The site of growth in the length of a long bone is?

NVS Staff Nurse - 2019

Applied Anatomy

Easy

Appeared in: NVS Staff Nurse - 2019

Explanation

The epiphyseal plate, also known as the growth plate, is a layer of hyaline cartilage located between the epiphysis and diaphysis of a long bone.
Longitudinal bone growth occurs here through a process called endochondral ossification.
Within the plate, cartilage cells (chondrocytes) proliferate on the epiphyseal side.
On the diaphyseal side, the older cartilage calcifies and is replaced by bone tissue, causing the bone to lengthen.
This process continues until early adulthood, when the plate fuses and becomes an epiphyseal line, halting further growth in length.

Option A: Bone marrow is the site of hematopoiesis (blood cell formation), not longitudinal bone growth.
Option B: The diaphysis is the shaft of the long bone. It is the part of the bone that gets longer, but the growth itself originates from the epiphyseal plates at its ends.
Option D: The periosteum is a membrane covering the bone's outer surface. It is responsible for growth in the bone's diameter (thickness), a process called appositional growth, not growth in length.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Anatomy and physiology of long bone growth as background academic context rather than a clinical decision trigger.
Understanding the function of the epiphyseal plate is crucial in pediatric nursing, especially when assessing musculoskeletal injuries.
Fractures that involve the growth plate (Salter-Harris fractures) require careful management to prevent complications like growth arrest, which can lead to limb length discrepancy or angular deformity.
A nurse assessing a child with a limb fracture must be vigilant for signs of growth plate injury and understand the importance of proper immobilization and orthopedic follow-up.

How to Approach the Question

First, identify the key terms in the question: 'growth in length' and 'long bone'. This specifies the exact process and location the question is asking about.
Recall the basic anatomy of a long bone, which includes the diaphysis (shaft), epiphyses (ends), and the structures in between.
Differentiate between the two types of bone growth: longitudinal (length) and appositional (width/thickness).
Evaluate each option based on its primary function: Bone marrow (blood cells), Diaphysis (shaft), Epiphyseal plate (length), and Periosteum (thickness).
Match the function to the question's requirement. The question asks for growth in 'length', which directly corresponds to the function of the epiphyseal plate.
Therefore, select the option that is specifically responsible for longitudinal growth.

Concept Tested & Keywords

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