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Meninges and Compartments

Main Text

TERMINOLOGY

Definitions

• Meninges = collective term for dura, arachnoid, pia

Pachy (“thick”) meninges = dura

Lepto (“thin”) meninges = arachnoid, pia
• Spaces = real or potential spaces between meningeal layers or adjacent structures
• Ligaments = suspend spinal cord within thecal sac
• Compartments = anatomic construct for location-based imaging differential diagnoses

GROSS ANATOMY

Overview

• Meninges

Dura

– Dense, tough outermost layer of connective tissue

– Only 1 dural layer in spine

– Attached by fibrous bands to posterior longitudinal ligament

– Tubular prolongations (nerve sheaths) of dura/arachnoid extend around roots/nerves through intervertebral foramina, terminate near dorsal root ganglia (DRG)

– Dura fuses with epineurium of spinal nerves distal to DRG

Arachnoid

– Thin, delicate, continuous with cranial arachnoid

– 2 layers: Outer (loosely attached to dura), intermediate (attached to pia)

Pia

– Delicate, innermost layer of meninges

– Closely applied to cord, spinal nerves
• Ligaments

Denticulate ligaments

– Flat, fibrous, serrated sheets that support spinal cord

– Collagenous core is continuous with pia

– Extend laterally from pia along each side of cord, between ventral/dorsal roots

– Insert into dura mater

Dorsal, dorsolateral, ventral spinal cord ligaments

– Thin, irregular, fenestrated; extend from cord to arachnoid

Septum posticum

– Incomplete longitudinal midline membrane

– Connects pia/cord dorsally to dura

– Partially divides subarachnoid space (SAS), creating “pseudocompartments”
• Spaces

Epidural space (extradural compartment)

– Between dura and surrounding vertebral canal

– Extends from foramen magnum to posterior sacrococcygeal ligament

– Contains fat, loose connective tissue, small arteries, veins, lymphatics

Subdural space

– Potential space between dura, outer surface of arachnoid

SAS

– Between inner surface of arachnoid, pia

– Contains CSF, vessels, spinal cord ligaments, nerves, filum terminale

– Continuous with intracranial SAS

Subpial space (potential space only)
• Compartments

Extradural compartment

– Epidural space

– Vertebral bodies, neural arches, intervertebral discs, paraspinous muscles

Intradural extramedullary compartment

– SAS

– Spinal cord ligaments, nerve roots, cauda equina, filum terminale

Intramedullary compartment

– Spinal cord, pia

IMAGING ANATOMY

Overview

• Meninges

Dura

– Thin black line on T2WI

– Vessels lack endothelial tight junctions so dura enhances strongly, uniformly

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Tags: Imaging Anatomy Brain and Spine

Mar 13, 2021 | Posted by admin in NUCLEAR MEDICINE | Comments Off

Main Text

TERMINOLOGY

Definitions

GROSS ANATOMY

Overview

IMAGING ANATOMY

Overview

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