Week 7- Cranial Nerves Flashcards
Where do somatic fibres come to and from?
Somatic structures such as skin, skeletal muscle and joints
Where do visceral fibres come to and from?
Organs
What is the second subgrouping of nerve fibres?
General or special
What are classified as a special fibre?
Special senses - Vision - Hearing - Taste - Smell Muscles that have developed within pharyngeal arches (most muscles of facial expression and of the head)
What are classified as general fibres?
Supply other sense, muscles and glands
What are efferent nerves?
Travel to muscles or glands (motor)
Describe the path of General Somatic Efferent (GSE)
From CNS to skeletal muscle
Describe the path of General Visceral Efferent (GVE)
CNS to smooth or cardiac muscle and glands
Describe the path of Special Visceral Efferents (SVE)
*Brachial Motor* Muscles of the face and neck which develop from pharyngeal arches - muscles of facial expression - mastication - inner ear - stylopharyngeus - pharynx -trapezius - sterncheidomastoid
Except tongue and extraoccular muscles
What do afferent nerves carry?
Sensory information
Describe the pathway of General Visceral Afferents (GVA)
Internal organ receptors to CNS
Describe the pathway of General Somatic Afferents (GSA)
Receptors in skin, muscle, joints to CNS
Describe the pathway of Special Somatic Afferents (SSA)
Special senses; vision, balance, hearing
Describe the pathway of Special Visceral Afferents (SVA)
Special senses; taste and smell
Name the 12 pairs of CNs
Olfactory I Optic II Oculomotor III Trochlear IV Trigeminal V Abducens VI Fascial VII Vestibulocochlear VIII Glossopharyngeal IX Vagus X Accessory XI Hypoglossal XII
What is the mnemonic to remember the cranial nerves?
On occasion out trusty truck acts funny very good vehicle any how
What is the mnemonic to remember the fibre types of each nerve?
Some say marry money but my brother says big brains matter more
What differentiates the olfactory and optic nerves from the rest in terms of origin?
Do not have nuclei in the brainstem or emerge from the brainstem. Instead, they carry the sensory info straight to their primary cortical areas
What is a brainstem nuclei?
Location in the brainstem where each nerve either starts or ends
*some sensory cranial nerves neurons begin in the same nuclei but their neurons leave and merge together to exit the brainstem as separate nerves.
How do mixed neurons come about?
Sensory and motor neurons all group together before exiting the brainstem, therefore looking like one cranial nerve containing a mix of neurons.
What CN number is the olfactory nerve?
I
What is the classification of the Olfactory nerve?
Special Visceral Afferent (SVA)
How can smells inter the body?
Through the nose (orthonasal) or via the oropharynx (retronasal)
What cells form the olfactory nerves?
Bipolar cells
Where are the receptors for olfaction located?
Imbedded in the nasal mucosa (cribriform of ethmoid bone); beginning of the bipolar cells
What is the name of the point of synapse for olfactory neurons?
The glomeruli
Describe the pathway of the olfactory nerve
olfactory nerves—> olfactory bulb—> olfactory tract—> olfactory cortex (piriform) and amygdala
What other senses are also forwarded to the olfactory cortex?
Taste and visual information
How does smell relate to emotion?
Piriform is located near the hippocampus. information is forwarded on to these areas that can trigger emotional responses (amygdala) due to connections with memories
What CN number is the optic nerve?
II
What nerve classification are the optic nerve fibres?
Special Somatic Afferent (SSA)
How does the optic nerve leave the orbit?
Via the optic canal of the skull
Where does the optic nerve transmit visual information from?
The retina
What do optic pathways include?
- Optic nerve
- posterior projections that travel until they synapse to the visual (striate) cortex
What CN number is the oculomotor nerve?
III
What classification are the oculomotor nucleus fibres?
General Somatic Efferent (GSE)
What muscles does the oculomotor nucleus innervate?
- Inferior oblique
- Superior rectus muscle
- Inferior rectus muscle
- Medial rectus muscle
- Levator palpebrae superioris
What classification are the Edinger Westphal nucleus fibres?
General Visceral Efferent