PNS Flashcards
What is the PNS divided into?
somatic and autonomic
what other words can be used to describe sensory and motor neurones?
Sensory- Afferent becuase they carry information towards the CNS Motor- Efferent because they carry information away from the CNS
What are the 12 pairs Cranial Nerves?
Optic Trigeminal Facial Glossopharyngeal Vagus Accessory Hypoglossal Vestibulocochlear Abducens Troclear Oculomotor Olfactory
How are spinal cord nerves organised?
31 pairs of spinal nerves that come from spinal cord segments and join up into collection of nerves called plexuses
What are the different plexuses of the spinal cord?
Cervical plexus, Brachial plexus, lumbar plexus, sacral plexus
What do somatic afferent and efferent nerves do?
Afferent- convey info from skin and skeletal muscle joints Efferent- convey information tpo the skeletal muscles
What is a dermatome?
An area of skin that is supplied by a single spinal nerve
What is a myotome?
Group of muscles innervated by a single spinal nerve
What is anaesthesia and parasthesia?
anaesthesia - no sensation parasthesia- change of sensation cause by nerve compression e.g pins and needle
What do visceral afferent nerves do?
They carry information from organs, glands and blood vessels to the CNS and are considered to be part of the autonomic nervous system
What is the viscera?
Thoracic, abdominal and pelvic organs
What does visceral mean?
organs
What can visceral efferent nerves be divided into?
sympathetic- innervate the viscera(organs) and periphery (vasculature and sweat glands) parasympathetic - innervate the viscera only
What is a collection of cell bodies called outside and inside the CNS?
outside- ganglion inside-nucleus
What is a network of interconnecting nerves called?
Plexus
Where are the cell bodies of ALL Visceral afferent fibres whether they are somatic or visceral?
In the spinal ganglia
where are the synapses of visceral efferent nerves?
in peripheral ganglian
Give an overview of the PNS?
PNS -> afferent (sensory) ->general visceral afferents -> general somatic efferents ->efferent(motor)-> general visceral afferents -> general visceral efferents
describe mixed spinal peripheral nerve structure?
Arranged in FASCICULI 3 layers of connective tissue Collection of fascicles is covered by external vascular layer called EPINEURIUM Individual fascicles are covered in PERINEURIUM Individual axons are covered in ENDONEURIUM
How do we classify sensory peripheral nerves?
2 Classifications: One based on CONDUCTION VELOCITY- uses letter A,B,&C with A being the fastest One based on AXONAL DIAMETER- Uses roman numerals I-IV with I being the largest diameter and this type of classification is only used for SENSORY neurones
Which neurones tend to have the fastest conduction?
Those that are highly myelinated and have a large diameter e.g Motor to skeletal muscles, sensory from muscle spindle
Give examples of nerves that conduct more slowly?
Pre/post ganglioic autonomic fibres post usually sensory for pain and temperature
How can sensory receptors detect external and internal stimuli?
External- via exteroceptors e.g. Pain, temperature, touch, presssure Internal- via Proprioceptors e.g movement, joint position OR via Enteroceptors- movement through the gut and blood pH
What are the names of further sensory receptors?
Chemoreceptor(detector molecules which bind to receptor e.e. in olfactory bulb), Photoreceptors, Thermoreceptors, Mechanoreceptors (detect pressure)and Nociceptors (transmit impulses related to tissue damage and can result in pain if it reaches brain)
