Advanced Accessory Nerve Quiz

Q1. A right accessory nerve lesion distal to the sternocleidomastoid branch would most strongly produce which deficit?

• Bilateral facial paralysis
• Right tongue paralysis
• Right trapezius weakness with relatively preserved sternocleidomastoid function
• Right sternocleidomastoid paralysis with normal trapezius

Q2. Why does a right sternocleidomastoid weakness impair rotation of the head to the left?

• CN XI crosses completely to innervate the opposite sternocleidomastoid
• The right trapezius is the only muscle that rotates the head left
• The right sternocleidomastoid normally rotates the face contralaterally
• The left sternocleidomastoid rotates the face left

Q3. Why can trapezius paralysis impair abduction of the upper limb above the horizontal plane?

• Trapezius is the primary rotator cuff muscle
• Trapezius directly flexes the elbow
• Trapezius contributes to upward rotation of the scapula required for full arm elevation
• CN XI innervates the deltoid

Q4. Which clinical setting is classically associated with iatrogenic spinal accessory nerve injury?

• Carpal tunnel release
• Surgery or lymph node biopsy in the posterior triangle
• Appendectomy
• Cataract extraction

Q5. Which examination pattern suggests a proximal right CN XI lesion affecting both major muscular targets?

• Right ptosis and pupillary dilation
• Weak right shoulder shrug and weak head rotation to the left
• Weak left shoulder shrug and weak head rotation to the left
• Weak right jaw closure and tongue protrusion

Q6. Why can a lesion near the jugular foramen produce broader deficits than an isolated distal accessory nerve injury?

• CN IX, CN X, and CN XI share the jugular foramen
• CN XI merges permanently with CN IX and CN X
• The facial and trigeminal nerves also exit through the jugular foramen
• All cervical spinal nerves pass through the jugular foramen

Q7. How does the modern anatomical interpretation treat the traditional cranial root of the accessory nerve?

• It forms the entire spinal accessory nerve
• It is a sensory root from the trigeminal ganglion
• It arises from the spinal accessory nucleus and supplies trapezius
• It is generally regarded as vagal in origin and function rather than part of the spinal accessory nerve proper

Q8. Which sequence correctly traces the spinal accessory nerve from its origin to trapezius?

• Trigeminal motor nucleus to foramen ovale to posterior triangle to trapezius
• Nucleus ambiguus to hypoglossal canal to carotid sheath to tongue to trapezius
• Facial nucleus to internal acoustic meatus to stylomastoid foramen to sternocleidomastoid
• Spinal accessory nucleus to cervical rootlets to foramen magnum to jugular foramen to sternocleidomastoid to posterior triangle to trapezius

Q9. Which finding best distinguishes trapezius weakness from serratus anterior weakness when evaluating scapular dysfunction?

• Trapezius weakness causes isolated loss of elbow flexion
• Serratus anterior weakness causes loss of facial expression
• Both muscles are supplied by CN XI, so the findings are identical
• Shoulder droop and weak shrug favor trapezius dysfunction, while prominent medial winging with wall pushing favors serratus anterior dysfunction

Q10. Which statement best integrates accessory nerve anatomy?

• CN XI exits through the hypoglossal canal and innervates the tongue
• CN XI is a sensory cranial nerve from the medulla that supplies the face
• CN XI is a parasympathetic nerve to the parotid gland
• CN XI is a motor nerve from the upper cervical cord that enters through the foramen magnum, exits the jugular foramen, and supplies sternocleidomastoid and trapezius