Advanced Accessory Nerve Quiz

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

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

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 sternocleidomastoid normally rotates the face contralaterally
• The left sternocleidomastoid rotates the face left
• The right trapezius is the only muscle that rotates the head left

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

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

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

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

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

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

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

• The facial and trigeminal nerves also exit through the jugular foramen
• CN XI merges permanently with CN IX and CN X
• CN IX, CN X, and CN XI share 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 is generally regarded as vagal in origin and function rather than part of the spinal accessory nerve proper
• It arises from the spinal accessory nucleus and supplies trapezius
• It is a sensory root from the trigeminal ganglion
• It forms the entire spinal accessory nerve

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
• Spinal accessory nucleus to cervical rootlets to foramen magnum to jugular foramen to sternocleidomastoid to posterior triangle to trapezius
• Facial nucleus to internal acoustic meatus to stylomastoid foramen to sternocleidomastoid

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

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

Q10. Which statement best integrates accessory nerve anatomy?

• 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
• CN XI is a parasympathetic nerve to the parotid gland
• CN XI is a sensory cranial nerve from the medulla that supplies the face
• CN XI exits through the hypoglossal canal and innervates the tongue