Which nerve is responsible for adductor muscle of thigh and skin of medial aspect of thigh?

RRB Nsg Superintendent -29 April 2025 (Shift-1st)

Applied Anatomy

Easy

Appeared in: RRB Nsg Superintendent -29 April 2025 (Shift-1st)

Explanation

The obturator nerve originates from the lumbar plexus (L2-L4) and is the primary nerve for the medial compartment of thethigh.
It provides motor innervation to the adductor muscle group (adductor longus, brevis, magnus, gracilis, and obturator externus), which are responsible for thigh adduction.
It also provides sensory (cutaneous) innervation to the skin on the medial aspect of the thigh.
This dual motor and sensory function for the medial thigh makes it the correct answer.

Option A: The phrenic nerve is located in the thorax and neck and is unrelated to the lower limbs.
Option B: The musculocutaneous nerve is part of the brachial plexus and innervates structures in the upper arm and forearm, not the thigh.
Option C: The iliohypogastric nerve innervates the lower abdominal wall and skin in the pubic and gluteal regions. It does not supply the adductor muscles.

Visual 1: Diagram of the Lumbar Plexus. This visual would illustrate the origins of the nerves of the lower limb, clearly showing the obturator nerve arising from L2, L3, and L4 and its path towards the medial thigh.
Visual 2: Cross-section of the Thigh. A diagram showing the three compartments of the thigh (anterior, medial, posterior) would help visualize the medial (adductor) compartment and the structures innervated by the obturator nerve.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Innervation of the Medial Compartment of the Thigh as background academic context rather than a clinical decision trigger.
An obturator nerve block is a procedure used to manage hip pain or provide anesthesia for procedures on the medial thigh by injecting anesthetic around the nerve.
During pelvic surgeries (e.g., gynecological or urological procedures), the obturator nerve is at risk of injury, which can lead to postoperative weakness in thigh adduction and sensory loss on the medial thigh.
What if? If a patient presents with weakness in thigh adduction but has normal sensation on the medial thigh, the injury might be to a specific motor branch of the obturator nerve or a muscle-tendon unit, rather than the main nerve trunk.

How to Approach the Question

First, identify the key anatomical structures mentioned in the question: 'adductor muscle of thigh' and 'skin of medial aspect of thigh'.
Recognize that the question is asking for the specific peripheral nerve that provides both motor and sensory supply to this region.
Systematically review the options and recall the primary function and distribution of each nerve.
Phrenic nerve supplies the diaphragm (respiration). Eliminate.
Musculocutaneous nerve supplies the arm/forearm. Eliminate.
Iliohypogastric nerve supplies the lower abdomen/buttock. Eliminate.

Concept Tested & Keywords

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