Pain Assessment
The Pain Process: Anatomy and Physiology
- Journey from the site of where the peripheral receptors are stimulated to the spinal
cord, up the spinal cord to the cerebral cortex and back down the spinal cord
- The process begins when nociceptors respond to stimuli causing tissue damage
- These nociceptors are primary sensory nerves located in tendons, muscles and
subcutaneous tissue, epidermis, dermis, and skeletal muscles
- As nociceptors are stimulated, they initiate the second phase of the journey which is to
stimulate sensory peripheral nerves
- These sensory nerve fibers carry pain impulses and include the large A-delta and small C
fibers
- The A-Delta fibers are sharp, pricking, acute or well-localized pain of SHORT duration
- The C fibers are associated with dull, aching, throbbing, or burning sensation that is
diffuse, has a slow onset, and LONG duration
- When these fibers are stimulated by nociceptors, they initiate an action potential that
travels along peripheral nerves to the dorsal horn of the spinal cord.
- Located in the dorsal horn of the spinal cord is the substantia gelatinosa (the gate),
which controls the stimulation of sensory tracts within the spinal cord
- According to the gate theory of pain, when the gate is opened, pain impulses enter the
spinal cord and ascend in the spinothalamic tract to the thalamus, resulting in the
perception of pain
- The third phase of the journey occurs when the thalamus receives impulses from the
spinothalamic tract and sends them to the parietal lobe in the cerebral cortex and onto
the limbic system
- When impulses reach the parietal lob, the patient feels the pain
- Stimulation of the limbic system generates the emotional response to the pain, such as
crying or anger
- The pain journey ends when the body produces substances to reduce the perception of
pain
- As sensory nerve fibers travel through the brainstem, they stimulate descending nerves
that inhibit nociceptor stimuli
- These nerves travel down to the dorsal horn of the spinal cord where they release
substances such as endogenous opioids (endorphins and enkephalins) that inhibit the
transmission of noxious stimuli and produce analgesia.
Types of Pain:
Classification by Duration – Acute: Recent Onset (less than 6 months), results from tissue
damage, self-limiting, ends when tissue heals. Persistent (Chronic): Intermittent or continuous,
lasting more than 6 months
Classification by Pain Pathology –
The Pain Process: Anatomy and Physiology
- Journey from the site of where the peripheral receptors are stimulated to the spinal
cord, up the spinal cord to the cerebral cortex and back down the spinal cord
- The process begins when nociceptors respond to stimuli causing tissue damage
- These nociceptors are primary sensory nerves located in tendons, muscles and
subcutaneous tissue, epidermis, dermis, and skeletal muscles
- As nociceptors are stimulated, they initiate the second phase of the journey which is to
stimulate sensory peripheral nerves
- These sensory nerve fibers carry pain impulses and include the large A-delta and small C
fibers
- The A-Delta fibers are sharp, pricking, acute or well-localized pain of SHORT duration
- The C fibers are associated with dull, aching, throbbing, or burning sensation that is
diffuse, has a slow onset, and LONG duration
- When these fibers are stimulated by nociceptors, they initiate an action potential that
travels along peripheral nerves to the dorsal horn of the spinal cord.
- Located in the dorsal horn of the spinal cord is the substantia gelatinosa (the gate),
which controls the stimulation of sensory tracts within the spinal cord
- According to the gate theory of pain, when the gate is opened, pain impulses enter the
spinal cord and ascend in the spinothalamic tract to the thalamus, resulting in the
perception of pain
- The third phase of the journey occurs when the thalamus receives impulses from the
spinothalamic tract and sends them to the parietal lobe in the cerebral cortex and onto
the limbic system
- When impulses reach the parietal lob, the patient feels the pain
- Stimulation of the limbic system generates the emotional response to the pain, such as
crying or anger
- The pain journey ends when the body produces substances to reduce the perception of
pain
- As sensory nerve fibers travel through the brainstem, they stimulate descending nerves
that inhibit nociceptor stimuli
- These nerves travel down to the dorsal horn of the spinal cord where they release
substances such as endogenous opioids (endorphins and enkephalins) that inhibit the
transmission of noxious stimuli and produce analgesia.
Types of Pain:
Classification by Duration – Acute: Recent Onset (less than 6 months), results from tissue
damage, self-limiting, ends when tissue heals. Persistent (Chronic): Intermittent or continuous,
lasting more than 6 months
Classification by Pain Pathology –
