Total no of vertebrae in sacrum is?

Appeared in: NCL (MP) Nursing Officer - 2020

Explanation

The sacrum is a composite bone formed from the fusion of five individual vertebrae.
These vertebrae are labeled S1, S2, S3, S4, and S5.
While they are separate bones in childhood, they fuse together to form a single, solid, triangular bone in adulthood.
This fusion process is typically complete between the ages of 18 and 30.

Option A: The number 2 does not correspond to any standard vertebral group count.
Option B: While the coccyx (tailbone) is commonly formed by the fusion of four vertebrae, the sacrum is formed by five.
Option D: The number 8 does not correspond to the number of vertebrae in the sacrum or any other section of the spine.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Anatomy of the vertebral column, specifically the number of vertebrae in the sacrum as background academic context rather than a clinical decision trigger.
The sacrum is a key anatomical structure for certain medical procedures. The sacral hiatus is the site for caudal epidural anesthesia, used for pain control below the umbilicus.
The sacrum forms the posterior wall of the pelvis and transmits the weight of the body to the pelvic girdle through the sacroiliac joints.
What if? If a patient has 'lumbarization' of the S1 vertebra, it means S1 is not fused to the rest of the sacrum and functions more like a sixth lumbar vertebra. This can sometimes be a source of lower back pain.

How to Approach the Question

This is a factual recall question from the subject of anatomy.
First, identify the specific anatomical structure the question is asking about, which is the 'sacrum'.
Recall the composition of the vertebral column, which is divided into five regions.
Remember the number of vertebrae in each region: Cervical (7), Thoracic (12), Lumbar (5), Sacral (5, fused), and Coccygeal (3-5, fused).
Select the option that matches the number of vertebrae in the sacral region.

Concept Tested & Keywords

Concept Tested: Anatomy of the vertebral column, specifically the number of vertebrae in the sacrum.
Stem keywords: vertebrae, sacrum
Lead-in keywords: Total no

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E6 Physiology Ganong 27e Vol 2 Part 3 p. 52-54

E6 Anatomy Applied Ashalatha 4e p. 291-293

E6 Anatomy Grays 43e Vol 2 Part 2 p. 20-22

Practise the full NCL (MP) Nursing Officer - 2020

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