The muscle that lies on the anterior thoracic wall is:-

Appeared in: AIIMS Manglagiri NO - 2019

Explanation

The Pectoralis major is a large, fan-shaped muscle located in the upper chest, covering a significant portion of the anterior thoracic wall.
Its origin is from the clavicle, sternum, and upper ribs, and it inserts on the humerus.
This location directly corresponds to the anatomical region specified in the question.
The primary functions of the Pectoralis major include adducting (bringing closer to the body), flexing, and internally rotating the arm.

Option B: The Deltoid muscle forms the rounded contour of the shoulder. It is located superior and lateral to the thoracic wall, not on it.
Option C: The Triceps brachii is located on the posterior (back) aspect of the upper arm. The provided image correctly illustrates its posterior position.
Option D: The Biceps brachii is located on the anterior (front) aspect of the upper arm, between the shoulder and the elbow, not on the thoracic wall.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Anatomy of the major muscles of the upper torso and arm as background academic context rather than a clinical decision trigger.
Understanding muscle locations is fundamental for physical assessment. A nurse assessing a patient with chest trauma would need to differentiate between pain originating from the Pectoralis major versus deeper structures like ribs or lungs.
Pectoralis major tears or strains are common in athletes (e.g., weightlifters). Nurses may be involved in the assessment and post-injury care, looking for signs like pain, bruising, and weakness in arm adduction.
Knowledge of muscle anatomy is crucial for correctly placing ECG leads on the chest to avoid muscle artifacts that can interfere with the reading.

How to Approach the Question

This is a factual recall question from the subject of anatomy.
First, identify the key anatomical landmark in the question stem: 'anterior thoracic wall'. This means the front of the chest.
Mentally visualize or recall the major muscles of the upper torso and arm.
Evaluate each option based on its known location:
Pectoralis major: The large chest muscle.
Deltoid: The shoulder cap muscle.

Concept Tested & Keywords

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E6 Anatomy Grays 43e Vol 2 Part 2 pp. 100-102, 101-103, 72-74

Practise the full AIIMS Manglagiri NO - 2019

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