In which are pseudo-unipolar neurons seen?

Bihar CHO - 2021

Applied Anatomy

Easy

Appeared in: Bihar CHO - 2021

Explanation

Pseudo-unipolar neurons are a specific type of sensory neuron where a single process splits into peripheral and central branches.
The most classic and numerous location for these neurons is the sensory ganglia of the spinal cord, also known as the dorsal root ganglia (DRG).
These neurons are responsible for transmitting primary sensory information like pain, touch, and temperature from the body to the central nervous system.
The structure of these neurons, with the cell body located off the main axon pathway in the ganglion, is key to their function in relaying sensory signals.

Option A: Motor ganglia contain multipolar neurons, which are involved in transmitting motor signals from the CNS to effector organs like muscles and glands.
Option B: This option is also a factually correct location for pseudo-unipolar neurons. However, in a single-best-answer question where both B and C are correct, the question is ambiguous. The dorsal root ganglia of the spinal cord (Option C) represent a more extensive and classic example.
Option D: This option is incorrect because not all the listed locations contain pseudo-unipolar neurons. Motor ganglia (Option A) contain multipolar neurons.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Anatomical location of pseudo-unipolar neurons as background academic context rather than a clinical decision trigger.
The cell bodies of the varicella-zoster virus (chickenpox virus) remain dormant in the pseudo-unipolar neurons of sensory ganglia. Reactivation of this virus later in life causes herpes zoster (shingles), a painful rash that follows the dermatomal distribution of the affected sensory nerve.
Compression of a dorsal root ganglion, for example by a herniated intervertebral disc, can cause radiculopathy, which manifests as pain, numbness, and tingling (paresthesia) in the area of skin supplied by that nerve root.
What if? If the question had asked for the location of bipolar neurons, the correct answer would involve special sensory systems, such as the retina of the eye, the olfactory epithelium of the nose, or the ganglia of the vestibulocochlear nerve (cranial nerve VIII).

How to Approach the Question

First, identify the key term in the question: 'pseudo-unipolar neurons'.
Recall the major classifications of neurons based on their structure: multipolar, bipolar, and unipolar/pseudo-unipolar.
Associate each neuron type with its primary function and location. Pseudo-unipolar neurons are fundamentally sensory.
Evaluate the options based on this association. 'Motor ganglia' (Option A) can be immediately eliminated because their function is motor, not sensory, and they contain multipolar neurons.
Recognize that both 'Sensory ganglia of cranial nerves' (Option B) and 'Sensory ganglia of spinal cord' (Option C) are correct locations for sensory neurons.
Since both B and C are correct, and 'All of the above' (Option D) is incorrect due to A, the question is flawed. In such a scenario, select the most common or classic textbook example, which is the dorsal root ganglia of the spinal cord (Option C).

Concept Tested & Keywords

QRERfucP1ElTUbGdu99P7f

E6 Anatomy Applied Ashalatha 4e p. 406-408

E6 Anatomy Grays 43e Vol 1 Part 2 p. 93-95