Please enable JavaScript.
Coggle requires JavaScript to display documents.
Cranial Nerves (CN X (Vagus nerve) (Recurrent laryngeal nerves (loop…
Cranial Nerves
CN X (Vagus nerve)
Sensory: somatic, special sensory (taste), visceral sensory
Motor: somatic ad visceral motor
Somatic sensory from inferior pharynx and larynx, vagus provides afferent limb of cough reflex stimulated by foreign irritants, preventing aspiration and infection
-
Taste and somatic sensation from root of tongue and taste buds on epiglottis. Branches of internal laryngeal nerve supply a small area, mostly somatic sensory but also some special sensory (taste)
Somatic (branchil) motor to soft palate, pharynx, intrinsic laryngeal muscles and a nominal extrinsic tongue muscle, palatoglossus which is actually a palatine muscle based on derivation and innervation
- and proprioception of these muscles
-
Longest and most extensive distribution of all cranial nerves, most of which is outside of head, arising from rootlets from lateral aspect of medulla that merge and leave cranium through jugular foramen between CN IX and XI
has a superior ganglion in the jugular foramen concerned with general sensory component of nerve
Inferior to foramen is the inferior ganglion, concerned with visceral and special sensory components of nerve
- in region of superior ganglion are connections to CN IX and superior cervical ganglion
CN X continues inferiorly in caarotid sheath to root of neck, supplying branches to palate, pharynx and larynx and cardiac branches
Course of Vagi asymmetrical in thorax, a consequence of transitions of great vessels and rotation of midgut during development
Supplies branches to mixed motor and sensory plexus that serve the heart, bronchi, lungs and esophagus
Anterior and posterior vagal trunks form as continuations of esophageal plexus which is also joined by branches of sympathetic trunks, which pass through the diaphragm into the abdomen, breaking up into branches and innervating structures as far as the left colic flexure
-
CN VII (Facial nerve)
Sensory: Special sensory (taste) and somatic sensory
Motor: Somatic (branchial) motor and visceral (parasympathetic) motor
Also carry proprioceptive fibers from the muscle it innervates, although muscles of facial expression include relatively few muscle spindles (mechanoreceptor for muscle stretch), so are fewer than in other motor nerves
Motor nucleus is in the Pons, cell bodies of primary sensory neurons are in geniculate ganglion
Facial nerve emerge from junction of pons and medulla as 2 divisions, primary root and intermediate nerve
-
smaller intermediate nerve: taste, parasympathetic and somatic sensory fibers
During its course, will transverse through posterior cranial fossa, internal acoustic meatus, proceeds a short distance anteriorly wwithin temporal bone, then turns abruptly posteriorly to course along the medial wall of the tympanic cavity. The sharp bend, geniculum of facial nerve (knee) is site of the geniculate ganglion
While transversing temporal bone within facial canal, CN VII gives rise to
-
-
-
-
-
-
Special sensory (taste)
Peripheral fibers of geniculate ganglion carried by chorda tympani which joins the lingual nerve on CN V3 in the infratemporal fossa to supply taste buds of anterior 2/3 of tongue and soft palate
-
-
CN V (Trigeminal Nerve)
4 trigeminal nucleis
- one motor and three sensory
Largest CN, emerge from lateral aspect of the pons of brainsteam by a large sensory root and a small motor root
-
Trigeminal ganglion is lateral to the cavernous sinus, forms three nerves: ophthalmic nerve (CN V1), Maxillary (CN V2), and sensory component of the mandubular nerve (CN V3)
Motor root of CN V pass adjacent to the trigeminal gnaglion, merge with the mandibular branch of CN V immediately distal to the ganglion, and distributed exclusivey via mandibular nerve, blending with its sensory fibers as the nerve transverse the foramen ovale
Motor root distributed to muscles of mastication, mylohyoid, anterior belly of digastric, tensor veli palatini and tensor tympani, which are derived from the 1st pharyngeal arch
All 4 parasympathetic ganglia are associated with divisions of CN V, with fibers joining branches of CN V and carried to their destination along with the CN V sensory and motor fibers
Ophthalmic Nerve (CN V1)
-
-
Somatic sensory fibers distributed to skin and mucous membranes and conjunctiva of the front of head and nose
To test for CN V1, check corneal reflex
- touch cornea (also supplied by CN V1) with a wisp of cotton will evoke a reflexive blink if the nerve is functional
Maxillary Nerve (CN V2)
-
Exit cranial cavity via foramen rotundum, somatic sensory fibers mainly distributed to skin and mucous membranes associated with the upper jaw
pterygopalatine ganglion associated with this division of CN V, involved in innervating lacrimal gland and glands of nose and palate
Mandibular nerve (CN V3)
-
Carries somatic motor fibers, distributed to the striated muscle derived from mandibular prominence mesoderm, primarily the muscle of mastication
2 parasympathetic ganglia, the otic and submandibular, are associated with this division of CN V, both concerned with innervation of salivary glands
-
Optic Nerve (CN II)
-
Paired, anterior extensions of the forebrain (diencephalon) and are actually CNS fiber tracts formed by axons of retinal ganglion cells
Surrounded by extensions of the cranial meninges and subarachnoid space, filled with CSF, extend all the way to the eye ball
Central artery and vein transverse the meningeal layers and course in the anterior part of the optic nerve
(in retrograde direction) CN II begins when unmyelinated axons of retinal ganglion cells pierce the sclera and become myelinated deep to the optic disc
Nerve pass posteromedially in the orbit, exit through optic canal and enter the middle cranial fossa where it forms the optic chiasm
- fibers of the medial (nasal) half of each retina decussate and join the uncrossed fibers from the lateral (temporal) half of the retina to form the optic tract
Crossing is a requirement for binocular vision, allow depth-of-field perception
- right half of both retinas form right optic tract
-
-
CN I: Olfactory Nerve
-
-
-
Apical surface of neurons have fine olfactory cilia, bathed by a film of watery mucus secreted by olfactory glands
- cilia stimulated by molecules of an odiferous gas dissolved in the fluid
Pass through tiny foramina in the cribriform plate of ethmoid bone, surrounded by sleeves of dura mater and arachnoid mater
-
Olfactory nerve fibers synapse with mitral cells in the olfactory bulb, and the axons of these form the olfactory tract that travels back to the brain
-bulbs and tract are anterior extensions of the forebrain
Each tract divides into lateral and medial olfactory striae
- lateral terminates in piriform cortex of anterior part of temporal lobe, medial project through anterior commissure to contralateral olfactory structures
-
CN XI (Spinal accessory)
-
CN XI emerges as a series of rootlets from first 5 or 6 cervical segments of spinal cord, and travels up into the cranial
Spinal accessory nerve joins CN X temporarily as they pass through the jugular foramen, separating again as they exit
CN XI descends along internal carotid artery, penetrates and innervates SCM and emerges from the muscle near the middle of its posterior border
CN XI then crosses posterior cervical region and passes deep to superior border of trapezius to descend on its deep surface and provide multiple branches to the muscle
Branches of cervical plexus conveying sensory fibers from spinal nerve C2-4 join the spinal accessory nerve in the posterior cervical region, providing the muscles with pain and proprioceptive fibers
-
Mnemonics
Some Say Marry Money, But My Brother Say Big Boobs Matter More
Oh Oh Oh, To Touch And Feel Very Good Velvet, Ah Heaven
-
-
CN VI (Abducent nerve)
Somatic motor to one extra-ocular muscle, the lateral rectus muscle
-
In its intradural course, bends sharply over the crest of the petrous part of the temporal one, then courses through the cavernous sinus
-
-
CN IV (Trochlear nerve)
Somatic motor to superior oblique, nucles located in midbrain
smallest cranial nerve, with the longest intracranial course
pass anteriorly in lateral wall of cavernous sinus, continue through the superior orbital fissure into orbit, where it supplies the superior oblique (uses a trochlea (pulley) to redirect its line of action