VET404 Exam 1 Flashcards
Grey matter
Aggregations of neuronal cell bodies that either belong to the CNS (referred to either nuclei or cortices) or the PNS (referred to as ganglia)
White matter
Myelinated axons
Ganglion vs. Nucleus
A ganglion is an aggregation of neuronal cell bodies outside of the brain or the spinal cord i.e. outside of the CNS
Ganglion
An aggregation of neuronal cell bodies outside of the CNS
Basic schematic of sensory perception and the reflex/response it would elicit
Sensory information passes through a ganglion before reaching the CNS. After reaching the CNS, the information is directed to one of two locations - the cerebral cortex for response/reaction generation and the spinal cord for a reflex
Neuron
The basic neural cell that aids in the transmission of information via chemical signaling
Bipolar Neuron
A neuron with 2 processes that arise from opposite poles of the cell body - one being the axon, and the other being the dendrites
Pseudo-unipolar Neuron
A neuron with one long axis that stretches into the CNS
Multipolar Neuron
The most common cell form
Interneurons
Interneurons connect neurons to other neurons within the brain and spinal cord, while maintaining the same direction of chemical synapsing
Synaptic Convergence
When many presynaptic neurons all synapse onto the same postsynaptic neuron
Synaptic Divergence
When a single presynaptic neuron synapses onto several postsynaptic neurons
Nucleus
A collection of cell bodies within the CNS, typically organized around a shared function
The 3 types of cerebral white matter
Association fibers
Association fibers
These fibers connect short areas between gyri ipsilaterally
Projection fibers
These fibers project to/from the thalamus and cerebral cortex
Commissural fibers
These fibers cross from one side of the cerebrum to the other, also known as decussation
The Cerebrum
Includes the cerebral hemispheres + the basal nuclei
The 5 Parts of the Brainstem
Thalamus, Hypothalamus, Midbrain, Pons, and Medulla
How is Voluntary Movement accomplished?
Initiated by the cerebrum and executed by the muscles
The Basal Nuclei
Involved in the “programming of movements”
Dysfunction of the Basal Nuclei
Common manifestations:
Clinical example of basal nuclei dysfunction
Yellow starthistle poisoning in horses
The Cerebellum
Coordinates all subsystems involved in movement and posture
Clinical signs of cerebellar disease
Will not cause paresis and paralysis (Why?)
Clinical example of cerebellar disease
Panleukopenia virus in kittens disrupts cerebellum development, leading to hypermetria, incoordination, head tremors, etc.
The normal functions of the Cerebrum
The seat of consciousness –> personality, memory, cognition
Lobes of the Cerebrum
The Frontal Lobe
Dysfunction of the Cerebrum
Disturbances in consciousness –> hyperreactive or obtunded
Olfactory Nerve (CN I) - Afferent, Efferent, or Mixed?
Afferent only
Olfactory Nerve (CN I) - Function
Allows for the sensation of smell
Olfactory Nerve (CN I) - Dysfunction
Something that disrupts the nasal cavity, like a nasal adenocarcinoma, will impair the ability to smell
Optic Nerve (CN II) - Afferent, Efferent, or Mixed?
Afferent only
Optic Nerve (CN II) - Function
Conveys visual information
Oculomotor Nerve (CN III) - Afferent, Efferent, or Mixed?
Efferent with motor and parasympathetic components
Occulomotor Nerve (CN III) - Function
Innervates the dorsal, ventral, medial rectus muscles, the ventral oblique muscle, and the levator palpebrae muscles
Function of the dorsal, medial, ventral, and lateral rectus muscles
They move the globe up, in, down, and out respectively
Function of the dorsal and ventral oblique muscles
They rotate the globe clockwise and counterclockwise respectively
Function of the levator palpebrae muscle
It raises the eyelid
Oculomotor Nerve (CN III) - Dysfunction
When the efferent component of CN III fails, the eye will rotate down and out (strabismus) - the medial rectus muscle no longer works and the lateral rectus muscle dominates
Trochlear Nerve (CN IV) - Afferent, Efferent, or Mixed?
Efferent only
Trochlear Nerve (CN IV) - Function
Innervates the contralateral dorsal oblique muscle
Trochlear Nerve (CN IV) - Dysfunction
Manifests as eyes with dorsal aspects that have rotated laterally
Trigeminal Nerve (CN V) - Afferent, Efferent, or Mixed?
Mixed - sensory and efferent
Trigeminal Nerve (CN V) - Names of the branches
Ophthalmic branch - passes through the orbital fissure
Trigeminal Nerve (CN V) - Ophthalmic Branch Function
Afferent only
Trigeminal Nerve (CN V) - Maxillary Branch Function
Afferent only
Trigeminal Nerve (CN V) - Mandibular branch
Afferent and efferent functions
Trigeminal Nerve (CN V) - Dysfunction
Since CN V’s ophthalmic branch innervates the cornea, dysfunction results in corneal inflammation or ulceration
Abducens Nerve (CN VI) - Afferent, Efferent, or Mixed?
Efferent only
Abducens Nerve (CN VI) - Function
Innervates the lateral rectus and retractor bulbi muscles
Abducens Nerve (CN VI) - Dysfunction
Dysfunction results in medial strabismus
Facial Nerve (CN VII) - Afferent, Efferent, or Mixed?
Mixed with afferent, efferent, and parasympathetic components
Facial Nerve (CN VII) - Function
As a minor function, provides taste from the rostral 2/3 of the tongue and the palates and sensation from a small part of the ear
Facial Nerve (CN VII) - Dysfunction
A deficit manifests as facial asymmetry or facial droopiness
Vestibuocochlear Nerve (CN VIII) - Afferent, Efferent, or Mixed?
Afferent only
Vestibulocochlear Nerve (CN VIII) - Function
The cochlear component is involved with hearing
Glossopharyngeal Nerve (CN IX) - Afferent, Efferent, or Mixed?
Mixed with afferent, efferent and parasympathetic functions
Glossopharyngeal Nerve (CN IX) - Function
The afferent component receives input from the upper pharynx and caudal 1/3 of the tongue
Vagus Nerve (CN X) - Afferent, Efferent, or Mixed?
Mixed, with afferent, efferent, and parasympathetic components
Vagus Nerve (CN X) - Function
The afferent component carries sensory information from the pharynx, the back of the ear, the external meatus, and some taste from the tongue
Accessory Nerve (CN XI) - Afferent, Efferent, or Mixed?
Efferent only
Accessory Nerve (CN XI) - Function
Carries motor function to the muscles of the larynx, esophagus, and muscles of the neck region e.g. the trapezius
Hypoglossal Nerve (CN XII) - Afferent, Efferent, or Mixed?
Efferent only
Hypoglossal Nerve (CN XII) - Function
Innervates the extrinsic and intrinsic muscles of the tongue
Hypoglossal Nerve (CN XII) - Dysfunction
A deficit results in paralysis/paresis or atrophy of the tongue
General schematic of a basic reflex arc
A sensory afferent synapses onto a lower efferent neuron to elicit a muscular response. A reflex is regulated by the spinal cord and requires no higher-up processing.
Upper Motor Neuron
UMN start in the cerebrum or brainstem and synapse onto lower motor neurons
Lower Motor Neurons
LMN start in the spinal cord and synapse onto muscles or glands in the periphery
Upper Motor Neuron Dysfunction
Increased segmental/limb reflexes
Lower Motor Neuron Dysfunction
Decreased segmental reflexes
Where is the Cervical Segment along the spinal cord?
C1-C5
Where are the nerves that contribute to the brachial plexus and innervate the thoracic limb along the spinal cord?
C6-T2
Where is the Thoracolumbar Segment along the spinal cord?
T3-L3
Where are nerves that contribute to the lumbosacral plexus and innervate the pelvic limb along the spinal cord?
L4-S3/caudal
If there was a lesion in the region of C1-5, what type of neurological deficiencies do we expect in the thoracic and pelvic limbs?
UMN deficiencies in both thoracic and pelvic limbs (increased segmental reflexes; increased muscle tone; disuse atrophy)
If there was a lesion in the region of C6-T2/cervical intumescence, what type of neurological deficiencies do we expect in the thoracic and pelvic limbs?
LMN deficiencies in the thoracic limb (decreased segmental reflexes; decreased muscle tone; denervation atrophy)
If there was a lesion in the region of T3-L3, what type of neurological deficiencies do we expect in the thoracic and pelvic limbs?
The thoracic limbs should be normal
If there was a lesion in the region of L4-S3, what type of neurological deficiencies do we expect in the thoracic and pelvic limbs?
The thoracic limbs should be normal
The first step of a neurological exam is a visual appraisal. What do you look at?
Mentation & Gait/Posture
Patient Mentation
How the patient interacts with their environment
Patient Posture
The positioning of the patient’s head, limb, and body