Spinal Cord and Spinal Nerves Flashcards
Where does the spinal cord begin
as the medulla oblongata exits the foramen magnum
Where does the spinal cord terminate
between L1 and L2 as the concus medullars
What is the filum terminale
an extension of the pia mater of the CNS that arises from the concus medullaris and anchors the spinal cord to the coccyx
What are the cervical and lumbar enlargements and what do they do
enlargement of the spinal cord in the in the cervical and lumbar regions that accommodates nerves from the upper and lower limbs respectively
What is the cauda equina
horse tail
nerves that remain in the vertebral canal in fine strands after the conus medullaris
What are the 3 meninges of the CNS
- Dura mater
- Arachnoid mater
- Pia mater
Where is the epidural space and what is its fxn
space between the vertebral canal and the dura mater
-provides a cushion of fat and connective tissue for the spinal cord
Where is the subdural space
space between the dura and arachnoid mater
it is filled w/ CSF
Where is the subarachnoid space
between the arachnoid mater and the pia mater
it is filled w/CSF
Which of the meninges contains blood vessels that supply O2 and nutrients to the spinal cord
Pia mater
What is the grey commissure of the spinal cord
forms the crossbar of the H like structure of the spinal cord grey matter
What area of the spinal cord is associated w/ the somatic motor neurons
the anterior grey horns
What area of the spinal cord is associated w/ the somatic and autonomic sensory neurons
the posterior grey horns
`What area of the spinal cord is associated w/ the autonomic motor neurons
the lateral grey horns, only present in T1-L2 and S2-S4 of the spinal cord
True or False the central canal extends from the 4th ventricle down the entire length of the spine
True
What is the role of grey matter in the spine
it receives and integrates incoming and outgoing messages
Name the 3 areas of white matter in the spinal cord
- Anterior columns
- Lateral columns
- Posterior columns
What is another name for sensory tracts
ascending
What is another name for motor tracts
descending
What are the 2 bundles of axons that connect each spinal nerve to a segment of the cord
The posterior root and the anterior root
How many spinal nerves are there
31 pairs ie 62 total
8 pair cervical 12 thoracic 5 lumbar 5 sacral 1 coccygeal
Define the intervertebral formaina
the opening between the adjoining vertebrae
How are spinal nerves named
Spinal nerve names correlate with the region and level when they exit from the vertebral column not the where they emerge from the spinal column
What causes the observed offset of the spinal nerve names with their exit from in between vertebrae
Spinal cord stops growing at ~age 4-5 but vertebral column continues to grow
Where does the first cervical pair of spinal nerves emerge
Between the occipital bone of the skull and the atlas (C1)
Do the cervical spinal nerves emerge inferiorly or superiorly of the vertebrae with the same number and why is this odd
superiorly
all the other spinal nerves exit inferiorly to the vertebrae with the same
What happens to the spinal nerve once it emerges from the vertebral column
it almost immediately divides into the dorsal primary ramus and ventral primary ramus
What do posterior (dorsal) rami innervate
deep muscles and skin of the dorsal trunk
What do anterior(ventral) rami innervate
muscles of the upper and lower limbs and the skin of the lateral and ventral surfaces of the trunk
Where does the meningeal branch of the spinal nerve go after dividing off
It reenters the vertebral canal to supply the vertebrae
What are plexuses
networks of axons that form from the anterior rami of adjacent spinal nerves they contain both motor and sensory neurons
What are the principle plexuses of the body
- Cervical plexus
- Brachial plexus
- Lumbar plexus
- Sacral plexus
- Coccygeal plexus
Why isn’t there a thoracic plexus
because the thoracic spinal nerves go directly to the body structures they supply and do not form a networks of axons
What is another name for the anterior rami of thoracic spinal nerves (T2-T12)
Intercostal nerves
What areas of the body does the cervical plexuses supply
The diaphragm and the skin and muscles of the head, neck, superior of the shoulders and chest
What are the phrenic nerves
nerves that arise from c3,4 and 5 an enter cervical plexuses that supply the motor fibers of the diaphragm
What happens if the spinal cord is severed above C5
breathing stops because the phrenic nerves can no longer send impulses to the diaphragm
What areas of the body does the brachial plexuses supply
the shoulders and upper limbs
What are the subunits of the brachial plexus
Root/ramus, Trunk, Division, Cord, Branch
Mnemonic= Read The Damn Cadaver Book
What are the radial nerves
nerve that arises from the brachial plexuses and supplies the muscles of the posterior aspect of the arm and forearm
What does radial nerve injury result in and how can it happen
- results in wrist drop
- caused by improper IM injection to deltoid or a cast being too tight around the mid-humerus
What areas of the body does the lumbar plexuses supply
the anterolateral abdominal wall, external genitals, and part of the lower limbs
What areas of the body does the sacral plexuses supply
the buttocks, perineum, and lower limbs
What are the sciatic nerves
largest nerve in the body, that emerges from the sacral plexus
True or False the sciatic nerve is actually 2 nerves
True, they are bound by a common sheath
What is sciatica
pain that extends down the buttock to the foot that can result from a herniated disc, dislocated hip, OA, pregnancy, or improper IM injection in the gluteal muscles
