Somatic Nervous System Flashcards
Is it voluntary or involuntary?
voluntary
What is the effacer organ?
skeletal muscle
Where is the anatomical boundary between the CNS and PNS?
- axonal processes are the only parts of a neurone that straddle the boundary between the CNS and PNS
- boundary is formed by a anatomically observable zone called the Redlich-Obersteiner’s zone (or root zone)
- located at point where cranial or segmental nerves join the substance of the brainstem ior spinal cord
What are the differences between tumours in the PNS and CNS?
- tumours of the CNS can either by malignant (due to glia) not not malignant (neurones)
- tumours of the PNS are benign
What is the structural difference between efferent and afferent neurones in the somatic system?
efferent = uniaxonal
afferent= pseudounipolar
what are some features of somatic motoneurons?
- have multipolar morphology
- cell bodies either located in ventral horn of spinal cord or cranial nerve motor nuclei of the brain
- largely myelinated (Aα classification)
What are some features of somatic sensory neurones?
- pseudo-unipolar morphology
- levels of myelination vary between functional subtypes
What two categories can motor neurones be split into?
- motoneurones that supply skeletal muscles directly
- motorneurones that supply skeletal muscles indirectly
OR
- upper motor neurones (indirect)
- lower mote neurones (direct)
How many neurones does it take to get from sense organs to CNS?
3
Is there more than one subtype of upper motor neurone?
yes
Is there more than one subtype for lower motor neurones?
no (one type)
How many times does a Schwann cell wrap around an axon?
100x
What diseases cause demyelination of axons?
- multiple sclerosis
- diabetes
- polyneuropathies
- Guillain Barre
What does the epineurium do?
-ensheaths the entire nerve
What does the perineurium ensheath?
a nerve fascicle (collection of axons)
