Cranial nerves Flashcards
What are the 4 fibre types that make up the cranial nerves?
- General sensory (sense of touch)
- Special sensory (smell, sight, taste, hearing and balance)
- Somatic motor (under conscious control)
- Parasympathetic (both afferent and efferent)
CN I
Fibre type:
Summary of action:
Originates..:
Exits cranial cavity via…:
Sensors in..:
> Olfactory nerve
* 1 fibre type – special sense
* Summary of action: sense of smell
* Originates as an extension of the telencephalon (part of forebrain)
* Exits cranial cavity via cribriform plate
* Sensors in superior part of nasal cavity
CN II
Fibre type:
Summary of action:
Originates..:
Exits cranial cavity via…:
Sensors in..:
> Optic nerve
* 1 fibre type – special sense
* Summary of action: sense of sight
* Originates from diencephalon as a tract or extension
* Exits cranial cavity via optic canal
* Sensors in retina
CN III
Fibre type:
Summary of action:
Originates..:
Exits cranial cavity via…:
Sensors in..:
> Oculomotor nerve
* 2 fibre types – somatic motor and parasympathetic
* Summary of action: motor innervation to majority of extrinsic eye muscles, parasympathetic motor innervation to intrinsic eye muscles
* Originates from anterior surface of midbrain
* Exits cranial cavity through superior orbital fissure
* Targets in and around eye and orbit
CN IV
Fibre type:
Summary of action:
Originates..:
Exits cranial cavity via…:
Sensors in..:
> Trochlear nerve
* 1 fibre type: somatic motor
* Summary of action: motor to superior oblique extrinsic muscle of the eye
* Originates from posterior surface of midbrain
* Exits cranial cavity via superior orbital fissure
* Target in orbit
CN VI
Fibre type:
Summary of action:
Originates..:
Exits cranial cavity via…:
Sensors in..:
> Abducens nerve
* 1 fibre type: somatic motor
* Summary of action: motor innervation to the lateral rectus extrinsic muscle of the orbit
* Originates between pons and medulla
* Exits cranial cavity via superior orbital fissure
* Target in orbit
CN V
Fibre type:
Summary of action:
Originates..:
Exits cranial cavity via…:
Sensors in..:
> Trigeminal nerve
* 2 fibre types: general sensory and somatic motor
* Summary of action: sensation across face and anterior scalp, motor to muscles of mastication 1- temporalis 2- masater
* Originates from pons, with a large sensory ganglion & a number of nuclei
* Exits cranial cavity via superior orbital fissure, foramen ovale and foramen rotundum
> Trigeminal nerve:
1- Name the 3 devisions.
2- What is the specific function of CNV1/2 compared to CNV3?
1.
- CNV1= Ophthalmic branch
- CNV2= Maxillary branch
- CNV3= Mandibular branch
> They all provide general somato-sensation across face and anterior scalp BUT CNV3 the mandibular nerve also has a somatic motor function.
> Trigeminal nerve:
1- What do the 3 devisions innervate?
- CNV1 - tip of nose, above the corner of eye
- CNV2 - from corner of eye to the corner of the mouth (maxilla region)
- CNV3 - from corner of mouth to edge of chin (mandible region)e.g. innervates anterior 2/3 of tongue
- The motor function of mandibular nerve innervates Mastication muscles (muscles which enable chewing)
Where do the CNV exit from out of cranial cavity?
3 regions-
- CNV1= Ophthalmic nerve exit via the superior orbital fissure
- CNV2= Maxillary nerve exit via the foramen rotundum
- CNV3= Mandibular nerve exit via the foramen ovale
How are parasympathetic fibres associated with trigeminal nerves?
> Parasympathetic fibres from other cranial nerves synapse in ganglion and some fibres proceed to join onto a trigeminal branch to reach their destination
CN VII
Fibre type:
Summary of action:
Originates..:
Exits cranial cavity via…:
Sensors in..:
> Facial nerve
* 4 fibre types: special sense, general sense, somatic motor, parasympathetic motor
- Summary of action:
- Somatic motor innervation to the facial expression muscles
- General sensory innervation to part of pinna
- Special sensory and parasympathetic innervation which both run together:
> special sensory innervate
anterior 2/3 of tongue = allows for taste
> parasympathetic counterparts innervate Sub-mandibular and sublingual salivary glands = allows salivation - Parasympathetic innervation = Lacrimal gland and mucosa of nasal cavity and sinus
- Originates from pons-medullary junction
- Exits cranial cavity via internal acoustic meatus
- Where do the CNVII exit from out of cranial cavity?
- After leaving the …. the stylomastoid foramen is the final exit for some branches. What branches emerge from this 2nd exit?
- Internal acoustic meatus
- Parotid plexus
- Posterior auricular nerve
CN VIII
Fibre type:
Summary of action:
Originates..:
Exits cranial cavity via…:
Sensors in..:
> Vestibulocochlear nerve
* 1 fibre type: special sensory
* Summary of action: detection of sense of balance and sense of hearing
* Originates from pons-medullary junction
* Sensors in inner ear in temporal bone
* Exits cranial cavity via internal acoustic meatus
CN IX
Fibre type:
Summary of action:
Originates..:
Exits cranial cavity via…:
Sensors in..:
> Glossopharyngeal nerve
* 4 fibre types: special sensory, general sensory, somatic motor and parasympathetic
* Summary of action:
- special sensory to taste to posterior 1/3 of tongue,
- general sensory to posterior 1/3 of tongue and all pharynx,
- somatic motor innervation to stylopharyngeus,
- parasympathetic to parotid salivary glands
* Originates from upper medulla oblongata
* Sensors and targets around throat
* Exits cranial cavity via jugular foramen
What are the organising principles of the cranial nerves?
> smell and sight
moving eyeballs
touch and movement in anterior half of head
hearing and balance
touch and movement in
posterior half of head
shrugging muscles
tongue
- I & II – smell and sight
- III, IV & VI – moving eyeballs
- V & VII – touch and movement in anterior half of head
- VIII – hearing and balance
- IX & X – touch and movement in
posterior half of head - XI – shrugging muscles
- XII – tongue
Label the exists of cranial nerves from cranium.
Label cranial nerves + cranial foramina.
