lecture 20 - spinal cord & nerves Flashcards
Where does the spinal cord originate?
The foramen magnum, the opening at the base of the skull.
Where does the spinal cord end?
At the inferior border of the 1st lumbar vertebra (L1)
What is the spinal cord contained within?
Sits within meningeal sac within the spinal cavity of the vertebrae.
Where does the meningeal sac extend down to?
The coccyx.
What is the ‘hole’ within a vertebra called?
The vertebral foramen
What is the orientation of a vertebra?
Vertebral body sits posterior, while the spinous process sits anteriorly.
What is the meningeal sac filled with?
Cerebrospinal fluid
What is the end of the spinal cord called?
Conus modularis
What anchors the spinal cord, and how?
The filium terminale - provides fibrous, non-neural anchor that extends to the base of the spinal cavity.
What are the filium terminale?
Fibrous, non-neural tissues that anchors the spinal cord to the base of the spinal cavity.
How many segments does the spinal cord have?
31
How many spinal nerves are associated with each segment of the spinal cord?
2
How are spinal nerves named?
By the vertebra they exit below (except for the cervical vertebra, that are ‘one off’)
How are the nerves of the cervical vertebrae named?
Based on the vertebrae they exit below, plus 1. The first exits between the skull and first cervical vertebra (above it).
Where do spinal nerves exit the spinal cord/vertebral column?
At the vertebral level appropriate to their origin. e.g. nerves originating in lumbar spinal cord exit between lumbar vertebrae.
What is the name for the large collection of long nerves at the inferior end of the spinal cord?
Cauda equina
In the spinal cord, where are bundles of axons found?
The dorsal, ventral and lateral columns
In the spinal cord, where are bundles of cell bodies found?
In the dorsal, lateral and ventral horns
What are the bundles of axons leaving the spinal cord?
Dorsal and ventral nerve roots.
Is the dorsal side of the spinal cord posterior or anterior?
Posterior
Is the ventral side of the spinal cord posterior or anterior?
Anterior
Where do dorsal and ventral nerve roots leave the spinal cord?
Via intervertebral foramen - holes formed between adjacent vertebrae
Where does afferent/sensory information arrive at the spinal cord?
At the dorsal nerve root (containing axons), via the dorsal root ganglion (containing cell bodies)
Where does efferent/motor info leave the spinal cord?
Through ventral nerve roots (containing axons)
Where are somatic efferent motor neurons found in the spinal cord?
Ventral horn
Where are autonomic (sympathetic) neurons found in the spinal cord?
Lateral horn
Where are the cell bodies of sensory neurons entering the spinal cord found?
Dorsal root ganglia.
What are the three branches of a spinal nerve?
dorsal ramus, ventral ramus, rami communicans
What is the information flowing through the dorsal ramus?
Efferent and afferent info to and from the back.
What is the information flowing through the ventral ramus?
Efferent and afferent info too/from the ventral/front side of the body.
What is the information flowing through the rami communicans?
Sympathetic info
What segments of the spinal cord are Rami communicans found in?
T1-L2
What is the structure of the Rami communicans?
Two branches from the spinal nerve come together to form the sympathetic chain ganglion
What connective tissue covers axons?
Endoneurium
What is a bundle of axons called?
A fascicle.
What is the connective tissue that covers peripheral nerve fascicles?
Perineurium
What is the structure of a nerve?
Bundles of fascicles and blood vessels covered by epineurium (connective tissue)
What is the connective tissue that covers nerves?
Epineurium
