Flashcards in Chapter 14 - Spinal Cord and Spinal Nerves Deck (47):
What is the spinal cord?
-part of the central nervous system that extends from the brain
What type of information does the spinal cord convey?
-sensory input up the cord
-motor input down the cord
Where does the spinal cord begin and end?
Begins as a continuation of the medulla oblongata extending from the foramen magnum of the occipital bone to its termination as the conus medullaris between L1 - L2.
what is the Cauda Equina of the spinal cord?
the roots of the lower spinal nerves (AKA horse tail)
name and describe the 3 layers of meninges.
1) Dura Mater
-thick fibrous layer which forms a sac that encloses the cord
2) Arachnoid Mater
-located against dura mater
3) Pia Mater
- against spinal cord
-supplies cord with nutrients
what is located between the layers of meninges mater?
1) epidural space
-outside dura mater
-btw dura and arachnoid mater
-btw arachnoid and pia mater
-circulates cerebral spinal fluid
explain the process of lumbar puncture.
-A needle inserted into the subarachnoid space for the purpose of withdrawing Cerebral Spinal Fluid
-BTW L3 and L4
explain the process of Epidurals
-An anesthetic is injected into the epidural space
-Numb sensory neurons unless put too much then can numb motor neurons
what is White matter of the brain and spinal cord?
-formed by groups of myelinated axons (make white)
what is Grey matter of the brain and spinal cord?
formed by neuronal cell bodied and dendrites.
what structure do somatic motor cell bodies form?
Anterior (ventral) gray horns
-inside spinal cord
describe the structure white matter within the spinal cord.
divided into anterior, posterior, and lateral columns
what is a bundle of neuronal axons called? and where is this located?
Tract (spinal pathway)
-located in a specific area of the cord, and are all traveling to the same place
Describe the posterior spinal pathway.
-Convey nerve impulses for discriminative touch, light pressure, vibration and conscious proprioception (awareness of your body in space) --> to cerebral cortex
describe the anterolateral pathway
-composed of afferent spinothalamic tracts
-Detect crude touch and pressure, pain, temp, itch, tickle
-go from spine to thalamus
describe the spinocerebellar tracts
carry signals from proprioception to the cerebellum.
Where do Motor Spinal Cord pathways convey information ?
convey nerve impulses from the brain stem
-Lateral and anterior cortico-spinal (from cerebellum to spine)
-Voluntary movement of skeletal muscles
Other: coordinate visual stimuli with body movements, maintain posture
what do spinal nerves do?
connect the CNS to muscles, glands, and receptors.
describe spinal nerves.
-Axons are surrounded by endoneurium, then bundled into fascicles and surrounded by perineurium.
-Multiple fascicles are bundled into nerves and surrounded by epineurium
Explain the arrangement of spinal nerves.
31 left-right pairs of spinal nerves emerge from the cord at regular intervals (called segments).
- leave from the intervertebral foramen between adjoining vertebrae
*Cervical – 8 pairs, C1-C8
*Thoracic – 12 pairs, T1-T12
*Lumbar – 5 pairs, L1-L5
*Sacral - 5 pairs, S1-S5
*Coccygeal – 1 nerve pair
How are spinal nerves connected to the spinal cord?
Two bundles of axons, called roots, connect each spinal nerve to the cord by rootlets.
*posterior root - sensory axon
*anterior root - motor axons
what is a dermatome?
A dermatome is an area of skin that is innervated by a single spinal nerve, indicated by the letters and number of a particular segmental nerve.
What part of the body is innervated by the dermatomes C6/C7?
thumb and index finger ("six Shooter")
What part of the body is innervated by the dermatome T4
What part of the body is innervated by the dermatome T10
What part of the body is innervated by the dermatomes L1-L5
what are peripheral nerves?
-a network of interweaving nerves
-anterior rami of spinal nerves
describe cervical pluxus.
-Formed by anterior rami of C1-C5
-Serves head, neck, and diaphragm
describe the phrenic nerve
-emerges from cervical pluxus
“C345 keep the diaphragm alive”
describe brachial pluxus
what 5 major nerves emerge from the brachial pluxus
1) Musculocutaneous nerve
-Biceps brachii and brachioradialis
2) axillary nerve
-Serves deltoid and shoulder
3) radial nerve
-Tricepts brachii, proximal and middle phlanges
-Flexors of the forearm, lateral aspect of palm and fingers
-Medial side of hand
describe lumbar pluxus
-Supplies absominal wall, external genitalia, part of the lower limbs
what 2 nerves emerge from the lumbar pluxus?
– hip joints, extensor of knee, medial side of leg and foot
– adductor of hip and medial thigh
describe the sacral pluxus
L4-L5 + S1-S4
-Supplies buttocks, perineum, part of the lower limbs
-gives rise to sciatic nerve
-Skin of leg, muscles of back of thigh, leg and foot
what is a reflex?
fast involuntary response to a stimulus
what is a reflex arc?
pathway that a nerve impulse follows to produce a reflex.
what is a reflex arc composed of?
an integrating center inside the cord
an exiting motor neuron
describe the stretch reflex
causes contraction of a skeletal muscle in response to over stretching
monosynaptic reflex arc
*look at diagram
what is the tendon reflex?
controls muscle tension
-causes muscles to relax before tendons are torn
help maintain balance
what is the consequence of a completely severed spinal cord?
no motor or sensory function
what is the consequence of an incomplete injury of the spinal cord?
preservation of motor OR sensory function
what functions are lost in anterior cord syndrome?
motor, pain, temp, sensations are lost
touch, proprioception, and vibration are okay
Explain spinal reflexes
in a spinal reflex integration takes place in the spinal cord, not the brain.
-either monosynaptic or polysynaptic
causes you to withdraw limb (often due to pain)