Which muscle injury causes torticollis during delivery?

Appeared in: RRB Nsg. Superintendent-20 July 2019 (Shift-2)

Explanation

Congenital muscular torticollis (CMT) is caused by a contracture (shortening) of the sternocleidomastoid (SCM) muscle.
This condition often results from muscle injury due to stretching or compression during the birthing process, particularly in difficult deliveries.
The injury can lead to localized ischemia and fibrosis within the SCM muscle, causing it to tighten.
This tightening pulls the head into a characteristic position: tilted toward the affected side with the chin rotated to the opposite side.

Option A: This option is too general. While the sternocleidomastoid is a skeletal muscle, the question asks for the specific muscle responsible for torticollis.
Option C: Cardiac muscle is found only in the heart and is responsible for pumping blood. It is not involved in the movement of the head and neck.
Option D: Smooth muscle is involuntary and found in the walls of internal organs, such as the intestines and blood vessels. It does not control head posture.

Clinical Relevance

Nursing practice connection: Knowing Etiology of Congenital Muscular Torticollis helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
Nurses play a crucial role in the early identification of congenital torticollis during newborn assessments, which allows for prompt intervention.
A key nursing responsibility is educating parents on performing gentle passive stretching exercises and proper positioning techniques (e.g., encouraging 'tummy time') to lengthen the shortened SCM muscle.
Early and consistent physical therapy is the cornerstone of treatment and resolves the condition in nearly all cases, preventing long-term complications like plagiocephaly (flattening of the head) and facial asymmetry.

How to Approach the Question

First, analyze the question to identify the key concepts: 'torticollis' (twisted neck) and 'delivery' (implying a congenital or birth-related cause).
Recall the different types of muscle tissue and their primary locations and functions in the body.
Eliminate the obviously incorrect options. 'Cardiac muscle' is in the heart, and 'smooth muscle' is in internal organs; neither is involved in voluntary neck movement.
Differentiate between the remaining options: 'Skeletal Muscle' and 'Sternocleidomastoid Muscle'.
Recognize that 'Skeletal Muscle' is a broad category, whereas 'Sternocleidomastoid Muscle' is a specific muscle in the neck.
Select the most precise answer. Medical questions often require identifying the specific anatomical structure involved, making 'Sternocleidomastoid Muscle' the best choice.

Concept Tested & Keywords

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E6 Nelson Textbook of Pediatrics(2024) — Volume 2 p. 2068-2070

E6 Obstetrics Williams p. 20-39

Practise the full RRB Nsg. Superintendent-20 July 2019 (Shift-2)

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