Spinal Cord: Cells, Receptors Reflexes

Front 1

Functions of the spinal cord

Back 1

1. sensory
2. motor
3. reflex

Front 2

The 3 types of sensory receptors and their cells?

Back 2

TACTILE
Meissner
Pacinian
Ruffini
Merkel
PROPRIOCEPTION
muscle spindles
joint receptors
Golgi tendon organs
PAIN (&TEMP)
free (nociceptors)

Front 3

TACTILE FIBRES

Back 3

Tactile: all alphabeta fibres or group 2
- medium size (6-12um)
- pretty quick (30-70m/s)
- all mylenated
BUT Differ in their locations and functions

Front 4

TACTILE LOCATIONS AND FUNCTIONS

Back 4

Meissner: glabrous (hairless) skin F: touch and press
Pacinian: Subcut. F: deep press, vibration
Ruffini: all skin F: stretch
Merkel: All skin F: touch and press

Front 5

PROPRIOCEPTION fibres

Back 5

- pretty quick (70-120m/s)
- all myleinated
- v.sensitive to relaxation

Front 6

PROPRIOCEPTION Receptors

Back 6

Muscle spindles: location in muscles and function in muscle legth (propioception)

Front 7

Grey Matter cells

Back 7

1. Spinal cells
- projection cells (large, MAKE, PNS and CNS, EXCITE)
- interneurons (Small, MODIFY, LOTS (7:1), inhbit or Excite)

Front 8

Subdivisions of the spinal cord

Back 8

(1) dorsal horn: somatic sensory
- tactile, pain*, proprioception
- tract cells, interneurones
(2) intermediate grey matter: autonomic
- sympathetics (thoracic/lumbar)
- parasympathetics (sacral)
(3) ventral horn: somatic motor
- α motoneurones (motor end-plate), γ motoneurones (spindles)

Front 9

Degeneration and Regeneration

Back 9

• little CNS regrowth
- NoGo, glial scars, afferents? (may provide nutrition)
- some plasticity: sprouts, synapses
• PNS better regrowth
- different stages after injury
- motor/sensory nerve preferences
• why so little?
- no connection better than wrong one?

Front 10

NoGo

Back 10

protein made by oligodendrocytes, inhibits regeneration

Front 11

Adult Neurogenesis

Back 11

• no set cell number
• cell birth in adult: STEM CELLS
- subventricular zone
- subgranular zone hippocampus (memory)
• new cells:
- survive and work
- do not live long
- learning and exercise helps survival
- stress not good

Front 12

Reflexes

Back 12

Front 13

Clinical Testing POPULAR

Back 13

Front 14

the 4 reflexes?

Back 14

Stretch
Gamma reflex loop
Flexor reflex
golgi tendon

Front 15

The stretch Reflex

Back 15

- muscle tone
- movement: reflex contraction
(deep tendon)
NB: synapse on inhibitory (-) interneurone (antagonists)

Front 16

(2) γ reflex loop

Back 16

- prompted contraction/tone from higher centres
- tricks into stretch

Front 17

Flexor reflex

Back 17

- movement: reflex contraction
- withdrawal of limb (eg pain)
- several levels/joints involved (they go up ad sown a few spinal levels so if your hand is affected by a noxious stimulus the shoulder and trunk are also pulled away

Front 18

(4) Golgi tendon reflex

Back 18

- STOP contraction
- releases tension (eg, heavy loads), too heavy the tendons under too much stress

Front 19

Ramus

Back 19

communication between 2 nerves

Front 20

Gray and white communicating rami

Back 20

When used without further definition, it almost always refers to a communicating branch between a spinal nerve and the sympathetic trunk. More specifically, it usually refers to one of the following:
Gray ramus communicans:
White ramus communicans

Front 21

Gray Communicating Rami

Back 21

umyelinated, postganglionic sympathetic fibres
- found at all levels

Front 22

White Communicating Rami

Back 22

myelinated preganglionic sympathetic fibres
- T1- L3
- lateral and intermediolateral cell column

Front 23

Termination of Conus Medullaris

Back 23

L3 in newborns
Lower border L1 in adults

Front 24

Cauda Equina

Back 24

Motor and sensory roots L2-Co
- subarachnoid below conus medullaris

Front 25

Major Motor and Sensory Nuclei of the Spinal Cord

Back 25

1. ciliospinal center of Budge (C8-T1)- SNS eye
2. Intermediolateral cell cloumn; C8-L3; entire SNS
3. nucleus dorsalis of clark; C8-L3; dorsal spinocerebellar tract
4. Parasympathetic nucleus (S2-4).

Front 26

Myotatic Reflex

Back 26

- afferent; spindle, DRG & Ia fiber
- efferent: ventral horn motor neuron

Front 27

Gamma motor neurons

Back 27

Gamma motoneurons (γ-motoneurons), also called gamma motor neurons, are a type of lower motor neuron used in the process of muscle contraction, and represents about 30% of fibers going to the muscle.[1] Like alpha motor neurons, another type of motor neuron, its cell bodies are located in the anterior horn of the spinal cord

Front 28

Oligodendrocytes

Back 28

Oligodendrocytes (from Greek, meaning cells with a few branches), or oligodendroglia (Greek, few tree glue),[1] are a type of brain cell. They are a variety of neuroglia. Their main functions are to provide support and to insulate the axons (the long projection of nerve cells) in the central nervous system (the brain and spinal cord) of some vertebrates. (The same function is performed by Schwann cells in the peripheral nervous system.) Oligodendrocytes do this by creating the myelin sheath, which is 80% lipid and 20% protein.[2] A single oligodendrocyte can extend its processes to 50 axons, wrapping approximately 1 μm of myelin sheath around each axon; Schwann cells, on the other hand, can wrap around only 1 axon. Each oligodendrocyte forms one segment of myelin for several adjacent axons