Neuroanatomy- Ascending and Descending Tracts Flashcards
How many pairs of spinal nerves are there?
31 pairs
Describe the pathway from spinal cord
Spinal cord –> Rootlets –> Roots –> Pass through subarachnoid space until reach intervertebral foramina –> Posterior root enlarged by dorsal root ganglion –> Roots fuse to form spinal nerve –> Posterior and anterior rami
In the PNS which cells produce myelination?
Swann cells
What is the name of cone-shaped formed by the termination of the spinal cord?
Conus medullaris
What does the conus medullaris continue on as?
Filum terminale which is a thin connective tissue cord anchored to dorsal of coccyx
What are the 3 layers of the meninges?
Dura mater
Arachnoid mater
Pia mater
What is the name of the ribbon of tissue on the lateral aspect of the spinal cord that suspends it in the canal?
Denticulate ligament
Which space in the spinal meninges is filled with CSF?
Subarachnoid space
What does the white matter consist of in the spinal cord?
Longitudinally oriented nerves fibres (axons), glial cells and blood vessels
What does the grey matter consist of in the spinal cord?
Neuronal soma Cell processes Synapses Glia Blood vesselsq
The small central canal in the spinal cord contains what?
CSF
Which ventricle does the small central canal in the spinal cord open into?
The 4th ventricle
What are the three columns in the white matter?
Posterior
2 Lateral
Anterior
What are the four parts that make up the ‘H’ grey matter in the spinal cord?
Left and right posterior horns
Left and right anterior horns
At which spinal levels is there also a lateral horn?
T1- L2
What neurons does the lateral horn contain?
Preganglionic sympathetic neurons
What are the three major longitudinal arteries and what are their origins?
One anterior spinal artery
Two posterior spinal arteries
Originate from the vertebral arteries and run the length of the spinal cord
What are the 3 segmental arteries?
Vertebral artery
Intercostal artery
Lumbar artery
What are the arteries that travel along the dorsal and ventral roots?
Posterior and anterior radicular arteries
What do cervical vertebrae look like?
Rugby ball
The further down the vertebral column the more. white/grey matter?
Grey matter
What are the venous drainage of the spinal cord?
Posterior internal vertebral venous plexus
Anterior internal vertebral venous plexus
What is the name of the space between the dura and bone in the spinal canal?
Epidural space
Where is the primary somatosensory cortex?
On the post-central gyrus
Do sensory fibres cross the midline?
Yes, thus the left side of the body is represented on the right cortex
How does information from periphery reach the somatosensory cortex?
Travel spinal cord (except face and scalp)
Why is there more grey matter in the cervical vertebrae?
Need more grey matter for more sensation in head and neck
What are the two ascending tracts that make up the dorsal column?
Fasciculus gracilis
Fasciculus cuneatus
What information is carried in the dorsal column?
Fine touch and conscious proprioception
Where do fibres cross in the dorsal column?
Fibres cross in medulla
How many neurons are involved in the relay from leg to cortex in sending sensory information in the dorsal column?
3!
Is spinothalamic ascending or descending?
Ascending (sensory)
What information does the spinothalamic tract carry?
Pain, temperature and deep pressue
Where do fibres cross in the spinothalamic tract?
Fibres cross segmentally (immediately)
Where is the primary motor cortex?
Precentral gyrus
Right cortex controls muscles on the right/left side of the body?
Left side of body (contralateral)
Motor information is relayed via the ascending/descending tract?
Descending tract
Give examples of descending tracts?
Corticospinal tract
Tectospinal tract
Reticulospinal tract
Vestibulospinal tract
What does the corticospinal tract divide into?
Lateral and anterior CST
What information does the corticospinal tract carry?
Fine, precise movement. particularly of distal limb muscles (e.g. digits)
What is the corticospinal tract also called and why?
Pyramidal tract because there are ‘pyramids’ on the anterior surface of the medulla.
Which fibres in the CST cross, lateral or anterior?
Lateral
A cerebral vascular accident can result in lack of descending control of corticospinal tract, what clinical impairment occurs?
Spastic paralysis with hyeprflexion of upper limbs
Where do the lateral fibres of CST cross?
Caudal medulla
Where is input mostly from in the tectospinal tract?
Cervical segments
What motor movements do the tectospinal tract mediate?
Reflex head and neck movement due to visual stimuli- tracking function
Is the reticulospinal tract ascending or descending?
Descending (motor)
Where do fibres originate in the reticulospinal tract?
Pons and medulla
What movements do fibres originating in the pons facilitate in the reticulospinal tract?
Extensor movement and inhibit flexor movements
How do movements in the reticulospinal tract originating in the medulla differ from the pons?
Facilitate and inhibit opposite movements
Is the vestibulospinal tract ascending or descending?
Descending motor
What information is carried in the vestibulospinal tract?
Excitatory input to “antigravity” extensor muscles
Falling forwards and counteracting it
Where do fibres originate in the vestibulospinal tract?
Vestibular nuclei of pons and medulla
What clinical symptoms do patients exhibit in vestibulospinal tract abnormalities?
Decerebrate rigidity
Paraplegia in extension
