NURS 1750 Lecture Notes - Lecture 5: List Of Lumbar Nerves, Cardiac Muscle, Multiple Sclerosis
28 Jun 2018
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Week Six (October 23 - 27, 2017)
Anatomy and Physiology
Chapter 13: The Spinal Cord and Spinal Nerves
13.1 Spinal Cord Anatomy
Protective Structures
- First layer of protection for the CNS is the hard
bony skull and vertebral column (protects
against damaging blows or bumps).
- Second protective layer is the meninges
(connective tissue), three membranes that lie
between the bony encasement and the nervous
tissue in both the brain and spinal cord.
- Cerebrospinal fluid suspends the central
nervous tissue in a weightless environment
while surrounding it with a shock-absorbing, hydraulic solution.
Vertebral Column
- The spinal cord is located within the vertebral canal of the vertebral
column.
- The surrounding vertebrae provide a sturdy shelter for the enclosed
spinal cord.
Meninges
- The meninges (singular minks) are three protective, connective tissue
coverings that encircle the spinal cord and brain.
- From superficial to deep, they are:
-Dura Mater:
- Dense irregular connective tissue.
- Forms a sac from the level of the foramen magnum in the
occipital bone where it is continuous with the meningeal
dura mater of the brain.
- Continuous with outer covering of spinal and cranial nerves
- Most superficial.
-Arachnoid Mater:
- Continuous through the foramen magnum into the brain.
- Avascular covering- cells & collagen and elastic fibers.
- Named because the mater resembles a spider’s web.
- Middle of the meningeal membrane.
-Pia Mater:
- Connective tissue layer-adheres to the surface of the
spinal cord and brain.
- Squamous to cuboidal cells, collagen & elastic fibers
blood vessels supply oxygen and nutrients to the spinal
cord.
- Innermost layer.
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- Suspend the spinal cord in the middle of its dural sheath
(denticulate ligaments)-protect against displacement.
Subdural Space: Space between dura mater and arachnoid mater. Contains
interstitial fluid.
Subarachnoid Space: between the arachnoid mater and pia mater. Contains
shock absorbing cerebrospinal fluid.
Spinal Tap (Lumbar Puncture (LP)) (Clinical Connection)
- A local anesthetic is given, and a long, hollow needle is inserted into the
subarachnoid space to withdraw cerebrospinal fluid (CSF).
- Patient lies on side with the vertebral column flexed.
- Performed to:
- Introduce antibiotics
- Contrast media
- Anesthetics
- Chemotherapy
- Measure CSF pressure
- Evaluate the effects of treatment-meningitis
- Normally performed in adults between L3 and L4 or
L4 and L5 lumbar vertebrae because this region
provides safe access to the subarachnoid space
without risk of damaging the spinal cord (spinal cord
ends at vertebra L2; spinal meninges and
cerebrospinal fluid extend to the second sacral
vertebra (S2)).
External Anatomy of the Spinal Cord
- In adults, the beginning of the spinal cord extends from medulla
oblongata (inferior part of brain).
- In newborns, it extends from the 3rd or 4th lumbar vertebra. During
early childhood, both the spinal cord and the vertebral column grow
longer (as part of overall body growth). Elongation of the spinal cord stops around age 4
or 5 but the growth of the vertebral column continues.
Spinal Cord and Nerves
-Cervical Enlargement: ends from fourth cervical vertebra (C4) to the first thoracic
vertebra (T1). Nerve to and from upper limbs arise from the cervical enlargement.
-Lumbar Enlargement: Extends from the ninth to the twelfth thoracic vertebra (T9-
T12). Nerves to and from the l ower limbs arise from the lumbar enlargement.
-Filum Terminale: is an extension of pia mater. It fuses with the arachnoid mater
and dura mater, and anchors the spinal cord to the coccyx.
-Spinal Nerves: are the paths of communication between the spinal cord and
specific regions of the body.
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Week Six (October 23 - 27, 2017)
-Bundles of axons: roots (two kinds), connect spinal nerve to a segment of the
cord by even smaller bundles of axons called rootlets.
-Posterior (Dorsal) Root Ganglion: cell bodies of sensory neurons.
-Posterior (Dorsal) Root: contains only sensory axons.
-Anterior (Ventral) Root: contain axons of motor
neurons.
Functions of the Spinal Cord:
1. Process reflexes.
2. Integrate (gray matter) postsynaptic potentials.
3. Conduct sensory impulses to brain - motor
impulses to effectors.
Differences Between White and Gray Matter
White Matter Grey Matter
Gray Matter Horns:
Spinal Cord and Brain
Clusters of neuronal cell bodies-(functional
groups called nuclei)
Sensory nuclei receive input from receptors
via sensory neurons
Motor nuclei provide output to effector tissues
via motor neurons
White matter columns-
Bundles of axons: travel up & down spinal
cord- called tracts.
Tracts are bundles of axons-CNS The
tract name often indicates its location in the
white matter and where it begins/ends.
Nerves are bundles of axons- PNS
Sensory (ascending) tracts: axons- nerve
impulses toward the brain
Motor (descending) tracts: axons- nerve
impulses from the brain
Upper vs. Lower
Motor Neuron
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Document Summary
Chapter 13: the spinal cord and spinal nerves. First layer of protection for the cns is the hard bony skull and vertebral column (protects against damaging blows or bumps). Second protective layer is the meninges (connective tissue), three membranes that lie between the bony encasement and the nervous tissue in both the brain and spinal cord. Cerebrospinal fluid suspends the central nervous tissue in a weightless environment while surrounding it with a shock-absorbing, hydraulic solution. The spinal cord is located within the vertebral canal of the vertebral column. The surrounding vertebrae provide a sturdy shelter for the enclosed spinal cord. The meninges (singular minks) are three protective, connective tissue coverings that encircle the spinal cord and brain. Forms a sac from the level of the foramen magnum in the occipital bone where it is continuous with the meningeal dura mater of the brain. Continuous with outer covering of spinal and cranial nerves. Continuous through the foramen magnum into the brain.
