Neuroanatomy 2: Spinal Cord and Ascending and Descending Pathways Flashcards
Where does the spinal cord end?
L1/L2
What are the two enlargements of the spinal cord?
Cervical (UL)
Lumbar (LL)
What are the terms used to describe a group of cell bodies outside the CNS vs. inside the CNS?
Ganglion
Nucleus
What is the pathway taken by each segment of the spinal cord?
Rootlets —> Roots —> Subarachnoid space —> Intervertebral foramina —> Roots fuse to form mixed spinal nerve –> Ramii
Posterior root is enlarged by…
Dorsal root ganglion
Where does the spinal cord terminate? What does it continue as?
Conus medullaris
Thin CT cord = Filum terminale
Which foramen allows spinal and cranial meninges to be continuous with each other?
Foramen magnum
The spinal cord is suspended in the spinal canal by what ligament? What is it formed from?
Denticulate ligament
Pial and arachnoid tissue
What are the 3 components of white matter in the spinal cord?
Posterior, lateral and anterior fasciculi
What are the 5 components of grey matter in the spinal cord?
Left and right posterior and anterior horns (arms of ‘H’)
Dorsal and ventral grey commisures (join of ‘H’) which surround central canal
What is the arterial supply of the spinal cord and what do they originate from?
Vertebral arteries —> 1 anterior and 2 posterior longitudinal arteries
Vertebral, intercostal, lumbar arteries —> Segmental arteries
Various spinal arteries —> Radicular arteries
Where do radicular arteries travel?
Along dorsal and ventral roots
What is the venous drainage of the spinal cord?
Similar to supply - longitudinal and segmental veins
In the spinal canal, what is the space between dura and bone known as? What is it composed of?
Epidural space
Adipose tissue and venous plexuses
Information from the periphery reaches the cortex in the spinal cord. What parts of the body are an exception to this?
Face and scalp
The ascending spinal cord tract is sensory/motor, whereas the descending is sensory/motor
Sensory
Motor
What is the role of the dorsal column/ medial lemniscus system?
SENSORY: Fine touch, vibration and conscious proprioception (mostly upper limb)
Where do the fibres from the medial lemniscus system originate, cross and synapse to reach the cortex?
Medial lemniscus!
Medulla
VPL nucleus of thalamus
What is the role of the spinothalamic tract? Where is it located on the spinal cord?
SENSORY: Carries pain, temperature and deep pressure
Anterior (split into ventral and lateral)
Where do the fibres from the spinothalamic tract originate, cross and synapse to reach the cortex?
Spinal lemniscus (Medulla)
Segmentally in spinal cord
Thalamus
What is the role of the corticospinal/pyramidal tract?
MOTOR: fine, precise movement especially of distal limb muscles, for example digits
Where do the fibres from the CST start and end?
Where do the fibres from the corticospinal tract cross?
Cortex and spinal cord (lumbar region)
Medulla at decussation of pyramids (why it is also referred to as pyramidal tract)
NOT ALL OF THEM!
The crossed fibres of the CST form what part of the CST? Where is this part of the tract located on the spinal cord?
Lateral Laterally (between dorsal horns and ventral body)
The uncrossed fibres of the CST form what part of the CST? Where is this part of the tract located on the spinal cord?
Ventral (cross segmentally in spinal cord)
Anteriorly in the midline
Which spinal tract is involved in decorticate posturing?
Corticospinal tract (FLEXOR - ARMS LIKE C)
What is the motor system outside the pyramidal tract known as? What tracts is it composed of?
Extrapyramidal system
Tectospinal, reticulospinal, vestibulospinal tracts
What is the role of the tectospinal tract?
Input to cervical segments - mediate reflex head and neck movement due to visual stimuli e.g. following a moving bus with your eyes
What is the role of the reticulospinal tract?
Forms central core of brainstem - receives input from all parts of CNS and influences voluntary movement, breathing and heart rate
Where do fibres from the reticulospinal tract originate from?
Reticular formations in the pons and medulla
Pons - extensor movement, inhibits flexor
Medulla - flexor movement, inhibits extensor
What is the role of the vestibulospinal tract?
Excitory input to ‘antigravity’ extensor muscles e.g. stabilise yourself if falling (LATERAL)
Control head movement via neck and back muscles (MEDIAL)
Where do fibres from the vestibulospinal tract originate from and where do they receive inputs from?
Vestibular nuclei (lateral (Deiters nucleus) and medial) of pons and medulla CNIII from vestibular labyrinths and cerebellum
Which spinal tract is involved in decerebrate posturing?
Vestibulospinal tract (EXTENSOR - ARMS LIKE E)
Where does the TST start and end?
Optic tectum or superior colliculus (roof of midbrain) and spinal cord (cervical region)
Where does the TST recieve inputs from?
Retina, visual cortex and afferents
Where does the lateral and medial VST terminate, respectively?
Lumbar spinal cord
Cervical spinal cord
Where do axons of the TST deccusate?
Dorsal tegmental decussation in the brainstem
What is the function of the rubrospinal tract, and where do the fibres originate?
Extra-pyramidal tract that excites flexors and inhibitis extensors of UL
Red nucleus in midbrain
What is the function of the spinocerebellar tract?
SENSORY
Transmits unconscious proprioceptive information for posture and movement
The DCML pathway divided into what two divisions after synapsing? How are these differentiated on the spinal cord?
> T6: Nucleus cuneatus (lateral between dorsal horns)
< T6: Nucleus gracillus (medial between dorsal horns)
Outline the somatotopic layout of the corticopsinal tract, in terms of anatomical location controlled, at the spinal cord
Medial = UL Lateral = LL
Label the parts of a cross-section of the spinal cord
GOOGLE IMAGES
