Spinal cord anatomical overview Flashcards
how many cervical segments of spine?
8
how many lumbar and sacral segments of spine?
5 each
Extenging from each section of the spine are:
8 ??? cervical spinal nerves, 12 pairs of thoracic spinal nerves, 5 pairs of lumber spinal nerves and 5 pairs of sacral spinal nerves
Pais of
TRUE or FALSE: Spinal nerves C1-C7 exit above their corresponding vertebral body, however from C8 spinal nerve onwards the spinal nerves exit below their corresponding vertebra
TRUE
The spinal cord ends at about vertebral level L1/2 as a cone shape called ???
conus medullari
In infants, the spinal cord reaches full adult length before the ???
vertebral canal
At what fetal stage do the vertebral canal and the spinal cord grow at the same rate? After this the body and the verterbral canal grow at a faster rate than the cord. At the time of birth the spinal cord ends at the third lumbar vertebrae.
third month
The spinal cord has 2 enlargements known as :
- ???
- Lumber
Cervical
Why does the spinal cord have 2 enlargements?
because extra neurons are needed at these levels to allow for innervation of the upper and lower limbs.
A dermatome is a ??? and an area they receive sensory innervation from
pair of spinal nerves
What kind of information do dorsal roots carry, motor or sensory?
sensory
Dermatomes often overlap so that injury to an individual dorsal root does not lead to ???
complete loss of sensation in the relevant skin region
TRUE or FALSE: the overlap of dermatomes is less extensive for touch pressure and vibration than for pain and temperature.
FALSE: more extensive for touch and pressure
Why does testing for pain sensation provide a more accurate assessment of a segmental nerve injury than testing for responses to touch, pressure or vibration?
because the overlap of dermatomes is more extensive for touch and pressure
If 1 dorsal root is cut, the corresponding dermatome on that side of the body does not lose all sensation. WHY?
The residual somatic sensation exists perhaps because the adjacent dorsal roots innervate overlapping areas
How many dorsal roots must be cut to lose all sensation in one dermatome?
3 dorsal roots
The dura mater surrounding the spinal cord consists of only a single layer. This is the ??? layer
meningeal layer. It has no periosteal layer, only the brain does
The epidural space is a space between the meningeal dura and the vertebrae created by the lack of a ??? - it is filled with fat and vessels
The lack of a periosteal dural layer creates a ‘space’ between the meningeal dura and the vertebrae.
The spinal ??? provides an avenue to inject anaesthesia into this area to anaesthetise the nerve roots,i.e. epidural anaesthesia
epidural space
??? is one of the subarachnoid cisterns
lumber cistern
What is is an enlarged region of the subarachnoid space that sits below the conus medullaris and contains the floating cauda equina?
the lumber cistern
The lumber cistern and epidural space are between different layers. The epidural space runs along the full length of the cord and sits between the dura mater and the ???
vertebrae.
Why is the lumber cistern not found at higher levels of the spinal cord?
because it sits below the conus medullaris between the pia mater and arachnoid mater in subarachnoid space
The lumber cistern is present below the conus medullaris which corresponds to the vertebral levels ???
L2/3
lumber cistern can be used as a diagnostic test for ??? without risk of damaging spinal tissue because ???
meningitis
because no spinal cord is present at this level, only cauda equina floating in the CSF
lumber cistern can be used for imaging i.e a myelogram which is ??? This allows visualisation of cord integrity and identification of injury, cysts, impinging discs or other structural anomalies.
is an X-ray that is taken of the spine after a dye has been injected into the CSF which would then travel around the subarachnoid space around the cord.
Anesthesia can be injected into this space.
lumber cistern
The spinal cord is anchored to the ??? bone by meningeal extensions called the Film Terminale
coccyx
the filum terminale is made of two parts. part 1 is the ??? and is an extension of pia mater from the bottom of the cord that attached to a piece of dura mater called the filum terminale externum.
filum terminale interum
The filum terminale externum OR interum (?) is made up of dura mater and attached to the coccyx bone
externum
which type of matter is primarily made up of axons? white or grey?
white
the dorsal or ventral horn of grey matter consists of cell bodies that process sensory information
dorsal horn of grey matter
which type of matter is primarily made up of cell bodies of interneurons and some efferent neurons, white or grey?
Grey matter
The ventral horn of grey matter contains cell bodies that contain motor or sensory information?
motor information
Extending from the dorsal horn is the ??? which carries ??? information from the periphery into the spinal cord.
dorsal root
carries sensory info
at which spinal levels does grey matter also contain a lateral hornm holding pre-ganglionic sympathetic cell bodies?
At the spinal levels of T1-L2
Extending from the ventral horn is the ??? which carries ??? information to muscles and glands
ventral root, carrying motor information
what combines to make the psinal nerve, protruding from the grey matter?
dorsal and ventral roots of the dorsal and ventral horns of grey matter
Motor neurons in the ventral horn are organised in a ???
somatotopic organisation
Somatotopic organisation:
- Motor neurons controlling more proximal/axial musculature are located more ??? in the ventral horn
- Motor neurons controlling more distal musculature are located more ??? in the ventral horn
medially
laterally
The white matter is divided into zones called Funiculi & ???
Fasciculi
Dorsal or Posterior Funiculus (Dorsal columns) has two smaller subdivisions, the ??? and Cuneate fasciculus
Gracile
the Gracile or Cuneate fasciculus (?) carries sensory information regarding lower limbs and is present at EVERY level of the cord
Gracile fasciculus
Which fasciculus, gracile or cuneate, carries sensory information regarding upper limbs and is present ONLY at cervical and upper thoracic levels.
cuneate fasciculus
Apart from the gracile and cuneate fasciculi, what other white matter areas are there?
Lateral Funiculus (Lateral columns)
Ventral or Anterior Funiculus (Ventral columns)
TRUE or FALSE: The size of funiculi change with the level of the cord
TRUE. Cervical cord has large funiculi which get progressively smaller as you descend the cord.
Why does the cervical region of the spinal cord have the largest amount of white matter?
Because the funiculi carry axons that travel up the cord = everything entering at sacral and lumber levels has to pass through cervical level to reach the brain. Likewise everything traveling down to the lumber/sacral levels has to travel through the cervical level to reach these lower levels.
??? funiculus carries both motor and sensory tracts:
- Motor tracts: corticospinal and rubrospinal tracts
- Sensory tracts: spinothalamic & spinocerebellar tracts
Lateral funiculus
??? funiculus carries both motor and sensory tracts:
- Motor: Anterior corticospinal, reticulospinal, vestibulospinal and tectospinal tracts
- Sensory tract: Spinothalamic tract
Ventral (anterior)
These are characteristics for which part of spinal cord?
- Presence of ??? enlargement
- Large amount of white matter
- Separation of dorsal funiculus into gracile and cuneate fascuculi
Cervical
These are characteristics for which part of spinal cord?
- Small amount of grey matter
- Upper shows separation of dorsal funiculus into gracile + cuneate. Mid-lower shows gracile only.
- Presence of lateral horn (containing pre-ganglionic sympathetic neurons)
Thoracic
These are characteristics for which part of spinal cord?
- Large dorsal and ventral horns
- No separation of the dorsal column, only gracile fasciculus is present at this level.
Lumbar
These are characteristics for which part of spinal cord?
- No separation of dorsal funiculus
- Little white matter
- Contains pre-ganglionic parasympathetic neurons
Sacral
Blood supply to the spinal cord is largely from how many arteries?
3 arteries
1 x anterior spinal artery supplies the anterior ??? of the cord (including the ventral horns, ventral and lateral funiculus)
2 x posterior spinal arteries which supply the posterior ??? of the cord (including the dorsal horn and dorsal funiculus)
2/3
1/3
