Cranial nerves Flashcards
When considering cranial nerves what does general mean?
Same general functions as spinal nerves
When considering cranial nerves what does special mean?
Functions found only in cranial nerves
When considering cranial nerves what do afferent and efferent mean?
Sensory or motor functions respectively
When considering cranial nerves what does somatic mean?
Related to skin and skeletal muscle
When considering cranial nerves what does visceral mean?
Related to smooth muscle, cardiac muscle or glands
SSA
Special somatic afferent meaning it contains special sensory fibers (e.g vision, balance and hearing)
GSE
General somatic afferent meaning it contains motor fibers to striated muscle
GVE
General visceral efferent meaning it contains motor fibers to visceral structures
GSA
General somatic afferent meaning it contains general sensory fibers from skin or muscle (touch, temperature and pain from non visceral structures)
SVE/ BE
Special visceral efferent or branchial efferent innervate muscles derived from the pharyngeal/branchial arches
SVA
Special visceral afferent for special senses such as taste and smell
GVA
General visceral afferent for sensory fibers from smooth muscle, cardiac or glandular tissue
What’s the order of nuclei types from the midline out
Motor
- GSE (III, IV, VI, IX, XII)
- SVE/BE (V, VII, IX/X/nucleus ambiguus)
- GVE (VII/superior salivatory, IX/inferior salivatory, X/dorsal motor nucleus)
Senory
- SVA/GVA (VII, IX, X, solitarius nucleus)
- GSA (V, VII, IX, X, trigeminal nucleus)
- SSA (vestibular, cochlear neuclei)
I
Name the cranial nerve.
What type of fibers does it contain?
What are the functions?
Olfactory
SSA
Special sense of smell
What can cause a unilateral loss of smell?
Meningioma compressing the olfactory bulb
Fracture of the anterior cranial fossa
Which neurodegenerative condition can decrease smell?
Parkinson’s disease
II
Name the cranial nerve.
What type of fibers does it contain?
Which nuclei do these fibers originate from?
What are the functions?
Optic
SSA
Lateral geniculate nucleus (or superior colliculus/pretectal nucleus for pupillary light reflex)
Vision
Which hole does the optic nerve pass through?
Optic canal
III
Name the cranial nerve.
What type of fibers does it contain?
Which nuclei do these fibers originate from?
What are the functions?
Oculomotor nerve
GSE (motor to extra-ocular muscles) from oculomotor nucleus
GVE (parasympathetic to smooth muscles in eye) from Edinger-Westphal nucleus
Which muscles does the oculomotor nerve innervate?
Inferior rectus Medial rectus Superior rectus Inferior oblique Levator palpebrae superioris
Parasympathetic fibres to sphincter pupillae muscle which constricts pupil
Which hole does the oculomotor nerve pass through?
Superior orbital fissure
Where do the pre-ganglionic parasympathetic fibres of CNIII synapse?
ciliary ganglion
What signs and symptoms would you expect for a complete oculomotor nerve palsy?
- Ptosis
- Eye position down and out (Exotropia/divergent squint) due to unopposed lateral rectus/superior oblique
- Dilated, non-reactive pupil
- Consensual light reflex intact in unaffected eye
- Diplopia
What could cause a partial oculomotor palsy?
Pressure on the lateral side of the nerve. Parasympathic functions are impaired.
IV
Name the cranial nerve.
What type of fibers does it contain?
Which nuclei do these fibers originate from?
What are the functions?
Trochlear
GSE
Trochlear nuclei
Innervates the superior oblique muscle so moves eye to look in and down
Which hole does the trochlear nerve pass through?
Superior orbital fissure
What symptom results from a trochlear nerve palsy?
Vertical diplopia (e.g descending stairs or reading)
V
Name the cranial nerve.
What type of fibers does it contain?
Which nuclei do these fibers originate from?
What are the functions?
Trigeminal nerve
GSA (sensory to face, orbit, nose and anterior tongue) from trigeminal sensory nuclei
SVE (motor to muscles of the first branchial (pharyngeal) arch) from the motor nuclei
What are the 3 branches of the trigeminal nerve and which holes do they exit the skull through?
Ophthalmic (superior orbital fissure)
Maxillary (foramen rotundum)
Mandibular (foramen ovale)
What are the branches of the ophthalmic nerve and what areas does it provide sensation to?
Frontal nerve (sensory to upper eyelids, forehead and anterior scalp)
- supraorbital
- supratrochlear
Nasociliary nerve
- long ciliary nerves (sensory to the eye)
- anterior and posterior ethmoidal nerves (sensory to nasal cavity/anterior cranial fossa and ethmoidal air cells/sphenoid sinus respectively and via external nasal branch of anterior ethmoidal, the anterior nose)
- infratrochlear nerve (sensory to medial upper eyelids and sides of the nose)
Lacrimal nerve (sensory to lateral upper eyelid, conjuctiva)
What are the branches of the maxillary nerve and what areas does it provide sensation to?
Zygomatic
- Zygomaticotemporal nerve (skin of the temple)
- Zygomaticofacial (skin of the upper cheek)
Infraorbital (below eye and cheek)
- superior alveolar nerve (maxillary sinus and upper dentition)
Nasal nerves (nasal cavity) - nasopalatine nerve (nasal septum) then passes through the incisive fossa of the hard palate to supply the gums close to the incisors
Greater and lesser palatine nerves pass through the palatine canal and enter the palate via the greater and lesser palatine foramina providing sensation to the mucosa of the hard palate.
Pharyngeal nerve passes through the palatovaginal canal to innervate the mucosa of the nasopharynx.
What are the branches of the mandibular nerve and what are the motor and sensory functions?
Main trunk:
- nervus spinosus (meningeal branch)
- medial pterygoid muscle
- nerve to tensor veli palatini muscle
- nerve to tensor tympani muscle
Anterior division
- deep temporal to the temporalis muscle
- lateral pterygoid muscle
- massetric (masseter and temporomandibular joint)
- buccinator (sensation to skin of lower cheek)
Posterior division
- auriculotemporal (sensory fibres to temporomandibular joint, parasympathetic fibres derived from the lesser petrosal nerve (IX) via the otic ganglion to the parotid gland)
- lingual (sensory fibres to the anterior 2/3 of the tongue, parasympathetic secretomotor fibres and special taste fibres to anterior 2/3 of tongue from the chorda tympani nerve (VII)
- inferior alveolar (nerve to mylohyoid/anterior belly of digastric, sensory branch to mandibular teeth, sensation to lower lip and chin via mental foramen)
Which muscles are innervated by the trigeminal nerve?
- lateral pterygoid
- medial pterygoid
- temporalis
- masseter
- tensor veli palatini
- tensor tympani
- nerve to mylohyoid
- anterior belly of digastric
VI
Name the cranial nerve.
What type of fibers does it contain?
Which nuclei do these fibers originate from?
What are the functions?
Abducent
GSE
Abducens nuclei
Innervates lateral rectus muscle and laterally rotates eye
What is the path of the abducent nerve?
- Leaves branstem between pons and the pyramids of the medulla.
- Pierces the dura and runs through the cavernous sinus lateral to the internal carotid artery.
- Enters the orbit via the SOF.
What are the signs and symptoms of a abducent nerve palsy?
Horizontal diplopia
Esotropia (convergent squint)
No lateral movement
VII
Name the cranial nerve.
What type of fibers does it contain?
Which nuclei do these fibers originate from/to?
What are the functions?
Facial nerve
SVE/BE (motor to facial muscles) from facial motor nucleus
GVE (motor to glands- salivary, nasal, lacrimal) from superior salivatory nucleus
GSA (sensory to skin of ear) to trigeminal nucleus
SVA (special sense of taste to anterior 2/3 of tongue) to solitatory nucleus
Which holes does the facial nerve enter and exit the skull?
Enters: internal acoustic meatus Exits: - main motor root- stylomastoid foramen - greater petrosal nerve- hiatus of the greater petrosal nerve - chorda tympani- petrotympanic fissure
Which nerves form the facial nerve?
A large motor root and a small sensory root (nervus intermedius).
What are the branches of the facial nerve? Which muscles do they innervate
Greater petrosal nerve
Nerve to stapedius
Chorda tympani
Posterior belly of digastric
Stylohyoid
Branches that exit the parotid gland:
- Posterior auricular (posterior auricular muscles and occipitalis)
- Temporal (supraorbital and forehead muscles)
- Zygomatic (infraorbital, nasal and upper lip muscles)
- Buccal (cheek and lip muscles)
- Marginal mandibular (lowe lip and chin muscles)
- Cervical (Platysma)
VIII
Name the cranial nerve.
What type of fibers does it contain?
Which nuclei do these fibers originate from/to?
What are the functions?
Vestibulocochlear nerve
SSA (hearing and balance)
To vestibular and cochlear nuclei
IX
Name the cranial nerve.
What type of fibers does it contain?
Which nuclei do these fibers originate from/to?
What are the functions?
Glossopharyngeal nerve
GSA (posterior 1/3 tongue, oropharynx, palatine tonsil, auditory tube, middle ear) to sensory nucleus V
SVA (taste to posterior 1/3 of tongue) to nucleus solitarius
GVA (from carotid body and sinus) to nucleus sloitarius
GVE (parasympathetic to parotid gland) from inf salivatory nucleus
SVE/BE (stylopharyngeus muscle) from nucleus ambiguus
Through what does the glossopharyngeal nerve exit the skull?
Jugular foramen
X
Name the cranial nerve.
What type of fibers does it contain?
Which nuclei do these fibers originate from/to?
What are the functions?
Vagus nerve
SVE/BE (muscles pharynx except stylopharyngeus, muscles of soft palate except tensor veli palatini, intrinsic laryngeal muscles and palatoglossus)) from nucleus ambiguus
GVE (smooth muscle and glands of larynx, pharynx, thoracic viscera and abdominal viscera to midgut/hindgut junction) from dorsal motor nucleus
GVA (thoracic viscera (oesophagus, bronchi, lungs, heart, including aortic baro/chemoreceptors) and abdominal viscera to midgut/hindgut junction) to nucleus solitarius
GSA (laryngopharynx, larynx, dura of poserior cranial fossa, part of external acoustic meatus and auricle) to trigeminal nucleus
SVA (Taste from posterior margin of tongue, epiglottis and pharynx) to nucleus solitarius
What is the path of the vagus nerve?
Leaves medulla posterior to the olive, passes into jugular foramen, descends neck in carotid sheath (with common/internal carotid artery, internal jugular vein)
XI
Name the cranial nerve.
What type of fibers does it contain?
Which nuclei do these fibers originate from/to?
What are the functions?
Spinal accessory nerve
GSE (innervates SCM, trapezius) from XI nucleus
XII
Name the cranial nerve.
What type of fibers does it contain?
Which nuclei do these fibers originate from/to?
What are the functions?
Hypoglossal nerve
GSE (intrinsic muscles of the tongue as well as some extrinsic; hyoglossus, styloglossus and genioglossus) from hypoglossal nucleus
What’s the path of the hypoglossal nerve?
- leaves medulla between olives and pyramids
- entery the hypoglossal canal
- leaves the canal and runs lateral to the occipital, internal carotid, external carotid and lingual arteries
- passes above the greater cornu of the hyoid bone, running lateral to hyoglossus and deep to mylohyoid
