Human Movement and Sensation Flashcards
Where does the spinal cord start and end?
Start: Foramen magnum (the opening at the base of the skull)
End: Inferior border of the 1st lumbar vertebra (L1)
Where is the spinal cord located?
Within a sac, made of meninges, that fits inside the spinal cavity. The spinal cavity is within the vertabra. The spinal cavity within vertebrae extends all the way to the coccygeal vertebrae.
What does dorsal and ventral mean?
Indicates what side of the spine we are talking about.
Dorsal: the back (posterior) of the vertebrae where a dorsal fin like structure extends out of.
Ventral: front (anterior) of the vertebrae. Is much rounder.
What are the non-neural structures associated with the spinal cord?
- Extends within a meningeal sac filled with cerebrospinal fluid (CSF)
- The end of the spinal cord forms a tapered cone called conus medularis. It is non-neural tissue, and is the attachment point for the filum terminale
- Fulum terminale extends from conus medularis to end of spinal cavity. It anchors the spinal cord and is made of fibrous, non-neural tissue.
How many segments does the spinal cord have? Break them down.
The spinal cord has 31 segments. One pair of spinal nerves associated with each segment.
- Cervical spine nerves: 8 pairs.
- Thoracic spine nerves: 12 pairs.
- Lumbar spine nerves: 5 pairs.
- Sacral spine nerves: 5 pairs.
- Coccygeal spine nerves: 1 pair
Describe the spinal nerve exit points
Spinal nerves are named by the spinal vertebrae they exit below.
- Cervical spinal nerves are the ONLY exception to this rule because there is an extra one. This first cervical nerve (C1) exits between the skull and the first cervical vertebra. Therefore each other cervical nerve is named after the vertebra it exits above.
Describe the spinal nerve exit points
- Spinal nerves exit at the level appropriate to their origin (eg. lumbar nerves exit between lumbar vertebrae)
- The spinal cord ends at the bottom of L1, therefore there is a long collection of nerves inferior to the spinal cord. These are called Cauda Equina (‘horses tail’)
The spinal cord is one long continuous structure. What is one section called?
A segment, which is defined as having one pair of spinal nerves coming out of it.
Describe the internal anatomy of the spinal cord in terms of the CNS (can refer to notes for visual)
- White matter (axons) - around the outside
- Grey mater (cell bodies) - on the inside
- Central canal
- Lateral horn (cell bodies)
- Lateral column (axons)
Dorsal: - Posterior (dorsal) median sulcus
- Dorsal horn (cell bodies)
- Dorsal column (axons)
Ventral: - Anterior (ventral) median fissure
- Ventral horn (cell bodies)
- Ventral column (axons)
What is a sulcus and a fissure?
Sulcus: Latin for furrow
Fissure: a deep sulcus
Describe the anatomy of the spinal cord in regards to the PNS (can refer to notes for a visual)
- Spinal nerve
Dorsal: - Dorsal nerve root
- Dorsal root ganglion (cell bodies)
Ventral: - Ventral nerve root (axons)
Describe the organisation and flow of information in the spinal cord
- Dorsal side controls sensory (afferent)
- Ventral side controls motor (efferent)
So information comes in from the PNS to the CNS via dorsal root ganglion and dorsal nerve root.
And information goes out of the CNS to the PNS through the ventral nerve root.
Describe the flow of information out of the spinal cord
- Somatic motor neuron cell bodies.
- Efferent motor information leaves through ventral roots.
- The motor commands go to effectors in the body
What would happen if there was damage to the ventral horn?
Paralysis of muscles supplied by somatic motor neurons from this spinal cord segment, on same side only
Describe the flow of afferent information into the spinal cord
- Cell bodies of sensory neurons are in dorsal root ganglion
- Input zone in body associates with receptors for sensory stimulus.
- Output zone enters the spinal cord through dorsal roots
- Stimulus
- Info comes in through the dorsal root ganglion (which are unipolar) and then the dorsal root nerve
