Cranial nerves Flashcards
What are the 12 cranial nerves?
I - Olfactory
II - Optic
III - Occulomotor
IV - Trochlear
V - Trigeminal
VI - Abducens
VII - Facial
VIII - Vestibulocochlear
IX - Glossopharyngeal
X - Vagus
XI - Accessory
XII - Hypoglossal
Function of cranial nerves
provide sensory and motor nerve supply to head and neck
Which cranial nerves contain parasympathetic nerve fibres?
Oculomotor (III), Facial (VII), Glossopharyngeal (IX), Vagus (X)
Name of nerve that carries information from the brain to the periphery
efferent (motor) nerve
Name of nerve that carries information from the periphery to the brain
afferent (sensory) nerve
What are mixed cranial nerves?
Carry information from the periphery to the brain (afferent), and from the brain to the periphery (efferent)
What does it mean if a nerve is classified as special?
If the nerve carries information from our special senses (vision, smell, gustation, hearing, balance).
What does it mean if a nerve is classified as general?
Carries information from/to everywhere else in the body except special senses e.g. other sensory information - touch, pressure, pain, temp.
What does it mean if a nerve is classifies as somatic?
The nerve carries information to/from the skin or skeletal muscles.
What does it mean if a nerve is classifies as visceral?
Carries information to/from internal organs
How are nerves classified?
Special/general, somatic/visceral, afferent/efferent
What is CN I?
Olfactory nerve - special somatic afferent (sensory) nerve that innervates the olfactory mucosa within nasal cavity.
Function of CN I
Olfactory nerve carries information about smell from the nasal cavity to the brain. (sensory)
What is CN II?
Optic nerve - special somatic afferent (sensory) nerve that innervates the retina.
Function of CN II
Optic nerve - sensory. Carries visual information from the retina to the brain.
What is CN III?
Oculomotor nerve - somatic and visceral efferent (motor) nerve. Innervates all extraocular muscles except those supplied by CN IV (trochlear) and CN VI (abducens) - superior oblique and rectus muscles
Function of CN III
Oculomotor nerve innervates most extraocular muscles (except superior oblique and lateral rectus). Enables eye movement, pupil constriction (miosis) and lens adjustment.
What is CN IV?
Trochlear nerve - general somatic efferent (motor) nerve that innervates the superior oblique muscle.
Function of CN IV
Trochlear nerve innervates the superior oblique muscle, playing a role in eye movement (down and out).
What is CN V?
Trigeminal nerve - mixed nerve containing both special visceral efferent (motor) and general somatic afferent (sensory) nerve fibres.
What do the motor fibres in the trigeminal nerve (CN V) innervate?
Muscles of mastication, mylohyoid
What do the sensory fibres of the trigeminal nerve (CN V) supply?
Scalp, face, orbit, sinuses, anterior 2/3 of tongue.
3 divisions of the trigeminal nerve (CN V)
Ophthalmic nerve (CN V1), maxillary nerve (CN V2), mandibular nerve (CN V3).
Dermatomes of CN V1 (ophthalmic nerve)
Forehead, orbit, nose
Dermatome of CN V2 (maxillary nerve)
Zygomatic region and upper lip
Dermatome of CN V3 (mandibular nerve)
Innervates buccal skin, lower lip, skin of mandibular region
What is CN VI?
Abducens nerve - general somatic efferent nerve (motor) that innervates lateral rectus muscle (one of the extraocular muscles).
Function of CN VI
Abducens nerve is involved in eye movement by innervating the lateral rectus muscle.
What is CN VII?
Facial nerve - sensory and motor (and parasympathetic) nerve fibres.
What do the sensory fibres of the facial nerve (CN VII) innervate?
middle ear, nasal cavity, soft palate, anterior 2/3 of tongue
What do the motor fibres of the facial nerve (CN VII) innervate?
Muscles of facial expression, and lacrimal, submandibular, sublingual, basal and palatine glands.
Function of facial nerve (CN VII)
Facial expressions, secretion of glands, gustation.
What is CN VIII?
Vestibulocochlear nerve - special somatic afferent nerve (sensory).
What are the 2 parts of CN VIII?
The vestibulocochlear nerve is comprised of the vestibular nerve and cochlear nerve.
Function of cochlear component of vestibulocochlear nerve (CN VIII)
Enables hearing
Function of vestibular component of vestibulocochlear nerve (VIII)
Mediates balance and motion
What is CN IX?
Glossopharyngeal nerve - motor (and parasympathetic) and sensory nerve fibres.
What do the motor fibres of the glossopharyngeal nerve (IX) innervate?
Pharyngeal constrictors, parotid gland, stylopharyngeus.
What do the sensory fibres of the glossopharyngeal nerve innervate?
Posterior 1/3 of tongue, middle ear, pharynx, epiglottis, soft palate, tonsils
Function of CN IX
Glossopharyngeal nerve enables deglutition, salivation, gustation, sensation in oral cavity.
What is CN X?
Vagus nerve - motor (parasympathetic) and sensory fibres.
What do the motor fibres of the vagus nerve (X) innervate?
Thoracic and abdominal viscera (heart, lungs, bronchi, GIT), laryngeal and pharyngeal muscles.
What do the sensory fibres of the vagus nerve (X) innervate?
epiglottis, thoracic and abdominal viscera (heart, lungs, bronchi, trachea, larynx, pharynx, GIT, external ear).
Function of CN X
Vagus nerve controls gland secretion, peristalsis, rest and digest (slows heart rate and breathing, increases gut motility).
What is CN XI?
Accessory nerve - efferent nerve (motor) that innervates the sternocleidomastoid, trapezius and laryngeal muscles.
Function of CN XI
Accessory nerve allows neck movement by innervating the sternocleidomastoid muscle, and shoulder raises by innervating the trapezius muscles, and phonation by innervating the laryngeal muscles.
What is CN XII?
Hypoglossal nerve - general somatic efferent nerve that innervates muscles of the tongue.
Function of CN XII
Hypoglossal nerve enables tongue movements by innervating intrinsic and extrinsic tongue muscles (except palatoglossus).
