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CNS and PNS
Week 1
119
Veterinary Medicine
Graduate
07/14/2015

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Term
Prosencephalon
Definition
Forebrain (2 parts)
Telencephalon
Diencephalon
Term
Telencephalon
Definition
cerebral hemisphere (2, l/r)
has Frontal, Parietal, Temporal, and Occipital areas
surface is grey matter - cerebral cortex
underlying white matter
CORPUS CALLOSUM
Term
Diencephalon
Definition
Thalamus
Hypothalamus
Subthalamus
Epithalamus
gives rise to OPTIC NERVE
contains 3rd ventricle (pineal gland on roof) (pituitary gland ventrally)
Term
Mesencephalon
Definition
Midbrain
gives rise to oculomotor (III) and trochlear (IV)
CRUS CEREBRI
Term
Rhombencephalon
Definition
hindbrain (2 parts)
Metencephalon
Myelencephalon
Term
Metencephalon
Definition
PONS
contains rostral end of 4th ventricle
gives rise to trigeminal nerve (V)
CEREBELLUM
vermis = media region
bilaterally cerebellar hemispheres
surface partitioned into FOLIA (ridges), separated by SULCI (grooves)
Term
Myelencephalon
Definition
MEDULLA OBLONGATA
contains most of 4th ventricle
gives rise to CN VI-XII
Term
Cranial Nerves
Definition
#1-12
control functions of head and 5 senses
Term
Cranial Nerve I
Definition
Olfactory
Telencephalon
Term
Cranial Nerve II
Definition
Optic
Diencephalon
Term
Cranial Nerve III
Definition
Oculomotor
Mesencephalon
Term
Cranial Nerve IV
Definition
Trochlear
Mesencephalon
Term
Cranial Nerve V
Definition
Trigeminal
Metencephalon
Term
Cranial Nerve VI
Definition
Abducens
Mylencephalon
Term
Cranial Nerve VII
Definition
Facial
Mylencephalon
Term
Cranial Nerve VIII
Definition
Vestibulocochlear
Mylencephalon
Term
Cranial Nerve IX
Definition
Glossopharyngeal
Mylencephalon
Term
Cranial Nerve X
Definition
Vagus
Mylencephalon
Term
Cranial Nerve XI
Definition
Accessory
Mylencephalon
Term
Cranial Nerve XII
Definition
Hypoglossus
Mylencephalon
Term
Peripheral Nervous System parts
Definition
Somatic (controls voluntary movement)
Autonomic (maintains homeostatis)
Term
Autonomic Nervous System parts
Definition
Parasympathetic (rest and digest)
Sympathetic (fight or flight)
Term
Neurological Signs of FOREBRAIN dysfunction
Definition
altered mentation
change in behaviour
seizures sometimes reported
contralateral proprioceptive deficits
contralateral menace absent
circling TOWARDS side of lesion
Term
Neurological Signs of CEREBELLAR dysfunction
Definition
mentation normal
hypermetria, dysmetria (coordination)
intention tremors
can have head tilt (contralateral)
Term
Neurological Signs of BRAINSTEM dysfunction
Definition
mentation can be normal to abnormal
head tilt and wide base stance
CN III-XII can show deficits
IPSILATERAL proprioceptive deficits
Term
Derivation of Nerves for Forelimb
Definition
Cranial Intumescence - brachial plexus - thoracic limb
Term
Derivation of Nerves for hindlimb
Definition
Caudal intumescence - lumbosacral plexus - pelvic limb, sphincter, tail
Term
Spinal nerves in Thoracic Plexus
Definition
C6-T2
Term
Spinal nerves in Lumbar Plexus
Definition
L4-Cd5
Term
Excitatory Neurones
Definition
Acetylcholine, Glutamine, Aspartate
Term
Inhibitory Neurones
Definition
Glycine, GABA
Term
Types of Sensory Receptors
Definition
Mechanoreceptors
Chemoreceptors
Thermal receptors
Photo receptors
Pain receptors
Term
Sensitivity vs. Localization
Definition
Primary afferent nerves connect to surface, lead to secondary fibres.
Many Primary nerves leading to few secondary = SENSITIVITY
Few/One Primary nerve leading to one secondary nerve = LOCALIZATION
Term
Lateral Inhibition
Definition
improves localization and pattern recognition
Term
Skin Afferent Nerve Fibres
Definition
Free nerve endings
Terminal encapsulations
Thermal receptors (free and encapsulated)
Nociceptors (free)
Joint receptors
Term
Free Nerve Endings
Definition
mainly in hairy skin
not specific to a particular stimulus
Term
Terminal Encapsulations
Definition
hairless skin, mostly mechanoreceptors
Pacinian
Ruffini
Merkel
Meissners
Term
Pacinian
Definition
detect local pressure
Term
Ruffini
Definition
detect tension in collagen fibres
Term
Merkel
Definition
detect deformation in skin
Term
Meissners
Definition
detects sideways shearing
Term
Classifications of AFFERENT Nerve Fibres
Definition
[image]
Term
Myotatic reflex
Definition
The stretch reflex
Muscle spindle stretching leads to increased alpha motor neuron activity, causing muscle fibers to contract and resist stretching.
secondary set of neurons causes opposing muscle to relax.
REFLEX MAINTAINS MUSCLE AT CONSTANT LENGTH
Term
Reflex arc Common Structure
Definition
Receptor system
Afferent (sensory) nerve
Efferent (motor) nerve
Effector system - muscle
Term
Monosynaptic Reflex Arc
Definition
Receptor -> Afferent Pathway via sensory neuron -> enter spine via dorsal roots -> exit via ventral roots -> Efferent Pathway via lower motor neuron -> muscle
Term
Polysynaptic Reflex Arc
Definition
Receptor -> Afferent Pathway via sensory neuron -> enter spine via dorsal roots -> interneuron within spine -> exit via ventral roots -> Efferent Pathway via lower motor neuron -> muscle
Term
Patellar Reflex
Definition
Spinal Reflex
Femoral nerve
Nerve roots and segments
L4-L6
Term
Thoracic Limb Withdrawal
Definition
Spinal reflex
Sensory pinch toes
Radial, median and ulna
C7,C8,T1,T2
Reflex
Flexion of carpus, elbow and shoulder
Axillary, musculocutaneous, median, ulnar (radial)
C6,C7,C8,T1,T2
Term
Pelvic Limb Withdrawal
Definition
Sensory pinch toes
Sciatic (tibial peroneal)
L6,7,S1,S2

Reflex
Flexion of hip, stifle and tarsus
Sciatic
L6,7,S1,S2
Term
Panniculus reflex
Definition
aka Cutaneous trunci reflex
Spinal reflex
Sensory pinch skin over dorsum
Spinal nerves T2-L2
Reflex
Bilateral contraction of the cutaneous trunci, which ever side stimulated
C8-T1
Term
Perineal reflex
Definition
Spinal Reflex
Sensory pinch perineum
Pudendal nerve
S1-Cd5
Reflex
Contraction of the anus and “clamping” of the tail
Pudendal nerve (anus)
Caudal nerves (tail)
Term
Hyper-reflexia
Definition
Real: Release of inhibition from UMNs
Pseudo: Reduction in action of antagonistic pair
Term
Clonus in Patellar Reflex
Definition
Oscillation of stifle
Classic finding with UMN lesion affecting pelvic limb
Term
Exaggerated Patellar Reflex
Definition
LMN sciatic dysfunction
Disproportionately large and uncontrolled stifle extension
Due to failure of antagonistic pair
Term
Localization of Spinal Nerves
Definition
C1-C5
C6-T2: Brachial Plexus
T3-L3
L4-S1: Lumbosacral Plexus
S1-Cd
Term
3 basic functions of neurons
Definition
Sensory input: collect info about ext environment and internal cond.
Integration: receive sensory input, analyze it, and make decisions
Motor output: Neurons that carry out the instructions
Term
Receptors classification
Definition
Anatomical: Encapsulated and non-encapsulated
OR
Location: Exteroreceptors, Proprioceptors, Interoceptors
Term
Exteroreceptors
Definition
Near the surface of the body. Sensitive to change in external environment.
Term
Proprioceptors
Definition
Sensitive to movement of muscles, tendons and joints
Term
Interoceptors
Definition
Located within the viscera. Sensitive to change in internal environment.
Term
Somatic afferent
Definition
the dendritic zone is on or near the surface of the body
Term
Visceral afferent
Definition
the dendritic zone in in the wall of the various viscera of the body
Term
General somatic afferent (GSA)
Definition
Touch, temperature, proprioception and noxious stimuli.
Cranial nerve V for the head
Spinal nerves for the rest of the body
Term
Special somatic afferent (SSA)
Definition
Vision: Cranial nerve II
Sound: Cranial nerve VIII
Term
General visceral afferent (GVA)
Definition
Organ content, distention, chemicals
Cranial nerves VII, IX and X to visceral structures in the head
Cranial nerve X and spinal nerves to the viscera and blood vessels of the rest of body.
Term
Special visceral afferent (SVA)
Definition
Taste: Cranial nerves VII, IX and X
Olfaction: Cranial nerve I
Term
Sensory inputs to the brain
Definition
Rostral Colliculus
Caudal Colliculus
Mesenphalic Nucleus
Main sensory Nucleus
Vestibulocochlear Nuclei
Spinal Nucleus
Solitary Nucleus
Term
Fasciculus gracilis
Definition
Proprioceptive information from pelvic limbs
Term
Fasciculus cuneatus
Definition
Proprioceptive information from thoracic limbs
Term
Dorsal and ventral Spinocerebellar tracts
Definition
Information to cerebellum for coordination
Term
Lateral and Ventral Spinothalamic tracts
Definition
Information to thalamus about pain, itch, touch and temperature
Term
UMN
Definition
Upper Motor Neuron
Motor neurons that originate in the motor region of the cerebral cortex or the brain stem and carry motor information down to the lower motor neurons
Term
LMN
Definition
Lower Motor Neurons
Neurons located in either the ventral horn of the spinal cord or the cranial nerve nuclei of the brainstem with motor function.
Term
General Somatic efferent (GSE)
Definition
Dendritic zone in striated muscle throughout body
Cranial nerves: all of them except from I, II and VIII.
Ventral nerve roots and spinal nerves for the rest of the body
Term
General Visceral efferent (GVE)
Definition
Dendritic zone in involuntary smooth muscle of viscera
Cranial nerves: III, VII, IX, X and XI.
Spinal nerves for the rest of the body
Term
Motor Outputs Spinal Tracts
Definition
Corticospinal tracts (pyramidal system)
Rubrospinal tracts (extrapyramidal system)
Reticulospinal tracts (extrapyramidal system)
Vestibulospinal tracts (extrapyramidal system)
Tectospinal tracts (extrapyramidal system)
Term
Corticospinal tracts (pyramidal system)
Definition
Motor information directly from cerebral cortex. Poorly developed in domestic animals
Term
Rubrospinal tracts (extrapyramidal system)
Definition
Motor information from red nucleus in the brainstem
Term
Reticulospinal tracts (extrapyramidal system)
Definition
Motor information from reticular formation in the brainstem
Term
Vestibulospinal tracts (extrapyramidal system)
Definition
Motor information from vestibular nuclei in the brainstem
Term
Tectospinal tracts (extrapyramidal system)
Definition
Motor information from the tectal region in the brainstem
Term
Grade of Spinal Injuries
Definition
0. Normal
1. Pain (no neurological deficits)
2. Ambulatory paresis
3. Non-ambulatory paresis
4. Plegia
5. Plegia with absent deep pain sensation
Term
Paresis
Definition
weakness of voluntary movement, or partial loss of voluntary movement or by impaired movement.
Term
Plegia
Definition
paralysis, cessation of motion
Term
Neurulation
Definition
The folding process in vertebrate embryos, which includes the transformation of the neural plate into the neural tube
Term
Grey Matter Differentiation
Definition
Dorsal Column
Intermediate Column
Ventral Column
Term
Dorsal Nerve Roots
Definition
develop into sensory/afferent pathways
Axons emerge from neural crests and grow into alar plate
Term
Intermediate Column
Definition
becomes Autonomic Nervous System
Term
Ventral Nerve Roots
Definition
develop into motor/efferent pathways
axoms grow from basal plate out of neural tube
Term
Cerebral Spinal Fluid
Definition
produced in choroid plexus of brain, acts as cushion for cortex.
occupies subarachnoid space and ventricular system, surrounded by grey matter
Term
Subarachnoid Space
Definition
Contains CSF (functions shared with CSF)
Contiguous with ventricular system circulation of CSF
A real space with clinical significance
Term
Subdural Space
Definition
A virtual space that can be “created” by introduction of “stuff”
Between dura and arachnoid
Haemorrhage (rare domestic species)
Injection of imaging contrast material
Term
CSF Collection Locations
Definition
Cervical
Lumbar
Term
Cervical CSF Collection
Definition
Technique very similar species
Under anaesthesia, flexion of the neck required
Enter in mid-line between C1 and C2
Needle enters between Atlas and base of skull into CISTERN MAGNA
Stop advancing needle as enter CSF space
Term
Lumbar CSF Collection
Definition
Variation between species depending on caudal extent spinal cord
Anaesthesia small animal, standing restraint large animal
Needle advanced to floor spinal canal and withdrawn
Term
Pro/Cons of each CSF collection location
Definition
Blood contamination less likely with cervical
Cervical likely to reflect brain and generalised condition
Lumbar tap more likely to reflect focal spinal and caudal lesion
Lumbar tap more likely to be “dry”, particularly small fat patients / cats
Term
Arterial Supply of CNS
Definition
Lumbar arteries of aorta, intercostal arteries and vertebral arteries
Supply
Paired spinal arteries
Supply
Dorsal & ventral root artery per spinal cord segments
Supply
Superficial and anastomosing arteries of the spinal cord
Supply
Deep arteries in the spinal cord leading to 3 vascular zones
Term
Venous Supply of CNS
Definition
Ventral spinal vein (drains the spinal cord)
Drain into
Vertebral venous sinus
Drain into
Segmental spinal veins
Drain into
Vertebral veins (neck, C1-T4), Azygos vein (thorax,T4-L3) & Caudal vena cava (abdomen, L4-L7)
Drain into
Systemic circulation
Term
Structure of Arterial Supply
Definition
Arterial supply reflects the segmental structure of the spinal cord
Term
Structure of Venous Supply
Definition
Ventral sinus arrangement predisposes to prolonged bleeding
Vessel distribution predisposes to focal disruption of cord function
Term
Location of CSF Lumbar Puncture
Definition
Dog L5-L6 (smaller dogs go caudally)
Cat L6-L7
Horse L6-S1
Cow L6-S1
Term
Three 'functional' divisions of Cerebral Cortex
Definition
Sensory
Motor
Association
Term
Sensory sections
Definition
Vision —> Visual cortex
Hearing —> Auditory cortex
Touch —> Somatosensory cortex

The two hemispheres receive information from the opposite (contralateral) side of the body.
Term
Motor Areas
Definition
related to controlling voluntary movements.

Two main types:
Pyramidal system:
Direct with no synapses in the brainstem.
Pass through the ventral pyramids.
Fine motor skills.

Extrapyramidal system:
Has synapses within the brainstem nuclei.
Term
Association Areas
Definition
Function to produce a perception of the world enabling an animal to interact with their environment effectively.
Term
Limbic system
Definition
within Telencephalon
correlates emotion and behaviour with the autonomic nervous system
Term
Thalamus
Definition
Translates signals to the cerebral cortex from auditory, somatic, visceral, gustatory and visual systems
Term
Hypothalamus
Definition
It is mainly related to the overall regulation of the Endocrine system.
It is closely related to the pituitary gland.
Controls the autonomic nervous system.
Term
Hypophysis
Definition
Pituitary Gland
Production of hormones as part of the endocrine system
Term
Neurological signs of forebrain dysfunction
Definition
Mentation: Normal, obtunded or stupor
Change in behaviour can be reported
Seizures can be reported
Contralateral proprioceptive deficits
Contralateral menace response absent
Circling towards the side of the lesion
Term
three main functions of brainstem
Definition
Conduction: All information relayed from body to the cerebrum/cerebellum and vice versa must traverse the brainstem.
Cranial nerves function: Cranial nerves III-XII emerge from the brainstem.
Integrative functions: Involved in cardiovascular system control, respiratory control, alertness, awareness and consciousness.
Term
Cardiovascular centre
Definition
medulla oblongata
Regulation of HR, Change of blood pH and CO2 —> Chemoreceptors, Change of BP —> Baroreceptors in aortic and carotid bodies.
Acts by sending nerve impulse to pacemaker via autonomic fibers
Term
Cushing reflex
Definition
physiological nervous system response to increased intracranial pressure (ICP) that results in Cushing's triad of increased blood pressure, irregular breathing, and a reduction of the heart rate
Term
Respiratory Centre
Definition
found in the medulla oblongata and pons
Control the rate and depth of respiratory movements.
Injury may lead to respiratory failure.
Change of blood pH and CO2 —> Chemoreceptors
Term
ARAS
Definition
Ascending reticular activating system
Responsible for awake state, level of consciousness and sleep
Term
Reticular formation
Definition
Collection of neuronal cell bodies that form a ill-defined meshwork in the central core of the brainstem. From the caudal diencephalon to the medulla oblongata.
Term
Cerebellar Function
Definition
smooth and coordinate motor function for posture and movement.
It acts as a regulator, not a primary initiator, of motor activity.
Term
Cerebellar afferents
Definition
convey proprioceptive information or information relevant to the planning and execution of motor activity
Term
Cerebellar efferents
Definition
are from the Purkinje cells and are inhibitory
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