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What are the two major parts of a typical vertebra?
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List the seven processes of a typical vertebra.
- 1 spine
- 2 transverse processes
- 4 articular processes (2 cranial & 2 caudal)
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Where do the spinal nerves leave the vertebral canal?
Intervertebral foramen
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What is formed by all the vertebral foramina of all the vertebrae?
Vertebral canal
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What is the laminae of a vertebrae?
Roof (top of arch) of vertebral foramen
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What is the interarcuate space?
Dorsal gap between adjacent vertebral arches
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With what does the atlas (C1) articulate?
Occipital condyles of skull
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What are the large lateral masses of the atlas?
Wings of the atlas (transverse processes)
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What peg-like process on the axis forms a pivot articulation with the atlas?
Dens
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What is the large ventral projection of the sixth cervical vertebra?
Transverse process ("sled")
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What joint is formed by the atlas and the skull?
Atlanto-occipital joint, "yes" joint
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The articulation of the axis with the atlas is known as the ___ joint.
Atlantoaxial joint, "no" joint
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Name the fibrocartilages between the bodies of adjacent vertebrae.
Intervertebral discs
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What are the two parts of an intervertebral disc?
Annulus fibrosus and nucleus pulposus
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What elastic connective tissue structure attaches the 1st thoracic spine to the spine of the axis (C2) in the dog?
Nuchal ligament, none in cat
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What elastic tissue fills the dorsal space (interarcuate space) between the arches of adjacent vertebrae?
Ligamentum flavum, interarcuate or yellow ligament
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What connects the heads of a pair of opposite ribs, crossing the dorsal part of the intervertebral discs?
Intercapital ligament
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What are the two paired "strap muscles" of the neck?
Sternohyoideus and sternothyroideus muscles
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Name the muscle extending from the sternum to the head.
Sternocephalicus muscle
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What forms "envelopes" around the muscles of the neck?
Deep fascia of neck.
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What muscles are above the transverse processes of the vertebrae?
Epaxial mm.
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Name the two major epaxial muscles of the back?
Iliocostalis and longissimus mm.
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What muscles are below the vertebrae's transverse processes?
Hypaxial muscles
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What is the hypaxial muscle in the neck and cranial thorax?
Longus colli m.
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What is the main hypaxial/sublumbar muscle of the abdomen?
Psoas major m.
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Where is the common carotid artery located?
Besides the trachea in carotid sheath.
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What glandular structures are under the omotransversarius muscle just cranial to the shoulder?
Superficial cervical (prescapular) lymph node
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List the two important structures enclosed in the carotid sheath.
Common carotid artery, vagosympathetic trunk
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Where is the esophagus located in the middle of the neck?
on left
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What is the gland just caudel to the larynx on the trachea?
Thyroid gland
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What is the part of the hyoid apparatus crossing the midline?
Basihyoid bone
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Name the five divisions of the spinal cord.
Cervical, thoracic, lumbar, sacral & caudal
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What are the ascending and descending tracks of the spinal cord and what do they carry?
- Ascending - sensory information
- Descending - upper motor neurons (UMN), motor information
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Where does the spinal cord end in the dog?
- Dog: L6 (6-7)
- Cat: S1-3
- Human: L2
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Ventral branches of spinal nerves interlace to form ____.
Plexuses
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What nerve travels along the dorsal border of the omotransversarius muscle?
Accessory nerve (CrN 11)
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What plexus supplies some of the extrinsic and all of the intrinsic muscles of the thoracic limb?
Brachial plexus
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Plexuses are formed by the ventral branches of spinal nerves in every region except which?
Thorax (except T1-2) = intercostal nn.
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The ventral branches of the thoracic nerves T3-13 do not form a plexus, but pass in the intercostal spaces as _____ nerves.
Intercostal
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What plexus supplies the abdominal wall, pelvic limb, external genitalia, rump and perineum?
Lumbosacral plexus
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What forms the spinal nerve? Into what do spinal nerves divide?
- Roots (dorsal & ventral)
- Branches (dorsal & ventral)
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How do spinal nerves leave the vertebral canal?
Through intervertebral foramen
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What spinal nerve branches supply sensation from the skin of the abdominal wall?
- Dorsal: upper flank (including area below transverse processes)
- Ventral: rest
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What are the six major functional regions of the spinal cord?
- Cranial cervical (C1-5)
- Cervical (brachial) enlargement (C6-T1)
- Thoracic and cranial lumbar (T2-L3)
- Lumbar (lumbosacral) enlargement (L4-S2)
- Sacral (S2-3)
- Caudal (Ca1-5)
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What does the sacral region of the spinal cord supply?
Reflex control of urination, defecation, sexual reflexes & parasympathetic outflow
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Where does the spinal cord end in the dog? cat?
- Dog: about L6-7
- Cat: sacrum
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What is the function of the proprioceptive fibers?
Sense position of body parts to each other and to environment
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Over what structures do proprioceptive fibers travel?
Peripheral nn., spinal cord, brain stem to cerebellum & cerebrum
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What is a dermatome? autonomous zone?
Area of skin innervated by a nerve, only 1 spinal n. respectively
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What are upper (UMN) and lower motor neurons (LMN)?
- LMN's: leave CNS as peripheral nerves
- UMN's: in CNS, affect LMN's
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What is the function of most UMN (upper motor neurons)?
Inhibit spontaneous activity of LMN until action desired
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LMN's are ______ ______ without the input of UMN's.
spontaneously active
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List the meninges from outer to inner.
Dura mater, arachnoid & pia mater
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List the spaces that are related to the meninges.
- Epidural: between dura mater and periosteum
- Subdural: potential space between the dura mater and arachnoid
- Subarachnoid space: between the arachnoid and pia mater (CSF)
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What is the enlargement of the subarachnoid space between the medulla oblongata and cerebellum?
Cisterna magna (cerebellomedullary cistern)
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What fills the gap between the dorsal edge of the foramen magnum and the atlas?
Dorsal atlanto-occipital membrane
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What is the unpaired artery running longitudinally on the vertebral canal floor in the ventral median fissure the length of the spinal cord?
Ventral spinal artery
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What are the paired, thin-walled, valveless vessels on the vertebral canal floor in the epidural space from the skull to the caudal vertebrae?
Internal vertebral venous plexus
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What are the vessels located on the ventral surface of the tail?
Median caudal artery & vein
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How are the dorsal and ventral edges of the vertebral canal checked in back radiographs?
Check for alignment, they should be straight lines without step defects
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What should be evaluated in the area of the axis and atlas?
The dens (odontoid process), it should be present and held in the ventral vertebral canal
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How are the intervertebral disc spaces in back radiographs evaluated?
Triads (3 adjacent spaces) are compared for size differences
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Describe the appearance of the intervertebral foramen, considered "windows" to the spinal cord.
Look like Snoopy's little bird buddy "Woodstock" or a "horse head" in profile
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How are the intervertebral foramen compared in back radiographs?
For differences due to disc space differences
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What is a landmark in a lateral film of the caudal neck?
"SLEDS" or tranverse process of C6
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How does a myelogram appear?
Subarachnoid space lights up = two white lines (columns) separated by a space (the invisible spinal cord)
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What may narrowing of the intervertebral space indicate?
Protruded disc
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Describe the three possible types of spinal cord lesion.
- a. Extradural lesion: outside the dura mater
- b. Intradural lesion: between spinal cord and dura mater
- c. Intramedullary (spinal cord) lesion: inside cord
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What are the myelogram findings for the following lesions?
a. Extradural lesion
b. Intradural lesion
c. Intramedullary lesion
- a. Thinning or break of columns pushed inward at lesion, +- expanded cord/thinned columns in other view
- b. Widening of subarachnoid space, +- expanded cord/thinned columns in other view
- c. Expanded cord/thinned columns in all views
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What are the myelogram findings for the following lesions?
a. Extradural lesion
a. Thinning or break of columns pushed inward at lesion, +- expanded cord/thinned columns in other view
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What are the myelogram findings for the following lesions?
b. Intradural lesion
b. Widening of subarachnoid space, +- expanded cord/thinned columns in other view
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What are the myelogram findings for the following lesions?
c. Intramedullary lesion
c. Expanded cord/thinned columns in all views
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What is the disease of the cervical vertebrae in large breeds causing stenosis of the vertebral canal resulting in ataxia (unsteady gait)?
Cervical spondylomyopathy, canine wobbler disease
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What is excessive ventral lumbar curvature?
Lordosis (swayback)
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What is an excessive thoracic curvature?
Kyphosis (hunchback in humans)
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What is lateral curvature to the spine?
Scoliosis
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What clinical problem would a fractured dens cause?
Spinal cord injury
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What is the removal of the right or left dorsal vertebral arch (lamina) to relieve pressure in the spinal canal?
Hemilaminectomy
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What is a hemivertebra?
Wedge-shaped vertebra resulting in severe angulation to spine in thoracolumbar region.
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Define and give another name for Wobbler's disease.
Cervical sponylomyelopathy - cervical spinal cord compression
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What are seen radiographically with spondylosis?
- Spurs: osteophytes intervertebral spaces
- Bridges (ankylose vertebrae)
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What is diskospondylitis?
Infection of IV discs & adjacent vertebrae
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What is another name for vertebral osteomyelitis/vertebral abscess?
Spondylitis
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What is spina bifida?
Failure of 1 or more vertebral arches to close
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Basically what are the two types of intervertebral disease?
- Type 1: disk rupture
- Type 2: disk bulging
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A slipped disc results when the soft ___ ___ is squeezed to one side of the disc, causing the firm ___ ___ to protrude and possibly rupture.
- Nucleus pulposus
- Annulus fibrosus
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What can a slipped disc protruding into the vertebral canal compress?
Spinal nerves or spinal cord itself
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Where is the annulus fibrosis thinnest?
Dorsally
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Why don't intervertebral disc commonly impinge on nerves in most of the thoracic region?
Protection of intercapital ligaments
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Where is rupture of an intervertebral disc common?
Thoracolumbar junction (T11-L2)
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Basically, what are the two types of intervertebral disease?
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What is the removal of the remaining nucleus pulposus from a rupture disc?
Disc fenestration
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What is the surgery for cervical disc disease?
Ventral decompression through longus colli m. to remove extruded disk
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What is the surgery for thoracolumbar disk disease?
Dorsal laminectomy/hemilaminectomy & fenestration (remove nucleus pulposus)
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What is atlantoaxial subluxation/instability?
Instability of C1-C2 joint due to dens problems (absence, malformation, failure to ossify or insufficient ligamentous support of the dens, rupture of ligaments of dens or fracture of dens)
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How would you place a tube for an emergency tracheostomy / tracheotomy?
Skin incision in the ventral neck, separate the strap mm., cut between the cartilages of the trachea, insert tube
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Why can a broken neck result in respiratoy paralysis?
Phrenic nerve to diaphragm arises in brachial & cervical plexuses
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Why is the jugular vein often used preferentially in venipuncture?
Saves easier cephalic v. for emergencies
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What is a trans tracheal wash?
Injection & aspiration of material into a from the trachea for lab work
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What is a myelogram?
Injecting contrast medium into the subarachnoid space & radiographing
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Describe how a spinal tap or myelogram is done with a spinal needle.
- Flex neck
- Palpate: wings of atlas, spine (axis) & external occipital protuberance
- Needle: midline, 1/2" cranial to line between wings, parallel to the caudal skull
- Feel "pop" (dorsal atlanto-occipital ligament) & immediately stop
- Pull out stylet & look for CSF fluid in the hub = right place (If hit bone, pull out and start again, or walk needle off bone into space
- CSF tap: collect CSF for analysis
- Myelogram: collect CSF for analysis & then inject contrast medium
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Where are CSF taps performed?
Cisterna magna or lumbar cistern
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Where is a lumbar CSF tap performed in the dog & cat?
L5-6 or forward or back 1 space
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What are the landmarks used for cerebrospinal fluid taps at the atlanto-occipital junction?
Wings of the atlas, spine of the axis, external occipital protuberance
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Describe doing a thoracolumbar myelogram or CSF (spinal) tap.
- Needle between L5-6 spines
- Through yellow ligament into spinal canal - Midline critical
- Through canal to vertebrae
- Withdraw needle a little (mm) into ventral subarachnoid space
- Remove stylet to see CSF in hub if correct
- CSF tap: collect CSF
- Myelogram: collect CSF, then inject contrast
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Where is epidural anesthesia given?
Through lumbosacral space into epidural space
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What is the lumbosacral space?
Interarcuate space between last lumbar vertebrae (L7) & sacrum
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Describe procedure for a epidural in the dog.
- Thumb & third finger on cranial end of sacral tuberosities
- Palpate (index finger) space between last lumbar spinous process (L7) & sacrum
- Needle perpendicular, "pop" through yellow ligament into epidural space
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What are the clinical signs of meningitis?
Cervical rigidity (due to pain [hyperesthesia]), fever and lameness
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What is the term for meningitis associated with inflammation of the underlying spinal cord?
Meningomyelitis
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How do lumbar, sacral and caudal spinal cord segments and the vertebrae relate?
They don't correlate with vertebrae of same number caudal to L4
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Why is it important to know relationship between the lumbar spinal cord segments and the vertebrae they overlie?
To localize the spinal cord lesions
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An easy way to remember where spinal cord segments lie in relationship to the vertebrae of the same number?
- L3 over vertebrae L3
- Sacral segments: over 5th vertebral (dog), sacrum (cat)
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Where is the lesion if proprioception is lost?
Peripheral n., spinal cord, brain stem, cerebellum, or cerebrum (thus anywhere)
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Does loss of proprioception localize the lesion?
No, but a sensitive indication of a neurological problem
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How is proprioception evaluated clinically?
Postural reactions (e.g. knuckle paw)
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Describe proprioceptive placing reaction in the dog and cat.
Placing the animal's weight on its dorsal paw should result in immediate adjustment to normal placement
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How can knowing the spinal cord segments innervating myotomes and dermatomes be used clinically?
Used to localize lesions
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Why should you palpate the entire body's muscles?
Check for muscle atrophy (head & limbs)
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Why is a patellar tap performed in a physical exam?
Test reflex arc of pelvic limb
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What easy, reliable reflexes are tested for peripheral reflex arcs?
Patellar tap, anal sphincter, tail bone, withdrawl reflex
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How is the withdrawl reflex tested in a screening physical?
Pinch toes of all 4 limbs
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Where does gait deficits without "head signs" localize the lesion?
To spinal cord, peripheral nerves, neuromuscular junction or diffuse muscular lesion
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What is the term for weakness?
Paresis
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What is complete to partial loss of voluntary motor activity?
Paralysis and paresis (weakness)
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What suffixes are used to paresis and paralysis, respectively?
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Define the following:
a. Monoparesis or monoplegia
Only one limb involved
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Define the following:
b. Hemiparesis or hemiplegia
Both limbs on one side
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Define the following:
c. Tetraparesis/quadraparesis or tetraplegia/quadriplegia
All 4 limbs involved
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Define the following:
d. Paraparesis or paraplegia
Only the pelvic limbs involved
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What is the effect of UMNs damage on LMNs?
LMNs increase their activity
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What localizes a lesion to the peripheral nerves, or spinal cord, or segment of brain stem LMNs arise from?
LMN signs
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What is the memory aid for LMN signs?
Thumbs down = everything decreased or disappears
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List 4 LMN disease signs (thumb down).
- Decreased or absent tone (hypotonia to atonia)
- Decreased to absent reflexes (hypo- to areflexia)
- Flaccid paralysis
- Rapid atrophy (neurogenic atrophy) 1 week
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List 4 UMN disease signs (thumb up).
- Normal to increased muscle tone
- Normal to increased reflexes (hyperreflexia)
- Spastic paresis to paralysis
- Slow (disuse) atrophy
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What is Shiff-Sherrington syndrome?
Hyperextension of forelimbs with lesions to thoracic spinal cord (T3-L3 / area 3)
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Localize the lesion:
a. UMN signs pelvic limbs, LMN signs thoracic limb
C6-T2 (Area 2)
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Localize the lesion:
b. UMN to all limbs
C1-C6 (area 1)
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Localize the lesion:
c. UMN to left pelvic, normal thoracic limb
T3-L3 (Area 3) on left
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Localize the lesion:
d. UMN signs to pelvic limb, hyperextended thoracic limb
T3-L3 (area 3) + Shiff-Sherrington
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Localize the lesion:
e. LMN signs to pelvic limb with normal thoracic limb
L4-S1 (area 4)
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List presenting signs to transection of the spinal cord:
a. C1-5 spinal cord (area 1)
- No LMN signs to either limb
- UMN & loss of proprioception to all 4 limbs
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List presenting signs to transection of the spinal cord:
b. Cervical enlargement, C6-T2 (area 2)
- LMN & loss of proprioception to thoracic limb
- UMN & loss of proprioception to PL
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List presenting signs to transection of the spinal cord:
c. T3-L3 (area 3)
- Normal TL (+- Shiff-Sherrington)
- UMN & loss of proprioception to PL
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List presenting signs to transection of the spinal cord:
d. L4-S1 (area 4)
- Normal TL
- LMN & loss of proprioception to PL
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What do ascending sensory / afferent tracts carry?
Sensory information including superficial & deep pain and proprioception
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What is indicated if a toe pinch elicits a withdrawl of limb, but no behavioral change?
Spinal cord or brain stem lesion cranial to reflex center
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What type of prognostic sign is loss of deep pain?
Bad prognostic sign
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What is usually the first sign in spinal cord compression?
Loss of proprioception
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Localize lesion:
loss of proprioception in pelvic limb, normal thoracic limb proprioception
Between T1 & S1
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What is the cutaneous trunci (panniculus) reflex?
Normal reflex: contraction of cutaneous trunci m. in response to a pin prick of trunk
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What is the path of the cutaneous trunci (panniculus) reflex?
Sensation from skin of trunk over thoracic & lumbar spinal nn. to spinal cord, up cord to lateral thoracic n. (C8), out to cutaneous trunci m.
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Clinically what is the panniculus response used to evaluate?
Level of thoracic spinal cord damage
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Where is the spinal cord damage if the panniculus response is absent caudal to the level of the 10th thoracic vertebrae?
Level of T8
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Where are the dermatomes of the cutaneous trunci response located?
1 or 2 vertebrae caudal to level of innervating cord segment
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What vessel is commonly used to bleed cattle?
Median caudal v. (tail v.)
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What is a fibrocartilaginous embolism?
Emboli occlude vessels in the spinal cord
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What clinical signs are seen with fibrocartilaginous embolism?
Paresis/paralysis caudal to the lesion
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How is a presumptive diagnosis of fibrocartilaginous embolism made?
From symmetric paresis with normal radiology
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