Chapter 13 Flashcards
What is ALS?
Amyotrophic Lateral Sclerosis (ALS)
- 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
What is Neuritis?
inflammation of one or more nerves
- causes pain along the pathway of the involved nerves
Ex: Sciatica = neuritis of the Sciatic nerve
What is 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
- the virus is often transmitted by fecal-oral contamination
What are 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
What are Dermatomes?
the area of the skin that provides sensory input through one pair of spinal nerves or Cranial nerve 5
What are Intercostal Nerves?
ventral rami
- innervate the intercostal spaces
What are Plexus?
ventral rami
a network of nerves
What is the branch? (Branch= ramus)
the spinal nerves divide into branches after leaving the Intervertebral Foramen
The Dorsal Ramus innervates what?
innervates deep muscles and skin of the dorsal trunk
What does the Ventral Ramus innervate?
innervates limb muscles, and skin of the extremities and the remaining trunk
What does the Meningeal Branch innervate?
It reenters the spinal cord to supply innervation to spinal cord structures
What does the Rami Communicantes innervate?
Autonomic Nervous System innervation
What is an Endoneurium?
A connective tissue covering that surrounds individual nerve fibers
What is a Perineurium?
A connective tissue covering that surrounds bundles of nerve fibers
What is a Fascicle?
bundle of nerve fibers
What is the Epineurium?
a connective tissue covering that surrounds a group of fascicles = Nerve
this layer is continuous with the Dura Mater of the spinal cord
What is the Contralateral Reflex Arc?
nerve impulses enter the cord, cross over in the Gray Commissure, then exit on the opposite side of the cord
contra= opposite side
What is the Intersegmental Reflex Arc?
the sensory impulse enters the spinal cord then ascends or descends in the cord
What is Reciprocal Innervation?
this prevents conflict between opposing muscles
while the agonist contracts the antagonist is inhibited
What is an Ipsilateral Reflex?
the sensory impulse enters the spinal cord on the same side that the motor impulse will leave (a monosynaptic reflex)
Ex: a stretch reflex
Ipsi= same side
What is an Effector?
the body part that responds to the nerve impulse
Ex: muscle
What does a Motor Neuron do?
carries the nerve impulse away from the spinal cord
What is a Polysynaptic Reflex?
assoc. with two or more synapses
- assoc. with Interneuron (a neuron located in the spinal cord) involvement
What is a Monosynaptic Reflex?
simplest type of reflex
- the sensory neuron synapses directly with the motor neuron
What does a Sensory Neuron do?
carries the nerve impulse to the spinal cord
Where is the Integrating Center located?
located in the gray matter
What is a Sensory Receptor?
a structure that responds to a specific stimulus
Ex: touch
What is a Reflex Arc?
the pathway followed by nerve impulses that produce a reflex
has many different components
What is a Reflex?
a fast, involuntary, unplanned sequence of actions that occur in response to a particular stimulus
* an unlearned response*
What is a Spinal Nerve?
combination of Dorsal and Ventral Roots (a mixed nerve) that come together in the intervertebral foramen
What are Anterior (Ventral) Roots?
made up of motor neurons
- exits from the Anterior Horns
What are Posterior (Dorsal) Roots?
made up of sensory neurons
- enters into the Posterior Horns
What is a Dorsal Root Ganglion?
contains the cell bodies of the sensory neurons
Note: Ganglion = a group of neuron cell bodies located outside the CNS
What is Sciatica?
inflammation of the Sciatic Nerve
- pain may follow the nerve all the way down the foot
The Sacral Plexus (L4 - S4) supplies innervation where?
supplies innervation to the lower limb
What is the Sciatic Nerve (L4 - S3)?
it’s the largest nerve in the body which is made up of two separate nerves (Tibial and Common Fibular)
The Lumbar Plexus (L1 - L4) supplies what parts of the body?
supplies part of the abdominal walls, external genitalia, and part of the proximal lower limb
The Brachial Plexus (C5 - T1) supplies innervation where?
supplies innervation to the shoulder and upper limb
The Cervical Plexus (C1 - C5) houses what nerve? What does that nerve innervate?
the Phrenic Nerve (C3 - C5) which innervates the Diaphragm
kill the phrenic nerve and you cannot breathe on your own
What is the Cauda Equina?
contains the nerves that leave the spinal cord then run inferiorly to exit from lower Intervertebral foramen
What is the Outer region?
- is mostly white matter (myelinated fibers) providing nerve impulse transmission to and from the Brain
- contains Posterior, Lateral and Anterior Columns (ALL WHITE MATTER)
- Anterior Median Fissure (ANTERIOR= VENTRAL)
- Posterior Median Sulcus (POSTERIOR= DORSAL)
What is the Inner region?
- contains gray matter (non-myelinated neurons)
- provides integrative functions
- contains the Anterior and Posterior Horns
- Gray Commissure and Central Canal (filled with CSF)
Note: The outer portion of the Brain contains gray matter while the white matter is deep
What are Filum Terminale?
a fibrous band of Pia that extends from the Conus Medullaris to the Coccyx
anchors the spinal cord
What is the Conus Medullaris?
the end of the spinal cord
-located between L1 and L2 vertebrae
What is the Lumbar Enlargement?
supplies nerves to the lower extremities
located between T9 and T12 vertebrae
What is the Cervical Enlargement?
supplies nerves to the upper extremities
-located between C4 and T1 vertebrae
What are Denticulate ligaments?
thickened Pia Mater that project laterally to fuse with the Dura Mater, these act as a shock absorber
What is the Subarachnoid Space?
lies outside of the Pia, contains Cerebral Spinal Fluid (CSF)
What is Pia Mater?
Innermost layer that covers the surface of the Brain and Spinal Cord
What is the Subdural Space?
lies outside of the arachnoid mater, contains interstitial fluid (lymph)
- in the middle layer (arachnoid mater)
What is the Arachnoid Mater?
The middle layer of connective tissue that surrounds the brain and spinal cord
What is the Epidural Space?
lies outside the Dura that is filled with fat and other connective tissues
What is the Dura Mater?
outer most layer
- anchors the meninges with in the spinal canal
What are the Meninges?
three connective tissue coverings that surround the Brain and Spinal Cord
How many spinal cord nerves branch off the spinal cord?
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)
Where does the spinal cord extend from?
extends from Foramen Magnum to the level of the disk between L1/L2 vertebrae
What’s the function of the spinal cord?
provides nervous pathways for nerve impulses between the Peripheral Nervous System and the Brain
& provides simple integrative functions (reflexes)
