Neuroanatomy 2: Spinal Cord and Ascending and Descending Pathways

Question 1

Where does the spinal cord end?

Answer 1

L1/L2

Question 2

What are the two enlargements of the spinal cord?

Answer 2

Cervical (UL)

Lumbar (LL)

Question 3

What are the terms used to describe a group of cell bodies outside the CNS vs. inside the CNS?

Answer 3

Ganglion

Nucleus

Question 4

What is the pathway taken by each segment of the spinal cord?

Answer 4

Rootlets —> Roots —> Subarachnoid space —> Intervertebral foramina —> Roots fuse to form mixed spinal nerve –> Ramii

Question 5

Posterior root is enlarged by…

Answer 5

Dorsal root ganglion

Question 6

Where does the spinal cord terminate? What does it continue as?

Answer 6

Conus medullaris

Thin CT cord = Filum terminale

Question 7

Which foramen allows spinal and cranial meninges to be continuous with each other?

Answer 7

Foramen magnum

Question 8

The spinal cord is suspended in the spinal canal by what ligament? What is it formed from?

Answer 8

Denticulate ligament

Pial and arachnoid tissue

Question 9

What are the 3 components of white matter in the spinal cord?

Answer 9

Posterior, lateral and anterior fasciculi

Question 10

What are the 5 components of grey matter in the spinal cord?

Answer 10

Left and right posterior and anterior horns (arms of ‘H’)

Dorsal and ventral grey commisures (join of ‘H’) which surround central canal

Question 11

What is the arterial supply of the spinal cord and what do they originate from?

Answer 11

Vertebral arteries —> 1 anterior and 2 posterior longitudinal arteries

Vertebral, intercostal, lumbar arteries —> Segmental arteries

Various spinal arteries —> Radicular arteries

Question 12

Where do radicular arteries travel?

Answer 12

Along dorsal and ventral roots

Question 13

What is the venous drainage of the spinal cord?

Answer 13

Similar to supply - longitudinal and segmental veins

Question 14

In the spinal canal, what is the space between dura and bone known as? What is it composed of?

Answer 14

Epidural space

Adipose tissue and venous plexuses

Question 15

Information from the periphery reaches the cortex in the spinal cord. What parts of the body are an exception to this?

Answer 15

Face and scalp

Question 16

The ascending spinal cord tract is sensory/motor, whereas the descending is sensory/motor

Answer 16

Sensory

Motor

Question 17

What is the role of the dorsal column/ medial lemniscus system?

Answer 17

SENSORY: Fine touch, vibration and conscious proprioception (mostly upper limb)

Question 18

Where do the fibres from the medial lemniscus system originate, cross and synapse to reach the cortex?

Answer 18

Medial lemniscus!
Medulla
VPL nucleus of thalamus

Question 19

What is the role of the spinothalamic tract? Where is it located on the spinal cord?

Answer 19

SENSORY: Carries pain, temperature and deep pressure

Anterior (split into ventral and lateral)

Question 20

Where do the fibres from the spinothalamic tract originate, cross and synapse to reach the cortex?

Answer 20

Spinal lemniscus (Medulla)
Segmentally in spinal cord
Thalamus

Question 21

What is the role of the corticospinal/pyramidal tract?

Answer 21

MOTOR: fine, precise movement especially of distal limb muscles, for example digits

Question 22

Where do the fibres from the CST start and end?

Where do the fibres from the corticospinal tract cross?

Answer 22

Cortex and spinal cord (lumbar region)
Medulla at decussation of pyramids (why it is also referred to as pyramidal tract)
NOT ALL OF THEM!

Question 23

The crossed fibres of the CST form what part of the CST? Where is this part of the tract located on the spinal cord?

Answer 23

Lateral
Laterally (between dorsal horns and ventral body)

Question 24

The uncrossed fibres of the CST form what part of the CST? Where is this part of the tract located on the spinal cord?

Answer 24

Ventral (cross segmentally in spinal cord)

Anteriorly in the midline

Question 25

Which spinal tract is involved in decorticate posturing?

Answer 25

Corticospinal tract (FLEXOR - ARMS LIKE C)

Question 26

What is the motor system outside the pyramidal tract known as? What tracts is it composed of?

Answer 26

Extrapyramidal system | Tectospinal, reticulospinal, vestibulospinal tracts

Question 27

What is the role of the tectospinal tract?

Answer 27

Input to cervical segments - mediate reflex head and neck movement due to visual stimuli e.g. following a moving bus with your eyes

Question 28

What is the role of the reticulospinal tract?

Answer 28

Forms central core of brainstem - receives input from all parts of CNS and influences voluntary movement, breathing and heart rate

Question 29

Where do fibres from the reticulospinal tract originate from?

Answer 29

Reticular formations in the pons and medulla Pons - extensor movement, inhibits flexor Medulla - flexor movement, inhibits extensor

Question 30

What is the role of the vestibulospinal tract?

Answer 30

Excitory input to 'antigravity' extensor muscles e.g. stabilise yourself if falling (LATERAL) Control head movement via neck and back muscles (MEDIAL)

Question 31

Where do fibres from the vestibulospinal tract originate from and where do they receive inputs from?

Answer 31

``` Vestibular nuclei (lateral (Deiters nucleus) and medial) of pons and medulla CNIII from vestibular labyrinths and cerebellum ```

Question 32

Which spinal tract is involved in decerebrate posturing?

Answer 32

Vestibulospinal tract (EXTENSOR - ARMS LIKE E)

Question 33

Where does the TST start and end?

Answer 33

Optic tectum or superior colliculus (roof of midbrain) and spinal cord (cervical region)

Question 34

Where does the TST recieve inputs from?

Answer 34

Retina, visual cortex and afferents

Question 35

Where does the lateral and medial VST terminate, respectively?

Answer 35

Lumbar spinal cord | Cervical spinal cord

Question 36

Where do axons of the TST deccusate?

Answer 36

Dorsal tegmental decussation in the brainstem

Question 37

What is the function of the rubrospinal tract, and where do the fibres originate?

Answer 37

Extra-pyramidal tract that excites flexors and inhibitis extensors of UL Red nucleus in midbrain

Question 38

What is the function of the spinocerebellar tract?

Answer 38

SENSORY | Transmits unconscious proprioceptive information for posture and movement

Question 39

The DCML pathway divided into what two divisions after synapsing? How are these differentiated on the spinal cord?

Answer 39

>T6: Nucleus cuneatus (lateral between dorsal horns) | < T6: Nucleus gracillus (medial between dorsal horns)

Question 40

Outline the somatotopic layout of the corticopsinal tract, in terms of anatomical location controlled, at the spinal cord

Answer 40

``` Medial = UL Lateral = LL ```

Question 41

Label the parts of a cross-section of the spinal cord

Answer 41

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