VET404 Exam 1 Flashcards
(205 cards)
1
Q
Grey matter
A
Aggregations of neuronal cell bodies that either belong to the CNS (referred to either nuclei or cortices) or the PNS (referred to as ganglia)
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Q
White matter
A
Myelinated axons
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Q
Ganglion vs. Nucleus
A
A ganglion is an aggregation of neuronal cell bodies outside of the brain or the spinal cord i.e. outside of the CNS
4
Q
Ganglion
A
An aggregation of neuronal cell bodies outside of the CNS
5
Q
Basic schematic of sensory perception and the reflex/response it would elicit
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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
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Q
Neuron
A
The basic neural cell that aids in the transmission of information via chemical signaling
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Q
Bipolar Neuron
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A neuron with 2 processes that arise from opposite poles of the cell body - one being the axon, and the other being the dendrites
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Pseudo-unipolar Neuron
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A neuron with one long axis that stretches into the CNS
9
Q
Multipolar Neuron
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The most common cell form
10
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Interneurons
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Interneurons connect neurons to other neurons within the brain and spinal cord, while maintaining the same direction of chemical synapsing
11
Q
Synaptic Convergence
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When many presynaptic neurons all synapse onto the same postsynaptic neuron
12
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Synaptic Divergence
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When a single presynaptic neuron synapses onto several postsynaptic neurons
13
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Nucleus
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A collection of cell bodies within the CNS, typically organized around a shared function
14
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The 3 types of cerebral white matter
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Association fibers
15
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Association fibers
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These fibers connect short areas between gyri ipsilaterally
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Projection fibers
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These fibers project to/from the thalamus and cerebral cortex
17
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Commissural fibers
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These fibers cross from one side of the cerebrum to the other, also known as decussation
18
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The Cerebrum
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Includes the cerebral hemispheres + the basal nuclei
19
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The 5 Parts of the Brainstem
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Thalamus, Hypothalamus, Midbrain, Pons, and Medulla
20
Q
How is Voluntary Movement accomplished?
A
Initiated by the cerebrum and executed by the muscles
21
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The Basal Nuclei
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Involved in the “programming of movements”
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Dysfunction of the Basal Nuclei
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Common manifestations:
23
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Clinical example of basal nuclei dysfunction
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Yellow starthistle poisoning in horses
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The Cerebellum
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Coordinates all subsystems involved in movement and posture
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Clinical signs of cerebellar disease
Will not cause paresis and paralysis (Why?)
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Clinical example of cerebellar disease
Panleukopenia virus in kittens disrupts cerebellum development, leading to hypermetria, incoordination, head tremors, etc.
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The normal functions of the Cerebrum
The seat of consciousness --> personality, memory, cognition
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Lobes of the Cerebrum
The Frontal Lobe
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Dysfunction of the Cerebrum
Disturbances in consciousness --> hyperreactive or obtunded
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Olfactory Nerve (CN I) - Afferent, Efferent, or Mixed?
Afferent only
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Olfactory Nerve (CN I) - Function
Allows for the sensation of smell
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Olfactory Nerve (CN I) - Dysfunction
Something that disrupts the nasal cavity, like a nasal adenocarcinoma, will impair the ability to smell
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Optic Nerve (CN II) - Afferent, Efferent, or Mixed?
Afferent only
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Optic Nerve (CN II) - Function
Conveys visual information
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Oculomotor Nerve (CN III) - Afferent, Efferent, or Mixed?
Efferent with motor and parasympathetic components
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Occulomotor Nerve (CN III) - Function
Innervates the dorsal, ventral, medial rectus muscles, the ventral oblique muscle, and the levator palpebrae muscles
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Function of the dorsal, medial, ventral, and lateral rectus muscles
They move the globe up, in, down, and out respectively
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Function of the dorsal and ventral oblique muscles
They rotate the globe clockwise and counterclockwise respectively
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Function of the levator palpebrae muscle
It raises the eyelid
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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
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Trochlear Nerve (CN IV) - Afferent, Efferent, or Mixed?
Efferent only
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Trochlear Nerve (CN IV) - Function
Innervates the contralateral dorsal oblique muscle
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Trochlear Nerve (CN IV) - Dysfunction
Manifests as eyes with dorsal aspects that have rotated laterally
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Trigeminal Nerve (CN V) - Afferent, Efferent, or Mixed?
Mixed - sensory and efferent
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Trigeminal Nerve (CN V) - Names of the branches
Ophthalmic branch - passes through the orbital fissure
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Trigeminal Nerve (CN V) - Ophthalmic Branch Function
Afferent only
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Trigeminal Nerve (CN V) - Maxillary Branch Function
Afferent only
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Trigeminal Nerve (CN V) - Mandibular branch
Afferent and efferent functions
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Trigeminal Nerve (CN V) - Dysfunction
Since CN V's ophthalmic branch innervates the cornea, dysfunction results in corneal inflammation or ulceration
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Abducens Nerve (CN VI) - Afferent, Efferent, or Mixed?
Efferent only
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Abducens Nerve (CN VI) - Function
Innervates the lateral rectus and retractor bulbi muscles
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Abducens Nerve (CN VI) - Dysfunction
Dysfunction results in medial strabismus
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Facial Nerve (CN VII) - Afferent, Efferent, or Mixed?
Mixed with afferent, efferent, and parasympathetic components
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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
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Facial Nerve (CN VII) - Dysfunction
A deficit manifests as facial asymmetry or facial droopiness
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Vestibuocochlear Nerve (CN VIII) - Afferent, Efferent, or Mixed?
Afferent only
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Vestibulocochlear Nerve (CN VIII) - Function
The cochlear component is involved with hearing
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Glossopharyngeal Nerve (CN IX) - Afferent, Efferent, or Mixed?
Mixed with afferent, efferent and parasympathetic functions
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Glossopharyngeal Nerve (CN IX) - Function
The afferent component receives input from the upper pharynx and caudal 1/3 of the tongue
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Vagus Nerve (CN X) - Afferent, Efferent, or Mixed?
Mixed, with afferent, efferent, and parasympathetic components
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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
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Accessory Nerve (CN XI) - Afferent, Efferent, or Mixed?
Efferent only
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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
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Hypoglossal Nerve (CN XII) - Afferent, Efferent, or Mixed?
Efferent only
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Hypoglossal Nerve (CN XII) - Function
Innervates the extrinsic and intrinsic muscles of the tongue
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Hypoglossal Nerve (CN XII) - Dysfunction
A deficit results in paralysis/paresis or atrophy of the tongue
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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.
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Upper Motor Neuron
UMN start in the cerebrum or brainstem and synapse onto lower motor neurons
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Lower Motor Neurons
LMN start in the spinal cord and synapse onto muscles or glands in the periphery
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Upper Motor Neuron Dysfunction
Increased segmental/limb reflexes
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Lower Motor Neuron Dysfunction
Decreased segmental reflexes
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Where is the Cervical Segment along the spinal cord?
C1-C5
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Where are the nerves that contribute to the brachial plexus and innervate the thoracic limb along the spinal cord?
C6-T2
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Where is the Thoracolumbar Segment along the spinal cord?
T3-L3
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Where are nerves that contribute to the lumbosacral plexus and innervate the pelvic limb along the spinal cord?
L4-S3/caudal
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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)
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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)
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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
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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
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The first step of a neurological exam is a visual appraisal. What do you look at?
Mentation & Gait/Posture
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Patient Mentation
How the patient interacts with their environment
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Patient Posture
The positioning of the patient's head, limb, and body
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Patient Gait
The quality and quantity of movement
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Opisthotonos
Abnormal posture where the head and neck are hyper-extended with extensor rigidity in the thoracic limbs
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Decereberate Posture
without cerebrum
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Decerebellate Posture
without cerebellum
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Schiff-Sherrington Posture
Opisthonos is observed, with the lesion is localized to T3-L5
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Evaluation of CN: CN I
Not done often because a complete lack of smell would be required to fail this test
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Evaluation of CN: Menace
Is a response - patient has to observe and recognize the menace gesture before blinking
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Evalution of CN: Visual Tracking
Is a response - patient has to recognize a falling object and follow it with their head/eyes
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Evaluation of CN: Pupillary Light Reflex
Is a reflex - a light is shown in one eye and both of the patient's pupils should contract
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Evaluation of CN: Corneal Reflex
Is a reflex - directly stimulating the patient's cornea should make them blink and/or retract their globe
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Evaluation of CN: Palpebral Reflex
Is a reflex - stimulating the lateral and medial canthi of the eye should make the patient blink
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Evaluation of CN: Physiologic Nystagmus
Is a reflex - when moving the patient's head in all directions, their eyes should rotate too
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Evaluation of CN: facial symmetry
Checking for bilateral muscle symmetry of the face
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Evaluation of CN: Vibrissae Reflex
Is a reflex - stimulating the whiskers should elicit a blink
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Evaluation of CN: Lip Pinch
Is a reflex - pinch the lip and the patient should respond by pulling it back
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Evaluation of CN: Nasocortical Response
Is a response - stimulate the interior of the patient's nasal cavity and the patient should pull its head away
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Evaluation of CN: Gag Reflex
Is a reflex - stimulate a gag
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Postural Reaction: Proprioceptive Placing
knuckling
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Postural Reaction: Hopping Reactions
Assesses whether the patient is able to perceive their limb position
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Postural Reaction: Extensor postural thrust
By lifting and placing the patient back on the ground on their hind limbs, this test assesses their ability to recognize the ground and place their legs in a weight-bearing position
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Postural Reaction: Placing Reactions
These tests involve moving a patient towards a surface and they should react by reaching out with their front limbs to steady themselves
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Postural Reaction: Wheelbarrowing
Patient's hind-end is lifted like a wheelbarrow and the patient is walked on their front limbs
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4 main segmental reflexes of the pelvic limb
Patellar Reflex
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The Patellar Reflex
Assesses the femoral nerve
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The Gastrocnemius Reflex
Assesses the sciatic nerve
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The Flexion/Withdrawal Reflex of the Pelvic Limb
Assesses the sciatic nerve
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The Perineal Reflex
Assesses the pudendal nerve
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3 main segmental reflexes of the thoracic limb
Biceps Reflex
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The Biceps Reflex
Assesses the musculocutaneous nerve
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The Triceps Reflex
Assesses the radial nerve
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The Flexion/Withdrawal Reflex of the Thoracic Limb
Assesses the musculocutaneous nerve
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Cutaneous Trunci Reflex
The afferent nerve to the cutaneous trunci muscles are the afferent T3-L3 cutaneous nerves
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Cutaneous Trunci Reflex Dysfunction
An afferent nerve dysfunction would produce no cutaenous trunci reflex
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Nociception
The experience and articulation of pain
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Why is assessment of nociception important?
Physiologically, deep nociception is one of the last neurological functions to be lost (after proprioception, voluntary movement, and superficial nociception) in a paralyzed limb. Thus, lost of deep pain reduces patient prognosis
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The Three Layers of the Meninges
The dura mater, arachnoid mater, and pia mater
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Functions of the Meninges
Provides protection from mechanical injury
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Three layers of the Dura Mater
Periosteal dura
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Two layers of the Arachnoid Mater
Arachnoid barrier cells
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Arachnoid Villi
Projections from the arachnoid mater into the sinus system
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Arachnoid Cisternae
Widened portions of the subarachnoid space
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Dural Reflections
The falx cerebrii
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Types of Hematomas that can occur in the skull
Epidural hematoma
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Epidural Hematoma
A hematoma that has formed between the dura mater and the skull without breaking the meninges
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Subdural Hematoma
A hematoma that has formed within the layers of the dura mater
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Subarachnoid Hematoma
A hematoma that has formed in the arachnoid space
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Intracerebral Hematoma
A hematoma that has formed in the parenchyma
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Meningioma
A tumor that arises from the arachnoid mater
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Meningitis
Most commonly a manifestation of secondary infection
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Meningoencephalitis
Meningeal infection secondary to infection of the ears, eyes, or nasal cavity
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Granulomatous meningoencephalitis
A specific form of meningoencephalitis caused by canine distemper virus
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Symptoms of meningitis
Fever, neck pain, painful muscle spasms
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Symptoms of meningoencephalitis
Depression, behavioral changes, agitation, blindness, loss of balance and motor control, partial paralysis of the face or limbs, seizures, circling
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Signs of an abnormal CSF tap
low in sugar, high protein, and/or increased cell count
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Functional differences between Veins and Venous Sinuses
Veins can be found inside and out of the brain and are meant to take blood away to systemic circulation
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Important Sinuses and where do Sinuses drain
The superior/dorsal sagittal sinus lies between the two hemispheres and is one of the most prominent sinuses
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The brain is supplied by which arteries
The basilar artery
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Basilar artery
The basilar artery is supplied by the vertebral artery and anterior spinal artery
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Internal carotid artery
The ICA is supplied by the common carotid artery
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The basilar artery and its association with the spinal cord
The BA is a culmination of various arteries that travel up the cervical vertebrae
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Species variation of the meningeal blood supply - cats and sheep
In cats and sheep, the ICA atrophies months after birth, making the Circle of Willis different
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The Arachnoid Barrier
considered on the of the true CNS barriers
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Ventricles of the brain
2 lateral ventricles (one in each hemisphere)
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Choroid Plexus Development
During embryogenesis, capillaries from the embryo surface descend from the meninges into the brain space, creating the choroid plexus. These vessels become torturous and villous, surrounding the roof of every ventricle. Ependymal cells near where the choroid plexuses form differentiate into choroid plexus epithelium cells
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Choroid Plexus and CSF Production
CSF is formed from blood flowing through associated capillaries and diffusing into adjacent choroid plexus epithelium cells
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Blood-CSF Barrier
Considered the second true CNS barrier
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CSF Absorption
Occurs at the arachnoid membrane, more specifically the arachnoid villi
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CSF Flow
CSF flows from the choroid plexus, where it's produced to the fourth ventricles. Once there, CSF is ejected into the arachnoid space through the lateral apertures of the fourth ventricles. When absorption is required, CSF flows into the venous sinus system, primarily the SSS through the arachnoid villi
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The driving force behind CSF flow
The heart keeps CSF flowing - each time the heart pumps, the increase in pressure it creates by moving blood through the choroid plexus also moves CSF along its path through the brain and the venous sinus system
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CSF composition
Is an ultrafiltrate of blood that is mostly water
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CSF Functions
Physical support
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Blood-Brain Barrier
The BBB tightly regulates the entry of solutes and water into the brain
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Hydrocephalus
Buildup of CSF in the head as a direct result of increased CSF volume in one or more of the ventricles
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Anatomy of the Cerebellum: Lobes
Rostral lobe and caudal lobe separated by the primary fissure
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Anatomy of the Cerebellum: Attachment to the Brainstem
The cerebellum is attached to the brainstem via the middle, caudal, and rostral peduncles
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Anatomy of the Cerebellum: Floculonodular Lobe
Is the nodulus plus the floculus
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Anatomy of the Cerebellum: Cell Layers of the Cerebellum
A molecular layer formed by the fibers of Purkinje and granule neruons
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Anatomy of the Cerebellum: Cerebellar Nuclei
The 2 pairs of grey matter nuclei found deep in the cerebellar medulla
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Germinal cells of the cerebellum: Mantel cells
The mantel cells form the Purkinje cells and the deep cerebellar nuclei neurons
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Germinal cells of the cerebellum: external germinal layer cells
The external germinal layer cells form the granule cell layer. They migrate to the surface of the cerebellum, where they proliferate and divide. They then dive back down into the cerebellar cortex to form the granule cell layer.
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Afferent pathways to the cerebellum
There are two major pathways to the cerebellum - from the spinal cord and cranial nerves & from feedback loops in the brain
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Spinal Cord Afferents to the Cerebellum
The 4 major spinocerebellar pathways to the cerebellum provide information about proprioception from the periphery. These pathways are called spinal cerebellar tracts (SCTs). These tracts are somatotopically arranged.
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Feedback loops to/from the cerebellar cortex
These loops can come from the pyramidal or extrapyramidal systems of the cerebrum. Within the extrapyramidal system, the loops are further divided into direct (from the vestibular nuclei) and indirect (from the olivary nucleus).
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Pyramidal tract
A tract from the cerebrum where the axons directly innervate neurons of the CN or spinal cord
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Extrapyramidal tracts
Tracts from the cerebrum to the cerebellum that do not originate in the pyramidal system. These sources may include the pons and the olivary nucleus of the medulla
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Mossy fibers
These fibers synapse onto the granule cells in the cerebellar cortex
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Climbing fibers
These fibers are axons of the olivary nucleus neurons and synapse with Purkinje fibers
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Efferent Pathways from the Cerebellum
Efferent neurons from the cerebellum either go through the Purkinje fibers or through the cerebellar nuclei.
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Purkinje cell efferent output
Purkinje cells are inhibitory and are the primary form of efferent output form the cerebellum
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Deep cerebellar nuclei efferent output
Deep cerebellar nuclei cells are influenced by the inhibitory function of Purkinje fibers
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Does the cerebellum modulate motor activity on the ipsilateral or contralateral side of the body?
The cerebellum modulates the motor activity of the ipsilateral side of the body. Movement is initiated in the contralateral motor cortex of the cerebrum but feedback loops from the CNS decussate to the opposite side of the cerebellum. Thus, the left cerebellum modulates the movement from the left side of the body.
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Functional Regions of the Cerebellum
The vestibular areas - e.g. floculonodular lobe
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Common Canine Nasal Disorders
Nonspecific immune-mediated rhinits
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Radiographic description of normal nasal turbinates
Normally, nasal turbinates are are covered in mucosa -- symmetric, fine bony wisps visible, aerated nasal chamber
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Radiographic description of nonspecific rhinitis
Bilateral increased soft tissue muddling of the nasal turbinates
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Radiographic description of mycotic rhinits
One of the key radiographic signs is the destruction of the nasal turbinates, which can be symmetric or asymmetric
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Radiographic description of nasal neoplasia
A carcinoma shows up as increased soft tissue opacity centered around a mass accompanied by turbinate destruction
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Common Equine Nasal/Paranasal Disorders
Sinusitis secondary to dental disease
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Radiographic description of an ethmoid hematoma in horses
Appears as a soft tissue opacity mass
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Common Disorders of the Canine and Equine Ear
Otitis externa
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Radiographic description of otitis externa
On CT, the ear canal may no longer have any air
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Radiographic description of otitis media
The tympanic bulla may be inflammed
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Temporohyoid Osteroarthropathy
Is an idiopathic degenerative disease
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Trauma's effect on the nasal cavity
Massive skull trauma may fracture the nasal bone, the turbinates, the hard palates, the temporomandibular joints, etc.
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Olfactory Region of the Cerebrum
Contains the olfactory bulbs and the pyriform lobes associated with CN I
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Frontal Lobe of the Cerebrum
Contains primary motor cortices and motor association cortices
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Parietal Lobe of the Cerebrum
Involved with somatosensory
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Temporal Lobe of the Cerebrum
The auditory cortex
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Occipital Lobe of the Cerebrum
The visual cortex
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Limbic System of the Cerebrum
Contains the hippocampus, the amgydala, and the hypothalamus
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Subdivision of the Cerebral Cortex: Allocortex
Considered the oldest part of the brain
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Subdivision of the Cerebral Cortex: Isocortex
Also known as the neocortex and includes the frontal, parietal, temporal, and occipital lobes
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Projection areas of the Cerebrum
The projection areas of the cerebrum are for vision, audition, primary motor cortices, and somatosensory areas
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Association Areas
Associated with problem solving and creative thinking
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The thalamus of the Cerebrum
All of the senses except smell pass through this structure
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Peripheral blindness
When there is vision loss with the PLRs also absent, this suggests that there is a lesion in the eye itself, in the optic nerve, the chiasm, and/or the optic tract
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Central blindness caused by cerebral dysfunction
Defined as vision loss with the PLRs intact
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Hemi-inattention caused by cerebellar dysfunction
Neglect or decreased awareness of the contralateral environment and/or the body
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The electroencephalography
The EEG records electrical activity of the brain and measures the voltage changes caused by the neurons of the head
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Narcolepsy and how it affects dogs
Dogs with narcolepsy fall into REM sleep suddenly and experience cataplexy after being too excited
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Cataplexy
A sudden and transient episode of muscle tone loss
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Corticopontocerebellar feedback loop
An afferent feedback loop from the cerebrum to the cerebellar cortex. The corticopontocerebellar loop goes from the cerebrum to the pons to the cerebellum via the pyramids
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Seizures
The hallmark of cerebral disease
