Neuro 1: Spinal cord

Question 1

Site of spinal cord

Answer 1

Occupies 2/3 of vertebral canal

Question 2

Length of spinal cord

Answer 2

45 in males/ 42 in females

Question 3

Length of vertebral canal

Answer 3

70 cm

Question 4

Beginning of spinal cord

Answer 4

As continuation of Medulla oblongata at level of foramine magnum/ 1st cervical vertebrae

Question 5

Ending of spinal cord

Answer 5

As Conus medullaris

Question 6

Extent of spinal cord depending on age

Answer 6

• 3rd month of intrauterine life: occupies all vertebral canal
• At birth: ends at level of L3 vertebrae
• Adult: ends at level of intervertebral disc between L1 & L2

Question 7

Enumerate enlargements of the spinal cord and their site

Answer 7

• Cervical englargement: C5-T1 segments, giving origin to brachial plexus
• Lumbar Enlargement: L1-S3 segments, giving origin to Lumbar and sacral plexuses

Question 8

6 longitudinal grooves of spinal cord

Answer 8

• Anterior median fissure (deepest)
• Posterior median sulcus
• 2 Anteriolateral sucli
• 2 posterolateral sulci

Question 9

how many spinal segments are there, and their distribution

Answer 9

total=31
* 8 cervical
* 12 thoracic
* 5 lumbar
* 5 sacral
* 1 coccygeal

Question 10

how spinal nerves come to be

Answer 10

• at the corresponding intervertebral foramen, Ventral root and dorsal root unite together forming Spinal Nerve trunk
• Spinal Nerve trunk is very short, and divides immediately after exiting Intervertbral foramen, into anterior and posterior rami
• Cervical spinal nerves emerge Above corresponding vertbrae, Thoracic spinal nerves and below emerge **below corresponding segment **

Question 11

describe vertebral levels of spinal cord segments in relation to corresponding vertbrae

Answer 11

• Spinal cord segments are present higher than their corresponding vertebrae, forming 1(cervical),2(upper thoracic),3(lower toracic) rule: with T11 opposite L2 to L5, and T12-L1 are opposite all sacral segments

Question 12

The gradual lengthening of Lumbar and sacral Nerves at the end of the spinal cord that descend downwards is called

Answer 12

Cauda equina

Question 13

Pia mater of spinal cord forms prolongations Outwards for —– and inwards for ——

Answer 13

Sheath around spinal nerve roots, Sheath around blood vessels

Question 14

Enumerate thickenings of pia mater of spinal cord

Answer 14

• Denticulate ligaments
• Subarachnoid septum
• Linea splendens
• Filum Terminale

Question 15

Describe denticulate ligaments

Answer 15

• It extends laterally from pia matter, pierces Arachnoid mater and anchors in Dura mater
• Each ligament extends midway between Ventral and dorsal roots, from foramen magnum level to L1 vertbrae level
• lateral edge of ligament is Serrated

Question 16

Describe subarachnoid Ligament

Answer 16

Backwards extension of pia mater from posterior median sulcus, attaching to dura mater

Question 17

Describe linea splendens

Answer 17

Band of Pia mater extending along Anterior median fissure

Question 18

Describe filum terminale

Answer 18

• fibrous band of Pia mater extending from conus medullaris among cauda equina roots
• At S2 verbrae level it pierces Arachnoid and dura mater, and acquires dural investment to attach to periosteum of coccyx bone

Question 19

Describe clincal importance of Lumbar puncture

Answer 19

• Introduction of needle into subarachnoid space (specifically at Lumbar cistern) below L2 to avoid injury of spinal cord

Question 20

Enumerate arterial supply of the spinal cord

Answer 20

• Anterior spinal Artery
• 2 posterior spinal Arteries
• Radicular (transverse) spinal Artery

Question 21

Origin of anterior spinal Artery

Answer 21

Arises by union of 2 anterior spinal arteries, each originating from 4th part vertebral Arteries

Question 22

Course of anterior spinal Artery

Answer 22

It exits the skull through foramen magnum & descends through anterior median fissure

Question 23

Anterior spinal artery supplies

Answer 23

Anterior 2/3 of spinal cord:
* Ventral and lateral horns
* Anterior funiculi
* Most of lateral funiculi

Question 24

Origin of the 2 posterior spinal Arteries

Answer 24

in the skull, from 4th part vertebral Artery or its posterior inferior cerebellar branch

Question 25

Course of posterior spinal arteries

Answer 25

exits skull through foramen magnum & continues downwards in posterolateral sulcus (along dorsal nerve roots)

Question 26

Posterior spinal Arteries supply

Answer 26

Posterior 1/3 of spinal cord (dorsal horn +posterior funiculi

Question 27

Anastomosis between anterior and posterior spinal Arteries occur where ?

Answer 27

Around conus medullaris

Question 28

Radicular (transverse) spinal Artery origin

Answer 28

* Cervical: vertebral Arteries * Thoracic: posterior intercostal Arteries * Lumbar Arteries * Lateral sacral Arteries

Question 29

Course of Radicular spinal Artery

Answer 29

enters Vertebral canal through intervertebral foramen and divide into anterior and posteior branches which run along ventral and dorsal spinal nerve roots

Question 30

End of Radicular spinal Artery

Answer 30

ends by anastomosing with anterior and posterior spinal Arteries

Question 31

Where does Radiuclar spinal Artery become the main blood supply of the spinal cord

Answer 31

Lower 1/3 of spinal cord

Question 32

Lumbar enlargement blood supply

Answer 32

Arteria radicularis magna (from second lumbar Artery)

Question 33

6 longitudinal venous channels of spinal cord

Answer 33

* Anteromedian * Posteromedian * Right and left anterolateral * right and left posterolateral

Question 34

Venous channels of spinal cord drainage path

Answer 34

Radicular veins, then internal vertebral venous plexus