Neuroanatomy & Neurologic Examination Flashcards
1
Q
What is the difference between UMN and LMN?
A
UMN = brain stem neurons that send axons down the spinal cord to “tell” LMN what to do
LMN = neurons directly innervating muscles that are required to so come action once the UMN directs them
2
Q
What is the difference between UMN and LMN paresis?
A
UMN = “release” phenomenon where muscles become rigid and reflexes increase (spastic)
LMN = flaccid paresis with muscle atrophy
3
Q
UMN vs LMN signs:
A
4
Q
What are stepping centers? What 2 things do they require for function?
A
neuronal circuits within the spinal cord that can generate stepping movements
- stimulus, normally from a brainstem motor tract
- purposefulness of movement from cerebrum
5
Q
What are 3 major clinically relevant components of the brain?
A
- forebrain - cerebrum, diencephalon
- brainstem - midbrain to medulla
- cerebellum
6
Q
What is the function of the cerebrum? How are the modalities represented?
A
sensory phenomena terminate here for processing —> corticospinal motor tracts are of little significance
contralaterally
7
Q
What serves as the relay center for sensory input in the cerebrum?
A
diencephalon
8
Q
What are the 5 clinical features of forebrain dysfunction?
A
- abnormal mental status, usually obtunded
- seizures
- proprioceptive placing deficits with normal to near-normal gait
- visual deficits contralateral to lesion side
- decreased facial sensation contralateral to lesion
9
Q
What are the 6 major physical exam findings in patients with forebrain dysfunction?
A
- circling, usually wide and in the direction of the lesion
- head and neck pain on palpation
- mild anisocoria contralateral to lesion
- mild facial paralysis contralateral to lesion
- hemineglect, hemi-inattention
- head turn
10
Q
What is hemineglect (hemi-inattention) syndrome?
A
evident with lateralized forebrain tumors, where there is…
- head turn and circle to the side of the lesion (ignoring the other side)
- difficulty responding to auditory stimuli, nociceptive stimuli, and food/treats on the inattentive side
11
Q
What are the 2 major functions of the diencephalon?
A
- thalamus acts as relay station
- hypothalamus acts as a hormonal center for ANS control
12
Q
What 3 aspects of the nervous system does the thalamus have control of?
A
- vision - lateral geniculate nucleus
- hearing - medial geniculate nucleus
- proprioception, nociception - VCT nucleus
13
Q
What’s the difference between conscious and unconscious proprioception?
A
CONSCIOUS - sense of limb movement and static limb position in space, forebrain
UNCONSCIOUS - arises from resting muscle tension and stretch, cerebellar
14
Q
12 y/o MC Staffordshire - Acute onset of circling and behavior change. There is also decreased proprioceptive positioning and menace reaction on the right side. Where is the lesion most likely located?
A
left forebrain
- conscious proprioception = forebrain
- right-sided hemineglect = left (forebrain)
15
Q
What are the 3 major manifestations of hypothalamic lesions?
A
- endocrine disorders
- temperature regulation problems
- changes in appetite
16
Q
What is the main function of the basal nuclei? What are the 3 structures found here?
A
modulates stereotypic motor movements and activity —> likely source of movement disorders
- caudate nucleus
- putamen
- globus pallidus
17
Q
What is the source of all seizures?
A
forebrain
18
Q
What is the hallmark of forebrain lesions? What else is commonly seen?
A
normal to near-normal gait (often circling) with decreased contralateral proprioceptions
behavior changes
19
Q
What are 4 clinical manifestations associated with brainstem dysfunction?
A
- more obvious gait abnormalities
- central vestibular dysfunction
- abnormal mentation
- pharyngeal dysfunction
20
Q
What are the 2 hallmarks of brainstem dysfunction? What important nerves are found here?
A
- gait and proprioceptive dysfunction ipsilateral to lesion
- central vestibular manifestations
cranial nerve nuclei of III-XII
21
Q
What are the 3 gait-generating nuclei in the brainstem?
A
- red nucleus - rubrospinal tract in midbrain
- pontine reticular formation - pons to spinal tract
- medullary reticular formation - medullat to spinal tract
22
Q
What 4 important nervous structures are found in the mesencephalon (midbrain)? What function do they have?
A
- red nucleus and rubrospinal tract - gait
- oculomotor nucleus (III) - eye movement and pupil constriction
- beginning of the sympathetic tract to the eye
- part of the ascending reticular activating system - arouse the cerebral cortex, awaken the brain to a conscious level, and prepare the cortex to receive the rostrally projecting impulses from any sensory modality
23
Q
What makes up the ventral metencephalon? What 4 important nervous structures are found here?
A
pons
- pontine reticulospinal tract - gait
- trigeminal nucleus (V) - masticatory muscles, sensory
- part of ARAS
- pneumotaxic center - I:E ratio
24
Q
Where does information from the sensory tract of the trigeminal nucleus (V) go?
A
crosses to the opposite cerebrum
- not localizing by itself
25
What makes up the myelencephalon? What are 5 important nervous systems found here?
medulla oblongata
1. medullary reticulospinal tract - gait
2. cranial nerve nuclei VI-XII
3. part of ARAS
4. major cardiac and respiratory centers
5. major control centers of BP
26
What are the major functions of the nucleus ambiguus and CNs IX, X, and XI?
laryngeal, pharyngeal, and esophageal function
27
How do patients with central vestibular dysfunction typically present?
- usually non-ambulatory
- slow or inapparent spontaneous nystagmus
28
What is the function of the cerebellum? How does it function?
uses incoming information to modify outgoing responses to smooth out movement
inhibits excitatory neurons
29
What inhibitory cells are found in the cerebellum? What are the 3 major outside anatomical structures?
Purkinje cells
1. spinocerebellum
2. pontocerebellum
3. vestibulocerebellum (flocculus + nodulus)
30
What are the internal structures found in the cerebellum? What are their functions?
- deep roof nuclei
- lateral (Dentate), interposital, and fastigial nuclei
axons of these nuclei serve as the only efferents from the cerebellum
31
What are the 3 functional pairings of the cerebellum? Where do they project?
1. fastigial nucleus + flocculonodular lobes - vestibular nuclei (vestibulocerebellum)
2. interposital nucleus + vermis - red nucleus and reticular formation (spinocerebellum)
3. dentate nucleus and hemispheres - red nucleus, reticular formation, thalamus (cerebrocerebellum)
32
What are the 7 most common clinical signs associated with cerebellar dysfunction?
1. dysmetria - usually hypermetria
2. ataxia without paresis if purely cerebellar
3. intention tremors
4. vestibular dysfunction
5. menace deficits with normal vision
6. aniscoria
7. enlarge palpebral fissure
33
What are the expected presentations of spinal cord injuries?
- paresis common, UMN or LMN
- conscious (ataxia) and unconscious (abnormal placing reactions) proprioceptive deficits
- mental status and cranial nerves typically normal
34
What are the 2 major subdivisions of the spinal cord?
C1-C5 and T3-L3 = UMN white matter tell LMNs to the limb muscles when to move
C6-T2 and L4-caudal segments - innervate muscles required for movement
35
Where are the spinal cord segments positioned? Where does it end in dogs and cats?
cranial to the vertebral segment of the same number
- DOGS = L6 or L7, sacral segments typically end at L5 vertebral level
- CATS = S1
36
What are 6 signs associated with C1-C5 spinal cord lesions? What portion of the spinal cord has the same signs? What additional sign is unique to that segment?
1. UMN signs to thoracic and pelvic limbs
2. neck pain
3. tetraparesis/plegia, hemiparesis/plegia
4. Horner's syndrome
5. respiratory compromise
6. UMN bladder dysfunction
C6-T2 - LMN signs to thoracic limbs, UMN signs to pelvic limbs
37
What are 5 characteristics of T3-L3 spinal cord lesions?
1. normal thoracic limbs (may display Schiff-Sherrington - severe extension of the forelimbs and hindlimb paralysis)
2. UMN signs to pelvic limbs
3. paraparesis/plegia, hemiparesis/plegia of pelvic limbs
4. UMN bladder
5. back pain
38
What is characteristic of L4-Cd5 spinal cord lesions? How does the location alter signs? How is the bladder affected?
LMN signs to pelvic limbs
- L4-L6 = femoral nerve dysfunction
- L7-Cd5 = cauda equina
UMN or LMN depending on whether sacral segments are affected
39
How is nociception transmitted? Why is this so important?
spinothalamic tract
important to evaluate for preservation of pain sensation in neurologic animals and assessing/treating hyperesthesia
40
What is the referred pain pathway? Why is it significant?
interconnecting sensory nerves that supply many different tissues and when there is an injury at one site in the network it is possible that when the signal is interpreted in the brain signals are experienced in the surrounding nervous tissue
used to assess areas for increased sensitivity
41
What is responsible for the autonomic control of respiration? Where do these pathways lead?
UMN center in the medulla and some influence on rhythm in the pons
reticulospinal tracts to the LMNs of phrenic nerve (C5, C6, C7) and intercostal muscles (T1-T13)
42
What are 4 ways heart rate and blood pressure are autonomically controlled?
1. chemoreceptors and baroreceptors in the periphery
2. afferents to medullary centers via the solitary tract
3. local medullary sensors for brain ischemia
4. balance of sympathetic and parasympathetic outflow
43
What is characteristic of peripheral nervous system dysfunction?
LMN type weakness that does not fit with CNS disease
44
What tools are commonly used for neurologic examinations?
- pleximeter
- hemostat
- strong light source
- cotton tip swab
45
What are the 4 subdivisions of the spinal cord assessed on neurological exams?
1. C1-C5
2. C6-T2
3. T2-L3
4. L4-Cd segments
46
What are the essential aspects of the neurological exam?
- mental status
- attitude and posture
- gait
- conformation/muscularity
- cranial nerves
- proprioception
- spinal reflexes
- pain sensation
47
What are the 4 quantitative assessments of mental status?
1. alert
2. obtunded - difficult to arouse
3. stuporous - extremely difficult to arouse
4. comatose - unarousable
48
What is attitude and posture?
position of eyes and head with respect to body
position of body with respect to gravity
49
What are the 4 general assessments of gait?
1. lameness - unusual but consistent change in gait
2. ataxia - inconsistent change in gait which can also change affected limb in some cases
3. paresis/plegia
4. abnormal movements
50
What is observed to assess conformation and muscularity?
- posture
- asymmetry
- atrophy or hypertrophy
visual and palpation
51
How can proprioception be assessed?
- tactile vs. visual placing
- hopping
- hemiwalking
- wheelbarrowing
assess for conscious vs. unconscious proprioception
52
What are the locations of the cranial nerves in the brain?
- FOREBRAIN - I and II
- MESENCEPHALON - III, IV
- PONS - V motor
- CERVICAL SPINE (extensive) - V sensory
- MEDULLA - VI-XII
53
What is the function of CN I? What is dysfunction typically related to?
OLFACTORY - sense of smell, difficult to test
hemineglect syndrome
54
What is the function of CN II? How is it assessed?
OPTIC - visual pathway
- menace response
- visual placing of cotton balls and obstacles
55
What is the function of CN III? How is it most commmonly assessed? What is evident of dysfunction?
OCCULOMOTOR - controls periorbital musculature and parasympathetic innervation of the pupil
PLR
abnormalities of eye position and movement, dilated pupil poorly or no response to light
56
What are the functions of the motor and sensory portions of CN V? How are each assessed?
TRIGEMINAL
- motor = innervates muscles of mastication; observe for atrophy/asymmetry
- sensory = sensation to various regions of the face; palpation
57
What is the function of CN VI? What is evident of dysfunction?
ABDUCENT - controls some periorbital musculature, like lateral rectus and retractor bulbi
abnormal eye position/movement
58
What are the 3 major functions of CN VII?
1. motor to muscles of facial expression - look for lopsided drooping
2. parasympathetic to lacrimal and salivary glands
3. sensory to inner pinna via the same tract as sensory CN V
59
What is the function of CN VIII? What is evident of dysfunction?
VESTIBULOCOCHLEAR - hearing and balance
- hearing hard to assess
- head tilt, strabismus (eyes don't line up in the same direction), nystagmus (fast, uncontrollable movements of eyes), ataxia
60
What is the overall function of CN IX, X, and XI? How are they assessed?
GLOSSOPHARYNGEAL, VAGUS, ACCESSORY - function as one nerve to control pharyngeal, laryngeal, and esophageal function
swallow or gag reflexes
61
What is the function of CN XII? How is it assessed?
HYPOGLOSSAL - innervates tongue musculature
evaluate tongue function and symmetry
62
What is Horner's syndrome? What are 3 signs?
dysfunction of sympathetic innervation to the eye
1. ptosis - upper eyelid droops over the eye
2. miosis - pupil constricted
3. enophthalmos - eyes sinking deeper in orbit
(not all 3 always present)
63
What 3 spinal reflexes are tested on neurologic exams?
1. patellar reflex
2. biceps reflex
3. withdrawal reflex
64
How are the spinal reflexes assessed?
absent, weak, normal, or exaggerated
- exaggerated can be normal!
65
What is considered the most reliable spinal reflex? What does it evaluate? How is it performed?
patellar reflex
L4-L6 spinal cord segments and femoral nerve
position patient is lateral recumbency and flex the stifle prior to striking the patellar ligament
66
In what animals is it normal to have a reduced patellar reflex?
older dogs
67
How is the biceps reflex performed? What is the normal response? What does it evaluate?
grasp the antebrachium, extend the elbow, pull the thoracic limb caudally, and place a finger on the biceps insertion ---> tap on finger
biceps contraction
C6-C8 spinal cord segments and musculocutaneous nerve
68
How is the withdrawal (flexor) reflex performed? What is the normal response? What does it evaluate?
pinch interdigital skin with finger
flexion of all joints ---> evaluate for crossed-extensor reflex (flexion of the upper limb and simultaneous extension of the lower limb)
polysynaptic reflex of C6-T2 of the thoracic limb and L6-S2 of the pelvic limb
69
What is the perineal (anal) reflex? What is the normal response? What does it evaluate?
light stimulation of the perineal region, resulting in contraction of the anal sphincter and tail flexion
S1-S3 and caudal spinal cord segments, perineal and pudendal nerves
70
How is the cutaneous trunci (panniculus) reflex performed? What is a normal response? What mediated the motor response?
pinch the skin lateral to the spine, working caudal to cranial
bilateral contraction of cutaneous trunci muscle
C8-T1 spinal cord segments and lateral thoracic nerves
71
What does a cut off point with the cutaneous trunci reflec indicate?
spinal cord lesion 1-4 cord segments cranial to the cut off
