Chapter 14 - Spinal Cord and Spinal Nerves Flashcards
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
- reflex arcs
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?
spaces.
1) epidural space
- outside dura mater
2) subdural space
- btw dura and arachnoid mater
3) subarachnoid space
- 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.
- afferent tract
- 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
nipple line
