Anatomy & Function of Spinal Cord & Spinal Nerves Flashcards
Where does the spinal cord start?
At the foramen magnum
What is 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 vertebrae so it doesn’t go down the whole spine
What is the spinal cord within?
A sac of meninges which fits inside the spinal cavity
What is the spinal cavity within?
The vertebrae
Where does the meningeal sac extend to?
The coccygeal vertebrae
What is found on the ventral side of the vertebrae?
The body
What is found on the dorsal side of the vertebrae?
The spinous process
What is the meningeal sac filled with?
Cerebrospinal fluid (CSF)
What is at the end of the spinal cord?
A tapered cone called the conus medularis
What is the conus medularis made of?
Non-neural tissue
What extends from the conus medularis to the end of the spinal cavity?
Filium terminale
What is the function of the filium terminale?
To anchor the spinal cord and prevent the spinal cord moving around
What is the filium terminale made of?
Fibrous, non-neural tissue
How many segments of spinal nerves are there?
31
How many cervical spinal nerves are there?
8 pairs
How many thoracic spinal nerves are there?
12 pairs
How many lumbar spinal nerves are there?
5 pairs
How many sacral spinal nerves are there?
5 pairs
How many coccygeal spinal nerves are there?
1 pair
What are nerves named by?
The vertebrae they exit below
What is the exception to the nerves exiting below the vertebrae they are named after?
The first cervical spine nerve exits between the skull and the first cervical vertebrae because there are 8 cervical nerves but only 7 cervical vertebrae
Where do spinal nerves exit?
At the level appropriate to their origin
What is the space between the ends of the spinal cord and meningeal sac filled with?
Nerves
What is the collection of nerves between the end of the spinal cord and meningeal sac?
Cauda equina
What is found in the surface of the spinal cord?
Indentations called sulcus
Where is the posterior median sulcus?
In the middle at the back of the spinal cord
What are deep indentations the spinal cord called?
Fissures
Where is the anterior median fissure?
In the middle at the front of the spinal cord
Where is the grey matter (cell bodies) in the spinal cord?
They form a butterfly like shape in the middle of the spinal cord
Where is the white matter (axons) in the spinal cord?
Surrounding the grey matter towards the outside of the spinal cord
Where is the central canal found?
Running through the centre of the spinal cord
Where are dorsal column axons found?
Between the two dorsal horns
Where are lateral column axons found?
Between the dorsal and ventral horns
Where are the ventral column axons found?
Between the two ventral horns
Where is the dorsal horn?
The dorsal part of the grey matter of the spinal cord
Where is the lateral horn?
The small bulge in the grey matter of the spinal cord
Where is the ventral horn?
The ventral part of the grey matter of the spinal cord
What comes out of the dorsal horn?
The dorsal nerve root (axons)
What is part of the dorsal nerve root?
Dorsal root ganglion (cell bodies)
What comes out of the ventral horn?
The ventral nerve root (axons)
What forms the spinal nerve?
The ventral and dorsal nerve roots coming together
Where does information come into the spinal cord?
The dorsal part (from the dorsal nerve root)
What information comes into the spinal cord from the PNS?
Sensory (afferent)
Where does information leave the spinal cord?
The ventral part (from the ventral nerve root)
What information leaves the spinal cord to the PNS?
Motor (efferent)
What information is carried by the spinal nerve?
Both efferent information out of the spinal cord and afferent information into the spinal cord
Where are autonomic neurons (cell bodies) found?
In the lateral horn of the grey matter in the spinal cord
Where are somatic motor neurons (cell bodies) found?
In the ventral horn of the grey matter of the spinal cord
What would happen if there was damage to the cell body in the ventral horn?
There would be no command sent to the skeletal muscle
What happens if there is damage to the efferent cell bodies?
Paralysis of muscles supplied by somatic motor neurons from this spinal cord segment on the same side only
Where are the cell bodies of sensory neurons?
In the dorsal root ganglion
What type of neurons are sensory neurons in the dorsal root ganglion?
Unipolar and splits into an input and output zone
What does the input zone of sensory neurons do?
Associates with receptors for sensory stimulus from the PNS
What does the output zone of sensory neurons do?
Enter the spinal cord through the dorsal roots
What happens if there is damage to the sensory neuron at the roots end point?
sensory information wouldn’t be received
What happens if there is damage to the afferent cell bodies?
Loss of sensation from regions of the body supplied by sensory neurons from this spinal cord segment on the same side only. Movement can still occur however
Why must the spinal nerve split?
So that information can get everywhere it needs to
What does the dorsal ramus (branch) do?
Carry efferent information to the back form the CNS and afferent information from the back to the CNS
What does the ventral ramus (branch) do?
Carry efferent information to the ventral body and afferent information from the ventral body
Wat is rami communicans?
Carry sympathetic information and are only present at T1 to L2 vertebrae
What are axons covered with?
Endoneurium
What do endometrium-covered axons bundle together to form?
Fascicle
What are fascicles covered with?
Perineurium
What do fascicles bundle together with?
Blood vessels
What do fascicles and blood vessels bundles together form?
Nerves
What are nerves covered by?
Epineurium
What are bundles of axons in the CNS called?
A tract
