Term
|
Definition
1. Sub-modality (type)
2. Intensity (strong/weak)
3. Duration and rate of change
4. Location |
|
|
Term
| Route from face sensory receptors? |
|
Definition
| Trigeminal ganglia -> Brainstem -> Thalamus -> Cerebrul Cortex, Somatic sensory cortex |
|
|
Term
| Route from body sensory receptors? |
|
Definition
| Dorsal root ganglia-> Spinal Chord -> Brainstem -> Thalamus -> Cerebrul Cortex, Somatic sensory cortex |
|
|
Term
|
Definition
|
|
Term
| What is the somatosensory system? |
|
Definition
| The somatosensory system is the one which deals with general sensations perceived at the body surface or within its deeper tissues. The principal modalities mediated by this system are the sensations of touch and pressure, position and movement, and pain and temperature |
|
|
Term
|
Definition
-the majority of sensory receptors in the skin.
-terminal branches lose all coverings (including Schwann cell wrapping)
-penetrate into the epidermis almost as superficially as stratum corneum.
-display no obvious structural specialization, but evidence suggests that different fibers respond preferentially to painful stimuli, or warmth or cold, or to mechanical displacement of the skin.
-Free nerve endings are the endings of unmyelinated parent axons (called “C” fibers) or thinly myelinated parent axons (A-delta fibers). |
|
|
Term
| Unencapsulated endings with accessory structures facts and examples? |
|
Definition
-terminal axon branches which end in intimate association with other cell types found in the skin.
-Hair receptors are one example: innervated by several unmyelinated branches which encircle the follicle. The terminal axon membrane is activated by hair deflection.
-Merkel’s touch corpuscle, in which a terminal axon branch expands to form a flattened disc that is closely apposed to a modified epidermal cell (a Merkel cell).
-Merkel cells are connected to neighboring cells via desmosomes, and cytoplasmic protrusions of the Merkel cell enclose the terminal disk of the axon.
-The axons which end in a Merkel’s corpuscle discharge when pressure is applied directly to the corpuscle |
|
|
Term
|
Definition
the terminal axon ends inside a distinct connective tissue capsule
-these endings are often specialized for determining the direction or type of displacing force that acts on the contained sensory nerve terminals.
-In general, the capsule is formed by the overlapping processes of several cells, often fibroblast-like cells, which form concentric lamella separated by fluid, resembling an onion |
|
|
Term
| Encapsulated endings examples? |
|
Definition
-in the skin and joints include Pacinian corpuscles and Ruffini endings—
-these are innervated by the largest diameter, myelinated axons (A-beta fibers), and encode vibratory or pressure information, respectively.
-In skeletal muscle, encapsulated mechanoreceptors include the muscle spindle and, in the myotendinous junction, the Golgi Tendon Organ (GTO) |
|
|
Term
|
Definition
generally encoded by the frequency of action potentials and the numbers of fibers recruited
-increase # of action potentials -> increase # of axons recruited |
|
|
Term
|
Definition
| location is perceived by the position and size of the neuron’s receptive field |
|
|
Term
| Duration and rate of change? |
|
Definition
| determined by the discharge characteristics of the axon: slowly adapting (will continue to discharge action potentials as long as stimulus is applied) vs. rapidly adapting (discharges during onset, offset or changes in intensity). |
|
|
Term
| Muscle afferents: Group 1 |
|
Definition
1a. primary endings in muscle spindles
1b. GTOs
Fiber diameter: 13-20 micrometers
Cond Vel: 80-120 m/sec |
|
|
Term
| Muscle afferents: Group II |
|
Definition
-secondary endings in muscle spindles
-Most encapsulated and unencapsulated endings
Fiber diameter: 6-12 micrometers
Cond Vel: 35-79 m/sec |
|
|
Term
| Muscle afferents: Group II |
|
Definition
-secondary endings in muscle spindles
Fiber diameter: 6-12 micrometers
Cond Vel: 35-79 m/sec |
|
|
Term
| Cutaneous afferents Abeta? |
|
Definition
-Most encapsulated and unencapsulated endings
Fiber diameter: 6-12 micrometers
Cond Vel: 35-79 m/sec |
|
|
Term
| Muscle afferents: Group III |
|
Definition
Nocireceptors (muscle)
Fiber diameter: 1-5 micrometers
Cond Vel: 5-34 m/sec |
|
|
Term
| Cutaneous afferents: Adelta |
|
Definition
Thermoreceptors,nociceptors, small diameter mechano-receptors-many are free nerve endings
Fiber diameter: 1-5 micrometers
Cond Vel: 5-34 m/sec |
|
|
Term
| Mylenation of muscle and cutaneous |
|
Definition
| By definition, Group IV (muscle) and “C” fibers (cutaneous) are unmyelinated; the rest are myelinated heavily (Group I, II, Aß) or thinly (Group III, Adelta). |
|
|
Term
| Muscle afferents, group IV |
|
Definition
nociceptors
(muscle)
Diameter: 0.2-1.5
Cond vel: 0.5-2 |
|
|
Term
|
Definition
Thermoreceptors,nociceptors, small diameter mechano-receptors-many are free nerve endings
Diameter: 0.2-1.5
Cond vel: 0.5-2 |
|
|
Term
| 2 major ascending systems of somatosensory system and purpose |
|
Definition
1. dorsal column-medial lemniscal (DC-ML) system: mechanosensation
2. the spinothalamic (also known as the anterolateral) system: pain and temperature |
|
|
Term
| Composition of ascending pathways? |
|
Definition
| the central processes of DRG cells (the DC-ML pathway) and/or the axons of second, third, or greater-order spinal neurons (found in both the DC-ML system and the spinothalamic system) which receive their information from DRG cell axons |
|
|
Term
| Medial division of dorsal root entry? |
|
Definition
| larger afferents (Groups I, II and A-beta)—proprioception and low-threshold cutaneous mechanoreceptors. |
|
|
Term
| Lateral division of dorsal root entry? |
|
Definition
| smaller afferents (Groups III, IV, A-delta and C)—pain and temperature largely, also inputs from viscera and some high-threshold tactile input |
|
|
Term
|
Definition
Same side as lesion: loss of position and vibration
Opposite side of lesion: Loss of pain and temp
Caused by lateral hemisection of the spinal chord |
|
|
Term
|
Definition
disorder in which a cyst or cavity forms within the spinal cord.
may result in pain, paralysis, weakness,stiffness in the back, shoulders, and extremities. May also cause a loss of the ability to feel extremes of hot or cold, especially in the hands. The disorder generally leads to a cape-like loss of pain and temperature sensation along the back and arms |
|
|
Term
Medial division termination
(see High Yield for more detail) |
|
Definition
| and terminates (if cutaneous afferents) in either laminae III/IV (nucleus proprius) or (if muscle afferents) in laminae VII (Clarke’s column) or IX (motoneuron pools |
|
|
