Neurology · MU Sofia

17. Bulbar cranial nerves, bulbar and pseudobulbar paresis

Covers the four bulbar cranial nerves (glossopharyngeal, vagus, accessory and hypoglossal) with their sensory, motor and reflex functions, then sets out a bedside examination sequence for each. It contrasts bulbar palsy, a lower motor neuron lesion of the medullary nuclei or nerves, with pseudobulbar paresis, an upper motor neuron lesion from bilateral corticobulbar damage, listing causes and clinical features for both.

Inside: 1 section · 2 labelled pictures · 14 flashcards · 2 min

Topic 17 of 88 in the MU Sofia syllabus for Neurology (Medicine, Year 4). The free AceMed note covers it in 1 section, about 293 words (2 min of reading), with 14 flashcards.

In this note

  1. Bulbar cranial nerves. Bulbar and pseudobulbar paresis

Bulbar cranial nerves. Bulbar and pseudobulbar paresis

Bulbar Cranial Nerves

The bulbar cranial nerves arise from the medulla oblongata and include:

  • CN IX – Glossopharyngeal nerve
  • CN X – Vagus nerve
  • CN XI – Accessory nerve
  • CN XII – Hypoglossal nerve

These nerves are responsible for swallowing, phonation, articulation, tongue movements, and palate function.

Anatomy and Physiology

CN IX (Glossopharyngeal)

  • Sensation from posterior 1/3 of tongue
  • Taste from posterior 1/3 of tongue
  • Afferent limb of gag reflex
  • Assists swallowing

CN X (Vagus)

  • Motor innervation of soft palate, pharynx, and larynx
  • Efferent limb of gag reflex
  • Controls phonation and swallowing

CN XI (Accessory)

  • Sternocleidomastoid muscle
  • Trapezius muscle

CN XII (Hypoglossal)

  • Motor innervation of tongue muscles
  • Controls tongue movements

Examination

1. Soft Palate and Uvula: Ask the patient to say "Ahhh".

  • Normal: Symmetrical elevation of soft palate. Uvula remains in the midline

2.Gag Reflex

  • Afferent: CN IX. Efferent: CN X

3.Voice Assessment

  • Look for: Hoarseness. Nasal speech. Dysarthria.

4. Swallowing

  • Assess for: Dysphagia. Choking. Nasal regurgitation

5.Tongue Examination (CN XII)

  • Inspect for: Atrophy. Fasciculations. Ask patient to protrude tongue.

6.Accessory Nerve (CN XI): Shoulder shrug against resistance. Head rotation against resistance

Bulbar Paresis (Bulbar Palsy)

Definition: A lower motor neuron (LMN) lesion affecting the nuclei or nerves IX, X, XI, and XII in the medulla.

Causes: Motor neuron disease (ALS). Brainstem infarction. Syringobulbia. Poliomyelitis. Brainstem tumors

Clinical Features: Dysarthria. Dysphagia. Nasal speech. Weak cough. Nasal regurgitation. Tongue atrophy. Tongue fasciculations. Absent gag reflex. Palatal weakness

Pseudobulbar Paresis

Definition: An upper motor neuron (UMN) lesion due to bilateral damage of the corticobulbar pathways.

Causes: Bilateral stroke. Multiple sclerosis. Motor neuron disease (UMN component). Diffuse cerebral disease

Clinical Features: Dysarthria. Dysphagia. Slow, spastic speech. Brisk jaw jerk reflex. Emotional lability (pathological laughing or crying). Increased gag reflex. No tongue fasciculations. No significant tongue atrophy.

Read the full note free

The whole note is free with an AceMed account, with its 14 flashcards. Premium adds flashcard recall, highlights and Ask AI.

Start freeAlready a member? Open the note