Session 2 - Spine Part 1 Flashcards
What is a dermatome?
An area of skin supplied by a single spinal nerve
How do dermatomes develop embryologically?
Somites differentiates into sclerotome and dermamyotome which then differentiates into dermatome and myotome
What does T4/5 dermatome innervate?
Nipples
What does T10 dermatome innervate?
Umbilicus
What does L1 dermatome innervate?
Groin
What is the anatomical definition of neural level?
Neural segment of the CNS
What is endoneurium?
Layer of connective tissue surrounding each axon
What is a fascicle?
Group of axons bundled together
What is a perineurium?
Layer of connective tissue wrapping each fascicle
What is a epineurium?
Layer of connective tissue surrounding a group of fascicles
What is vasa nervorum?
Blood vessels of nerves in epineurium
What is a spinal nerve?
Mixed nerve that carries motor, sensory and autonomic signals between body and spinal cord
What does the vertebral foramen do?
Spinal cord runs through
What forms the spinal canal?
Multiple vertebrae foramina
What are intervertebral foramina?
Gaps between the vertebrae
Where does the spinal cord begin and end?
Starts at medulla oblongata, base of brain stem
Ends at conus medullaris at L2
Where is the cauda equina located?
Below conus medullaris
How do cervical spinal roots emerge and what is the exception?
All merge above corresponding vertebral body with exception of 8th cervical spinal root, with emerges below C7 and above T1
How do the thoracic nerve roots exit?
Inferior to vertebral body
What does posterior or dorsal ramus supply?
Deep muscles and skin of dorsal trunk
What does the anterior or ventral ramus supply?
Muscles and skin of upper and lower limbs and lateral and ventral trunk
What is a myotome?
Group of muscle fibres supplied by a single spinal nerve
What is a motor unit?
Single motor neuron and the skeletal muscle fibres it innervates
What are the 2 actions that C5 myotome do?
Shoulder abduction and external rotation
What are the 3 actions that C6 myotome do?
Elbow flexion
Wrist extension
Supination
What are the 3 actions that C7 myotome do?
Elbow extension
Wrist flexion
Pronation
What are the 2 actions that C8 myotome do?
Finger flexion
Finger extension
What are the 2 actions that T1 myotome do?
Finger abduction
Finger abduction
What is the action that L2 myotome do?
Hip flexion
What is the action that L3 myotome does?
Knee extension
What is the action that L4 myotome does?
Ankle dorsiflexion
What is the action that L5 myotome does?
Great toe extension
What is the action that S1 myotome does?
Ankle plantar flexion
What is the action that S2 myotome does?
Great toe flexion
What is the clinical definition of neural level?
Lowest level of fully intact sensation and motor function
What are the 2 regions of an intervertebral disc?
Nucleus pulposus
Annulus fibrosus
What are the 2 major ligaments of the vertebral column?
Anterior longitudinal and posterior longitudinal ligaments
What is the function of the anterior longitudinal ligament?
Prevent hyperextension
What is the function of the posterior longitudinal ligament?
Prevents hyper flexion
What is the function of interspinous ligaments?
Resist hyper flexion
What do the cauda equina innervate?
Pelvic organs and lower limbs
What is the primary curvature?
C-shaped concave anteriorly
What is a kyphosis?
Anterior flexion or anteriorly concave curvature
What is a lordosis?
Posterior flexion or posterior lay concave curvature
What is mechanical back pain?
Pain when spine is loaded, that worsens with exercise and is relieved by rest
What is marginal osteophytosis?
Osteocytes develop adjacent to the end plates of discs
How does degenerative changes in vertebral column cause radicular or nerve pain?
Disc height decreases and arthritis develops in facet joints and vertebral bodies, intervertebral foramina decreases in size and compresses spinal nerves
What are the 4 stages of disc herniation?
Disc degeneration
Prolapse
Extrusion
Sequestration
What happens during disc degeneration?
Chemical changes associated with seeing causes discs to dehydrate and bulge
What happens during prolapse?
Protrusion of nucleus pulposus occurs with slight impingement into spinal canal but still contained within annulus fibrosus
What happens during extrusion?
Nucleus pulposus breaks through annulus fibrosus but is still contained within disc space
What happens during sequestration?
Nucleus pulposus separates from main body of disc and enters spinal canal
What are the 2 most common sites for slipped discs?
L4/5
L5/S1
What is an existing nerve root?
Nerve root that emerges from spinal canal at same level as intervertebral disc
What is a traversing nerve root?
Nerve root that emerges at the level below
What kind of nerve root does far lateral disc herniation compress?
Exiting
What kind of nerve root does paracentral herniation compress?
Traversing
What is sciatica?
Pain caused by irritation or compression of one or more of the nerve roots that contribute to the sciatic nerve
Where is pain typically experienced in sciatica?
Back and buttock, radiates to dermatome supplied by affected nerve root
What is cauda equina syndrome?
When there is a canal filling disc that compresses the lumbar and sacral nerve roots within the spinal canal
What are 5 red flag symptoms of cauda equina?
Bilateral sciatica Perianal numbness Painless retention of urine Urinary incontinence Erectile dysfunction
How to treat cauda equina syndrome?
Surgical decompression within 48 hours of onset of sphincter st,proms
What is spinal canal stenosis?
Abnormal narrowing of spinal canal that compresses either spinal cord or nerve roots
What is neurogenic claudication?
Compression of spinal nerves as they emerge from lumnosacral spinal cord causes ischaemia and causes pain and or or paraesthesia
What is spondylolosthesis?
Anterior displacement of the vertebra above relative to the vertebra below
What is a lumbar puncture?
Withdrawal of fluid from subarachnoid space of the lumbar cistern
