Diaphragm is supplied by which nerve?

Appeared in: ISRO- 2016

Explanation

The diaphragm is the chief muscle of respiration, and its function is controlled by the phrenic nerve.
The phrenic nerve originates from the cervical plexus, with contributions from spinal nerves C3, C4, and C5.
This nerve provides the exclusive motor supply to the diaphragm, making it essential for breathing.
A helpful mnemonic is 'C3, C4, C5 keep the diaphragm alive,' highlighting the critical role of these spinal roots.

Option B: The intercostal nerves supply the intercostal muscles between the ribs. They only provide sensory innervation to the peripheral (outer) edges of the diaphragm, not the primary motor control.
Option C: The peroneal nerve is located in the lower limb and is responsible for movement and sensation in the foot and leg. It has no anatomical or functional connection to the diaphragm.
Option D: The vagus nerve is a major component of the parasympathetic nervous system, controlling functions like heart rate, digestion, and respiratory rate, but it does not provide motor innervation to the diaphragm muscle itself.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Innervation of the Diaphragm as background academic context rather than a clinical decision trigger.
A key nursing assessment for patients with high cervical spine injuries (at or above C5) is respiratory function, as diaphragm paralysis is a major risk.
Patients with phrenic nerve palsy may present with unexplained shortness of breath (dyspnea), and a chest X-ray might show an elevated hemidiaphragm.
What if? If a patient experiences hiccups (singultus), it is due to involuntary spasms of the diaphragm, often caused by irritation of the phrenic nerve. Nursing care would focus on identifying and managing the underlying cause of irritation.

How to Approach the Question

First, identify the key terms in the question: 'Diaphragm' and 'nerve supply'.
Recall the primary function of the diaphragm as the main muscle of breathing.
Access your anatomical knowledge about the major nerves of the thorax and neck.
Use the mnemonic 'C3, C4, C5 keep the diaphragm alive' to link the phrenic nerve to the diaphragm.
Evaluate the other options to confirm they are incorrect. The intercostal nerves supply the rib muscles, the peroneal nerve is in the leg, and the vagus nerve has a different function.

Concept Tested & Keywords

QU9g5QOrA4rkq5OnIT5ph5

E6 Anatomy BDChaurasia V2 10e Part 2 p. 116-118

Practise the full ISRO- 2016

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