Peripheral Nervous System Flashcards
Describe the PNS
- PNS can be divided into somatic autonomic nervous
- Sensory (afferent) nerves carry info towards the CNS system
- Motor (efferent) nerves carry information away from the CNA
How many pairs of cranial nerves are there?
12
How many pairs of spinal nerves are there?
31
What is a plexus?
Collection of nerves
What is a spinal nerve named by?
Has letter and number
What is a peripheral nerve named by?
Has name
What is a plexus named after?
Based on either where going or innervating
What does cervical nerves go up to?
C1 - C8
What does thoracic nerves go up to?
T1 - T12
What do lumbar nerves go up to?
L1 - L5
What do sacral nerves go up to?
S1 - S5
What do coccygeal nerves go up to?
Co1
Where do somatic afferent nerves covey information from?
Skin, skeletal muscle and joint
Where do somatic efferent nerves convert information to?
Skeletal muscle
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
Where do visceral afferent nerves carry information from?
the viscera (thoracic, abdominal and pelvic organs)
What can visceral efferent nerves be divided into ?
- Sympathetic and parasympathetic
- Sympathetic efferent nerve innervate the viscera (organs) and periphery (vasculature and sweat glands)
- Parasympathetic efferent nerve innervate the viscera (organs) only
What is a ganglion?
Collection of cell bodies outside the CNA
What is a nucleus?
Collection of cell bodies inside the CNS
What is a plexus?
A network of interconnecting nerves
Where do all afferent (visceral and somatic) fibres have their cell bodies?
In spinal ganglia
Where do visceral efferent nerves synapse?
In a peripheral ganglion
Where is there no parasympathetic outflow to?
The periphery
What are peripheral nerves arranged in ?
fasciculi
What are the three layers of connective tissue?
- External vascular layer - epineurium
- Individual fascicles covered in perineurium
- Individual axons covered in endoneurium
What are the two classification systems of peripheral nerves?
- Based on conduction velocity (A B and C with A fastest)
2. 2 Based on axonal diameter (sensory only) uses roman numeral I-IV with I the largest diameter
What are sensory receptors?
- Detect external or internal information
- Can be classified as source of stimulus or by mode of detection
What are external sensory receptors?
exteroceptors e.g. pain/temp/touch/pressure
What are the different internal sensory receptors?
- Proprioceptors - e.g. movement/joint position
2. Interceptors e.g. movement through gut/ blood pH
What are chemoreceptors?
Detector molecules which bind to receptor, e.g. in olfactory bulb
What are photoreceptors?
Detect light in retina
What are thermoreceptors?
Detect temperature in skin
Wha are mechanoreceptor?
Mechanical opening of ion channels e.g. touch receptors in skin
What are nocieptors?
Detect tissue damage, interpreted as pain
