Cranial Nerves II

Question 1

Innervation Chart

Answer 1

Question 2

CN VII Modalities

Answer 2

• Facial nerve
  
  • Visceromotor (GVE)
  • Branchiomotor (SVE)
  • Somatosensory (GSA)
  • Viscerosensory (GVA)
  • Special sensory (SVA)

Question 3

Facial Canal

Answer 3

Between the IAM and stylomastoid foramen

Question 4

CN VII exits the cranial cavity through…

Answer 4

the internal acoustic meatus

Question 5

• Facial canal
  
  • Geniculate ganglion

Answer 5

• contains cell bodies for sensory neurons (1^o GSA/GVA/SVA) in CN VII
  
  • Vestibular nerve (CN VIII)
  • Cochlear nerve (CN XIII)
  • Geniculate ganglion
  • Chorda tympani
  • Cochlea
  • Semicircular canals (vestibular apparatus)
  • Malleus
  • Tympanic membrane
  • Auditory canal

Question 6

CN VII: Visceromotor (GVE)

Answer 6

• Lacrimal gland
• Nasal mucosa
• Sublingual gland
• Submandibular gland
• Functions
  
  • parasympathetic: stimulates productions of tears, mucous, and saliva

Question 7

CN VII: Branchiomotor (SVE)

Answer 7

• Muscles of facial expression
• Stapedius muscle
• Posterior belly of digastric muscle
• Stylohyoid muscle

Question 8

CN VII: Somatosensory (GSA)

Answer 8

External ear (pinna)

Question 9

CN VII: Viscerosensory (GVA)

Answer 9

• Sensation from the mucosal lining of the nasopharynx and soft palate
• Follows the same path as SVA fibers

Question 10

CN VII: Special sensory (SVA)

Answer 10

• taste of anterior 2/3 of tongue
• synapse in geniculate ganglion
• Chorda tympani n.

Question 11

CN VIII

Answer 11

• Vestibulocochlear nerve
• Modalities: SSA
• Sensations of hearing (from cochlea) and balance (from vestibular apparatus)

Question 12

Middle ear function

Answer 12

transmit sounds between tympanic membrane (ear drum) and the cochlea (inner ear); convert mechanical vibrations to pressure waves in cochlear fluid

Question 13

3 ossicles of middle ear

Answer 13

• Malleus (“hammer”): sits on the tympanic membrane
• Incus (“anvil”)
• Stapes (“stirrup”): sits on the oval window of the cochlea

Question 14

Middle ear muscles

Answer 14

• Stapedius m.
  
  • CN VII (SVE)
  • Stabilize stapes
• Tensor tympani m.
  
  • CN V₃ (SVE)
  • Dampens sounds (e.g. chewing sounds)

Question 15

The middle ear connects

Answer 15

• pharynx via the auditory tube
• mastoid air cells via the aditus ad antrum

Question 16

Inner ear

Answer 16

• Cochlea
  
  • spiral shaped organ responsible for hearing
• Vestibular apparatus
  
  • balance and orientation in space
  • semicircular canals: measure head rotations
  • otoliths: measure linear acceleration, contained within utricle and saccule

Question 17

CN IX modalities

Answer 17

• Glossopharyngeal nerve
  
  • Viscermotor (GVE)
  • Branchiomotor (SVE)
  • Somatosensory (GSA)
  • Viscerosensory (GVA)
  • Special sensory (SVA)

Question 18

CN IX: Visceromotor (GVE)

Answer 18

• Parotid gland
• Parasympathetic, stimulates saliva production

Question 19

CN IX: Branchiomotor

Answer 19

Stylopharyngeus m.

Question 20

CN IX: Somatosensory (GSA)

Answer 20

Posterior 1/3 of tongue

Question 21

CN IX: Special Sensory (SVA)

Answer 21

Taste from posterior 1/3 of tongue

Question 22

CN IX: Viscerosensory (GVA)

Answer 22

• Carotid sinus (baroreceptors)
• Carotid body (chemoreceptors)
• Upper pharynx
  
  • Oro- and naso- pharynx
• Middle ear

Question 23

CN X Modalities

Answer 23

• Vagus nerve
  
  • Visceromotor (GVE)
  • Branchiomotor (SVE)
  • Somatosensory (GSA)
  • Viscerosensory (GVA)
  • Special sensory (SVA)

Question 24

CN X: Visceromotor (GVE)

Answer 24

• Mucous membranes
  
  • pharynx
  • larynx
  • trachea
• thoracic organs
  
  • heart and lungs
• abdominal organs
  
  • foregut and midgut

Question 25

CN X: Branchiomotor (SVE)

Answer 25

• Soft palate mm.
  
  • Levator veli palatini m.
  • Palatopharyngeus m.
  • Palatoglossis m.
  • Salpingopharyngeus m.
• Pharyngeal constrictors
• Intrinsic laryngeal muscles (via recurrent laryngeal nerve)
• Cricothyroid m. (via external branch od superior laryngeal nerve)

Question 26

CN X: Somatosensory (GSA)

Answer 26

• External ear and canal
• Tympanic membrane (external)

Question 27

CN X: Viscerosensory (GVA)

Answer 27

• Inferior pharynx
  
  • Laryngopharynx
• Larynx
• Thoracic organs
  
  • heart and lungs
  • aortic body
• Abdominal organs
  
  • foregut and midgut

Question 28

CN X: Special sensory (SVA)

Answer 28

• Sense of taste
  
  • Root of tongue
  • Epiglottis

Question 29

CN IX

Answer 29

• Spinal accessory nerve
  
  • Two parts:
    
    • Cranial part (CN XI_C)
    • Spinal part (CN XI_S)
  • Modalities
    
    • SVE (CN XI_C)
    • GSE (CN XI_S)

Question 30

Cranial part of CN XI: Branchiomotor (SVE)

Answer 30

• Accompanies CN X
• Motor part of pharyngeal plexus
• Musculus uvulae m.
• Levator veli palatini m.

CN XI_C is functionally (clinically) and often anatomically indistinguishable from CN X

Question 31

Spinal part of CN XI: Somatomotor (GSE)

Answer 31

• Trapezius m.
• Sternocleidomastoid m.

Question 32

CN XII Modalities

Answer 32

• Hypoglossal Nerve
  
  • Somatomotor (GSE)

Question 33

CN XII: Somatomotor (GSE)

Answer 33

• Extrinsic tongue mm.
  
  • Genioglossus m.
  • Hyoglossus m.
  • Styloglossus m.
• Intrinsic tongue mm.

Question 34

Clinical tests for lower cranial nerves

Answer 34

• Shrug test
  
  • elevate shoulders against resistance
  • Motor: Accessory nerve (CN XI)
  • structure: trapezius
• Head turn
  
  • turn head against resistance
  • motor: accessory nerve (CN XI)
  • structure: SCM muscle
• Tongue protrusion
  
  • Motor:
  • Tongue deviates towards side of lesion
  • Unopposed genioglossus m. (protracts tongue)
• Left hypoglossal nerve lesion
• Soft palate- uvula position
  
  • left CN X/XI_C lesion (nucleus ambiguus)
  • uvula deviates away from side of lesion
  • unopposed levator veli palatini m. (elevates uvula)