Ascending and Descending Pathways

Question 1

What is the name given to the end of the spinal cord situated at L1/2?

Answer 1

Conus medullaris

Question 2

What connects the spinal cord to the dura?

Answer 2

Denticulate ligament

Question 3

What is present in the white matter?

Answer 3

Longitudinally oriented axons, glial cells and blood vessels

Question 4

What is present in the grey matter?

Answer 4

Neuronal soma
Cell process
Synapses
Glia
Blood vessels

Question 5

What is an extra addition to the grey matter at T1-L2?

Answer 5

Lateral horn containing the preganglionic sympathetic neurones

Question 6

What is the arterial supply to the spinal cord?

Answer 6

3 major longitudinal arteries
Segmental arteries
Radicular arteries

Question 7

What is the origin of the major longitudinal arteries supplying the spinal cord?

Answer 7

Vertebral arteries

Question 8

What is the origin of the segmental arteries supplying the spinal cord?

Answer 8

Vertebral
Intercostal
Lumbar arteries

Question 9

What is the venous drainage of the spinal cord?

Answer 9

Longitudinal and segmental veins

Question 10

What do the radicular arteries supply?

Answer 10

The dorsal and ventral roots

Question 11

What is the epidural space?

Answer 11

Space between the dura and bone which contains adipose tissue and the anterior and posterior epidural venous plexuses

Question 12

Where is the primary somatosensory cortex and the sensory cortical homunculus?

Answer 12

Post central gyrus

Question 13

What does the dorsal column/medial lemniscus system detect?

Answer 13

Fine touch

Proprioception

Question 14

Where do fibres from the dorsal column decussate?

Answer 14

Medulla

Question 15

Describe the dorsal column

Answer 15

Fibres enter dorsal root ganglion where they will project into dorsal column
Ascend to the medulla where they will synapse at the nucleus gracilis/cuneatus
Decussate after synapse and ascend to the thalamus via the medial lemniscus
Synapse in thalamus and ascend to the postcentral gyrus at the somatosensory cortex

Question 16

What does the spinothalamic tract detect?

Answer 16

Pain
Temperature
Deep pressure

Question 17

Describe the spinothalamic tract

Answer 17

Nervce cell bodies in dorsal root ganglion
Enter spinal cord and synapse in the posterior horn in tract cells
Decussate and ascend up the spinal cord on the contralateral side
Synapse in thalamus
Ascend to the postcentral gyrus of at the somatosensory cortex

Question 18

Where is the primary motor cortex found?

Answer 18

Precentral gyrus

Question 19

What is the main motor tract?

Answer 19

Descending corticospinal tract which is divided into the lateral and ventral tracts

Question 20

What movements will the corticospinal tract control?

Answer 20

Fine, precise movements particularly of distal limb

Question 21

Where will the corticospinal tract decussate?

Answer 21

85% at the caudal medulla called the decussation of the pyramids

Question 22

What will crossed fibres of the corticospinal tract form?

Answer 22

Lateral CST

Question 23

What will uncrossed fibres form?

Answer 23

Ventral CST

Question 24

What will the motor fibres pass through whilst in the brain from the motor cortex to the thalamus?

Answer 24

Internal capsule

Question 25

Where are the pyramids of the medulla found?

Answer 25

Anterior surface of medulla

Question 26

What can a CVA of the internal capsule result in?

Answer 26

Lack of descending control of the corticospinal tract resulting in spastic paralysis with hyperflexion of upper limbs Decortical posturing

Question 27

What is the tectospinal tract?

Answer 27

Input to cervical segments | Mediates reflex head and neck movement due to visual stimuli

Question 28

Where is the tectum found?

Answer 28

Posterior area of midbrain

Question 29

Where does the reticulospinal tract originate?

Answer 29

Areas of reticular formation in pons and medulla

Question 30

What is the function of the reticular system?

Answer 30

Integrate cranial nerve reflexes Participate in conduction and modulation of pain Influence voluntary movement Regulate autonomic activity Integrate basic functions like respiration and sleep Activate the cerebral cortex

Question 31

What is the vestibulospinal tract?

Answer 31

Excitatory input to antigravity extensor muscles

Question 32

Where do the vestibulospinal fibres originate?

Answer 32

Medial and lateral vestibular nuclei in the pons

Question 33

From where do the medial and lateral vestibular nuclei receive input?

Answer 33

Vestibular apparatus and cerebellum

Question 34

Describe decerebrate rigidity

Answer 34

Vestibulospinal tract; lesions of the brainstem at level of midbrain can result in a lack of descending cortical control of this tract resulting in domination of extensor muscle tone and hyperextended spastic paralysis