with neurological disorders, function can change in what ways?
can be a loss OR a GAIN of function
neuro signs can be due to what three different things?
(1) Signs due to destruction of functional tissue (2) Signs due to release or loss of inhibition (3) Signs due to excitation or increased stimulation
Manifestation of signs depends on the__
physiologic importance of that location
tremors is an example of a _________ of function
what 5 areas should you consider when doing Neuroanatomic Localization?
spinal cord, brainstem/cranial nerves/vision, Cerebellum and vestibular system, forebrain, and neuromuscular
where are lower motor neurons (LMNs) located?
Housed in the ventral grey matter of the spinal cord at intumescences (thickened areas)
Where do LMNs go/do?
Axons leave spinal cord and become spinal nerves for the limbs
where are upper motor nurons (UMNs) located?
Housed in the cerebrum and brainstem
where do UMNs go/do?
Axons descend in the ventral and lateral white matter, and they give direction to the LMNs (inhibit or facilitate)
What are Intumescences?
These are the thickened areas of the spinal cord, which are bigger because they house the LMNs for the thoracic and pelvic limbs
what is in-between the intumescences?
the white matter tracks, which house the Descending motor information (from UMNs), and the Ascending sensory information
list the 4 functional segments of the spinal cord in order from front to back
C1-5, C6-T2, T3-L3, L4-S3
what are the two segments related to LMNs?
C6-T2, L4-S3 (second and last)
what are the two segments related to UMNs?
C1-5, T3-L3 (first and third)
what should you know about the spinal cord segment numbers?
they don't necessarily correlate with the vertebral segment they are under
what do LMNs do?
theyre the Cells that tell the limbs when/how to move
what are the three main functions of the spinal cord?
Houses LMNs(that tell the limbs how/when to move), Delivers descending UMN information, Integrates incoming sensations and sends this sensory information up to the brain (Temperature, mechanical, light touch, pain, proprioception)
what are some signs that there is spinal cord dysfunction?
Ataxia, Proprioceptive deficits, Decreased or absent motor function, Urinary/fecal incontinence, Decreased or absent nociception. The Reflexes and muscle tone vary based on lesion location
how can you determine where the lesion on the SC is, using LMN and UMN signs, and sensory ability?
you will see LMN deficits AT the level of the lesion, and you will see UMN signs CAUDAL to the lesion. you will also see Sensory deficits at the level of and caudal to the lesion
**what are the 3 big UMN signs? (for UMN paresis or paralysis)
(1) Normal or exaggerated spinal reflexes (2) Increased muscle tone (rigidity, spasticity) (3) Mild muscle atrophy due to disuse
**what are the 3 big LMN signs? (for LMN paresis or paralysis)
(1) Weak or absent spinal cord reflexes (2) Decreased muscle tone (flaccid) (3) Marked early muscle atrophy
how would you describe the gait of limbs affected by UMN signs?
a long, loping gait
how would you describe the gait of limbs affected by LMN signs?
short, shuffling gait
how would a dog with a lesion at T3-L3 present?
long loping gait in hind limbs, front limbs normal
L the L: long loping gait in hind limbs, front limbs normal
lesion at T3-L3
how would a dog with a lesion at C6-T2 present?
the front limbs would show LMN gait (short and shuffling) and the back legs would have UMN gait (long and loping)
L the L: forelimbs have a short shuffling gait and hindlimbs have a long and loping gait
how would a dog with a lesion at C1-C5 look like?
long, loping UMN gait in front and hind limbs
Spinal Hyperesthesia--> what is occurring in this situation? (list structures involved)
The SC can only carry pain signals, not feel pain. However, Some spinal column diseases can cause paraspinal pain, where structures associated with the SC CAN feel pain, and this pain is transmitted. (structures of this nature include intervertebral disk, meninges, vertebra, nerve roots)
as you start to lose function, what is the first thing to go, and then list in order until the last thing to go (4 things, two clinical sigs associated with 2 of the 4 things)
1st thing to go is proprioception (you will see ataxia), then loss of voluntary motor control (you will see a loss of voluntary urination), then superficial pain is lost, then deep pain is lost
you an animal starts to heal and regain function, what is regained first, and then what is regained last?
(this is in opposite order of how things are lost!) deep pain is regained first, then superficial pain, then voluntary motor control (the animal will be able to start urinating voluntarily again), then lastly proprioception will be regained (animal will no longer have ataxia)
where is the medullary reticular formation, and what does it do?
in the medullar oblongata, it is another important UMN system (not as important as the red nucleus in the midbrain though)
what is CN I and what does it do?
olfactory, sense of smell
what is CN II and what does it do?
optic, sense of sight
what is CN III and what does it do?
oculomotor, eye position and movements, pupillary constriction
which CN of pupilalry constriction?
CN III, oculomotor
what is CN IV, and what does it do?
trochlear, eye position and movement
what is CN V (opthalmic branch), and what does it do?
trigeminal--> the opthalmic branch does sensation from the eye and nose
what is CN V (maxillary branch), and what does it do?
trigeminal--> the maxillary branch provides Sensation from the lower eyelid, nose, cheek
what is CN V (Mandibular branch), and what does it do?
Trigeminal--> Sensation from the chin and some sensations from the mouth, and Motor to all of the masticatory muscles
which nerve has the three branches we care about and what are the three branches?
TRIgeminal nerve, has opthalmic, maxillary, and mandibular
what is CN VI and what does it do?
abducens (abductent) nerve, this relates to eye position and movement
what is CN VII and what does it do?
FACIAL nerve. Motor to muscles of facial expression, as well as has some parasympathetic function as it is motor to lacrimal gland and controls taste on the rostral 2/3 of the tongue
what is CN VIII and what does it do?
vestibulocochlear nerve---> SPECIAL proprioception--> Maintains the position of the eyes, neck, and limbs relative to the head. Also pertains to sense of hearing
what is CN IX, what what does it do?
Glossopharyngeal nerve, it is MOTOR to PHARYNGEAL muscles, has parasympathetic function as motor to salivary glands, and also helps with taste on the caudal 1/3 of the tongue and the rostral pharynx
what is CN X, what does it do?
VAGUS nerve. Motor to striated muscle of larynx, pharynx, esophagus. also has parasympathetic functions with cardiac mm, the sm mm of the esophagus and lungs, and enteric functions. also responsible for taste in the Caudal pharynx, larynx
what is CN XI, what does it do?
accessory nerve, it is Motor to strap muscles in the neck, Motor to the larynx, esophagus. Because of this function and it's shared functions with other nerves, Dysfunction is rarely recognized
which CN is part from within the skull, part comes from the spinal cord?