Lecture 7: The Spinal Cord

Question 1

What are the meninges and spaces from close to the spinal cord to out, and special structures made from these layers

Answer 1

1. Pia mater
2. Sub arachnoid space: contains CSF
3. Arachnoid mater
4. Subdural space
5. Dural mater
6. Epidural space: Fat

• Filum terminale is derived from pia mater
• Denticulate ligament connects pia to dura to support spinal cord within the vertebral column.

Question 2

Where does the spinal cord start and end

Answer 2

1. Starts at occipital bone
2. Passes through foramen magnum into spinal canal at beginning of cervical vertebrae
3. Spinal cord proper finishes between L1 & 2 in conus medullaris
4. Spinal nerves continue travelling below the conus medullaris through vertebral column as the cauda equina
5. From L1- S2 Filum terminale internum continues within the dura mater
6. S2- coccyx filum terminale externum continues and anchors spinal cord.

Question 3

What are the major differences between cervical, thoracic and lumbar spinal cord segments regarding white and grey matter

Answer 3

There is greater grey matter in cervical and lumbar segments because it is controlling more muscles of the upper and lower limbs. Thoracic has fewer neurons exiting at each level but covers a large surface area so has more sensory info coming in- more white matter.

Cervical also has 1 more neuron than vertebrae because it has C1 exiting above the vertebrae.

Question 4

Where is sensory information received (dorsal to ventral) in the gray matter of the spinal cord and what type of info is it

Answer 4

Dorsal horn:
Pain info: 1-2,
pain modulation from the brain: 2

Temperature and touch: 3-4

Spinal reflexes (interneurons that integrate info): 5-6

Question 5

Where is motor information transmitted in the gray matter of the spinal cord (dorsal to ventral) and what type of info is it

Answer 5

Ventral Horn:

Reticulospinal and Vestibulospinal inputs (modulation of motor output to muscles)= 8

Skeletal muscle conscious control=9

Question 6

Where is autonomic system information transmitted in the gray matter of the spinal cord and what type of info is it

Answer 6

Lateral Gray horn (T1-L2)

Intermediolateral nucleus controls smooth muscle as part of the symp ns.

Question 7

Where is proprioception information transmitted in the gray matter of the spinal cord and what type of info is it

Answer 7

Lateral Gray horn (T1-L2)
Dorsal Nucleus of Clark in the intermediate grey horn.
Helps relay info about muscle position in space to the cerebellum

Question 8

What white matter tracts are in the Dorsal funiculus and what information is it related to

Answer 8

Dorsal Column pathway: sensory information

Lower body info in the medial Gracile fasciculus and Upper body info in the Cuneate fasciculus

Question 9

What white matter tracts are in the Lateral funiculus and what information is it related to

Answer 9

Dorsal and Ventral Spinocerebellar tract on the lateral edge: proprioceptive info to the cerebellum

Lateral spinothalamic tract: pain and temperature info to the brain

Corticospinal tract (dorsomedial) brings info down from the cortex to synapse in the ventral horn at right level for motor function. Has arm, trunk and leg area.

Question 10

What white matter tracts are in the Ventral funiculus and what information is it related to

Answer 10

Anterior Spinothalamic tract: crude touch info to the brain

Question 11

What are the 3 types of fibres that are dorsal root afferents, what info do they carry and where

Answer 11

1. unmyelinated C fibres: pain to Lam 1-3
2. finely myelinated A delta fibres: temp or pain to Lam 2-3
3. heavily Myelinated A fibres:
   a) Dorsal column pathway directly up
   b) touch to lam 3-4
   c) proprioception to DNC
   d) stretch reflex to Lam 9

Question 12

What are the 3 types of ventral root efferents, what do they innervate and where do they come from

Answer 12

1. Alpha motor neurons (LMN/pyramidal cell from corticospinal tract) innervate striated muscle leave medial ventral horn if axial, lateral if distal. Dorsal if flexor, ventral if extensor.
2. Gamma motor neurons innervate muscle spindles to relax them after sending proprioceptive info (feedback)
3. Sympathetic (T1-L2) preganglionic neurons innveting SM and autonomic ganglia in the intermediolateral nucleus

Question 13

What info does the dorsolateral tract of lissaeuer carry

Answer 13

DToL: Tract allowing dorsal root afferents to go through to synapse with rexed’s laminae (grey matter)

Question 14

What are the 3 types of intrinsic connections in the spinal cord segment, what info does it carry and give eg of path

Answer 14

1. Spinal interneurons: after synapsing with outside info this neuron just communicates with another lamina within the same side- eg. pain reflex
2. Intrasegmental commissural neurons: coordinate response that involves both sides of the body by going across both sides of same segment. EG. Ventral white commissure
3. Intersegmental neurons: coordinate between different levels of spinal cord through Propriospinal tract

Question 15

What are 2 extrinsic connections that leave the spinal cord and what is their route

Answer 15

1. Anterior spinothalamic:
   a) sensory information is received at lam 3-4
   b) travels through VWC to synpase with Anterior spinothalamic tract to thalamus
2. Dorsal spinocerebellar
   a) After synapsing with a nerve in the DNC proprioceptive info sent to
   b) dorsal spinocerebellar tract to cerebellum

Question 16

What is the arterial supply to the spinal cord segment and spinal roots

Answer 16

One Anterior spinal artery derived from vertebral arteries which supplies everything except for the dorsal funiculus which is supplied by 1 post spinal artery each side.

Spinal branch of local artery splits into ant and pos radicular arteries to supply the ventral and dorsal roots.

Question 17

What is the veinous drainage of the spinal cord segment and spinal roots

Answer 17

One ant and one post spinal vein drains half of the segment on both sides.

Ant and post radicular veins drain dorsal and ventral roots