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Termination in adults

L2 vertebrae
newborns terminate lower

Length of spinal cord

varies depending on height

Cervical and Lumbar Enlargements

where spinal cord is larger in diameter in these regions

Anterior Horn

where motor neurons originate
axons go out to spinal nerves

Ventral and Anterior horns larger in

lower cervical and lower lumbar regions
corresponds to cervical and lumbar enlargements

Nerve Rootlets

originate from ventral(ventral rootlets) and dorsal (dorsal rootlets) surfaces
merge to form dorsal and ventral spinal nerve rootlets

Conus Medularis

terminal portion of the spinal cord

Cauda Equina

large collection of nerve roots on both sides of conus medularis

Filum Terminal

consists of pia mater-not nerve tissue

3 layers of meninges

pia mater, arachnoid membrane, and dura mater

Pia Mater

gentle mother
adhered tightly to the spinal cord
can't pull it off
forms outer layer of spinal cord

Filum terminale

formed by pia mater and the inferior end of the spinal cord
remnant of the caudal part of spinal cord that was in the embryo

Denticulate ligaments

lateral extensions of the pia mater
attach to the inner surface of the dura mater
anchor the spinal cord to the dura mater

Arachnoid Membrane

consists of two layers of tissue
inner and outer layer
extends to S2

Inner layer of Arachnoid Membrane

gives way to fibers that pass to the pia mater
traversing the sub arachnoid space

Outer layer of Arachnoid Membrane

in physical contact with the dura mater

Subarachnoid Space

located between the arachnoid membrane and pia mater
contains CSF
extends from cranial cavity to S2
continuous with cranial subarachnoid space

Dura Mater

tough mother
lies directly on surface of arachnoid membrane (no space between, not attached)
continuous with cranial dura mater
extends to S2
composed of tough collagenous tissue

Subdural Space

occurs in pathological situations

Epidural Space

contains internal vertebral venous plexus embedded in a fatty matrix(epidural fat)
extends from foramen magnum to sacrum

Spinal Nerves

31 pairs
8 pairs cervical, 12 thoracic, 5 lumbar, 5 sacral, & 1 coccygeal


area of skin supplied by one pair of spinal nerves
usually overlap each other

Blood Supply to Spinal Cord

3 arteries run length of spinal cord
2 posterior and 1 anterior
very small
supplemented with other arteries

Anterior Spinal Artery

formed from union of 2 anterior spinal branches of the 2 vertebral arteries
descends to conus medullaris

Posterior Spinal Arteries

branches of the vertebral arteries
smaller than anterior artery
connected across the midline

Segmental Spinal Arteries

supply vertebrae, intervertebral discs, contents of epidural space, and dura mater
come in a multiple levels
enter via intervertebral foramina

Cervical Branches Of Segmental Spinal Arteries

originate from vertebral arteries, thyrocervical trunk, and costocervical trunk

Thoracic Branches Of Segmental Spinal Arteries

come from posterior intercostal arteries

Lumbar Branches of Segmental Spinal Arteries

come from lumbar arteries

Artery of Adamkiewicz

only found on left side of body
is the greater anterior medullary artery
reinforces circulation to lumbar enlargement of spinal cord
anastomosis with anterior spinal artery


when two arteries join together

Veins Of Spinal Cord

drains to venous plexus on surface of spinal cord (located in subarachnoid space)
surface venous plexus joins intervertebral veins to external venous plexus


network of veins

External Venous Plexus

surrounds vertebral column

Batsons Veins

external and internal venous plexuses that connect the cranial cavity with venous plexus in pelvic cavity
no valves
how diseases spread from pelvis to cranium

Communicating Neuron

connects sensory and motor neurons
AKA interneuron

Sensory Neuron

Pseudobipolar neuron

Dorsal Nerve Root

only contains afferent neurons

Ventral Nerve Root

only contains efferent neurons


is a collection of nerve cell bodies in the peripheral nervous system

Peripheral Nervous System

outside spinal cord and brain

Each Ramus Has

motor and sensory branches

Motor Neurons Originate

in ventral horn of spinal cord axons
go out dorsal primary ramus

Sensory Neurons Originate

in dorsal root ganglion
go out through ventral primary ramus
also go into dorsal horn

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