Neuro 1: Spinal cord Flashcards
Site of spinal cord
Occupies 2/3 of vertebral canal
Length of spinal cord
45 in males/ 42 in females
Length of vertebral canal
70 cm
Beginning of spinal cord
As continuation of Medulla oblongata at level of foramine magnum/ 1st cervical vertebrae
Ending of spinal cord
As Conus medullaris
Extent of spinal cord depending on age
- 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
Enumerate enlargements of the spinal cord and their site
- Cervical englargement: C5-T1 segments, giving origin to brachial plexus
- Lumbar Enlargement: L1-S3 segments, giving origin to Lumbar and sacral plexuses
6 longitudinal grooves of spinal cord
- Anterior median fissure (deepest)
- Posterior median sulcus
- 2 Anteriolateral sucli
- 2 posterolateral sulci
how many spinal segments are there, and their distribution
total=31
* 8 cervical
* 12 thoracic
* 5 lumbar
* 5 sacral
* 1 coccygeal
how spinal nerves come to be
- 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 **
describe vertebral levels of spinal cord segments in relation to corresponding vertbrae
- 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
The gradual lengthening of Lumbar and sacral Nerves at the end of the spinal cord that descend downwards is called
Cauda equina
Pia mater of spinal cord forms prolongations Outwards for —– and inwards for ——
Sheath around spinal nerve roots, Sheath around blood vessels
Enumerate thickenings of pia mater of spinal cord
- Denticulate ligaments
- Subarachnoid septum
- Linea splendens
- Filum Terminale
Describe denticulate ligaments
- 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
Describe subarachnoid Ligament
Backwards extension of pia mater from posterior median sulcus, attaching to dura mater
Describe linea splendens
Band of Pia mater extending along Anterior median fissure
Describe filum terminale
- 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
Describe clincal importance of Lumbar puncture
- Introduction of needle into subarachnoid space (specifically at Lumbar cistern) below L2 to avoid injury of spinal cord
Enumerate arterial supply of the spinal cord
- Anterior spinal Artery
- 2 posterior spinal Arteries
- Radicular (transverse) spinal Artery
Origin of anterior spinal Artery
Arises by union of 2 anterior spinal arteries, each originating from 4th part vertebral Arteries
Course of anterior spinal Artery
It exits the skull through foramen magnum & descends through anterior median fissure
Anterior spinal artery supplies
Anterior 2/3 of spinal cord:
* Ventral and lateral horns
* Anterior funiculi
* Most of lateral funiculi
Origin of the 2 posterior spinal Arteries
in the skull, from 4th part vertebral Artery or its posterior inferior cerebellar branch
Course of posterior spinal arteries
exits skull through foramen magnum & continues downwards in posterolateral sulcus (along dorsal nerve roots)
Posterior spinal Arteries supply
Posterior 1/3 of spinal cord (dorsal horn +posterior funiculi
Anastomosis between anterior and posterior spinal Arteries occur where ?
Around conus medullaris
Radicular (transverse) spinal Artery origin
- Cervical: vertebral Arteries
- Thoracic: posterior intercostal Arteries
- Lumbar Arteries
- Lateral sacral Arteries
Course of Radicular spinal Artery
enters Vertebral canal through intervertebral foramen and divide into anterior and posteior branches which run along ventral and dorsal spinal nerve roots
End of Radicular spinal Artery
ends by anastomosing with anterior and posterior spinal Arteries
Where does Radiuclar spinal Artery become the main blood supply of the spinal cord
Lower 1/3 of spinal cord
Lumbar enlargement blood supply
Arteria radicularis magna (from second lumbar Artery)
6 longitudinal venous channels of spinal cord
- Anteromedian
- Posteromedian
- Right and left anterolateral
- right and left posterolateral
Venous channels of spinal cord drainage path
Radicular veins, then internal vertebral venous plexus
