Lecture 10- Spinal Cord

What and where is the spinal cord?

• Extends from the medulla

• Spinal reflexes

• Communication between brain & PNS

Surface anatomy of the spinal cord

• Typical length is 16-18

in (42-45 cm)

• Ends about L1 level in

adults

• Important parts:

1. Cervical

enlargement

2. Lumbar

enlargement

3. Conus medullaris

4. Cauda equina

(*PNS)

What are the meninges?

three protective connective tissue coverings

(and spaces) that wrap the brain and spinal cord

What are the meninges in order from most superficial to deep?

1. Dura mater

2. Arachnoid mater

3. Pia mater

What us the dura mater?

• The most superficial,

thickest layer

• “Tough mother”

• Dense irregular connective

tissue

How many layers are in the spinal dura mater?

One

How many layers are in the cranial dura mater?

Two layers that are fused almost everywhere

What are where is the periosteal layer?

Part of the cranial dura mater, touches craniumW

What and where is the meningeal layer?

Part of the cranial dura mater that touches the arachnoid mater

What do the dural venous sinuses form?

Space between periosteal & meningeal layer

What does the dural venous sinuses do?

Collects blood leaving the brain. Tough reinforced space

What are dural folds?

Where meningeal dura mater fold inward to separate & anchor lobes of the brain

What is the arachnoid mater?

Middle layer

• Thin layer comprised of cells

and loosely arranged fibers

• Web-like appearance

• “Arachnoides”= spider

What is the pia mater?

• Deepest of the three layers

• Adheres to the surface of the

brain and spinal cord

What helps pia mater anchor the spinal cord?

Denticulate ligaments and filum terminale

What are the three meningeal spaces we need to know?

1. Epidural space

2. Subdural space

3. Subarachnoid space

What is the epidural space?

• Between dura mater & bone

• In the vertebral canal: a wide space w/

adipose, lymphatics, blood vessels, etc.

• Epidural blocks

• In the cranial cavity: a potential space that

exists when there is a bleed

• Epidural hemorrhage

What is the subdural space?

• Between dura mater & arachnoid mater

• Potential space unless subdural hemorrhage

What is the subarachnoid space?

• Between arachnoid mater &

pia mater

• Contains cerebrospinal

fluid

• CSF physically & chemically

protects CNS

• A bleed into this space =

subarachnoid hemorrhage

• Spinal taps

What are ventricles?

• Hollow spaces in the brain that

makes & is filled with

cerebrospinal fluid

• Remnant of the lumen of the

neural tube in embryos

• Each ventricle is associated with a

specific region of the brain

• Continuous with the central canal

of the spinal cord

What is the pathway of cerebrospinal fluid?

1. CSF is produced by the

choroid plexus (5 min video)

• A network of capillaries covered

in ependymal cells

2. CSF circulates through the

ventricles before entering the

subarachnoid space

3. CSF eventually returns to

blood via arachnoid

granulations

What are arachnoid granulations?

• Outgrowths of arachnoid mater into dural

venous sinuses

What nervous system are spinal nerves apart of?

Peripheral nervous system. Sensory and motor neuron axons

What is the cauda equina?

• “Horse’s tail”

• Spinal nerve roots of

the lower spinal nerves

• Spinal taps/lumbar

punctures are aimed at

this region of the

vertebral canal

Where can inferiorly spinal roots collect into?

Cauda equina

What is the spinal nerve plexuses?

• A network of intertwining nerves

that forms from the axons from the

ventral rami of spinal nerves, except

for thoracic nerves T2–T12

What are the principal plexuses?

1. Cervical plexus

2. Brachial plexus

3. Lumbar plexus

4. Sacral plexus

• Groups of nerves emerge from the

plexuses