone'.
Systematically review the options provided, which are all major long bones.
Mentally visualize or recall the location of each bone: Humerus (upper arm), Femur (thigh), Tibia and Fibula (lower leg).
Based on general anatomical proportions, the thigh is the longest segment of the limbs.
Therefore, the femur, the bone of the thigh, is the longest bone in the body. Select this option.

Concept Tested & Keywords

Concept Tested: Anatomy of the human skeletal system, specifically the long bones.
Stem keywords: longest bone, human body
Lead-in keywords: is

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E6 Anatomy BDChaurasia V2 10e Part 1 p. 36-38

E6 Physiology Ganong 27e Vol 2 Part 3 p. 27-29

Practise the full MNS 2015

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