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58 Cards in this Set

  • Front
  • Back
Why spinal cord important?
1. Diagnostic Prodcedures
2. Therapeutic Procedures
3. Referred Pain
4. Vascular system
Central Nervous System
Brain and spinal cord-both continuous with the foramen magnum at the base of skull
Peripheral Nervous System
12pairs of cranial nerves + 31 pairs of spinal nerves
Somatic Nervous System
1. Definition
2. Composition
1. Part of the nervous system that controls and supplies the body (other than internal organs)
2. Contains both sensory & motor components
Visceral Nervous System
1. Definition
2. How info conveyed
1. Part of nervous system that controls internal organs
2. Sensory fibers convey info to the CNS to the brain and then motor back to the body
1. Definition
2. Structure
1. Structural & function unit of nervous system
2. Contains body(soma), one or more dendrites (conduct impulses TO body), a single axon (conduct impulses FROM body).
1. Definition
1. Junction where one neuron ends on another neuron.
Example of Chemical Synapse
1. pre-synaptic neuron releases a chemical neurotransmitter into synaptic cleft
2. that substance will bind to a receptor molecule on the post-synaptic neuron
3. the post-synaptic membrane will be either excited or inhibited
Myelin Sheath
1. Purpose
2. Appearance
1. Myelin is a lipoprotein substance that forms a sheath around some axons which acts to increase conduction veloctiy.
2. Imparts whitish color.
Explain difference in lengths of spinal cord vs. verterbral column
1. Spinal cord is shorter than vertebral column - ends btwn L1 & L2.
2. During development, growth of cord not maintained relative to vertebral column--progressive shortening
Conus medullaris
The end of the spinal cord (~L1-L2)
Spinal cord segment
Area of the spinal cord where the nerves attach.
Account for different types of spinal nerves
1. 8 Cervical
2. 12 Thoracic
3. 5 Lumbar
4. 5 Sacral
5. 1 Coccyxgeal
How are the nerves named (based on column segment)?
Cervical (Special): Nerve emerges superior to respective vertebra
(8th nerve btwn C7 & T1)
All other: nerves emerge below respective vertebra
NOTE: lumbar/sacral/coccygeal nerves are longer & more oblique due to end of spinal cord ~L1 & L2
Cauda Equina
Leash like bundle of fibers of lumbar/sacral/coccygeal to get to their foramina to exit
(horse's tail)
Filum terminale internum
Delicate filament of non-nervous tissue made of pia mater
Filum terminale externum
Filum terminal internum called this after exits dural sac (~S2). Goes down along sacrum, then exits sacral hiatus and binds to coccyx.
Two enlargements of the spinal cord
Enlarged b/c these are areas of cord to which spinal nerves innervating either upper/lower limbs attach.
1. Cervical enlargement (C4-T1)
Gray Matter
1. 'H' shaped in cross section
2. Made up of cell bodies
White Matter
1. Made up of myelinated axons that surround gray matter
2. Either ascend to brain or descend from brain to cord.
Gray matter "structures"
1. Ventral horn
2. Dorsal horn
Ventral Horn

Dorsal Horn
1. Contains motor neurons that supply skeletal muscle of body
2. Contains sensory neurons that receive impulses from spinal nerves sensory info
What is different about T1-L2?

What is its function?
1. Additional horn: Lateral horn
2. Contains cell bodies of the Autonomic Nervous System
3. These neurons supply(involuntary): cardiac muscle, smooth muscle & glands
Describe the typical structure of a spinal nerve.
1. Dorsal & ventral root which attach to cord by "rootlets". Dorsal root has spinal ganglion (DRG).
2. Two roots unite to form spinal nerve = mixed signal (sensory & motor)
3. Spinal nerve exits intervertebral foramen and divides into branches/rami = dorsal and ventral ramus
(NOTE: since spinal nerve is mixed, so are both dorsal & ventral rami.
Dorsal roots

Ventral roots
1. Sensory conveying info INTO cord
2. Motor carrying impulses AWAY from cord

Sympathetic Ganglion
1. Collection of neurons outside of the CNS.
2. A cluster of nuerons outside the CNS, but different from DRG.
Gray & White Rami Communicantes
1. Definition
1. Connects the ventral ramus of the spinal nerve to the sympathetic ganglion from T1-L2
2. If above T1, contains only gray ramus
2b. If below L2, contains only gray ramus
Two types of Ganglia
1. sensory (dorsal)
2. autonomic (ventral)
Autonomic Ganglia
1. All autonomic ganglia (whether sympathetic or parasympathetic are MOTOR ganglia)
2. Therefore, all of these are motor neurons carrying impulses to cardiac muscle, smooth muscle, glands
3. All autonomic ganglia have a synapse in them
Dorsal Ramus
1. Mixed
2. Motor fibers supply erector spinae and a branch will continue to supply skin of back
Ventral Ramus
1. Innervation?
1. Everything except deep back muscles and skin of back
2. Supplies muscles in body walls (intercostal muscles), skin by either lateral cutaneous branch or anterior cutaneous branch
(anterior body wall)-ventral ramus
3. Innervates limbs also
Brachial Plexus
1. Composition
2. Innervation
1. Lower cervical nerves and upper thoracic nerves
2. Branches of this supply motor & sensory innervations to entire limb
Lower limb innervated by what?
Lumbar & sacral plexuses
To devuse scheme of functional components of nerves, what 3 questions need to be asked?
1. Is the nerve fiber sensory/afferent (convey impulse from body to CNS) or motor/efferent (convey impulse from CNS to body)?
2. Is it somatic (going to outer part of body wall) or visceral (internal organs)?
3. Is it general or special? (general nerve fibers distribute to tissue or structures with a relatively wide distribution in the body)
Example of Scheme:
What would a sensory fiber from the skin be classified as?
skin-General, Somatic, Afferent
How many possible functional components?
Where do they occur-cranial vs. spinal?
7 (SSE doesn't exist)
NOTE: special components occur in most cranial nerves. General components occur in most cranial nerves and in all spinal nerves; all spinal nerves have all four general compomnents and only general components
What are GVE Fibers?

What happens if they are sympathetic?
1. Autonomic nervous system (pre/post synaptic)
2. Pre-synaptic neurons lie in lateral horn & axon leaves through ventral root into spinal nerve; goes down white ramus communicantes where it synapses on post-synaptic neuron; then goes out gray ramus back to spinal nerve and either follow dorsal or venntral depending on location of innervation
What about GVA Fibers?

1. They follow GVE's that go to internal organs and their cell bodies lie in dorsal root ganglion.
2. Have cells in DRG
In typical spinal nerve, T1-L2, dorsal roots are...
ventral roots are...
1. Dorsal roots are entirely sensory = GSA, GVA
2. Ventral roots are entirely motor = GSE, GVE
Where do pre-synaptic GVEs travel?

Where do post-synaptic GVEs travel?
1. White rami

2. Gray rami
Strips of skin that are innervated by a single pair of spinal nerves
Referred Pain

Landmark: T10 dermatome
T10 dermotome supplied by T10 spinal nerve includes skin around umbilicis (people who have appendicitus feel pain here since Afferent/sensory fibers in appendix end in T10 spinal cord segment, in dorsal horn; CNS misinterprets where pain is coming from.
What are limbs innervated by?

What is a nerve plexus?
1. Ventral rami but through plexuses.

2. Where ventral rami of adjacent spinal nerves comine and redivide.

Note: Fibers leave cord in one spinal nerve are going to redistribute through mulitiple branches of the plexus.
Comparison of dermatomal map vs. sensory distribution of peripheral nerve map.
Two different maps except in the thoracic region where there is no plexus formation and the thoracic nerves remain un-united and the strips of skin are the same.
Three spinal arteries
1. Type
2. Where originate?
3. Size
1. anterior spinal artery
1b. 2 posterior spinal arteries
2. They branch off veterbral arteries in the skull and then run down on spinal cord - either along ventral median fissure or posteriolaterally (for posterior arteries).
3. Spinal arteries are small with insufficient blood supply, so segmental arteries must anastamose (join) spinal arteries to supply enough blood.
Segmental medullary arteries
Segmental arteries that anastamose (join) spinal arteries to supply enough blood to spinal cord.
Cervical region
Thoracic region
Lumbar region
1. Verterbral arteries
2. Intercostal arteries
3. Lumbar arteries
Great Anterior Medullary Segmental Artery/Artery of Adamkiewicz

Why is it important?
1. Segmental medullary artery that is especially large, springs off theleft side and usualy comes from a lower intercostal artery - in this case, the lumbar artery.
2. This segment supplies the lumbral-sacral enlargement of teh spinal cord.
NOTE: if this artery is occluded, lower part of spinal cord will lose its blood supply and person will likely become paraplegic.
What are the layers of meninges?
1. Epidural space
2.Dura Mater (potential)
3. Arachnoid Mater
4. Subarachnoid space - CSF here (real)\
5. Pia mater
Dura Mater
Arachnoid Mater
Pia Mater
1. Very tough fibrous coat that surrounds outermost covering of cord
2. Delicate spider-web like layer that lies just inside dura
3. Vascular membrane that adheres so closely to cord that it is impossible to separate from cord.
Denticulate ligament

Useful landmark for?
1. Pia mater extends bilaterally from cord as toothed processess that attach to the inner surface of the dura.
2. Holds spinal cord in place and anchors it to dura.
3. Separates dorsal rootlets from ventral rootlets of spinal nerve. (Dorsal on top)
Where does the sac of dura mater and arachnoid end
S2 vertebral level, below which is the dural part of the filum terminale which exits sacral hiatus & attaches to coccyx.
Spaces Related to Meninges
1. Subarachnoid space: between arachnoid and pia mater = real space of CSF (protects spinal cord and brain)
2. Subdural space = narrow potential space (blood could enter)
3. Epidural space = btwn dura mater and periosteum lining of vertebral canal. (contains fat, connective tissue, plexus of veins) = Batson's plexus
Batson's plexus
1. Internal vertebral venous plexus in epidural space
2. Drains the vertebral column and is drained by intervertebral veins which exit through the intervertebral foramina.
What unique quality is there about Batson's plexus and intervertebral veins?
1. Valve-less
2. Clinically provides a pathway for infection or cancer to spread.
Lumbar cistern
1. Area entered during a lumbra puncture (into the subarachnoid space) btwn L2 and S2
Supracristal plane
1. Plane cuts across the upper border of iliac crests which lies at L4 verterbral level--place to insert needle above or below
Remove laminae of spine via chisel and hammer--removes spine and adjacent parts of laminae--> exposes cord and meninges.