Introduction to the Spinal Cord and Spinal Nerves Flashcards
What is the spinal cord?
Provides a vital link between the brain and the rest of the body. Exhibits some functional independence from the brain (reflexes)
What are two important functions of the spinal cord and its attached spinal nerves?
Pathway for sensory and motor impulses
Responsible for reflexes
Where does the spinal cord develop from?
Ectoderm (neuroectoderm/neuroepithelium) as neural plate
What forms after a neural plate? As that formation progresses, what is eventually formed after?
Neural groove and as formation progresses, a neural tube is eventually formed.
What cells become part of the peripheral nervous system?
Neural crest cells
Is dorsal horn sensory or motor?
Sensory
Is ventral horn sensory or motor?
Motor
What do neural crest cells become
Become everything from structures in the head and neck to dorsal root ganglion. Responsible for pigmentation
They migrate down and become structures of the heart (valves)
Where will central processes from the developing dorsal root ganglia grow into?
The spinal cord into the dorsal horn
Where will peripheral processes grow?
Grow into the body and connect with structures so that they can receive somato, sensory and visceral sensory impulses that would travel back to the dorsal horn
What does the ventral horn develop?
Develops the motor cell bodies that will send peripheral processes for motor impulses
Anything happening dorsally has to do with _______
Afferent (effect)
Anything happening ventrally has to do with ________
Efferent (response)
What is cervical enlargement?
Thicker area of the spinal cord that a lot of spinal nerves come out of that form the brachial plexuses and the cervical plexuses
What does the lumbar enlargement provide?
Lumbar and sacral plexuses
How many pairs of spinal nerves are there in the spinal cord?
31
When does the spinal cord end?
Lower thoracic, upper lumbar region and the rest is the cauda equina
What does a long nerve represent?
Lots of cells with single peripheral processes growing out
Are posterior rootlets sensory or motor?
Sensory because posterior is back therefore dorsal and dorsal is sensory
At what age are the 2 enlargements visible on the CNS?
At 3 months old
What is well distinguished by 3 months old?
Spinal cord portion of CNS well distinguished from brain and brainstem regions
How many regions can the spinal cord be divided into?
4 regions that have associated structures and functions Cervical Thoracic Lumbar Sacral
What is the function of cervical plexus?
Innervates things in the neck
What is the function of brachial plexus?
Innervates superficial back muscles, pectoral muscles and upper limb
What does the thoracic region of the spinal cord house?
Houses the sympathetic outflow for the body and intercostal nerves
What are intercostal nerves?
Special spinal nerves that go directly in between ribs. Some of them come down to the lateral portions of the lower torso
What does the Lumbar region house?
Small portion of the sympathetic outflow and the lumbosacral enlargement
What does the cervical region house?
The cervical enlargement
What does the Sacral region house?
Little portion of the parasympathetic outflow. Most of the PS outflow comes from cranial nerves. This region takes care of the bladder, reproductive organs, etc.
What are the three major meningeal coverings of the spinal cord?
Dura mater: tough outer covering
Arachnoid mater: Production of spinal fluid, webby translucent and intimately connected to dura mater
Pia Mater: right up against the neural tissue of the spinal cord and the white matter sections.
What are the two important structures of Pia mater? Describe them
Denticulate ligaments: little structures that are lateral projections of pia mater that attach to the inside of dura mater and help anchor the spinal cord. Tooth like structures. Visible between the dorsal and ventral rootlets
Filum terminalis: inferior projections of pia mater directly of the tip of the spinal cord into the sacral canal. Helps to anchor the spinal cord to the coccyx
What are the three spaces between the menigeal layers of the spinal cord?
Subdural, subarachnoid, and epidural space
Where is the epidural space? Describe
Between the vertibral bone and the spinal cord dura mater. There is fat in the epidural space and this is where the numbing agent goes
Where is the subarachnoid space?
Between the arachnoid and pia mater.Contains cerebrospinal fluid
Where is the subdural space?
Between dura mater and arachnoid mater
What is a process?
Noun-structure that comes off of something
What are the processes of the spinal cord?
Anterior rootlets, posterior rootlets, and spinal nerve
What is the order of the processes?
Rootlets converge on roots and roots converge on spinal nerves
What modalities do spinal cord roots have?
either mortar or sensory
What modalities do spinal nerves have?
All modalities
What root is the spinal ganglion?
Posterior root
What is sensory dorsal root ganglion?
Cluster of neuron cell bodies that are outside the CNS
What are the divisions of the spinal nerve? Describe
anterior rami- some spinal nerves have grey and white communicantes. Relatively large and make up the spinal nerve plexus in the body or intercostal nerves. Hypaxial innervation
Posterior rami - Small and are limited to the region they provide innervation to. Occipital region to sacral region on the back. Does Epaxial innervation
Where is epaxial innervation?
Poserior/dorsal rami
Where is hypaxial innervation?
Anterior/ventral rami
What is filum terminale?
Extension of the pia mater
What is the spinal column
The back bone
What is the spinal cord?
Cylindrical bundle of nerve fibers and associated tissues that is enclosed in the spine
What part of the nervous system are spinal nerves considered to be part of?
PNS
What is the function of spinal nerves?
provide a direct link between the CNS and organ systems in the body. Carry both sensory and motor impulses
How many pairs of spinal nerves are in the cervical, thoracic, lumbar, sacral and coccyx vertebral regions?
C=8 T=12 L=5 S=5 Co=1
What are the two structural divisions of the nervous system?
CNS and PNS
