Neuroamatomy 3 Flashcards
External anatomy of spinal cord
- starts at forum magnum (opening at base of skull - where transmission betweeen brain and spinal cord takes place)
- ends at inferior boarder of 1st lumbar vertebra (L1)
- spinal cord is within a sac made of meninges that fits inside the spinal cavity
- spinal cavity within vertebrae extends all the way to coccygeal vertebrae (Called the minigeal sac)
- vertebrae - (Dorsal side = spinous process), (ventral side = body)
Nen-neural structures associated with the spinal cord ( how its protected)
- spinal cord extends within a meningeal sac - filled with cerebrospinal fluid (CSF) - fluid acts as a gel cousin
- end is a tapered cone called the conus modularis
- a cone of non-neuronal tissue
- help stabilise spinal cord
- attatchment for filum terminale
- Filium terminal (attaches) extends from conus medularis to end of spinal cavity
- anchors the spinal cord
- fibrous, non-neural tissue
(Look at slide diagram)
Spinal nerves number of segments
- the spinal cord has 31 segments
Spinal nerves: end points EXCEPTION
- spinal cords are names by the vertebra the exit below
ONE EXECPTION:
- the forst vertical spinal nerve exits between the skull and the first cervical vertebra (above the first nerve)
- there are 8 spinal nerves (but only 7 cervical vertebrae)
Where so spinal nerves exist the vertebral column?
- at the appropriate level to their column
- nerves originating in lumbar spinal cord exit between lumbar vertebrae
- large collection of long nerves inferior to end of spinal cord = Cauda Equina (horses tail)
Spinal cord is _______________
One long continuous structure
- one segment has a pair of spinal cords - dorsal and ventral side
Internal anatomy of the spinal cord
(Refer to lecture diagram)
Label:
- posterior - dorsal - median sulcus
- white matter (axons)
- dorsal columns
- ventral columns
- lateral columns
- grey matter (cell bodies) - kinda shape of butterfly
- dorsal horn
- ventral horn
- lateral horn
- central canal
- anterior - ventral median fissure - deeper
Internal anatomy of the PNS of the spinal cord
- Dorsal nerve roots (axons)
- Ventral nerve roots
- dorsal root ganglion (cell bodies
- spinal nerve
LABEL THEM
Organisation and flow of information in the spinal cord
Dorsal - afferent - sensory
- dorsal root ganglion and dorsal nerve root bringing AP in from PNS to CNS
Ventral - efferent - motor
- ventral nerve room sending AP out from CNS TO PNS outgoing information.
Type of efferent neurons - flow of efferent information - put of the spinal cord
Efferent lower motor neurons which have their cell body in the spinal cord send their axon out into the body to make a synapse - somatic efferent motor neurons
Autonomic neurons who have their cell bodies in the spinal cord have their cell bodies in the lateral horn
- extend axons out through ventral nerve roots
What would happen if there was damage to a ventral horn?
- neuron would die
- no cell to.carry outgoing information
- paralysis of muscles supplied by somatic motor neurons from this spinal cord segment, on same side only
Flow into 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
What happend if there is damage in the spinal cord in this postiton?
- loss of sensation from regions of the body supplied by sensory neurons from this spinal card segment only, on same side only
What do spinal nerves do
- carry information into and out of the spinal cord (both efferent and afferent
dorsal nerve roots - only carry AFFERENT information
Ventral nerve roots - only carry EFFERENT information
What happens to the spinal cords once they leave the spinal cord
- spinal nerve splits into two bracches - dorsal ramus and ventral ramus and rami communicans
Dorsal ramus:
- efferent to back
- afferent from back muscles etc
Ventral ramus
- efferent to ventral body
- afferent to ventral body
/
Rami communications
- sympathetic
- only at T1-L2
(sympathetic nervous system is only present in thotic lumbar level from T1 down to L1 is where the cell bodies are - they send a short axon out to sympathetic chain ganglion on either side of vaterbral coloumn )
Structure of a peripheral nerve
DRAW DIAGRAM FROM SLIDES
- individual axons may be myelinated or unmyelinated
- axons are covered with endoneurium
- endoneurium-covered axons are bundled together to form a fassicle
- fascicles are covered with perineurium
- fascicles bundle with each other and with blood vessels to form a nerve
- nerves are covered by epineurium
Flow of efferent information out of the spinal cord diagram
