Peripheral nervous system Flashcards
Somatic afferent nerves convey information from?
Skin, Skeletal muscle and joints
Somatic efferent nerves convey information to ?
Skeletal muscles
What is a Dermatome
An area of skin supplied by a single spinal nerve
What is a myotome?
Group of muscles innervated by a single spinal nerve
What is the difference between what sympathetic and parasympathetic efferent nerves innervate?
Sympathetic - viscera and periphery (vasculature and sweat glands)
parasympathetic - viscera only
What is a plexus?
A network of interconnecting nerves
All afferent fibres have their cell bodies in?
Spinal ganglia
Visceral efferent nerves synapse in a?
Peripheral ganglion
Peripheral nerves structure?
Arranged in fasciculi Three layers of connective tissues Epineurium - external vascular layer Perineurium - indivitual fascicles covered by it Endoneurium - covers individual axons
What are the two classification systems of peripheral nerves?
- Conduction velocity: A being the fastest - B, C etc
2. Axonal diameter (sensory only) use roman numerals, I being largest diameter
Exteroceptors stimuli?
Pain, temp, touch, pressure
Proprioceptors stimuli?
Movement, Joint, Position
Enteroceptors stimuli?
Movement through gut, blood pH
Sensory receptors which are classified by mode of detection?
Chemoreceptors (detector molecules which bind to receptor)
Photoreceptors
Thermoreceptors
Mechanoreceptors (touch opening ion channels)
Nociceptors (tissue damage - pain)
Three examples of proprioceptors?
Muscle spindles: detect muscle length change
Golgi tendon organs: detect tension in tendons
Joint receptors: in joint capsules, detect start and end of movement
What is the smallest functional unit with which to produce force?
A single motor neurone together with all its muscle fibres it innervates (600 muscle fibres)
What is a reflex action?
Involuntary coordinated pattern of muscle contraction and relaxation elicited by peripheral stimuli.
Are there exceptions to the rule that the sympathetic system releases noradrenaline at post ganglionic neurons?
Sweat glands ands blood vessels - acetylcholine is Nt released
Which nerves are a part of the visceral sensory system?
T1-L2, S2-S4, cranial nerves IX and X
Which nerves are a part of the visceral motor system?
Thoracolumbar T1-L2 and craniosacral outflow - Cranial nerves III, VII, IX, X
controls pupils, sweat glands, heart muscles, airways
Where do sympathetic nerves not emerge from?
Cervical cord or low lumbar cord.
come out from thoracic and lumber cord - T1 to L2
What is the lateral horn?
lateral projection of grey matter between the dorsal and ventral horn. contains the neuronal cell bodies of the sympathetic nervous system.
What are paravertebral sympathetic chains?
Run either side of the vertebral column
What is the White ramus communicas?
(white due to its colour as it contains preganglionic neurones which have myelin sheaths) It is a structure that anteriorly connects spinal nerve to sympathetic trunk.
What is they Grey ramus communicas?
When the post ganglionic nerve goes back to the mixed spinal nerve it goes through the grey ramus communicas branch.
What are the nerves surrounding the heart called?
Cardiac plexus, emerging from thoracic segment T1 to T4
The sympathetic nerves can innervate the periphery and the viscera
Where do the neurones for each type synapse?
Visceral : There are no synapses in the sympathetic trunk, they synapse in the pre-aortic ganglia.
compared to sympathetic output to periphery:
these pre-ganglionic nerves can travel through chains and synapse at different levels.
What are splanchnic nerves?
preganglionic nerves go straight to gut through splanchnic nerves. Form greater, lesser and least splanchnic nerves.
