NERVOUS SYSTEM Flashcards by Ella Lujan

Structural division

CNS
PNS

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Functional division

 Somatic Nervous system
 Autonomic nervous system – sympathetic and
parasympathetic n.s

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conducts sensory (afferent)
information from the periphery to the CNS. Sensory info
travels in ascending tracts from spinal cord (“lower”) to the
brain (“higher”)

Sensory (afferent) System

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sensory fibers in the spinal cord that
travel toward the brain

Ascending Tracts

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consists of motor (efferent)
nerves that conduct from higher to lower levels of the CNS
and from the CNS to the periphery

Motor (efferent) System

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extend from the brain
down descending tracts in the cord to synapse on lower
motor neurons (LMN)

Upper Motor Neuron

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extend away from the
spinal cord and brain to the muscles and glands of the
body

Lower Motor Neuron

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bundles of upper motor neuron
fibers that move caudally in the spinal cord

Descending Tracts

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Components of the nervous tissue

Components of the nervous tissue
 Neuroglia
 Neurons - its parts (cell body, nucleus and processes) and
classification

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inflammation of a nerve

Neuritis

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– allows diseases to differentially affect separate parts of the nerve cell.

Compartmentalization

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– proliferate after brain damage, forming a
scar (gliosis). This can be detrimental, mechanically placing stress on the surrounding brain tissue, causing
irritation of adjacent tissue, and/or a possible epileptic focus

Astrocytes

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A specialized site of apposition where information
passes from one nerve cell to another cell

Synapse

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 The first cell

Presynaptic Cell

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Second Cell

Post synaptic Cell

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 Between the two cells

– synaptic cleft

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– an electrical event that travels
down an axon

Nerve action potential

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 – the neuron that is transferring info to
the postsynaptic cell

Presynaptic cell

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– the terminal end of the presynaptic nerve that is in apposition with the post synaptic cell; contains the synaptic vesicles

Synaptic button/knob

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– membrane-bound organelles containing neurotransmitters located in the synaptic button

Synaptic vesicles

– a chemical substance within the
synaptic vesicle that mediates info transfer between
nerve cells and other cells at synapses; different sets of
neurons use different neurotransmitter

Neurotransmitters

– the neuron, muscle or gland
receiving info from the presynaptic cell

Postsynaptic cell

– integral protein inserted in the membrane of the postsynaptic cell; function to bind with a neurotransmitter, resulting in a change in the membrane of the post synaptic cell

Receptors

– the synaptic connection
between a neuron and muscular tissue where electrical
impulses pass from the neuron to the muscle cell; this

Neuromuscular junction

- nerve action potential propagates down the axon to reach the synaptic knob; causes the synaptic vesicles to release their neurotransmitters into the synaptic cleft; the neurotransmitters diffuse across the cleft to bind to receptors on the postsynaptic membrane; if the postsynaptic cell is a nerve, it can initiate or inhibit another nerve action potential in the

Synaptic event

CRANIAL NERVES- CLINICAL – can be palpated and anesthetized as it comes out of the infraorbital foramen

Infraorbital nerve

CRANIAL NERVES- CLINICAL – can be palpated and anesthetized as it comes out of the mental foramen

 Mental nerve

CRANIAL NERVES- CLINICAL can result in sensory deficit of the face and dropped jaw due to paralysis of the muscles of mastication

Injury to the trigeminal nerve

CRANIAL NERVES - CLINICAL  Injury to abducent nerve –

results in inability to gaze

CRANIAL NERVES - CLINICAL can cause paralysis of the facial nerve. This can cause loss of taste, facial paralysis and loss of lacrimation. Dogs have little vanity about their appearance, and the glossopharyngeal nerve also has taste fibers, but without a functioning lacrimal gland or the orbicularis oculi muscle the eye can seriously dry up

MIDDLE EAR INFECTIONS

– cross the lateral aspect of the masseter muscle. This can be injured, causing facial paralysis [example, horse lying on a harness buckle during surgery (buccal on buckle)]

Buccal branches of the facial nerve

– the facial nerve supplies the motor component to the sensory component of the trigeminal nerve. Pricking the face with a pin checks this arc. If either nerve is paralyzed, then a twitch of the muscles will not be elicite

Facial/trigeminal reflex arc

 Damage to the glossopharyngeal nerve or vagus–

may cause difficulty in swallowing

– a zoonotic importance, causing hydrophobia (fear of water, as in drinking) due to paralysis of the pharynx (IX and X). With pharyngeal paralysis, salivation or choke first think rabies!

RABIES

– common in racehorses causing paralysis of the muscle that opens the larynx (dorsal cricoarytenoideus), resulting in a condition called “roaring”

Damage to the recurrent laryngeal nerve

causes paralysis to the tongue’s muscles and unilateral damage causes deviation of the tongue toward the normal side

Damage to the Hypoglossal Nerve

– anesthetize the mental nerve as it comes out of the mental foramen to anesthetize the lower chin

Mental nerve block

– injection at the mandibular foramen. The foramen is on the medial side of the mandible, opposite the points at which a line across the occlusal surface of the cheek teeth crosses a perpendicular line from the caudal edge of the eye. Insert a 6” inch needle medial to the mandible straight up to this point and inject anesthetic. This anesthetizes the lower lip but doesn’t get the incisors because those Fibers are internal. This block can be used when repairing lacerations of the lower lip

Mandibular alveolar nerve block

palpate the rostral end of the facial crest. Run your finger dorsally to the infraorbital foramen and palpate the nerve under the levator labii superioris muscle. This block only anesthetizes superficial structures from the point of the foramen to the lip. Remember, nerves do not respect the midline, so do both sides to anesthetize the middle of the upper lip. This can be used when repairing lacerations on the lips or the bridge of the nose. Injecting into the foramen one inch, which is difficult, anesthetizes the face back to the orbit

Infraorbital Nerve Block

find the caudal angle of the eye and palpate the notch in the lower part of the zygomatic arch, just below the caudal angle of the eye. Pass the needle under the notch and aim rostrally and ventrally to anesthetize the maxillary nerve where it enters into the maxillary foramen. This anesthetizes the upper cheek teeth

Maxillary nerve block

– palpate the foramen in the zygomatic process of the frontal bone. Inject a “bleb” of anesthetic over the foramen and rub it in. this anesthetizes the area over the forehead between the eyes. Do not inject into the foramen and thus the eyeball

Supraorbital Block

A region of the spinal cord from which a pair of spinal nerves arise.  The last lumbar, the sacral, the caudal segments and the end of the spinal cord are more cranial to the corresponding vertebrae

Spinal Segment

MENINGES-CLINICAL – (G. hydro water + enkephalos brain) – an accumulation of cerebrospinal fluid in the brain’s ventricles due to obstruction of the flow of fluid. The blockade can occur in the cerebral aqueduct or the lateral apertures

Internal hydrocephalus

– an accumulation of CSF in the subarachnoid space due to interference with absorption into the dural venous diseases

External hydrocephalus

EPIDUEAL ANESTHESIA-CLINICAL – injection of a small volume of analgesic into the epidural space at either the sacrocaudal (S5- Ca1) or first intercaudal space (Ca1-Ca2). This inexpensive, simple procedure is commonly performed on cows, sheep and goats for obstetrical manipulations and surgeries involving the tail, anus, rectum, vulva, perineum, and prepuce. Just enough analgesia to block the sacral and caudal nerves is needed. If

Caudal epidural analgesia

ANESTHESIA FOR ABDOMINAL SURGERY-CLINICAL – opening the paralumbar fossa to deal with such problems as “hardware disease”, dystocia, displaced abomasum, etc. the first three or four ventral lumbar nerves and the last thoracic nerve are anesthetized in flank surgery of horse and ox

Standing flank surgery in the ox

ANESTHESIA FOR ABDOMINAL SURGERY-CLINICAL concerned with T13, L1 and L2 nerves and can be done in a number of ways

Local/Regional anesthesia for a flank surgery –

– injections are done in the abdominal wall, from the subcutaneous area to the peritoneum

Inverted L block

ANESTHESIA FOR ABDOMINAL SURGERY-CLINICAL Local/Regional anesthesia for a flank surgery • ____________– block all branches of the spinal nerves • Proximal Paravertebral anesthesia (Farquharson, Hall or Cambridge Technique) • Distal paralumbar anesthesia (Magda, Cakala or Cornell Technique)– blocks only the ventral and lateral and dorsal branches of the spinal nerves

Paravertebral block