Neuroanatomy 3 Flashcards

(82 cards)

0
Q

Spinal Cord: Structure

Describe the shape and organization of the spinal cord.

A

It is a cylindrical structure characterized by a central H shaped region of gray matter and a peripheral region of white matter. This gray matter/white matter arrangement is opposite the arrangement in the brain.

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1
Q

Spinal Cord: Structure

Where is it and what is it continuous with?

A

The spinal cord is continuous rostrally with the brainstem. It extends from the foramen magnum of the occipital bone to LV2 level. It lies in the vertebral cnal created by successive vertebral foramen.

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2
Q

Spinal Cord: Structure

Describe the organization of the spinal cord levels

A

It is divided into 31 spinal cord levels or segments: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal. The level is specified by the intervertebral foramina through which the dorsal and ventral roots attached to that segment enter the vertebral canal.

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3
Q

Spinal Cord: External Anatomy

Regions - Cervical Enlargement

A

Extends from the C4 segment to the T1 segment.

Gives rise to nerves that innervate the UE

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4
Q

Spinal Cord: External Anatomy

Regions - Lumbosacral Enlargement

A

Extends from the L1 to S2 segments.

Gives rise to nerves that innervate the LE

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5
Q

Spinal Cord: External Anatomy

Regions - Medullary Cone

A

Tapering inferior end of the spinal cord at about the level of LV2

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6
Q

Spinal Cord: External Anatomy

Regions - Cauda Equina

A

aka Rootlets

It is composed of the dorsal and ventral roots arising from the lumbosacral enlargement and the medullary cone.

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7
Q

Spinal Cord: External Anatomy

What fissures/sulci are on the ventral surface?

A

Anterior median fissure - continuous with the anterior median fissure of the medulla

Anterolateral sulcus - this is where the ventral roots emerge

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9
Q

Spinal Cord: External Anatomy

What fissures/sulci are on the dorsal surface?

A

Posterior median sulcus - continuou with the posterior median sulcus of the medulla

Posterolateral sulcus - this is where the dorsal roots emerge.

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10
Q

Spinal Cord: External Anatomy

Spinal Nerves - How many are there? Where are they found?

A

There are 31 pairs of spinal nerves

They occupy the space within the intervertebral foramen created by the vertebral notches of successive vertebrae.

C1 - C7 are located ABOVE the vertebrae of the same number, C8 is below CV7, and T1 - L5 are located BELOW the same numbered vertebrae

There is only about 1 com of that we call the “spinal nerve” where the dorsal and ventral roots come together before they split into the dorsal and ventral rami. This area is MIXED (carries both sensory and motor fibers.

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11
Q

Spinal Cord: External Anatomy

Dorsal Roots

A

Carry afferent fibers from the periphery.

Cell bodies of these axons are in the dorsal root ganglia

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12
Q

Spinal Cord: External Anatomy

Ventral Roots

A

Carry efferent fibers to the periphery.

Cell bodies of these axons are in the ventral horn of the spinal cord

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13
Q

Spinal Cord: External Anatomy

Dorsal Primary Rami

A

Supply the vertebral column joints, deep back muscles, and overlying skin.

They are smaller because they innervate less.

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14
Q

Spinal Cord: External Anatomy

Ventral Primary Rami

A

Supply anterior and lateral trunk, upper limbs, and lower limbs.

Certain rami form plexes

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15
Q

Spinal Cord: Internal Anatomy

Gray matter - structural characteristics

A

Central H shaped region

Contains neuronal cell bodies, dendrites, unmyelinated axons, and glial cells

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16
Q

Spinal Cord: Internal Anatomy

Gray matter - where is it most predominant and why?

A

Greater in the cervical and lumbosacral regions due to the innervations of the UE and LE respectively.

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17
Q

Spinal Cord: Internal Anatomy

Gray matter - Dorsal Horn

A

Sensory

Neurons in the dorsal horn receive the central processes of the neuron cell bodies in the dorsal root ganglia through the dorsal roots

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18
Q

Spinal Cord: Internal Anatomy

Gray matter - Ventral Horn

A

Motor neurons send their axons from the ventral horn towards the periphery via the ventral roots

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19
Q

Spinal Cord: Internal Anatomy

Gray matter - Lateral Horn

A

The lateral horn is present ONLY in the thoracic region from T1 to L2.

The motor neurons here send their axons to autonomic ganglia through the ventral roots.

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20
Q

Spinal Cord: Internal Anatomy

White Matter - Structure, contents

A

It is the peripheral region of the spinal cord (including the anterior white commisure)

It contains myelinated axons and oligodendrocytes

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21
Q

Spinal Cord: Internal Anatomy

White matter - in which direction does the white matter increase and why?

A

Increases from sacral to cervical regions as the volume of sensory fibers increases at each ascending level and motor fibers decrease at each descending level.

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22
Q

Spinal Cord: Internal Anatomy

White matter - How is white matter subdivided?

A

Subdivided into funiculi, fasciculi, and tracts

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23
Q

Spinal Cord: Internal Anatomy

White matter - Dorsal Funiculus

A

Carries ascending sensory information

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24
Q

Spinal Cord: Internal Anatomy

White matter - Lateral Funiculus

A

Carries ascending sensory information and descending motor information

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Spinal Cord: Internal Anatomy White matter - Ventral Funiculus
Carries ascending sensory information and descending motor information
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Spinal Cord: Functions
1) Carries sensory information from the extremities, trunk, and viscera to the brain 2) Conveys motor information to the extremities, trunk, and viscera 3) Site of spinal reflexes which are essential to normal function 4) Conveys modulatory information from the brain - the brain controls what is going on in the spinal cord
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Ventricular System: definition
Continuous fluid filled system in the CNS lined with ependymal cells.
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Ventricular System: Structures Lateral Ventricles (2)
Associated with the telencephalon C-shaped structures separated by the septum pellucidum
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Ventricular System: Structures Interventricular foramina (2)
Aka foramina of Munro Connect the lateral ventricles to the third ventricle
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Ventricular System: Structures Third Ventricle
Associated with the thalamus and hypothalamus It is a thin, midline structure it is interrupted with the interthalamic adhesion adhesion that connects the 2 thalmi
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Ventricular System: Structures Cerebral Aqueduct
aka aqueduct of Sylvius Connects the 3rf ventricle to the 4th ventricle Associated with the midbrain
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Ventricular System: Structures 4th Ventricle
Associated with the pons and medulla Pyramid shaped space covered on its dorsal aspect by the cerebellum Continues into the central canal of the spinal cord, which does not remain fully patent beyond the early postnatal period Opens into the subarachnoid space through laterally placed foramina of Luschka and the medial foramen of Magendie
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CSF - Where is it formed?
CSF is formed in the Choroid plexes, which are located in the ventricles. Choroid plexes are composed of the endothelial walls of capillaries, pia mater, and choroid epithelial (specialized ependymal) cells
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CSF - What is the composition of CSF?
It is a clear, colorless liquid. Low in cells and protein. Similar to plasma in ion concentration.
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CSF - How does CSF circulate? Describe the sequence.
Flows freely from the ventricular system into the subarachnoid space where it is taken up into the venous system by arachnoid villi. Flow: 1) Lateral Ventricles 2) Interventricular foramina 3) Third Ventricle 4) Cerebral Aqueduct 5) Fourth Ventricle 6) Foramen of Magendie and Foramina of Lushcka 7) Subarachnoid space 8) Venous system
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CSF - How is it absorbed?
It is absorbed into the venous system at the superior sagittal sinus through arachnoid granulations, which consist of collections of arachnoid villi that protrude through the dura mater into the sinuses
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CSF - Function
1) Mechanically supportive of the brain due to its buoyant effect 2) Maintenance of the extracellular environment 3) Route for the spread of neuroactive hormones through the CNS
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Meninges: What are the three meningeal layers?
Dura mater, Arachnoid Mater, Pia Mater
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Meninges: Dura mater Structural specializations - What are Dural Infoldings?
These exist in the BRIAIN ONLY The inner portions of the dura mater give rise to septa that separate brain regions from each other and contain venous sinuses.
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Meninges: Dura mater Structural specializations - Dural infoldings --> Falx cerebri
Located between cerebral hemispheres
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Meninges: Dura mater Structural specializations - Dural infoldings --> Tentorium Cerebelli
Located between the cerebral hemispheres and the cerebellum
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Meninges: Dura mater Structural specializations - Dural infoldings --> Falx cerebelli
between the cerebellar hemispheres
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Meninges: Dura mater Structural specializations - Dural Sac
This is in the SPINAL CORD ONLY It is a tubular sheath surrounding the spinal cord in the vertebral canal. It is anchored rostrally to the foramen magnum, and cadally to the coccyx via the filum terminal externum which is composed of dura mater as well
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Meninges: Dura mater Spaces - Subdural
Potential space between the dura mater and the arachnoid mater
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Meninges: Dura mater Spaces - Epidural Space
This exists in the SPINAL CORD ONLY It is the space between the dura mater and the vertebral canal
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Meninges: Arachnoid mater Arachnoid Trabeculae - definition
CT strands that connect the arachnoid mater to the pia mater
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Meninges: Arachnoid mater Arachnoid Villi - definition
These are in the BRAIN ONLY The are specializations of the arachnoid that are structurally adapted for transporting CSF from the subarachnoid space into venous circulation.
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Meninges: Arachnoid mater Subarachnoid Space
Space between the arachnoid mater and the pia mater. Contains CSF
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Meninges: Arachnoid mater Cisterns - Definition; names and locations of 2 cisterns
Dilations within the subarachnoid space Cisterna Magna - Dorsal to the medulla Lumbar - Caudal to the Medullary Cone
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Meninges: Pia mater Specializations - denticulate ligaments
These are in the SPINAL CORD ONLY They are extensions from the lateral surfaces of the pia mater to the dural sac
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Meninges: Pia mater Specializations - filum terminal internum
This is in the SPINAL CORD ONLY A tough strand of the pia mater that anchors the medullary cone to the caudal end of the dural sac Located in the cauda equina
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Meninges: Function
Stabilize the shape and position oft he CNS during head and body movements.
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Vasculature of the Brain How much of the body weight is the brain? How much blood does it receive? How much oxygen does it use? What does this reflect?
The brain is only 2% of the total body weight but it receives about 15% of the total CO and consumes about 20% of the oxygen used by the entire body. this reflects the high metabolic rate and therefore oxygen requirements of the brain
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Vasculature of the Brain What happens when the Brian is deprived of blood for certain amounts of time?
10 seconds - loss of consciousness 3-5 min - irreparable brain damage or death may result
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Vasculature of the Brain Arteries: Internal Carotid Origin Course Branches
Constitutes the anterior circulation of the brain Origin: Right - Brachiocephalic trunk Left: Arch of the aorta Course: Ascends through the anterior triangle of the neck, enters the carotid canal of the temporal bone, traverses the cavernous sinus, the pierces the dura mater ``` Branches: Ophthalmic Posterior Communicating Middle Cerebral Anterior Cerebral ```
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Vasculature of the Brain Arteries: Internal Carotid - Ophtalmic branch Course Distribution
Course: Branches from the internal carotid rostrally and travels with CNII through the optic canal into the orbit; anastomoses with the facial artery (communication between internal and external carotid arteries. Distribution: Orbit (only artery that is not a branch of the facial nerve that has any distribution in the face)
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Vasculature of the Brain Arteries: Internal Carotid - Posterior communicating branch Course Distribution
Course: Connects the internal carotid artery to the posterior cerebral artery Distribution: n/a
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Vasculature of the Brain Arteries: Internal Carotid - Middle Cerebral branch Course Distribution
Course: This terminal branch comes off laterally and proceeds through the lateral sulcus extending laterally to spread out over the lateral surface of the cerebral hemisphere. Distribution: Lateral convexity of the cerebral cortex; Internal Capsule, Basal Ganglia
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Vasculature of the Brain Arteries: Internal Carotid - Anterior Cerebral branch Course Distribution
Course: This terminal branch proceeds into the longitudinal fissure, loops around the medial surface of the cerebral hemisphere, and runs just superior to the corpus callosum. Distribution: Medial frontal and parietal cerebral cortex; Internal capsule, basal ganglia, hypothalamus
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Vasculature of the Brain Arteries: Vertebral Origin Course Branches
Constitutes the posterior circulation of the brain Origin: Subclavian Artery Course: Ascend through the transverse foramina of the cervical vertebrae and enter the cranium through the foramen magnum. ``` Branches: Anterior Spinal Posterior Inferior Cerebellar (PICA) Posterior Spinal Basliar Posterior Cerebral ```
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Vasculature of the Brain Arteries: Vertebral - Anterior Spinal branch Course Distribution
Course: Joints counterpart from the opposite side and runs caudally along the midline of the spinal cord Distribution: Anterior 2/3 of the spinal cord
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Vasculature of the Brain Arteries: Internal Carotid - Posterior Inferior Cerebellar (PICA) branch Course Branch Distribution
Course: arches around the dorsolateral medulla Branch: Gives off the POSTERIOR SPINAL branch, which runs caudally along the posterolateral aspect of the spinal cord and supplies the posterior 1/3 of the spine Distribution: Dorsolateral medulla; cerebellum
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Vasculature of the Brain Arteries: Vertebral - Basilar branch Course Distribution
Course: Formed from the fusion of the vertebral arteries at the junction of the medulla and the pons. Runs in the ventral midline of the pons. Distribution: n/a
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Vasculature of the Brain Arteries: Vertebral - Posterior Cerebral branch Course Distribution
Course: This terminal branch passes lateral just rostral to the occulomotor nerve. It connects to the posterior communication branch of the internal carotid artery, completing the circle of Willis. Distribution: Midbrain, Thalamus, Occipital and Inferior temporal cerebral cortex
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Vasculature of the Brain Arterial anastomoses - Circle of willis
Located on the ventral surface of the brain, surrounding the optic tracts, infundibulum, and basal hypothalamus.
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Vasculature of the Brain Watershed border zones
Regions of the lateral surface of the cerebellar hemisphere where the terminal branches of the anterior, middle, and posterior cerebral arteries terminate.
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Vasculature of the Brain Veins - Where do they empty into?
Veins empty into venous sinuses
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Vasculature of the Brain Sinuses - where are they? What is their purpose?
Sinuses are located between the inner and outer layers of dura mater. They serve as conduits to drain venous blood from the brain into the internal jugular veins
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Vasculature of the Brain Sinuses - Superior Sagittal Sinus Location Termination
Location: ATTACHED edge of the falx cerebri Termination: Confluence
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Vasculature of the Brain Sinuses - Inferior Sagittal Sinus Location Termination
Location: Free edge of the falx cerebri Termination: Straight Sinus
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Vasculature of the Brain Sinuses - Straight Sinus Location Termination
Location: where the falx cerebri attaches to the tentorium cerebelli Termination: Confluence
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Vasculature of the Brain Sinuses - Transverse Sinus Location Termination
Location: Courses laterally from the confluence sinus in a shallow groove on the internal surface of the occipital bone. Termination: Sigmoid
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Vasculature of the Brain Sinuses - Confluence Sinus Location Termination
Location: Junction of the superior sagittal, straight, and transverse sinuses Termination: Transverse Sinus
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Vasculature of the Brain Sinuses - Sigmoid Sinus Location Termination
Location: Courses inferiorly from the transverse sinus in a shallow groove on the internal surface of the temporal bone, and traverses the jugular foramen. Termination: Internal Jugular
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Vasculature of the Brain Sinuses - Cavernous Sinus Location Contents Termination
Location: Side of the sphenoid bone. Contains the internal carotid artery, CN3, 4, and all 3 parts of 5 Termination: Superior petrosal and inferior petrosal into the sigmoid sinus
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Vasculature of the Brain Blood Brain Barrier - structure
1) There are tight junction between the capillary endothelial cells in the brain. 2) the capillaries are lined with astrocytes, whose endfoot processes are very closely associated with the endothelial cells, creating a barrier
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Vasculature of the Brain Blood brain barrier - function
Highly selective barrier
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Vasculature of the Spinal Cord Arteries - how many longitudinal ones are there anteriorly and posteriorly? Where do they extend from/to?
There are one and anterior and 2 posterior longitudinal arteries associated with the spinal cord. They run from the medulla to the medullary cone of the spinal cord. Additional arteries run horizontally along the spinal nerve roots
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Vasculature of the Spinal Cord Arteries - anterior spinal Origin Course Distribution
Origin: Vertebral Course: Joins counterpart from the opposite side, runs caudally along the midline of the spinal cord Distribution: Anterior 2/3 of the spinal cord
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Vasculature of the Spinal Cord Arteries - Posterior spinal Origin Course Distribution
Origin: PICA Course: Runs causally along the posterolateral aspect of the spinal cord Distribution: Posterior 1/3 of the spinal cord
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Vasculature of the Spinal Cord Arteries - Segmental Medullary Course Distribution
Course: Run along the spinal nerve roots, segmental medullary arteries replace radicular arteries at the irregular levels at which they occur. Otherwise, radicular occur at every level. Distribution: Anterior and posterior spinal arteries in the cervical and lumbosacral enlargements
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Vasculature of the Spinal Cord Arteries - Radicular Course Distribution
Course: Run along the spinal nerve roots, segmental medullary arteries replace radicular arteries at the irregular levels at which they occur. Otherwise, radicular occur at every level. Distribution: Nerve roots