Chapter 13 Flashcards
Examples of protective structures in the spinal cord?
Vertabral colulumn
Meninges
Meninges
Layers of connective tissue that surround the spinal cord and the brain
Where are meninges located
Spine AND brain
Epidural space
Space bw vertabral wall and first layer of connective tissue (dura mater)
- Lots of fat and connective tissue
Dura Mater
- Official first layer, most superficial layer
- Made of tough irregular connective tissue
- “tough mother”
What is subdural space
Filled with interstitial fluid
- Underneath dura mater
Arachnoid Mater
Very delicate collagan w/ elastic tissue
- is AVASCLAR (no/very poor blood supply)
Subarachnoid space
Below Arachnoid mater
Filled with CSF
Pia Mater
Most delicate transparent layer of connective tissue
- Very vascular
- “delicate mother”
- Lays right on brain and spinal cord
- Supplies a lot of blood into nervous tissue.
Denticulate Ligaments
- Helps hold the spinal cord in its location.
- An extension of the pia mater
Spinal Cord Diamer
2cm
When does spinal cord stop growing?
4-5 yrs
42-54 cm
From Medulla to L3-4
Cervical Enlargement
- From 4th Cervical to Thoracic 1
- Where nerves that control upper limbs will leave the spinal cord
Lumbar Enlargement
- Thoracic 9-12
- Nerves that control lower limbs leave the spinal cord
Conus Medullaris
- End of spinal cord “proper”
- Just below the lumbar enlargement
Filum Terminale
- An extension of the pia mater that anchors the spinal cord the coccyx
Cauda Equina
- “horses tail” appearance
- AFTER the proper spinal cord ends, spinal nerves continue to go down before going out to their region
Spinal Nerves
C = 1-8 (Actually only 7 vertabrae)
T = 1-12
L = 1-5
S = 1-5
Co = 1
Where do Spinal Taps take CSF out of?
Subarachnoid Space
- Bw lumbar 3-4 OR 4-5 into subarachnoid space
- Spinal cord proper has stopped by this location
Spinal Nerves are
paths of communication between the spinal cord and the nerves innervating specific regions of the body (MOTOR NEURONS)
- connected to the spinal cord by two bundles of axons called roots.
Types of Spinal Nerves
- Mixed nerves
i). Posterior (dorsal root) - sensory
ii). Anterior (ventral) root – motor
Posterior Dorsal root (Spinal Nerve)
Sensory - Incoming
Carries sensory info
- A ganglion is the location of a collection of cell bodies
- Sensory information travels to association (inter) neuron
Anterior Ventral Root (Spinal Nerve)
Motor
-From CNS outward
-Most of the 31 spinal nerves are mixed (Carrying both motor and sensory information)
Denticulate ligaments
Lateral extensions of pia mater that fuse with arachnoid mater and secure the spinal cord.
Purpose of subarachnoid space?
To cushion the Spinal Cord
Purpose of Cervical Enlargement of spinal cord
The location of nuclei for the upper extremities
Purpose of Lumbar enlargement
contains Nuclei for lower extremities
What is the Conus medullaris
End of the spinal cord (Bw L1 and L2)
Schwann cells are also
Neurolemmacells
Where are satellite cells found?
Dorsal root ganglion of sensory neurons
What is reflex
Automatic, fast, predictable, is a response
What is the H zone?
The area of Gray matter in the middle of the spinal cord that fluctuates in size depending on it’s location vertically
What is the center back “crevice” of the spinal cord?
Center front?
Posterior Median sulcus
Anterior Median Fissure
What are specific areas of the white matter in the spinal cord referred to as?
(location) white column
What are areas of gray matter in the spinal cord referred to as?
(Location) gray horn
Sensory receptros condunct AP from WHERE to WHERE
Receptors into spinal nerves (posterior root)
What is the track of sensory neurons travelling into the spinal cord for a “Spinal reflex”?
Dorsal root Ganglion - Into posterior Gray horn - synapse with interneurons - synapse with somatic motor neurons - “Spinal Reflex”
How many spinal nerves?
31 pairs
Connective tissue convering spinal nerves
Epineureum
Perineureum
Fascicle
Endoneureum
Branches (rami) of spinal nerves
Posterior
Anterior
Meningeal
Rami communicates
Plexusese
Network of nerves
5 main networks of nerves throughout the body?
Cervical, Brachial, Lumbar, Sacral, and Coccygeal
Where do the Cervical plexus span?
C1-C5
Where do the Brachial plexus span?
C4-T2
Where do the Lumbar plexus span?
L1-L5
Where do the Sacral and Coccygeal plexus span?
L4-S5
Where do most herniated discs occur?
L3/L4
What does disfunction of Brachial nerves result in?
Palsy, wrist drop, winging of right scapula
What is a Dermatome?
The area of the skin that provides sensory input
to the CNS via one pair of spinal nerves
i.e. Checking bottom of feet for sensation
What are the acsending neurons?
Sensory - going towards the brain
Descending Neurons
Motor
White columns carry what?
Bundles of nerve axons - tracts on sensory AND motor pathways
Anytime a pathway travels up throught the spinal cord it travels by:
A column of the white matter
What info does spinothalamic Tract carry?
Impulse for pain, temp, itch and tickle
What info does Posterior Column Tract Carry?
AKA gracile and cuneate faciculus [bundle]
Proprioception (Body movement/position), discriminative touch, two point touch, pressure, vibrations
Two major outgoing (motor) patjways
Direct (pyramidal) and Indirect (Extrapyrmaidal)
Direct motor pathways
- Originate in cerebellum
- Precice, voluntary, skeletal muscle movement
Know the 3
- a) Lateral Corticospinal Tracts
b) Anterior Corticospinal Tracts
c) Corticobulbar Tracts
Indirect motor pathways
Automatic responses + Movements
Muscle tone, equilibrium
- Coordinate boy + head
-All carry impulses from brain stem
Know the 5
a) Rubrospinal Tracts
b) Tectospinal Tracts
c) Vestibulospinal Tracts
d) Lateral reticulospinal tracts
e) Medial reticulospinal tract
How to understand motor pathway tract names?
i.e.
a) Rubrospinal Tracts
b) Tectospinal Tracts
c) Vestibulospinal Tracts
d) Lateral reticulospinal tracts
e) Medial reticulospinal tract
First part tells where it comes from and spinal is where it ends
Two ways spinal cord promotes homeostasis
Conducting motor+sensory APs
Reflexes (autonomic responses)
- Spinal cord = intergration center in involuntary movements
Cranial nerves reflex intergration center?
Brain stem - for eye tracking
Somatic nerve reflex ?
Contraction of skeletal muscle
Autonomic (Viceral) reflex?
Effects Smooth and cardiac muscles and glands
Spinal nerve reflex?
Integration in spinal cord
i.e knee jerk
5 components of all reflexes
- Sensory receptor (generate GP/AP)
- Sensory Neuron (Carries impulses)
- Integration Center (Interneuron, cortex, brainstem, cerebellum - regions contribute to final outcome)
- Motor Neuron
(Impulse conducted back towards effecter)
5.Effector
Monosynaptic
Sensory pathway involving only one synapse
Ipsilateral
Sensory and motor on same side of spinal cord
Reciprocal inhibition
Contraction of one muscle causes relaxation of antagonist muscle
Muscle spindle
Receptor located in muscle fiber
If rate/length of stretch = greater than normal, muscle spindle is activated (reflex/protective mechanism)
Axon collateral
Additional axons that travel to other regions of CNS
Describe Tendon reflex
Ipsilateral
Muscle spindle creates tension if actibated
Golgi Tendon Organ
Monitors amount of force/tension
GTOs always present if there are tendons
- ipsilateral
-Causes reflex relaxation to prevent damage from extreme force
- Polysynaptic
Purpose of GTO
Reduce damage that could occur
Flexor Reflex
Withdraw reflex (Pain stimulus)
- Polysynaptic
- Ipsilateral
- Intersegmental
Intersegmental
- More than just one spinal cord segment
(hamstring is large muscle, controlled by more than one spinal nerve)
Crossed Extensor Reflex
To support other leg/limb during withdraw reflex
- Polysynaptic
-Contralateral - Intersegmental
Contralateral
Sensory and motor neurons are on opposite sides of body
Babinski sign
Positive: Great toe extends
Negative: No extension (Unless younger than 1.5 yrs)
Babinski sign positive older than 1.5 yrs indicates?
corticospinal tract lesions
Abdominal Reflex
Belly button shifts twoards laterally stroked abdominal wall
Negative: Cortical spinal tract issue, lesions in PNS, intergration center OR MS
Negative Achilles Reflex due to
diabetes, neurosyphilis, alcoholism
Shingles
- Infection of varicella virus (took up residence in spinal ganglia (posterior root))
- Later on (under stress) the vurus appears along pathway of specific dermatone
- Surfaces as raised blisters, persisting
Spinal Cord compression
If spinal cord compressed but not severed (Transected)
- For period of time, appearance of spinal cord trauma
-Most of functions can/will return (if not cutting occurred)
What do degenerative NS diseases generally cause?
demyelination, breaking of neuronal pathways
Meningitis
- Infection of meninges (connenctive tissue surrounding spinal cord)
- Have to test CSF
- Viral OR bacterial (particular deadly)
- Can result in death or amputations
How do epidural blocks work?
- Injecting anisthetic into epidural space (in meningeal layer)
- Lose sensation.
- In lumbar spine for birthing
Complete Transection
Severed
Incomplete “quad”
Spinal compression BUT NOT transection resulting in quadriplegia with potential to improve function dramatically
adult length of spinal cord vs newborn
Adult - Runs from Medulla to L2
Newborn- Runs from Medulla to L3-4
Disorder associated with Brachial plexus?
Winging of R scapula, wrist drop, Palsy
Name 4 principal reflexes
Stretch, Tendon, Flexor (withdraw), Crossed Extension
