Brainstem and Cranial Nerves

Question 1

upper motor neurons (UMN)

Answer 1

• the descending motor tracts from the cortex (corticospinal/corticobulbar) and brainstem (vestibulospinal/reticulospinal/rubrospinal/tectospinal) that influence the LMNs
  -your brain sends motor signals down and throughout the UMN in order for signals to reach LMN and cause movements

Question 2

lower motor neurons (LMN

Answer 2

-the motor neurons from the anterior horn of central gray matter in the spinal cord and the brainstem nuclei of cranial nerves in the brainstem
- The UMN synapse with LMN in spinal cord or brainstem motor nuclei in order for the signal to continue down towards target structures (ex muscles) allowing them to move

Question 3

Pathology in UMN results in

Answer 3

increased tone
spasticity
hyperreflexia
ex: tourrettes, dysarthria, cerebral palsy

Question 4

Pathology in LMN results in

Answer 4

decreased tone
hyporeflexia
flexor response (toes down/neutral)
atrophy (in the weak muscle)
ex: stroke, TBI

Question 5

UMN signs/symptoms

Answer 5

• Initial period of spinal shock, then spasticity ensues
• Babinski’s sign and clonus
• More widespread (nongeographic) distribution of impairment in body regions
• Impairment of fine voluntary movements: gross movements relatively unimpaired

Question 6

LMN signs and symptoms

Answer 6

• initial signs and symptoms persist
• Fasciculations and fibrillations
• geographic distribution of impairment (reflecting distribution of affected spinal segments, cranial nuclei, or spinal/cranial nerves)
• Impairments of reflexive and gross and/or fine voluntary movements

Question 7

If your patient has a LMN of CN VII, what impairment will you see? How will this be different from an UMN lesion affecting CN VII?

Question 8

If your patient has a LMN lesion of CN XII, what will you see? How about an UMN lesion of CN XII?

Question 9

Determine site of lesion if shown a photograph or cartoon depicting paresis / paralysis of the face (laterality and upper verse lower motor lesion)

Question 10

neuromuscular junction (NMJ)

Answer 10

• The area where electrical signals from the LMN are transducer into chemical signals that can be interpreted and understood by the muscle
• results in a contraction of the muscle and movement of choice

Question 11

What is the relationship between LMN and the NMJ?

Question 12

NMJ components/ultrastructure

Answer 12

-pre-synaptic terminal (end of LMN)
-synaptic cleft (small space)
-post synaptic membrane (muscle fiber)

Question 13

Describe Myasthenia Gravis (MG) and how it relates to the NMJ.

Answer 13

• MG is an autoimmune disease that is caused by antibodies being raised against tissues that are naturally present in our bodies
• With MG, the tissue is being attacked by the person’s own immune response in the NMJ, resulting in reduced muscle contraction and force production (difficulty with expressions, swallowing, shortness of breath, etc.

Question 14

Classifications study tip

Answer 14

*general = not a special sense
*somatic = structures derived from the embryological somites (skin, skeletal muscle, joints)
*Afferent = sensory information

Question 15

General Somatic Efferent (GSE)

Answer 15

• refers to nuclei or the ventral
  horn of spinal cord that innervates muscle directly

*classifications of cranial nuclei & cranial nerves

Question 16

Special Visceral Efferents (SVE)

Answer 16

*known as brachial motor innervates muscles from the pharyngeal arches (all of face except eyes and tongues)
*classifications of cranial nuclei & cranial nerves

Question 17

General Visceral Efferents (GVE)

Answer 17

*refers to efferent neurons of the autonomic nervous system that innervate smooth muscle, cardiac muscle and glands
*classifications of cranial nuclei & cranial nerves

Question 18

General Somatic Afferents (GSA)

Answer 18

• refers to sensory nerves that carry touch information from the extremities and face including pain and temperature
  *classifications of cranial nuclei & cranial nerves

Question 19

General Visceral Afferents (GVA)

Answer 19

*refers to sensory nerves that carry mostly pain information from the viscera, glands, and blood vessels
*classifications of cranial nuclei & cranial nerves

Question 20

Special Somatic Afferents (SSA)

Answer 20

*refers to nerves that carry information from ‘special’ senses including vision, hearing and balance
*classifications of cranial nuclei & cranial nerves

Question 21

Special Visceral Afferents (SVA)

Answer 21

*refers to nerves that carry information from ‘special’ visceral senses including olfaction and taste

Question 22

CN I: Olfactory Nerve

Answer 22

sensory functions:
- Smell

Question 23

CN II: Optic Nerve

Answer 23

sensory functions:
- Vision

Question 24

CN III: Oculomotor Nerve

Answer 24

motor functions:
- Pupillary reflex
- eye motion/ eyelid elevation

Question 25

CN IV: Trochlear Nerve

Answer 25

motor functions:
- Eye motion

Question 26

CN V: Trigeminal Nerve

Answer 26

sensory functions:
- Somatosensation to face, jaw, oral mucosa, teeth, tongue surface, external auditory canal, tympanic membrane
motor functions:
- Muscles of Mastication

Question 27

CN VI: Abducens Nerve

Answer 27

motor functions:
- eye motion

Question 28

CN VII: Facial Nerve

Answer 28

sensory functions:
- taste to anterior two thirds of tongue
-tactile from skin on back side of the pinna and the external auditory canal
motor functions:
- secretion of nasal, lachrymal, submaxillary, sublingual glands, nasopharynx, mucous membrane
- muscles of the face, stapedius muscle

Question 29

CN VIII

Answer 29

motor functions:
-

Question 30

CN IX: Glossopharyngeal nerve

Answer 30

sensory functions:
- Somatosensation from palate region, posterior tongue, oropharynx, middle ear, Eustachian tube
- Monitor changes in O2, CO@, and blood pH; Taste from posterior 1/3 of tongue
- Transduces blood pressure changes via receptors within carotid sinus

motor functions:
- Secretion of parotid, oral mucosal glands
- Stylopharyngess muscle

Question 31

CN X: Vagus Nerve

Answer 31

motor functions:
-

Question 32

CN XI: Spinal Accessory Nerve

Answer 32

motor functions:
-

Question 33

CN XII: Hypoglossal Nerve

Answer 33

motor functions:
-