Spinal Cord Meninges Anatomy

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Questions and Answers

What is the name of the layer of dense irregular connective tissue that attaches to the foramen magnum, the 2nd & 3rd cervical vertebrae, and the sacrum?

Arachnoid Mater

Filum Terminale

Pia Mater

Dura Mater (correct)

Which layer of the spinal cord meninges is firmly bonded to the underlying neural tissues and contains the blood vessels?

Epidural Space

Dura Mater

Pia Mater (correct)

Arachnoid Mater

At which spinal cord levels do the lateral horns of gray matter exist?

Lateral horns do not exist in the spinal cord

C1 to L5

S1 to S5

T1 to L1 (correct)

Which part of the spinal cord meninges creates the epidural space?

The outer epithelium that is not connected to the vertebral column Signup and view all the answers

Which gray matter region of the spinal cord contains the somatic and visceral sensory nuclei?

Posterior horns Signup and view all the answers

What is the name of the connective tissue of the pia mater that forms the filum terminale at the inferior tip of the spinal cord?

Filum terminale Signup and view all the answers

Where does the cauda equina originate from?

First lumbar vertebrae Signup and view all the answers

Which spinal region supplies the pelvic girdle and limbs?

Lumbar enlargement Signup and view all the answers

In which region does the amount of gray matter increase substantially in areas that handle sensory and motor information?

Cervical region Signup and view all the answers

What is located distal to each dorsal root ganglion?

Spinal nerve Signup and view all the answers

Which layer of the spinal meninges is responsible for covering and protecting the spinal cord and nerve roots?

Dura mater Signup and view all the answers

What type of fibers does a spinal nerve contain?

Both afferent and efferent fibers Signup and view all the answers

Which of the following is the outermost connective tissue layer surrounding a peripheral nerve?

Epineurium Signup and view all the answers

What is the primary function of the dorsal ramus of a spinal nerve?

Receiving sensory information from and sending motor commands to the back muscles Signup and view all the answers

Which of the following is NOT a region of the spinal cord?

Cauda equina Signup and view all the answers

Where are the cell bodies of lower motor neurons located?

In the lateral horn of the spinal cord Signup and view all the answers

Which of the following nerve plexuses is responsible for innervating the upper limbs?

Brachial plexus Signup and view all the answers

How many pairs of spinal nerves are there in total?

31 Signup and view all the answers

Study Notes

Spinal Cord Structure

The spinal cord is attached to the foramen magnum, 2nd & 3rd cervical vertebrae, and the sacrum, and stabilizes within the vertebral canal.
The outer epithelium is not connected to the vertebral column, creating the epidural space.
The subarachnoid space separates the dura mater from the innermost layer of the spinal cord and contains cerebrospinal fluid.

Meninges

Three meningeal layers cover and protect the spinal cord and spinal nerve roots: dura mater, arachnoid layer, and pia mater.
The pia mater is firmly bonded to the underlying neural tissues and contains the blood vessels of the spinal cord.
Denticulate ligaments interweave and connect the pia mater, arachnoid layer, and dura mater.

Sectional Anatomy

The anterior median fissure and posterior median fissure divide the spinal cord into left and right halves.
A central H-shaped mass of gray matter contains the cell bodies of neuroglia and neurons.
The gray matter surrounds the central canal, and gray matter called horns project toward the outer surface of the spinal cord.
The peripheral white matter contains the myelinated and unmyelinated axons organized into tracks or columns.

Gray Matter

Cell bodies within the gray matter are organized into groups called nuclei.
Sensory nuclei receive and transmit information from peripheral receptors.
Motor nuclei send motor commands back to the peripheral receptors.
The posterior horns contain the somatic and visceral sensory nuclei.
The anterior horns contain the somatic motor neurons.
Lateral horns exist only in regions T1 to L1 and contain visceral motor nuclei.

White Matter

The overall pattern of gray/white matter is consistent throughout the spinal cord.
The amount of white matter decreases as you move caudally.
White matter is divided into regions called columns, including the anterior, posterior, and lateral white columns.
Each column contains tracts of ascending or descending fibers.
A specific tract contains either sensory or motor axons.

Spinal Cord Tracts

The ascending (sensory) and descending (motor) tracts each consist of a chain of neurons and associated nuclei.
All involve both the brain and spinal cord.
The name of a tract often indicates its origin: tracts beginning with "Spino-" begin in the spine and end in the brain, and tracts ending with "Spinal" begin in the brain and end in the spinal cord.

Sensory Tracts

The posterior (dorsal) columns carry highly localized information from receptors in the skin and musculoskeletal system regarding proprioception.

Spinal Nerves and Sensory/Motor Tracks

The spinal cord and brain are physically distinct but have very distinct roles.
The brain is the site of processing of all information and the coordinator of all responses to stimuli.
The spinal cord is the transmitter of sensory and motor data to and from the brain.
The spinal cord also integrates and processes certain levels of information on its own.
The adult spinal cord extends from the foramen magnum to the first lumbar vertebrae.
The nerves that continue into the pelvic girdle form the cauda equina.
Each region of the spinal cord (cervical, thoracic, lumbar, sacral) contains tracks that share functional similarities.
The amount of gray matter increases substantially in areas that handle sensory and motor information.
These areas form the cervical enlargement, which supplies the pectoral girdle and limbs, and the lumbosacral enlargement, which supplies the pelvic girdle and limbs.
Every spinal segment is associated with a dorsal root ganglia that contains the cell bodies of afferent sensory neurons.
Anterior to the dorsal root is a ventral root containing efferent axons of somatic motor neurons.
Distal to each ganglion, the spinal nerve forms, containing both afferent and efferent fibers.

Spinal Meninges

Blood vessels branching within the meninges deliver oxygen and nutrients to the spinal cord.

Motor Tracts

The CNS sends motor commands in response to the sensory information it receives.
These efferent commands are distributed to the effectors by either the somatic motor system or the autonomic motor system.
All descending motor tracts are two-neuron systems and decussate as they reach the spinal segments.
The upper motor neuron originates within the brain, and the lower motor neuron is found in the lateral horn of the spinal cord.

Spinal Nerves

There are 31 pairs of spinal nerves, including 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal.
Three pairs of connective tissue surround each peripheral nerve: epineurium, perineurium, and endoneurium.
All spinal nerves form 2 branches: a dorsal and ventral ramus.
The dorsal ramus receives sensory information from and sends motor commands to skeletal muscles of the back.
The ventral ramus supplies the ventrolateral body surface, structures of the body wall, and limbs.
In adult spinal cord segments, the ventral rami controlling skeletal muscle of the neck and the upper and lower limbs do not directly contact their targets.
Instead, they form complex nerve trunks called a nerve plexus, including the cervical, brachial, lumbar, and sacral plexus.

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Description

Test your knowledge on the layers surrounding the spinal cord. Learn about the functions and structures of the dura mater, arachnoid mater, and pia mater.