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Anatomy - Spinal Cord and Meninges

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What is the difference in location of spinal cord in infants and adults
In infants spinal cord occupies entire vertebral canal extending into sacrum
In adult the cord is shorter than the vertebral canal
What is the location of the spinal cord
Spinal cord extends from the cranial border of the atlas to L2 only
What is the significance of the discrepancy between length of spinal cord and vertebral canal
The cord is shorter then the canal, so spinal roots and nerves of the lower segments must transverse longer distance to reach appropriate vertebral foramen
Cauda equina
A bundle of dorsal and ventral roots descending from the lumbar and sacral segments of the spinal cord to the appropriate intervertebral foramina
Name two enlargements of the spinal cord
Cervical enlargement - from C3 to T2, the larger and more pronounced enlargement
Lumbosacral enlargement - from L1 to S3
What is a conus medularis
cone shaped marking end of spinal cord, located below the lumbar enlargement
What is filum terminale
a thin filament originating from the conus medullaris - anchors it to coccyx
Has two parts - internal located inside dural sac and external, located below S2
Where are dorsal rootlets coming from
Posterolateral sulcus
Name three meningeal layers
Pia mater
Arachnoid mater
Dura mater
What is another name for dura mater
Pachymeninx
What is another name for pia+arachnoid mater
Leptomeninx
Name spaces between meninges
Epidural - contains external venous and arterial plexi
Subdural - a virtual space, arachnoid is held by in position by the pressure of CSF
Subarachnoid space - filled with CSF and arachnoid trabeculae surrounding vessels
Subpial space - internal venoud and arterial plexi
Describe anatomy of dura mater (pachymenix)
Outermost envelope of the spinal cord, thick and dense with a lot of collagen fibers.Separated from the periosteum of vertebral canal by epidural space. Forms a tubular sac, the upper end of which is attached to the edge of foramen magnum and to the bodies of 2nd and 3d cervical vertebrae. Caudally the sac covers cauda equina and extends to S2, attached to filum terminale. Forms tubular prolongations around nerves that fuses with epineurium
Describe anatomy of arachnoid
Delicate membrane, separated from dura by subdural space that contains little serous fluid.
Not attached to the dura mater, only held in position by the pressure of CSF
Subarachnoid space contains CSF, blood vessels and connective tissue trabeculae.
Surrounds spinal cord and nerves, end at S2
Describe anatomy of pia mater
Covers surface of spinal cord following sulci.
Between spinal cord and pia mater there is subpial space containing vessels
Forms denticulate ligament
Describe denticulate ligament
Formed by the duplication of the pia mater between dorsal and ventral roots
Anchors dural sac to spinal cord
Triangular tooth like ligaments, about 21 at cervical and thoracic levels
Why is pia mater important
To supply vessels on surface of spinal cord during extension and flexion of spine
What are two medications used for spinal anesthesia
Lidocain - 2 hours
Bupivacain- 8 hours
Target autonomic pain and motor fibers
Lumbar puncture
The dural sac and its inner arachnoidal covering enclose large space around cauda equina called subarachnoid lumbar cistern, which doesnt have spinal cord, only spinal nerves and CSF
This allows to do spinal tap, between L3 and L4
Epidural injection
Unlike spinal tap, can be done at thoracic and cervical regions.Epidural space is small so done under fluoroscopy. Most commonly used for surgery around neck and chest, also for anti inflammatory and local anesthetics
What type of arteries supply spinal cord
Longitudinal arteries and Segmental arteries
Name longitudinal arteries
One anterior located along anterior fissure and two posterior located along posterior lateral sulci
Name segmental arteries
Also called radicuar arteries - vertebral, ascending cervical, intercostal, lumbar
What is the strongest segmental spinal artery
at upper lumbar levels, great anterior segmental medullary artery or Adamkiewicz artery
Name and describe two venous plexuses supplying spinal cord
Pial venous plexus and epidural venoud plexus
Describe Pial Venous plexus
located in pia mater, drains into epidural plexus
One anterior spinal vein located along anterior fissure
Two posterolateral veins located along posterior lateral sulci
One posterior spinal vein located along posterior spinal sulcus
Numerous small branches between them complete plexus
Describe Epidural Venous Plexus
Located between dura mater and periosteum of vertebra
Drains into intervertebral veins
NO venous valves

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