what are the two division of the dorsal root?

describe axons & what info they carry of each type.

1. Medial 

Large Diameter Axons

Carry touch, 2pt discrimination, position sense, vibration sense

2. Lateral

Small Diameter

Carry Pain, Temp sensation

cervical: C5- T1

Lumbar: L1 - S3

large cuz carry more neurons where extremities are located

where does the conus medularis end in adult/infant

where does cauda equina start

lumbar puncture after which point is safe

adult: L1, infant: L3

cauda equina start at L1

lumbar puncture below L3

II - Substantia Gelatinosa (mostly interneurons)

III, IV, V - nucleus proprius (nonnoxious stimuli)

VI - lateral neurons (cortico/rubro-spinal neurons)

medial neurons (afferent fr muscle spindles & joints)

IX - alpha motor neurons

lateral horn of spinal chord grey matter

2 parts - what verterbrae levels? what type of neurons? 

what info does clark's column carry?

where do you see it in the spinal chord?

in thoracic & upper lumbar segments only

lateral horn: C8-L2 (can see little nipple like outgrowths) they are preganglionic sympathetic neuron cell bodies

intermediate zone: sacral autonomic nuclei, S2 - S4

Clark's Column (towards the middle) - send unconscious proprioception to cerebellum

These are only in thoracic spinal chord!

Ventral Horn

what two neurons? what are their functions?

how are the neurons arranged somatotopically?

Alpha Motor Neurons - extrafusal fibers of skeletal muscles

Gamma Motor Neurons - supply muscle spindles

proximal muscles have neurons more medial

flexor neurons are more dorsal than extensors

UMN (upper motor neurons)

1. what do they control

2. where are their cell bodies located?

3. what's significant about their location compared to the LMN's

4. thru which tract to most neurons act?

5. what are 3 other places for neurons to origininate from?

1. control lower motor neurons

2. cell bodies are in brain stem & cerebral cortex

3. axons descend in spinal chord & synapse on neurons contralateral to where they are

4. most neurons reach LMN in corticospinal tract

5. other neurons arise from Red Nucleus, Reticular Formation & Vestibular Nuclei

Lower Motor Neurons

1. name two places these are located

1. Located in ventral horn of spinal chord & cranial nerve nuclei in brain stem

Lower Motor Neuron Lesions

1. main effect?

name 4 secondary effects.

1. Flaccid Paralysis

hypotonicity of muscle

absent / hypotonic reflexes

fasciculations (twitching)

muscle atrophy

UMN (upper motor neuron) lesions

1. main effect

name 4 secondary effects

1. spastic paralysis

weakness of muscles (paresis)

hyperflexia

hypertonia

babinski sign

Brown-Sequard Syndrome

what sides are what sensation / motor control affected

compression / lesion of 1/2 of spinal chord

loose motor control & vibration/postion sense on same side as lesion

loose pain & temp on other side as lesion

Syringomyelia

what sense lost? where in comparison with problem?

Why is this sense lost?

Formation of a cyst in central region of spinal chord

Loss of Pain / Temp sensation at / just below it.

due to compression on anterior white commisure

Friedrich's Ataxia

what 3 areas are affected in spinal chord

Degeneration of

Clark's Nucleus & Spinocerebellar tracts

Dorsal Columns

Corticospinal tracts

Central Chord Syndrome (large lesion)

Vibration & position loss

Pain & Temp loss

Motor control loss

Pain / Temp loss

Motor Loss

Subacute combined degeneration

linked with what nutritional deficiency

what affect on motor control?

affect on sensory input?

commonly seen w/ Vit B12 dificiency

Bilateral Spastic Paralysis

Bilateral loss of proprioception & discriminative touch

Amyotrophic Lateral Sclerosis

which neurons affected?

what 2 affects?

Both UMN & LMN affected

Flaccid Paralysis @ level of lesion

Spastic Paralysis below lesion

An affect of Neurosyphilis

Destroys large diameter dorsal root fibers & dorsal column of spinal chord

Symptoms: sensory loss, tabetic gait, incontinence