SHORT Peripheral Nervous System Quiz

Study Notes

The part of the Nervous System that is outside the central nervous system (CNS).
Responsible for communication between the CNS and the rest of the body.

Composed of bundles of axons (nerve fibers), enclosed by connective tissue.
Endoneurium: delicate layer of connective tissue that surrounds each individual axon.
Perineurium: a thicker layer of connective tissue that surrounds groups of axons, forming bundles called fascicles.
Epineurium: outermost layer of connective tissue that encloses the entire nerve.
The endoneurium, perineurium, and epineurium all work together to protect, support, and nourish the axons within the nerve.

Sensory (Afferent) division
- Carries sensory input from the body to the CNS.
- Brings sensory stimuli to the CNS.
- Consists of sensory neurons.
Motor (Efferent) division
- Carries motor commands from the CNS to the body.
- Causes muscles to contract and organs to secrete.
- Consists of motor neurons.
  - Somatic nervous system (SNS)
    - Controls voluntary movements of skeletal muscles.
    - Has a single motor neuron extending from the CNS to the effector (muscle).
  - Autonomic nervous system (ANS)
    - Controls involuntary actions – heart rate, digestion, breathing
    - Regulates and controls the body's internal environment.
    - Has two motor neurons in the pathway – a preganglionic neuron and a postganglionic neuron.

Nerves that connect the CNS to the rest of the body
Spinal nerves (31 pairs) emerge from the spinal cord.
Branch out to innervate everything from the skin and muscles to the organs and glands.

Nerves that connect the CNS to the head, neck, and some organs.
12 pairs of cranial nerves originate from the brainstem.
Each cranial nerve has a distinct function, including sensory input, motor output, or both.

Specialized structures that detect changes in the environment.
All classified by their origin, structure, and function.
Exteroceptors: detect stimuli from the external environment (light, sound, touch, pain, temperature, etc.)
- Mechanoreceptors: detect mechanical stimuli such as pressure, touch, and vibration.
- Tactile corpuscles (Meissner's corpuscles): detect light touch and vibrations.
- Lamellar corpuscles (Pacinian corpuscles): detect deep pressure and vibrations.
- Bulbous corpuscles (Ruffini endings): detect sustained pressure and stretch.
- Hair follicle receptors: detect hair movement.
- Thermoreceptors: detect changes in temperature.
  - Cold receptors: detect cold temperatures.
  - Warm receptors: detect warm temperatures.
- Nociceptors: detect pain
  - Free nerve endings: detect pain, temperature, and pressure.
  - Merkel discs: detect light touch and pressure.
Interoceptors: detect stimuli from internal environments (digestive systems, blood vessels, etc)
- Baroreceptors: detect changes in blood pressure.
- Chemoreceptors: detect changes in chemical composition of the blood.
- Stretch receptors: detect changes in the length of muscles and tendons.
Proprioceptors: detect stimuli from within the body, such as muscle length, joint position, and body movement
- Muscle spindles: detect changes in muscle length.
- Golgi tendon organs: detect changes in muscle tension

Cervical plexus: supplies the skin and muscles of the neck and shoulders.
Brachial plexus: supplies the skin and muscles of the upper limbs.
Lumbar plexus: supplies the skin and muscles of the lower limbs.
Sacral plexus: supplies the skin and muscles of the lower limbs and pelvic region.