PNS, Ch 13 Flashcards
Originate from spinal cord and innervate structures below the head and neck. Anterior root contains motor neurons from its horn. Posterior root contains sensory neurons that enter its horn. Posterior/dorsal root ganglion fuses with anterior root to create this. 31 pairs.
Spinal nerves
Attach to the brain and mainly innervate structure of the head and neck. Some are purely sensory, others are mixed, others are mostly motor. 12 pairs.
Cranial nerves
Each axon in a fascicles is surrounded by its own connective sheath called?
Endoneurium
Motor and sensory axons making up a nerve are held together by a connective tissue sheath called?
Epineurium
What binds fascicles together in a nerve?
Perineurium
Fight or flight division of the ANS. Maintains homeostasis when the body is involved in any type of physical work and mediates the body’s visceral responses to emotion.
Sympathetic nervous system
The rest and digest system of the ANS. Plays a role in digestion and in maintaining the body’s homeostasis at rest.
Parasympathetic nervous system
Oh, Oh, Oh
I Olfactory
II Optic
III Oculomotor
They Traveled And Found
IV Trochlear
V Trigeminal
VI Abducens
VII Facial
Voldemort Guarding Very Ancient Horcruxes
VIII Vestibulocochlear IX Glossopharyngeal X Vagus XI Accessory XII Hypoglossal
After leaving the vertebral cavity, the spinal nerve splits into two nerves. One travels to the posterior side of the body. The other travels to the anterior and/or the upper and lower limbs. Mixed nerves that carry sensory and somatic motor info.
Posterior ramus
Anterior ramus
Small branches from the anterior ramus that contain visceral motor or autonomic neurons of the sympathetic nervous system, and so are not mixed.
Rami communicantes
What do the 31 pairs of spinal nerves consist of?
8 cervical 12 thoracic spinal 5 lumbar 5 sacral 1 coccygeal
The anterior rami of the cervical, lumbar, and sacral spinal nerves come together and merge to form networks of nerves called this.
Nerve plexuses
What are the four spinal nerve plexuses?
Cervical
Brachial
Lumbar
Sacral
Sensory receptors that are typically close to the surface of the body, detecting stimuli originating outside of it.
Exteroceptors
Sensory receptors that generally lie within the body’s interior, detecting stimuli originating from inside the body.
Interocepters
Encapsulated exteroceptors or interocepters found in the skin, musculoskeletal, and viscera. Specialized mechanically gated ion channels.
Mechanoreceptors
Exteroceptors that respond to thermal stimuli. Most are slowly adapting receptors.
Thermoreceptor
Exteroceptors or interoceptor that depolarizers in response to certain chemicals. Internals detect hydrogen ion concentration, the level of carbon dioxide, and the level of oxygen in the body’s fluids. Externals are for smell and taste.
Chemoreceptor
Sensory exteroceptors found only in the eye that depolarize in response to light.
Photoreceptors
Sensory receptors that depolarize in response to nociception and pain. Generally exteroceptors. Slowly adapting.
Nociceptors
The detection of noxious stimuli, and the perception and interpretation of these stimuli.
Nociception
Pain
Tapered structures that are found embedded among the regular contractile muscle fibers.
Muscle spindles
The fibers are extrafusal muscle fibers
Within each muscle spindle are 2-12 of these. They have contractile filaments composed of actin and myosin at their poles, with a central area where contractile filaments are absent.
Intrafusal muscle fibers
Two types of structural and functional classes of sensory neurons innervate the intrafusal fibers. Contain mechanically gated ion channels that open when the fibers are stretched. The first responds during initiation, the second responds to the static length and the position of a limb.
Primary afferent
Secondary afferent
Mechanoreceptors composed of an encapsulated bundle of collagen fibers attached to muscle ones. Single somatic sensory axon whose endings are wrapped around collagen fibers. Monster tension generated by contraction.
Golgi tendon organs
Reflex arc that involves only a single synapse within the spinal cord between the sensory and motor neurons.
One that involves multiple synapses.
Monosynaptic arc
Polysynaptic arc
The body’s reflexive response to shorten a muscle so that it returns to its optimal length via a monosynaptic reflex.
Simple stretch reflex
When tension in the muscle and tendon increase dramatically, the Golgi tendon organs signal the spinal cord and cerebellum, causing events that lead to muscle relaxation. Polysynaptic.
Golgi tendon reflex
Involves rapidly conducting nociceptive afferents and multiple synapses in the spinal cord, a polysynaptic reflex.
Flexion/withdrawal reflex
Occurs simultaneously with the flexion reflex. Helps keep balance and protects when withdrawing from pain stimuli.
Crossed-extension reflex
Most peripheral neuropathies. Often result from injury to a spinal or cranial nerve or to these cell bodies in the spinal cord. Prevents alpha-motor neuron from stimulating a skeletal muscle fiber to contract, can’t respond to feedback from muscle spindles.
Lower motor neuron disorders
Paralysis
Paresis
Reduction or absence of stretch reflexes and muscle tone
Conditions that result from damage or disease anywhere along the pathways from the motor cortices to the spinal cord.
Upper motor neuron disorders Spinal shock Spasticity Babinski sign Plantar reflex
