Class #10 Flashcards
What are the 4 somatosensory modalities?
- Tactile (mechanoreception)
- Thermal
(Thermoception) - Position
(proprioception) - Pain
(nociception)
Explain mechanoreception
The sensation of pressure/vibration. You will often feel the initial response, but will experience total adaptation over time. For example, feel your shirt going on, but then forget about it
Explain thermoception
The sensation of heat. Often you will experience an initial response, and then have partial adaptation. For example, the hot tub is really hot at first and then you will adapt
What is proprioception?
The send of limb/body movement in space without using vision
What is nociception?
The sensation of pain
Define pain
Unpleasant sensory and emotional sensation associated with actual and potential tissue damage
What are the 3 benefits of pain?
- Warns of impending injury
- Motivates seeking help
- Motivates to avoid future injury
Explain the 3 pathways that transmit somatosensory information
- A–> large myelinated fibers, fastest rate of conduction, convey cutaneous pressure, touch, cold/heat, and mechanical pain
- B–> Large, myelinated fibers, transmit information from cutaneous and subcutaneous mechanoreceptors
- C–> “slow pain”
-small, non-myelinated fibers
-Warm/hot, mechanical/chemical/
heat/cold induced pain
Explain the 3 levels of neurone involved in somatic sensation
- first order
- detect the sensation from sensory receptors to dorsal horn neurons - second-order
- occurs in the spinal cord, transmits the information to the thalamus
3, third order
-transmits information from the thalamus to the sensory cortex
How is the somatosensory component of the nervous system different than the specialized senses?
it provides an awareness of the body’s deep and superficial parts as opposed to awareness of the external world
What are the 3 types of sensory neurons present in the somatosensory system?
- General somatic afferent
- pain, touch, temperature - Special somatic afferent
- located in muscles, tendons and joints - General visceral afferent
- located on visceral structures that sense fullness and discomfort
What is a dermatome?
The region of the body wall that is supplied by a single pair of dorsal root ganglia
If your patient loses one dorsal root or root ganglion, will they completely lose sensation in this area? Why or why not?
Reduced but not total loss of sensory innervation of a dermatome, because neighbouring dermatomes overlap one another sufficiently
The _____________ system is considered the basic somatosensory system
tactile
What are free nerve endings responsible for?
They are found in the skin and the cornea, and they detect touch and pressure
What are Meissner corpuscles responsible for?
found in non-hairy parts of the skin like the fingertips, lips and other areas where the sense of touch is highly developed. They are able to adapt in a fraction of a second.
How are Merkel disks different from Meissner corpuscles?
Merkel disks transmit an initial strong signal that diminishes in strength but is SLOW in adapting. They allow for continuous determination of touch against the skin
When you feel a light hair brushing against your lips, what kind of tactile receptor is likely informing you of this?
Meissner corpuscles, because they are extremely sensitive to light touch and low frequency
What type of specialized receptor is specialized for detecting tissue vibration?
pacinian corpuscle immediately beneath the skin and deep in the fascial tissues
Explain the specificity theory
Considers pain to be a separate modality evoked by the activity of specific receptors (nociceptors) that transmit information to pain centres in the brain
How does the pattern theory explain pain?
Pain receptors share pathways and/or nerve endings with other sensory modalities. For example, light touch may not cause pain, but heavy touch of the same area may cause pain
Explain the gate control theory of pain
claims that there are neural gate mechanisms in the spinal cord that can block info from going to the brain by, for example, involving fibers that sense touch
What is the neuromatrix theory of pain?
a multifactoral theory of pain that claims that the brain a widely distributed neural network that contains genetic, cognitive and sensory influences. This theory helps explain phantom limb pain and chronic pain
Define pain threshold
The point at which a nociceptive stimulus is perceived as painful. This threshold is uniform from person to person
Define pain tolerance?
Maximum intensity or duration of pain a person is willing or able to endure. This is variable from person to person, depending on psychological, familial, cultural, and environmental factors
What is acute pain? Explain the early wave and the secondary wave.
Short-lasting pain that ceases when the cause is removed.
EARLY: hyper excites the neuron
SECONDARY: the longer lasting re-percussions of the acute injury, including the inflammatory reaction to the tissue injury
What are the 4 types of chronic pain?
- Highly variable
- not “usual” pain characteristics - Peripheral
- musculoskeletal, organ, vascular - Peripheral-central
- neuralgias, phantom limb pain - Central
- CNS disease or injury
What are the possible negative consequences of chronic pain?
- Psysiological
- loss of appetite, sleep disorders - Psychological
- depression - Familial
- Economic
What is the difference between cutaneous pain and deep somatic pain?
CUTANEOUS -arises from skin, cutaneous tissues -localized sharp, burning DEEP SOMATIC -from deep structures like muscles, tendons, joints, and blood vessels -difuse, radiating pain
What causes visceral pain?
activation of nociceptors of thoracic, pelvic or abdominal viscera.
- extremely sensitive to distension, ischemia and inflammation (diseases)
- Relatively insensitive to cutting/burning
How does visceral pain present in a patient?
- diffuse
- often referred
- deep, squeezing, sickening
- nausea, vomitting, emotional
What is referred pain? Why does this happen?
pain/injury originating in the viscera that is experienced as pain more near the body’s surface
- visceral and peripheral neurons converge
- structures develop nearby as embryo
- *LOOK THIS UP**
Define analgesia
Absence of pain
What is Hyperalgesia
increased sensitivity to pain
If someone has a decreased sensitivity to pain, what is this called?
hypoalgesia
What is hyperpathia?
unpleasant, prolonged response to pain that appears as an explosive overreaction to pain
Define hyperesthesia
Abnormal increase in sensitivity to sensation
What is Hypoesthesia?
Abnormal decrease in sensitivity to sensation
Define paresthesia
Abnormal touch sensation without external stimuli; tingling, pins and needles