Brainstem and Cranial Nerves Flashcards
upper motor neurons (UMN)
- 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
lower motor neurons (LMN
-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
Pathology in UMN results in
increased tone
spasticity
hyperreflexia
ex: tourrettes, dysarthria, cerebral palsy
Pathology in LMN results in
decreased tone
hyporeflexia
flexor response (toes down/neutral)
atrophy (in the weak muscle)
ex: stroke, TBI
UMN signs/symptoms
- 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
LMN signs and symptoms
- 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
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?
If your patient has a LMN lesion of CN XII, what will you see? How about an UMN lesion of CN XII?
Determine site of lesion if shown a photograph or cartoon depicting paresis / paralysis of the face (laterality and upper verse lower motor lesion)
neuromuscular junction (NMJ)
- 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
What is the relationship between LMN and the NMJ?
NMJ components/ultrastructure
-pre-synaptic terminal (end of LMN)
-synaptic cleft (small space)
-post synaptic membrane (muscle fiber)
Describe Myasthenia Gravis (MG) and how it relates to the NMJ.
- 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.
Classifications study tip
*general = not a special sense
*somatic = structures derived from the embryological somites (skin, skeletal muscle, joints)
*Afferent = sensory information
General Somatic Efferent (GSE)
- refers to nuclei or the ventral
horn of spinal cord that innervates muscle directly
*classifications of cranial nuclei & cranial nerves
Special Visceral Efferents (SVE)
*known as brachial motor innervates muscles from the pharyngeal arches (all of face except eyes and tongues)
*classifications of cranial nuclei & cranial nerves
General Visceral Efferents (GVE)
*refers to efferent neurons of the autonomic nervous system that innervate smooth muscle, cardiac muscle and glands
*classifications of cranial nuclei & cranial nerves
General Somatic Afferents (GSA)
- refers to sensory nerves that carry touch information from the extremities and face including pain and temperature
*classifications of cranial nuclei & cranial nerves
General Visceral Afferents (GVA)
*refers to sensory nerves that carry mostly pain information from the viscera, glands, and blood vessels
*classifications of cranial nuclei & cranial nerves
Special Somatic Afferents (SSA)
*refers to nerves that carry information from ‘special’ senses including vision, hearing and balance
*classifications of cranial nuclei & cranial nerves
Special Visceral Afferents (SVA)
*refers to nerves that carry information from ‘special’ visceral senses including olfaction and taste
CN I: Olfactory Nerve
sensory functions:
- Smell
CN II: Optic Nerve
sensory functions:
- Vision
CN III: Oculomotor Nerve
motor functions:
- Pupillary reflex
- eye motion/ eyelid elevation
CN IV: Trochlear Nerve
motor functions:
- Eye motion
CN V: Trigeminal Nerve
sensory functions:
- Somatosensation to face, jaw, oral mucosa, teeth, tongue surface, external auditory canal, tympanic membrane
motor functions:
- Muscles of Mastication
CN VI: Abducens Nerve
motor functions:
- eye motion
CN VII: Facial Nerve
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
CN VIII
motor functions:
-
CN IX: Glossopharyngeal nerve
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
CN X: Vagus Nerve
motor functions:
-
CN XI: Spinal Accessory Nerve
motor functions:
-
CN XII: Hypoglossal Nerve
motor functions:
-
