Spinal Cord and Spinal Nerves Flashcards
Describe the size and location of the spinal cord
- Slender nerve column
- About 45 cm long
- Starts at foramen magnum & ends between L1 & L2 (does not go into the sacrum)
- 31 pair spinal nerves
does the spinal cord have bilateral symmetry?
yes
What are the two types of matter found in the spinal cord?
gray and white matter
What is the central canal? What does it contain?
Hole down the center of cord; continuous with brain ventricles; both contain CSF
There are two grooves in the spinal cord.. what are they?
Anterior median fissure
Posterior median sulcus
What are enlargements?
Swollen regions of the spinal cord
What are two regions for enlargement?
Cervical enlargement
Lumbar enlargement
What is the Conus Medullaris ?
inferior-most tip of spinal cord; cone shaped
What is the Cauda Equina ?
means horse’s tail; bundle of nerves inferior to spinal cord
What is the Filum terminale ?
inferior most spinal nerve
Describe Gray Matter
Cell bodies, dendrites & synapses Projections called horns Cell bodies organized into nuclei -Sensory -Motor
What are the three interior horns of the gray matter?
Posterior gray horn
Anterior gray horn
Lateral gray horn
What are the two Gray commissures? What separates them?
Anterior Commissure and Posterior Commissure
Separated by the central canal
White matter is made up of ______ and ________
tracts and columns
What are the three columns in white matter?
Posterior White column
Anterior white column
Lateral white column
What are the two tracts in white matter? What are they responsible for?
Ascending= sensory Descending= motor
What are meninges? Are they similar in both the spinal cord and brain? explain
Membranes covering CNS
Are similar in both brain and spinal cord
Meninges are split into layers called what?
Mater (meaning mother)
vertebrae consist of what?
vertebral arches
What is the epidural space? What does it contain?
- Space between meninges and vertebra
- Contains BV and adipose
Meninges connect to ______ covering of __________
Connective Tissue; spinal nerves
describe the Dura Mater
- “tough mother”
- Durable
- Deep to epidural space
- Superficial to subdural space
- Stabilized by coccygeal ligament
describe the Arachnoid Mater
- “spidery mother”
- Superficial to subarachnoid space
- Contains CSF
- CT looks like a spider web
describe the Pia Mater
- “delicate mother”
- Light layer adhering to cord
- Forms part of filum terminale
from superficial to deep, name the parts of the spinal meninges (8)
Vertebra Epidural space Dura mater Subdural space Arachnoid mater Subarachnoid space (with CSF) Pia mater Neural tissue
How many pairs of spinal nerves are there?
31
Where are all the spinal nerves located? How many in each location?
8 cervical 12 thoracic 5 lumbar 5 sacral 1 coccygeal
for the nerve components you have the _____ and _____ root. Describe them
Doral and Ventral Root
Dorsal (posterior) root
- dorsal root ganglion
- soma
- usually sensory
Ventral (anterior) root
- No ganglion
- Usually motor
______ merge to form _______. Hence _____ nerves are usually mixed (_____ and ______)
Roots, Nerves, Spinal nerves, sensory, motor
All roots go through…..
intervertebral foramina
What are the three Connective tissue coverings and describe them
Epineurium-surrounds the entire nerve
Perineurium-Surrounds bundles of 10-100 axons (known as fascicles)
Endoneurium-Surrounds each individual axon of each neuron
What are Rami?
offshoots of a nerve once it exits the vertebra
What are the three types of Rami?
Dorsal ramus
Ventral ramus
Ramus communicantes
What is a rami communicantes?
A spitting in the ramus separating sensory and motor fiber
What are the two types of Rami Communicantes?
White ramus communicantes
Gray ramus communicantes
What are Dermatomes?
Sensory innervation by specific spinal nerves
Dermatomes are used as a….
detection method
______ damage will result in loss of sensation in _______
Spinal cord, dermatome
What are Nerve Plexuses?
braid off ventral rami
Nerve Plexuses are found in several regions… what are they?
Cervical
Lumbar
Sacral
(Most thoracic nerves are all isolated)
describe the cervical plexus
C1-C4 & part of C5 Innervate certain muscles of neck and torso phrenic nerve C3, 4 & 5 go to diaphragm
describe the brachial plexus
C4-C8 & T1
Innervate the chest, upper back, and arm
Slide 25
fun fact: im drunk and typing these so enjoy :)
lumbosacral plexus is located where? It may be split into what?
Last thoracic, lumbar, sacral & coccygeal nerves
May be split into lumbar and sacral plexuses
the lumbosacral plexus intervates the …..
lower limb regions
What are the three lower limb nerves and describe them
obturator nerve: to adductors of leg
femoral nerve: motor impulses to leg & thigh & receive sensory from skin of leg & thigh
sciatic nerve: to muscles & skin in thighs, legs & feet
What are reflexes?
Rapid automatic involuntary motor response to stimuli
reflexes help preserve…..
homeostasis
where do reflexes occur?
spinal cord or brain stem
do reflexes require cerebral processing?
no
reflexes can be modified by…
cerebral control
What are the 4 ways reflexes are classified?
By development
Site of processing
Nature of motor response
Complexity of neural circuit
What are the two types of site of processing classification? describe them
Spinal reflex: impulse only goes to the spinal cord
Cranial reflex: Makes it to the brain
What are the two types of motor response classification? describe them
Somatic: influences the skeletal muscle system
Visceral (autonomic): influences the involuntary systems such as smooth muscle and glands
Slide 31-32
fun fact: im drunk off 5 different types of tequila :)
What are step 1-5 of the reflex arc?
Step 1: The receptor is stimulated by a detectible environmental stimulus
Step 2: The receptor stimulates a sensory neuron that sends a signal to the CNS for processing
Step 3: The information is processed by being transmitted to the appropriate neurons (This could be an interneuron or motor neuron)
Step 4-5: A motor neuron is stimulated, sending a signal to an effector. This results in behavior
What is a stretch reflex?
A reflex stimulated by the stretching of a muscle
______________________are receptors that detect stretching
Muscle spindle fibers
_____________is the contraction of the muscle
The effector
The patellar reflex is a ________
stretch reflex.
the patellar reflex functions to… (2 things)
Prevent muscles from being overstretched
Prevent one from falling forward
