Spinal Cord Flashcards
Embryological development spinal cord
Neural plate forms on overlying ectoderm and closes = neural tube (NCC above)
Closure sites = ant (—> encephalon) and post (—> spinal cord) neuropore.
The tube closed by 4th week
- Basal lamina→ ant horn
- Alar lamina→ post horn
- Marginal layer→ white matter (axons)
NCC migrates towards spinal cord —> dorsal root ganglia.
Rachischisis cause
Neural tube doesn’t close
Rachischisis consequences
Whole spinal cord is exposed to amniotic fluid
Meningomyelocele cause
Differentiated nervous tissue and body of vertebrae, but no lamina posteriorly = no protection for post part
Meningomyelocele consequences
Spinal cord & meningeal sac protrude out of spinal canal
Meningocele cause
No lamina but spinal cord remains in the canal
Meningocele consequences
Only the meninges + CSF protrude out of spinal canal
Spina bifida occulta
Manifests as a tuft of hair. Can be asymptomatic
Spinal cord finishes at level
L1-L2
Spinal cord contains
The meninges, CSF, nerve roots and vessels
Filum terminale externum - definition
Extension of dural sac from where it ends (lumbar cisternae) till coccyx (also called “coccygeal ligament”).
Filum terminale externum - function
It keeps the dural sac in place within the vertebrae.
Denticulate ligaments - function
They hold spinal cord in place within spinal canal
Denticulate ligaments - definition
Alternating extensions of pia mater that anchor the cord to the arachnoid mater.
Filum terminale internum - definition
Extension of pia mater beyond conus medullaris that keeps spinal cord in place in rostral-caudal way
Neurons in gray matter are classified into
Rexed laminae (I-X)
Laminae I - VI
Sensory neurons
Laminae VII - IX
Motor neurons
Laminae X
Surrounds central medullary canal and
contains ants white commissure & its fibres
White matter is divided into
Posterior funiculus
Lateral funiculus
Anterior funiculus
Fascículos proprius
Posterolateral sulcus
Small sulcus that separates post funiculus from lat funiculus.
Where the sensory roots enter post horn (DREZ: “dorsal root entry zone”)
Anterolateral sulcus
Separates lateral from anterior funiculus
Fasciculus proprius
ONLY communicates areas of the spinal cord with other areas of it
Enlargements along spinal cord
Cervical enlargement
Lumbar enlargement
How do the roots exit the vertebrae?
Cervical roots above vertebrae of = name.
C8 root between C7 and T1
From C8 onwards, below the vertebrae of = name
Amount of white matter
Decreases as we descend through spinal cord
Amount of grey matter
More in cervical & lumbar enlargements
Intermediolateral horn
T1-L2
Soma of peripheral motor neurons are in
Ant horn
Soma of peripheral sensory neurons are in
Dorsal root ganglion
A spinal segment includes
All the parts of spinal cord generating a root
Dermatome
Area of skin whose sensation is carried by a specific spinal root / level
Myotome
All the muscles that depend on the same spinal root
Dermatome of the face
CN V
Dermatome of back of the head and neck
Cervical plexus
Dermatome of the hand
C6, C7 and C8
Dermatome of the foot
Sole of foot, mostly S1
Dorsum of foot, mostly L5
Big toe, L4
Dermatome of the leg
Lat part is L5 (to the dorsum)
Post part is S1 (to the sole)
Posterior root
Enters spinal cord through DREZ
Anterior roots
Somatic efferents
S fibres exit within this ant root too, and then enter sympathetic trunk
