Wk6 Cranial Nerves Flashcards
What is a nucleus?
Cell bodies of neurones with common functions clumping together (CNS)
What is a ganglion?
Collection of cell bodies of neurones with common functions (PNS)
What is a fibre tract/fasciculus?
A bundle of axons travelling within the CNS
What is a nerve/peripheral nerve?
Bundle of axons travelling in PNS
Peripheral nerves axons
axons are said to be mixed in that they carry electrical signals travelling in two opposite directions
Efferent or motor axons
have their cell bodies in nuclei (i.e. CNS) and their axons convey commands from the brain or spinal cord to skeletal muscles, smooth muscles or glands
Afférent or sensory axons
their cell bodies in dorsal root ganglia and convey sensory information from the body’s surfaces and visceral organs to the CNS (i.e. brain and spinal cord).
What are peripheral nerves split into?
Cranial nerves - those collections of peripheral nerves whose axons connect the brain to/and from targets structures of the head and neck region
Spinal or segmental nerves - axons of spinal or segmental nerves connect the spinal cord to/and from targets structures from all parts of the body apart from the head region.
General somatic afférent
General sensation
Fine touch, crude touch, pressure, pain, temperature
Special somatic afférent
Special sensation
Vision, smell, hearing and balance
General visceral afférent
Pain, temperature, general sensations from viscera
General somatic efferent
Somatic or voluntary
Supply skeletal muscles of the body (trunk and limbs)
General visceral efferent
Visceral or autonomic
Supply smooth muscles, cardiac muscle
Glands
Special visceral efferent or BE
Branchiomotor
Muscles derived from pharyngeal arches
Olfactory nerve (CNI)
distributed to the uppermost part of the nasal cavity and is concerned with smell; it contains only special sensation fibres. It reaches the nose via the cribriform plate of the ethmoid bone and fractures of the ethmoid involving the dura mater may be associated with leakage of CSF from the nose