9. Cranial Nerves 4/ Serving Parotid, Tongue, Pharynx and Larynx Flashcards
What are the two different roots of the accessory nerve
Cranial and Spinal
The cranial root of CN XI joins CN X to become its special visceral efferent component from the ______ _________
The cranial root of CN XI joins CN X to become its special visceral efferent component from the nucleus ambiguus
Which CNs are sensory, motor or mixed?
Sensory:
CN I Olfactory
CN II Optic
CN V III Vestibulocochlear
Motor: CN III Oculomotor CN IV Trochlear CN VI Abducens CN XI Spinal accessory CN XII Hypoglossal
Mixed: CN V Trigeminal CN VII Facial CN IX Glossopharyngeal CN X Vagus
CN IX, X & cranial root of XI emerge from the medulla oblongata & pass through the _____ _______
jugular foramen
CN XII emerges from the medulla oblongata & passes through the _____ ______ _______
Anterior condylar canal
Spinal root of CN XI emerges from the superior spinal cord, ascends to the skull via the foramen magnum before passing through the _______ _______
jugular foramen
Function of the CN IX (glossopharngeal)?
Primary function:
General Sensation: (Posterior 1/3) Tongue & Oropharynx (general somatic afferent)
Additional function:
Parasympathetic (general visceral efferent)
Posterior 1/3 Taste/Gustation (special visceral afferent)
Carotid Body & Sinus (general visceral afferent)
Function of the CN X (Vagus)?
Primary function:
General Sensation: Pharynx & Larynx (general somatic afferent) Parasympathetic Heart, Lungs, GI Tract (general visceral efferent)
Additional function:
Motor to Pharynx & Larynx via Cranial Root of XI (special visceral efferent) Epiglottis Taste/Gustation (special visceral afferent)
Aortic Arch & Bodies (general visceral afferent)
Function of the CN XII (hypoglossal)?
Primary function:
Motor: Tongue (general somatic efferent)
Where is the inferior salivatory nucleus located in the brainstem?
Pons
For CN IX, X, XI and XII, one of the nerve components arises from a nucleus in the ____ (inferior salivatory nucleus) with all others arising from nuclei in the medulla oblongata
The spinal tract & nucleus of CN V receive general somatic afferent from CN IX & __ (pharynx & larynx)
The nucleus ______ receives both special (taste/gustation) & general visceral afferent from CN IX & X
The inferior salivatory nucleus (pons) sends general visceral efferent (parasympathetic) to the ______ salivary gland via CN IX
The nucleus ambiguus sends special _______ efferent to the pharyngeal & laryngeal muscles that are derived from pharyngeal arches (4 & 6) via CN IX, X & Cranial XI
The hypoglossal nucleus sends general somatic efferent to the tongue muscles (derived from occipital somites) via CN ____
One of the nerve components arises from a nucleus in the pons (inferior salivatory nucleus) with all others arising from nuclei in the medulla oblongata
The spinal tract & nucleus of CN V receive general somatic afferent from CN IX & X (pharynx & larynx)
The nucleus solitarius receives both special (taste/gustation) & general visceral afferent from CN IX & X
The inferior salivatory nucleus (pons) sends general visceral efferent (parasympathetic) to the parotid salivary gland via CN IX
The nucleus ambiguus sends special visceral efferent to the pharyngeal & laryngeal muscles that are derived from pharyngeal arches (4 & 6) via CN IX, X & Cranial XI
The hypoglossal nucleus sends general somatic efferent to the tongue muscles (derived from occipital somites) via CN XII
Importance of the CN V spinal nucleus for CN IX and X?
For general conscious sensation for the viscera supplied by these nerves
Why is an isolated lesions rare between CN IX and XII at the skull base?
CN IX to XII lie so closely together at the base of the skull that isolated lesions are rare
Nuclei of CN IX (spinal accessory)
INFERIOR SALIVATORY NUCLEUS with parasympathetic secretomotor to parotid gland
SPINAL NUCLEUS OF V for general sensation
SOLITARY NUCLEUS for taste and visceral sensation
AMBIGUUS NUCLEUS sends motor to pharyngeal and laryngeal striated muscles
Nuclei of CN X (vagus)
SOLITARY NUCLEUS for taste and visceral sensation
AMBIGUUS NUCLEUS sends motor to pharyngeal and laryngeal striated muscles
SPINAL NUCLEUS OF V for general sensation
DORAL MOTOR NUCLEUS OF VAGUS with PS to heart, lungs and GI tracts
Nuclei of CN XII (hypoglossal)
HYPOGLOSSAL NUCLEUS for motor to tongue
SPINAL root of XI arising from C1 to C5 supplies the _______ & _______ muscles
Spinal root of XI arising from C1 to C5 supplies the sternocleidomastoid & trapezius muscles
Between which two vessels do the CN IX, X, XI & XII lie?
Internal carotid artery
+
Internal jugular
Hence: CN IX, X, XI all pass through jugular foramen
What nerve does the auriculotemporal nerve branch from?
Receives contribution from which nerve?
What nerve does the auriculotemporal nerve branch from? CN V3
Receives contribution from which nerve? CN IX (glossopharnygeal)
What is the supply of the CN IX?
Somatic motor:
To stylopharnygeus
Visceral PS motor:
Presynaptic PS fibres are provided to the otic ganglion for innervation of the paratid gland.
Somatic sensory:
Branches..
-Tympanic nerve (to middle ear, tympanic membrane and mastoid air cell).
-Carotid sinus nerve to the carotid sinus
-The pharyngeal, tonsillar and lingual nerves to the mucosa of the oropharynx, isthmus of the fauces, palatine tonsil, soft palate, posterior 1/3 of tongue
Special sensory (taste) -From the posterior 1/3 of the tongue to the sensory inferior ganglia of CN IX
Parotid gland innervation
Tympanic nerve forms plexus that supplies parotid gland with pre-synpatic PS supply from the inferior salivatory nucleus. Exit via lesser petrosal nerve. This then passes through foramen ovale and synapses in otic ganglion.
Postganglionic fibres pass to the auriculotemporal nerve, which sends a brnach to the parotid gland
What structures pass through the jugular foramen?
Jugular foramen with internal jugular vein, CN IX, X & XI
Distribution of the CN X?
General sensation from deep auricle & parts of the external acoustic meatus. Also from laryngopharynx and larynx
Taste from vallecula and epiglottis
General visceral sensory afferents from blood vessels (for CVS control), heart, lungs and GI
CN X with Cranial XI Distribution?
Motor supply to the striated muscles of the pharynx & larynx derived from 4th & 6th pharyngeal arches via Cranial Root of XI
Parasympathetic supply to the heart, lungs & GI tract as far as 2/3 along the transverse colon
Defects in which CN affect swallowing & the gag reflex?
Defects in CN IX & X affect swallowing & the gag reflex!
How is the innervation to the pharynx started?
The nerve supply to the pharynx is via the PHARYNGEAL PLEXUS that lies on the external pharyngeal wall (over middle constrictor) & receives branches of CN IX & X as well as cervical sympathetics
The plexus supplies:
-The pharyngeal musculature (plus levator palati, palatopharyngeus & palatoglossus)
-Sensation to the underlying mucous membrane
What is the sensory pharyngeal innervation?
Oropharynx, palatine tonsil, inferior aspect of soft palate & posterior 1/3 of tongue supplied by CN IX
Note: Referred pain to middle ear
Laryngopharynx, vallecula & epiglottis supplied by CN X
What is the motor pharyngeal innervation?
Parasympathetic secretomotor by CN X directly & pterygopalatine ganglion (CN VII) via CN V2
Musculature by CN X except stylopharyngeus that is by CN IX
What is the efferent and afferent fibres in the swallowing gag reflex?
Afferent: CN IX (detects in theOropharynx, palatine tonsil, inferior aspect of soft palate & posterior 1/3 of tongue)
Brainstem nuclei: Nucleus ambiguus
Efferent: CN X (innervates all musculature apart for stylopharyngeus)
What is the efferent and afferent fibres in the sneezing and coughing reflexes?
Afferent: CN V2
Brainstem nuclei: Nucleus ambiguus
Efferent: CN X and X + Phrenic nerve
Course of the CN XII?
CN XII emerges from the HYPOGLOSSAL (anterior condylar) CANAL
- CN XII descends to the neck passing lateral to the internal & external carotid arteries associated with a loop of cervical nerves that supply the STRAP MUSCLES of the NECK
- CN XII enters the oral cavity under the tongue between the mylohyoid & hyoglossus to supply all TONGUE MUSCLES except the palatoglossus that is supplied by CN X via the pharyngeal plexus
If CN XII is injury, what is the clinical sign?
If CN XII is injured there is ipsilateral tongue weakness with deviation to the side of the lesion
What is the tongue innervation?
Anterior 2/3 via:
LINGUAL nerve (CN V3 branch) for general SENSATION
Taste from the NERVUS INTERMEDIUS of CN VIII (chorda tympani hitch-hiking with the lingual nerve)
Posterior 1/3 is by:
CN IX for both general sensation & taste
Motor supply to all muscles is by:
CN XII except palatoglossus that is by CN X via the pharyngeal plexus
Laryngeal innervation?
Internal laryngeal nerve = Sensation to larynx above vocal folds
External laryngeal nerve = Motor to cricothyroid
Recurrent laryngeal nerve = Larynx musculature (apart from cricothyroid) and sensation to larynx below vocal folds
CN X sends the ______ laryngeal nerve that passes with the superior thyroid ____ until it divides into internal & external branches
CN X sends the superior laryngeal nerve that passes with the superior thyroid artery until it divides into internal & external branches
Sensation of the larynx down to just above the vocal folds is by the _____ laryngeal branch that is accompanied by the superior laryngeal artery from the superior ______ artery
Sensation of the larynx down to just above the vocal folds is by the internal laryngeal branch that is accompanied by the superior laryngeal artery from the superior thyroid artery
Recurrent laryngeal is a branch of the….
CN X (vagus)
Course of the recurrent laryngeal nerve?
The recurrent laryngeal passes inferior to the aortic arch on the left (close to the lung hilum) or the subclavian artery on the right.
Then ascends between the trachea & oesophagus to intermingle with branches of the inferior thyroid artery close to the thyroid gland before entering the larynx
Result of complete paralysis of the recurrent laryngeal nerve?
- Vocal fold lying in a semi-abducted position
- Vocal fold vibrates & respiration is noisy
- The voice is hoarse but there is compensation by extra movement of
the opposite fold
Result of Partial paralysis of the recurrent laryngeal nerve?
Vocal fold moves into the midline & even crosses it
Bilateral partial paralysis is life threatening
Result of paralysis of the external laryngeal nerve?
May not be noticed or there may be some hoarseness of the voice Recovery is good due to hypertrophy of the opposite cricothyroid
