cranial nerves

Question 1

what are cranial nerves?

Answer 1

• part of periphernal nervous system
• sensory, motor, and parasympathetic nerve fibers that innervate the head and viscera

Question 2

where do cranial nerves originate?

Answer 2

originate at the brain or brainstem. they are named in order, from anterior to posterior, where they emerge from the brain

Question 3

how many cranial nerves are there?

Answer 3

• 12 pairs (CNI-CNXII)
  + 3 pairs of sensory nerves
  + 5 pairs of motor nerves
  + 4 pairs of mixed nerves (both sensory and motor)

Question 4

what are the 12 cranial nerves?

Answer 4

• olfactory (I)
• optic (II)
• oculomotor (III)
• trochlea (IV)
• trigeminal (V)
• abducens (VI)
• facial (VII)
• vestibulocochlear (VIII)
• glossopharyngeal (IX)
• vagus (X)
• spinal accessory (XI)
• hypoglossal (XII)

Question 5

where do the olfactory and optic nerves attach?

Answer 5

they attach to the forebrain

Question 6

which nerve extends past the head and neck?

Answer 6

the vagus nerve

Question 7

is the olfactory nerve sensory or motor?

Answer 7

sensory

Question 8

is the optic nerve sensory or motor?

Answer 8

sensory

Question 9

is the oculomotor nerve sensory or motor?

Answer 9

motor

Question 10

is the trochlear nerve sensory or motor?

Answer 10

motor

Question 11

is the trigeminal nerve sensory or motor?

Answer 11

both

Question 12

is the abducens nerve sensory or motor?

Answer 12

motor

Question 13

is the facial nerve sensory or motor?

Answer 13

both

Question 14

is the vestibulocochlear nerve sensory or motor?

Answer 14

sensory

Question 15

is the glossopharyngeal nerve sensory or motor?

Answer 15

both

Question 16

is the vagus nerve sensory or motor?

Answer 16

both

Question 17

is the spinal accessory nerve sensory or motor?

Answer 17

motor

Question 18

is the hypoglossal nerve sensory or motor?

Answer 18

motor

Question 19

what are the 3 sensory cranial nerves?

Answer 19

olfactory (CNI), optic (CNII), and vestibulocochlear (CNVIII)
- innervation for special sensory structures (smell, vision, equilibrium, and hearing)

Question 20

what is the olfactory nerve?

Answer 20

• sensory: olfaction (smell)
• origin: olfactory epithelium of nose (terminate in posterior olfactory cortex)

Question 21

what is the optic nerve?

Answer 21

• technically not a nerve, but a brain tract (still refered to as a nerve). junction between the two is called the optic chiasma
• sensory: vision
• origin: retina of the eye (terminate in primary visual cortex)

Question 22

what is the vestibulocochlear nerve?

Answer 22

• sensory: hearing and balance (equilibrium)
• origin: inner ear, enters brainstem at pons

Question 23

what are the 5 motor cranial nerves?

Answer 23

oculomotor (CNIII), trochlear (CN IV), abducens (CN VI), spinal accessory (CN XI), hypoglossal (CN XII)
- somatic motor fibers to skeletal muscles of eye, neck/back, and tongue

Question 24

what are the oculomotor, trochlear, and abducens nerves?

Answer 24

• oculomotor: midbrain (parasympathetic)
• trochlear: midbrain
• abducens: pons
• functions: all of these are primarily motor nerves to extrinsic eye muscles

Question 25

what are some problems with eye innervation?

Answer 25

when the nerves tht control the muscles that move the eye are damaged, lots of potential issues. conditions include strabismus (eyes not parallel), ptosis (drooping eyelids), and diplopia (double vision)

Question 26

what is the spinal accessory nerve (CN XI)

Answer 26

motor nerve to trapezius and sternoclomastoid muscles origin: rootlets at cervical region of spinal cord

Question 27

what is the hypoglossal nerve (CN XII)

Answer 27

- hypo: below, glossal: tongue - motor to tongue muscles - origin: medulla oblongata

Question 28

what are the 4 mixed cranial nerves?

Answer 28

- trigeminal (CN V) - facial (CN VII) - glossopharyngeal (CN IX) - vagus (CN X) - mixed nerves: sensory innervation to the face, mouth, and viscera and also motor inervation to pharyngeal arch muscles (chewing, facial expression)

Question 29

what is the trigeminal nerve?

Answer 29

- three branches: V1 opthalmic, V2 maxillary, V3 mandibular - motor: V3 only (muscles of mastication) - sensory: V1, V2, and V3 (somatic sensory for face, oral cavity, nasal cavity, anterior 2/3 of tongue [not taste]) - origin: sensory receptors to pons

Question 30

what is the facial nerve? (CN VII)

Answer 30

- somatic motor: muscles of facial expression, 5 major motor branches - visceral motor (parasympathetic): lacrimal gland (tears), submandibular, and sublingual salivary glands (digestion), and nasal and palatine glands - sensory: taste (anterior 2/3 of tongue), small patch at ear for somatic sensory - origin: pons

Question 31

what is the glossopharygeal (CN IX)?

Answer 31

- somatic motor: stylopharyngeus muscle (swallowing) - visceral motor (parasympathetic): parotid salivary gland (involved with digestion) - sensory: general visceral sensory, taste posterior 1/3 of the tongue - origin: medulla oblongata

Question 32

what is the vagus nerve (CN X)?

Answer 32

- somatic motor: larynx and pharyngeal muscles - visceral motor (parasympathetic): thoracoabdominal viscera through 2/3 of the intestines; regulates heartrate, breathing and digestive system activity - sensory: external auditory meatus and laryngopharynx. also visceral sensory from most thoracoabdominal viscera - origin: medulla oblongata - only cranial nerve to extend beyond head/neck

Question 33

describe the innervation of the tongue

Answer 33

- taste (right side): vagus (backmost), glossopharyngeal (center), facial (front) - somatic sensation (left side): vagus (backmost), glossopharyngeal (posterior 1/3), mandibular (remaining part)

Question 34

what are the visceral motor (parasympathetic system)?

Answer 34

- CN III: oculomotor (pupils) - CN VII: facial (lacrimal and salivary glands) - CN IX: glossopharyngeal (parotid salivary glands) - CN X: vagus (thoracoabdominal)