Advanced Sternocleidomastoid Quiz

Q1. Why can injury to the accessory nerve weaken head rotation?

• The accessory nerve supplies the tongue
• The nerve controls the atlantoaxial joint directly
• The accessory nerve supplies the muscles of mastication
• Loss of sternocleidomastoid motor supply weakens contralateral facial rotation

Q2. Why is the accessory nerve vulnerable after it exits sternocleidomastoid?

• It passes inside the internal jugular vein
• It becomes enclosed by the thyroid gland
• It crosses the posterior triangle relatively superficially
• It enters the vertebral canal immediately

Q3. How can sternocleidomastoid produce both cervical flexion and upper cervical extension during bilateral contraction?

• The muscle changes its bony attachments during contraction
• The two heads are supplied by different cranial nerves
• One side always contracts while the other relaxes
• Its line of pull acts differently across lower and upper cervical joints

Q4. Why is sternocleidomastoid an important landmark for internal jugular venous access?

• The vein lies superficial to the skin
• The vein runs inside the sternal head
• The internal jugular vein lies deep to the muscle in a predictable regional relationship
• The muscle forms the wall of the vein

Q5. What anatomical change underlies congenital muscular torticollis involving sternocleidomastoid?

• Ossification of the hyoid bone
• Fibrotic shortening of one sternocleidomastoid
• Paralysis of the diaphragm
• Bilateral rupture of trapezius

Q6. Why is sternocleidomastoid useful for testing accessory nerve function clinically?

• The muscle is the only structure supplied by C1
• Resisted head rotation directly tests its CN XI-dependent motor action
• The muscle controls pupillary constriction
• Its contraction tests the facial nerve

Q7. How does sternocleidomastoid help organize lymph node examination of the neck?

• All cervical lymph nodes lie within the muscle
• Only axillary nodes are related to it
• It separates useful superficial and deep lymphatic landmarks
• It prevents lymphatic drainage between neck regions

Q8. Why can the posterior border of sternocleidomastoid be used for a superficial cervical plexus block?

• Cutaneous cervical plexus branches emerge near its midpoint
• The brachial artery crosses the border
• The vagus nerve becomes superficial there
• The recurrent laryngeal nerve exits the larynx there

Q9. Which functional combination best explains the muscle's name?

• The name refers to three separate muscles
• Sterno- refers to the hyoid, cleido- to the mandible, and mastoid to the scapula
• The name describes its nerve supply rather than attachments
• Sterno- refers to sternum, cleido- to clavicle, and mastoid to the mastoid process

Q10. Which statement best integrates sternocleidomastoid anatomy?

• It is a muscle of mastication supplied by the mandibular nerve
• It is a deep prevertebral muscle supplied only by sympathetic fibers
• It is a major superficial landmark linking head movement, cervical triangles, CN XI function, and deep neurovascular relationships
• It is an infrahyoid muscle supplied by the ansa cervicalis