PNS Overview Flashcards
What structure of a neuron conducts APs away from the cell body?
Axon
What is the function of dendrites?
Communicate with adjacent neurons
The myelin sheath surrounding the axon does what?
Ensures fast conduction of action potentials
What produces the myelin sheath in the PNS?
Schwann cells
What are the two main types of neurons?
Multipolar
Unipolar
A multipolar neuron contains two or more what?
Dendrites
What is a nerve?
A collection of axons bundled together and cased within connective tissue
What cranial nerves arise from the forebrain?
CNs I and II
What cranial nerves arise from the midbrain?
CNs III and IV
What cranial nerve arises from the pons?
CN V
Where do cranial nerves VI, VII and VIII arise from?
Junction between pons and medulla
What cranial nerves arise from the medulla?
CNs IX, X and XII
Why is the accessory nerve not considered a true cranial nerve?
As it arises from the spinal cord
Within what structure is a spinal nerve only found?
Intervertebral foramina
What does a spinal nerve branch into?
Anterior and posterior rami
A spinal nerve is formed by what coming together?
Anterior and posterior roots
A root is formed by the joining of what?
Rootlets
The anterior horn of the spinal cord only ever contains what fibres?
Motor fibres
The posterior horn of the spinal cord will only ever contain what fibres?
Sensory fibres
Where do motor and sensory fibres mix?
At the spinal nerve
What landmarks are represented by the T4 and T10 dermatomes?
T4 - male nipple
T10 - umbilicus
Sympathetic axons leave the spinal cord at what levels?
T1-L2
What prevertebral ganglia for sympathetic outflow are located in front of the abdominal aorta?
Celiac
Aorticorenal
Superior mesenteric
Inferior mesenteric
Presynaptic parasympathetic axons leave the CNS via what?
CNs III, VII, IX and X
Sacral spinal nerves
