Q 1.14. Caudal Group Cranial Nerves: Anatomy and Physiology

Let’s explore the anatomy and physiology of the caudal cranial nerves, which include nerves IX (glossopharyngeal)X (vagus)XI (accessory), and XII (hypoglossal):

  1. Glossopharyngeal Nerve (CN IX):

    • Origin: Emerges from the medulla oblongata.
    • Function:
      • Sensory: Innervates the posterior third of the tongue, the tonsils, and the pharynx.
      • Motor: Controls swallowing and the gag reflex.
    • Clinical Significance: Damage can lead to difficulty swallowing and altered taste perception.

2. Vagus Nerve (CN X):

    • Origin: Arises from the medulla oblongata.
    • Function:
      • Sensory: Provides sensation to the pharynxlarynx, and viscera.
      • Motor: Regulates heart ratedigestion, and speech.
    • Clinical Significance: Vagus nerve dysfunction can affect various bodily functions.

3. Accessory Nerve (CN XI):

    • Origin: Arises from the medulla oblongata and upper spinal cord.
    • Function:
      • Motor: Controls neck and shoulder movements (trapezius and sternocleidomastoid muscles).
    • Clinical Significance: Damage may lead to weakness in neck rotation and shoulder elevation.

4. Hypoglossal Nerve (CN XII):

    • Origin: Emerges from the medulla oblongata.
    • Function:
      • Motor: Innervates the tongue muscles for speech, swallowing, and tongue movement.
    • Clinical Significance: Hypoglossal nerve lesions result in tongue deviation and impaired speech.

These caudal cranial nerves play vital roles in swallowingspeech, and neck movements.

Bulbar Palsy

Definition: Bulbar palsy refers to a set of signs and symptoms resulting from impaired function of the lower cranial nerves (IX, X, XI, XII).


    • Brainstem Strokes and Tumors: Damage to the brainstem disrupts motor control signals, affecting cranial nerves.
    • Degenerative Diseases: Conditions like amyotrophic lateral sclerosis (ALS) and motor neuron disease (MND).
    • Autoimmune Diseases: Guillain–Barré syndrome.

Clinical Features:

    • Difficulty Swallowing (Dysphagia): Due to involvement of glossopharyngeal nerve (CN IX).
    • Reduced Gag Reflex: Also related to CN IX.
    • Other Symptoms:
      • Nasal speech lacking modulation.
      • Difficulty with consonants.
      • Atrophic (wasting) tongue.
      • Drooling.
      • Weakness of jaw and facial muscles.
      • Absent jaw jerk.
      • Absent gag reflex.


    • Progressive Bulbar Palsy: Symptoms worsen over time (more common).
    • Non-progressive Bulbar Palsy: Rare, with stable symptoms.

Differentiation from Pseudobulbar Palsy:

    • Emotional Lability: Pseudobulbar palsy shows atypical emotional outbursts (laughing or crying), while bulbar palsy emotions remain unaffected.
    • Facial Emotions: Absent in pseudobulbar palsy.
    • Tongue Characteristics: Spastic and pointed in pseudobulbar palsy.
    • Jaw Jerk: Exaggerated in pseudobulbar palsy.

Pseudobulbar Palsy

Cause: Damage to upper motor neurons.

Symptoms: Similar to bulbar palsy but often includes emotional lability (unusual laughing or crying).







Verified by Dr. Petya Stefanova