- extends from Foramen Magnum to the level of the disk between L1/L2 vertebrae - provides nervous pathways for nerve impulses between the Peripheral Nervous System and the Brain - provides simple integrative functions (reflexes) - 31 pair of spinal nerves come off of the cord to exit through the intervertebral foramen (8 pair of cervical, 12 pair of thoracic, 5 pair of lumbar, 5 pair of sacral,1 pair of coccygeal spinal nerves)

- outer most layer - anchors the meninges with in the spinal canal - Epidural Space = lies outside the Dura that is filled with fat and other connective tissues

- middle layer - Subdural Space = lies outside of the arachnoid mater, contains interstitial fluid (lymph)

- covers the surface of the Brain and Spinal Cord - Subarachnoid Space = lies outside of the Pia, contains Cerebral Spinal Fluid (CSF) - Denticulate ligaments = thickened Pia Mater that project laterally to fuse with the Dura Mater, these act as a shock absorber

- roughly cylindrical - slightly flattened in the A-P dimension

- located between L1 and L2 vertebrae - the end of the spinal cord

- contains the nerves that leave the spinal cord then run inferiorly to exit from lower Intervertebral foramen

1. Reflex = a fast, involuntary, unplanned sequence of actions that occur in response to a particular stimulus 2. Reflex Arc - the pathway followed by nerve impulses that produce a reflex - components:

Chapter 13 Flashcards by Maleah Michelle

Spinal

extends from Foramen Magnum to the level of the disk between
L1/L2 vertebrae
provides nervous pathways for nerve impulses between the
Peripheral Nervous System and the Brain
provides simple integrative functions (reflexes)
31 pair of spinal nerves come off of the cord to exit through the
intervertebral foramen (8 pair of cervical, 12 pair of thoracic, 5
pair of lumbar, 5 pair of sacral,1 pair of coccygeal spinal nerves)

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Protective Structures

Vertebral Column
Meninges:

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Meninges

three connective tissue coverings that surround the Brain and
Spinal Cord

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a. Dura Mater

outer most layer
anchors the meninges with in the spinal canal
Epidural Space = lies outside the Dura that is filled with
fat and other connective tissues

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Arachnoid Mater

middle layer
Subdural Space = lies outside of the arachnoid mater,
contains interstitial fluid (lymph)

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Pia Mater

covers the surface of the Brain and Spinal Cord
Subarachnoid Space = lies outside of the Pia, contains
Cerebral Spinal Fluid (CSF)
Denticulate ligaments = thickened Pia Mater that project
laterally to fuse with the Dura Mater, these act as a shock
absorber

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External Anatomy

roughly cylindrical
slightly flattened in the A-P dimension

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Cervical Enlargement

located between C4 and T1 vertebrae
- supplies nerves to the upper extremities

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Lumbar Enlargement

located between T9 and T12 vertebrae
- supplies nerves to the lower extremities

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Conus Medullaris

located between L1 and L2 vertebrae
the end of the spinal cord

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Filum Terminale

a fibrous band of Pia that extends from the Conus Medullaris to
the Coccyx
- anchors the spinal cord

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Cauda Equina

contains the nerves that leave the spinal cord then run
inferiorly to exit from lower Intervertebral foramen

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Cross Sectional Anatomy

Outer region
- is mostly white matter (myelinated fibers) providing nerve
impulse transmission to and from the Brain
- contains Posterior, Lateral and Anterior Columns
- Anterior Median Fissure
- Posterior Median Sulcus

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Inner region

contains gray matter (non-myelinated neurons)
Note: The outer portion of the Brain contains gray matter while
the white matter is deep
- provides integrative functions
- contains the Anterior and Posterior Horns
- Gray Commissure and Central Canal (filled with CSF)

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Associated Spinal Cord Structures

Posterior (Dorsal) Root
- made up of sensory neurons
- enters into the Posterior Horns
- Dorsal Root Ganglion = contains the cell bodies of the sensory
neurons
Note: Ganglion = a group of neuron cell bodies located outside the
CNS

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Spinal Nerve

combination of Dorsal and Ventral Roots (a mixed nerve) that come
together in the intervertebral foramen

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Anterior (Ventral) Root

made up of motor neurons
exits from the Anterior Horns

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Spinal Cord Physiology

Sensory and Motor Tracts
- located in the Columns of the spinal cord
- Tract = a bundle of nerve axons in the CNS (as opposed to a nerve
which is located outside the CNS

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Lateral and Anterior Spinothalamic Tracts

convey nerve impulses assoc. with pain, temperature change, deep
pressure, etc…

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Posterior Columns

convey nerve impulses assoc. with proprioception (position
sense), discriminitive touch, two point discrimination, light
pressure, vibration

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Reflexes

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Reflex = a fast, involuntary, unplanned sequence of actions that
occur in response to a particular stimulus
Reflex Arc
- the pathway followed by nerve impulses that produce a reflex
- components:

Sensory Receptor

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a structure that responds to a specific stimulus
ex. touch

Sensory Neuron

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carries the nerve impulse to the spinal cord

Integrating Center

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located in the gray matter
(1) Monosynaptic Reflex
simplest type
the sensory neuron synapses directly with the motor
neuron
(2) Polysynaptic Reflex
assoc. with two or more synapses
assoc. with Interneuron (a neuron located in the
spinal cord) involvement

Monosynaptic Reflex

- simplest type - the sensory neuron synapses directly with the motor neuron

Polysynaptic Reflex

assoc. with two or more synapses - assoc. with Interneuron (a neuron located in the spinal cord) involvement

Motor Neuron

- carries the nerve impulse away from the spinal cord

Effector

the body part that responds to the nerve impulse - ex. muscle

Stretch Reflex

causes contraction of skeletal muscle in response to stretching of the muscle

Ipsilateral

the sensory impulse enters the spinal cord on the same side that the motor impulse will leave (a monosynaptic reflex) - ex. a stretch reflex

Reciprocal Innervation

this prevents conflict between opposing muscles - while the agonist contracts the antagonist is inhibited

Tendon Reflex

leads to muscle relaxation when the stretch on tendons may lead to damage

Flexor (Withdrawal) Reflex

assoc. with withdrawal from a negative (painful) stimulus

Intersegmental Reflex Arc

the sensory impulse enters the spinal cord then ascends or descends in the cord

Crossed Extensor Reflex

assoc. with extension of joints on one side of the body while the flexors are contracting in the contralateral muscle

Contralateral Reflex Arc

nerve impulses enter the cord, cross over in the Gray Commissure, then exit on the opposite side of the cord

Spinal Nerves

a mixed nerve formed by a combination of the Ventral and Dorsal Roots

Connective Tissue Coverings

Endoneurium Perineurium Epineurium

Endoneurium

- surrounds individual nerve fibers

Perineurium

surrounds bundles of nerve fibers - Fascicle = bundle of nerve fibers

Epineurium

- surrounds a group of fascicles = Nerve - this layer is continuous with the Dura Mater of the spinal cord

Plexus

- a network of nerves - ventral rami

a. Cervical Plexus

(C1 - C5) - the Phrenic Nerve (C3 - C5) which innervates the Diaphragm

Brachial Plexus (C5 - T1)

supplies innervation to the shoulder and upper limb

Lumbar Plexus (L1 - L4

supplies part of the abdominal walls, external genitalia, and part of the proximal lower limb

Sacral Plexus (L4 - S4)

- supplies innervation to the lower limb - Sciatic Nerve (L4 - S3) = largest nerve in the body which is made up of two separate nerves (Tibial and Common Fibular) Note: Sciatica = inflammation of the Sciatic Nerve

Intercostal Nerves

- ventral rami - innervate the intercostal spaces

Dermatomes

the area of the skin that provides sensory input through one pair of spinal nerves or Cranial nerve 5

Shingles

- an infection caused by the Herpes Zoster virus - this virus also causes Chicken Pox - this virus remains dormant in the Dorsal Root Ganglion - can cause skin eruptions along the infected nerve - lesions are acutely painful

Poliomyelitis = Polio

- caused by the Poliovirus - causes fever, severe headaches and muscle aches, weakness - can cause paralysis - virus can destroy motor neuron cell bodyies in the Anterior Horn - death associated with Respiratory or Heart failure - the virus is often transmitted by fecal-oral contamination(and Yeah it’s just what you think! Well, maybe not the way you think.

Neuritis

- inflammation of one or more nerves - causes pain along the pathway of the involved nerves - ex. Sciatica = neuritis of the Sciatic nerve

Amyotrophic Lateral Sclerosis (ALS)

"Lou Gehrig's Disease" - disease that effect nerve cell bodies in the Anterior Horn and Brain (i.e. motor neurons) - leads to progressive muscle degeneration - person often retains most of their sensory stimulus - often begins in mid-life - a chronic, progressive disease _

Chapter 13 Flashcards

Spinal Cord and Spinal Nerves (52 cards)