Sensory Spinal Cord (Pavlick)

Pavlick

Somatosensation

1st order neuron in _____-

2nd order neuron in ________

3rd order neuron in ________

Terminate in somatosensory cortex (post-central gyrus)

DRG

Spinal cord (decussates)

Thalamus

DRG

egg with halo of satellite cells

Pacinian corpuscle

Vibration

Ruffini ending

Skin stretch

Free nerve ending

nociception

Meissner’s corpuscle

movement across skin (slippage)

Merkel disc

light pressure, edges (reading Braille)

Golgi tendon organ

tension

Muscle spindle

changes in muscle length and rate of length change

First order neuron that conveys ________ stimulus

environmental

Proprioception, 2-point discrimination, vibration

Dorsal Column- Medial Lemniscus

Dorsal Column- Medial Lemniscus detects

Proprioception, 2-point discrimination, vibration

Nociception (pain), temperature, crude touch

Spinothalamic (Anterolateral)

Spinothalamic (Anterolateral) detects

Nociception (pain), temperature, crude touch

Unconscious proprioception/balance

Spinocerabellar tracts

Spinocerabellar tracts does

Unconscious proprioception/balance

Dorsal column in spinal cord get name change in sensory decussation in caudal medulla to the _____ ______

medial lemniscus

not actively thinking about needing to stay in the center and which muscles to contract

Spinocerabellar tract

Responsible for transmitting proprioception, 2-point discrimination, and fine touch

Dorsal-Column Medial-Lemniscus (DCML)

Dorsal-Column Medial-Lemniscus (DCML) above T6 travels through _____ fasciculus

Dorsal-Column Medial-Lemniscus (DCML) below T6 travels through _____ fasciculus

cuneate

gracile

gracile fasciculus

What DCML travels through below T6

cuneate fasciculus

What DCML travels through above T6

2nd order neuron for DCML

cuneate or gracile nucleus in caudal medulla

Decussate to ascend contralaterally as medial lemniscus and synapse on 3rd order neurons in VPL of thalamus

DCML

VPL

Ventral posterior lateral

4th order neurons in

primary sensory cortex

Depending on which part of the body it comes from different synapse point in primary _____ cortex

sensory

Incomplete SCI affecting the dorsal columns

Posterior Cord Syndrome

• Demyelinating disorders (e.g., B12 Deficiency, multiple sclerosis)

• External compression (e.g., tumor)

• Loss of blood supply from posterior spinal artery

• Neurosyphilis → tabes dorsalis

Causes of posterior cord syndrome

Posterior cord syndrome

Sensory ataxia (coordination difficulties, particularly when visual cues are absent)

Decreased sensation of vibration and fine touch

Posterior cord syndrome

tabes dorsalis

Neurosyphilis

posterior cord syndrome

Responsible for transmitting proprioceptive information

Spinocerebellar tracts

Spinocerebellar tracts 2nd order neuron

nucleus dorsalis

Spinocerebellar tract ascend to enter

cerebellum through cerebellar peduncles

Spinocerebellar tract is from spinal cord to ______

cerebellum

Responsible for transmitting nociception, temperature, and crude touch

Spinothalamic Tracts

Spinothalamic tracts 2nd order neuron is in

substantia gelatinosa

Spinothalamic tract decussates within 1-2 levels through

anterior white commissure

Synapses on 3rd order neurons in VPL of thalamus

DCML and Spinothalamic tracts

Spinothalamic tracts project to 4th order neurons in

primary sensory cortex

With respect to somatosensory homunculus

Noxious stimulus damage to tissues

Nociception

another name for the spinothalamic tract?

Anterolateral

Fluid-filled cyst forms within central canal and compromises anterior white commissure (where spinothalamic tract decussates)

Syringomyelia

“cape” distribution of sensory loss

Syringomyelia

central cord syndrome

pain and temperature loss

Syringomyelia

central cord syndrome

compromises anterior white commissure of spinothalamic tract

Lesion above motor/sensory decussation will present with motor/sensory deficits ______ to lesion, while lesion below decussation will present with deficits _______ to lesion

contralateral

ipsilateral

Lumbar spine

Blue DCML

Red ALS spinothalamic tract

Caudal medulla

Somatic sensory decussation

Blue DCML where dorsal column becomes medial lemniscus

Red ALS spinothalamic tract

Caudel medulla at Obex (4th ventricle)

Blue medial lemniscus (DCML)

Red ALS spinothalamic tract

Rostral pons

Boomerang

Blue Ventral medial lemniscus (DCML)

Red ALS spinothalamic tract

Geisha Caudal midbrain level of inferior colliculus

Boomerang still

Blue medial lemniscus

Red ALS spinothalamic tract

Rostral midbrain level of superior colliculus

Red ALS spinothalamic

Blue Medial lemniscus (DCML)

Rostral midbrain level of superior colliculus

Red ALS spinothalamic

Blue Medial lemniscus (DCML)

unpleasant sensory and/or emotional experience which RESULTS FROM THE INTEGRATION of physical stimuli, memory, environment, and/or mental state.

Pain

Pain is a

perception

Midbrain structure which sends descending projections important for pain modulation

Periaqueductal Gray

important for pain modulation

Periaqueductal Gray

Midbrain structure which sends descending projections important for pain modulation:

• Reticular formation

• Raphe nuclei

• Locus coeruleus

• Descending pain control tracts from higher centers (e.g., hypothalamus, forebrain)

Periaqueductal Gray

As afferent pain signals ascend, collateral axons synapse with __________ ____ to activate release of pain modulating products

Periaqueductal gray

area that sends descending projection through brain stem and spinal cord for pain modulation to try to reduce perception of pain.

Periaqueductal Gray

Yellow Periaqueductal gray in brainstem

Pain modulation

Pain modulating products activated by periaqueductal gray

Serotonin

Norepinephrine

Endogenous opiate peptides (e.g., enkephalins)

Periaqueductal Gray

for pain modulation

you just stubbed your pinky toe what do you do after you scream and cuss? Rub it. Why do we rub our stubbed toe?

Gate Theory of Pain Modulation

Override nociceptive signals coming through the spinal cord by highjacking the second order neurons

Pain signals can be interrupted in the _____ _______ of the spinal cord which acts as a gate

substantia gelitanosa

Pain fibers sensing pain signal excites to continue pathway. Rubbing the toe uses a different pathway activating _____ instead of spinothalamic tract. Activating _______ sends excitatory signals to some interneurons that release _______ signals onto the pain pathway.

DCML; DCML

inhibitory

Signals from the DCML pathway are faster than pain signals. Therefore it is not able to react to the pain signal.

Pain activates _______ tract.

Livia sticks to hypogastric region and emits vibration frequencies that hijack the system and help block/reduce change of pain pathway being activated.

spinothalamic tract

A 42-year-old female presents to the emergency department after being shot in the back by a spear-gun while deep-sea fishing. Her vitals are stable but upon examination you find she cannot extend her right knee and has weakened flexion of the hip. She does not respond to vibratory stimuli on her right lower extremity and does not respond to painful stimuli on her left lower extremity, though motor functions are intact. All motor function and sensation is intact for both upper extremities.

Which of the following best explains her presentation?

a.Left spinal cord hemisection at C4

b.Right spinal cord hemisection at C4

c.Left spinal cord hemisection at T12

d.Right spinal cord hemisection at T12

e.Left spinal cord hemisection at L3

f.Right spinal cord hemisection at L3

g.Left spinal cord hemisection at S1

h.Right spinal cord hemisection at S1

DCML and spinothalamic

below decussation for DCML but at decussation for spinothalamic

f.Right spinal cord hemisection at L3

Motor and sensory deficits. Motor issues are on the right. Sensory issues one on the right and one on the left.

Motor issue cannot extend right need and weak flexion of the hip.

In back below motor decussation so ipsilateral to lesion so the right.

Vibration on the right DCML pathway

Pain on the left spinothalamic tract has different decussation tract so it decussates at the level of where the spinal tract is at so contralateral

Sensory below decussation so also ipsilateral on the right for vibration DCML

What level? Return to motor information myoterms extension of knee and hip flexion is at L3.

Lost corticospinal tract on that side laterally

Lost Dorsal column

Lost spinothalamic tract.

Loss of contralateral pain/temperature below level of lesion

Loss of ipsilateral vibration and/ or proprioception below level of lesion

Loss of ipsilateral motor function below level of lesion

Lost spinothalamic tract.

Lost Dorsal column

Lost spinothalamic tract.

Centrally located lesions (i.e., syringomyelia) results in _____ loss of pain/temperature sensation

bilateral

If lesion boundaries are T1-T2, deficits will be observed bilaterally from T2-T3 dermatomes

T1 and T4 dermatomes are “safe”

Spinothalamic tract additional info

Unilateral lesions results in ______ loss of pain/temperature sensation

contralateral