Cranial Nerves 4 Flashcards
What do the cranial root of CN XI joining CN X become?
The special visceral efferent component from the nucleus ambiguus
Describe the course of CN IX, X and the cranial root of XI.
Emerge from the medulla oblongata and pass through the jugular foramen
Describe the course of the 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.
Describe the course of CN XII.
Emerges from the medulla oblongata and passes through the hypoglossal canal (anterior condylar canal)
What is the function of the glossopharyngeal nerve (CN IX)?
PRIMARY:
General Sensation: (Posterior 1/3) Tongue & Oropharynx (general somatic afferent)
ADDITIONAL:
Parasympathetic (general visceral efferent)
Posterior 1/3 Taste/Gustation (special visceral afferent)
Carotid Body & Sinus (general visceral afferent)
What is the function of the vagus nerve (CN X)?
PRIMARY:
General Sensation: Pharynx & Larynx (general somatic afferent) Parasympathetic Heart, Lungs, GI Tract (general visceral efferent)
ADDITIONAL:
Motor to Pharynx & Larynx via Cranial Root of XI (special visceral efferent) Epiglottis Taste/Gustation (special visceral afferent)
Aortic Arch & Bodies (general visceral afferent)
What is the function of the hypoglossal nerve (CN XII)
Motor: Tongue (general somatic efferent)
What are the nuclei of CN IX?
- CN IX inferior salivatory nucleus with parasympathetic secretomotor to parotid gland (in the pons)
- CN IX & X (also CN VII) solitary nucleus for taste and visceral sensation (in the medulla)
- CN IX & X nucleus ambiguus to striated muscles of pharynx and larynx (in the medulla)
- Spinal nucleus of CN V also receiving general sensation from CN IX & X (in the medulla)
What are the nuclei of CN X?
- CN IX & X (also CN VII) solitary nucleus for taste & visceral sensation (in the medulla)
- CN IX & X nucleus ambiguus to striated muscles of pharynx & larynx (in the medulla)
- Spinal nucleus of CN V also receiving general sensation from CN IX and X (in the medulla)
- CN X dorsal nucleus with parasympathetic to heart, lungs and GI tract (in the medulla)
What are the nuclei of CN XII?
- CN XII hypoglossal nucleus for motor to tongue (in the medulla)
Describe the course and distribution of CN XI spinal root?
Spinal root of XI arising from C1 to C5, going through the jugular foramen, and crossing the posterior triangle of the neck supplies the sternocleidomastoid & trapezius muscles
Describe the course and distribution of CN IX?
- CN IX emerging from the jugular foramen, adjacent to the wall of the pharynx, with CN X & XI
- General visceral afferent (sensory) supply from the carotid body (chemoreceptors) & carotid sinus (baroreceptors) for reflex cardiovascular control
- Tympanic branch of CN IX to middle ear (general sensation), tympanic membrane & mastoid air cells. (also contains preganglionic parasymp. neurons for the parotid gland that leave the plexus in the lesser petrosal nerve)
- Taste fibres from posterior 1/3 of tongue (general sensation to posterior 1/3 of tongue, tonsils and oropharynx)
Describe the course of the lesser petrosal nerve.
Lesser Petrosal nerve escapes from the middle ear & lies on the surface of the petrous temporal bone in the middle cranial fossa before emerging through the foramen ovale
Describe the innervation of the parotid gland.
- Tympanic branch of CN IX carrying preganglionic parasympathetics from the inferior salivatory nucleus to the tympanic plexus (also receiving somatic sensation via CN IX)
- Gives off lesser petrosal nerve passing through foramen ovale & synapsing in otic ganglion (suspended from CN V3)
- Postganglionic fibres passing to the auriculotemporal nerve that sends a branch to the parotid gland
What is the distribution of the vagus nerve (CN X)?
- General sensation from the laryngopharynx & larynx
- General sensation from deep auricle & parts of the external acoustic meatus
- General visceral sensory afferents from blood vessels for control of CVS plus afferents from the heart, lungs & GI tract
- Taste from the vallecula & epiglottis
- 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