Human Structure Head and Neck Review: All Things Cranial (Nerves) (caveat – this summary is not all inclusive – it is likely I’ve left out some minor details here and there!) Dr. Valerie O'Loughlin 1 Intro to cranial nerves • Cranial nerves originate from the brain • Designated ‘CN’ and with a roman numeral – Why? • 12 pairs of cranial nerves Dr. Valerie O'Loughlin Thieme Atlas of Anatomy © 2016 2 Cranial nerves may contain any of the following: • Sensory axons • Somatic motor axons – voluntary • Parasympathetic motor axons – ANS – involuntary McKinley/O’Loughlin/Pennefather‐O’Brien – Human Anatomy 5e Dr. Valerie O'Loughlin © 2017 Fig 15.24 3 Cranial Nerves summarized Dr. Valerie O'Loughlin McKinley/O’Loughlin/Pennefather‐O’Brien – Human Anatomy 5e © 2017 4 G‐rated Cranial Nerve Mnemonic • Oh • Olfactory • Once • Optic • One • Oculomotor • Takes • Trochlear • The • Trigeminal • Anatomy • Abducens • Final • Facial • Very • Vestibulocochlear • Good • Glossopharyngeal • Vacations • Vagus • Are • Accessory • Heavenly! • Hypoglossal Dr. Valerie O'Loughlin 5 CN I: olfactory nerves • Q: leave anterior cranial fossa through which openings? • Sensory only • olfaction McKinley/O’Loughlin/Pennefather‐O’Brien – Human Anatomy 5e © 2017 Dr. Valerie O'Loughlin 6 Primary nerves associated with/involved with Orbit: • CN II • CN III • CN IV • CN V1 • CN VI Dr. Valerie O'Loughlin 7 CN II (optic nerve) • CN II (Optic Nerve): vision – Q: leaves cranium and enters orbit through which openings? Dr. Valerie O'Loughlin Thieme Atlas of Anatomy 8 Oculomotor (CN III) • Q: Leaves the middle cranial fossa through which opening? • Somatic motor to these muscles: – Levator palpebrae superioris – Superior rectus – Inferior rectus – Medial rectus – Inferior oblique McKinley/O’Loughlin/Pennefather‐O’Brien – Human Anatomy 5e © 2017 Dr. Valerie O'Loughlin 9 CN III (continued) • Also provides parasympathetic motor innervation to ciliary body, sphincter pupillae * connects to the ciliary ganglion Functions: • Constrict pupil • Contract ciliary muscle (releases tension on suspensory ligaments) – so lens becomes more rounded/puffy – needed for close‐up vision Dr. Valerie O'Loughlin 10 Trochlear Nerve (CN IV) • Somatic motor only • Innervates superior oblique muscle • Q: Leaves the middle cranial fossa and travels through which opening to reach the orbit? Dr. Valerie O'Loughlin Thieme atlas of 11 anatomy Abducens Nerve (CN VI) • Somatic motor innervation to lateral rectus muscle • Q: Leaves the middle cranial fossa and travels through which opening to reach the orbit? Thieme atlas of anatomy Dr. Valerie O'Loughlin 12 Review and Integrate: CN V (Trigeminal) • Innervates – pharyngeal arch 1 structures – meninges (in anterior and middle cranial fossae) Dr. Valerie O'Loughlin Moore’s Clinically Oriented Anatomy 13 CN V (Trigeminal) • Three divisions: – V1 (ophthalmic) • Sensory (frontonasal prominence) – V2 (maxillary) • Sensory (maxillary prominence) – V3 (mandibular) • Sensory (mandibular prominence) & somatic motor Dr. Valerie O'Loughlin 14 Review and Integrate: CN V (Trigeminal) • CN V1 (ophthalmic) – Sensory nerve only – Innervates skin of frontonasal prominence – Question: through what foramen does V1 exit middle cranial fossa of the skull? Dr. Valerie O'Loughlin 15 V1 (ophthalmic) • General sensory only to skin of frontonasal prominence, upper eyelid, orbit, anterosuperior part of nasal cavity, cornea • Branches include: – Frontal branch – Nasociliary branch – Lacrimal branch Dr. Valerie O'Loughlin 16 Review and Integrate: CN V (Trigeminal) • CN V2 (maxillary) – Sensory nerve only – Innervates skin of maxillary prominence – Question: through what foramen does V2 exit the skull? Dr. Valerie O'Loughlin 17 V2 (maxillary) • Leaves middle cranial fossa through foramen rotundum • Enters pterygopalatine fossa – ptergyopalatine ganglion hangs off this nerve • General sensory to lower eyelid, nostrils, posterior part of nasal cavity, nasopharynx, skin of maxillary prominence, palate, maxillary teeth, maxillary gingiva, upper lip Dr. Valerie O'Loughlin 18 Review and Integrate: CN V (Trigeminal) • CN V3 (mandibular) – Sensory AND motor – Innervates skin of mandibular prominence, oral cavity, gingiva, teeth, inferior lip, meninges of middle cranial fossa – Sensation from mucosa of anterior 2/3 of tongue – Motor: pharyngeal arch 1 muscles (name these muscles!) – Question: through what foramen does V3 exit middle cranial fossa of the skull? Dr. Valerie O'Loughlin 19 V3 (mandibular) • Leaves middle cranial fossa through foramen ovale • Somatic motor to muscles of mastication, tensor tympani and tensor veli palatini, mylohyoid, anterior belly of digastric • General sensory to ant 2/3 of tongue, skin of mandibular prominence, part of auricle, external acoustic meatus, tympanic membrane, mandibular teeth, gingiva, inner cheek, meninges Dr. Valerie O'Loughlin 20 Review and Integrate: CN VII (facial) • Innervates pharyngeal arch 2 structures • Question: CN VII exits the posterior cranial fossa through what foramen? Dr. Valerie O'Loughlin 21 Review and Integrate: CN VII (facial) • Somatic Motor: muscles of facial expression – This branch leaves skull via stylomastoid foramen – Innervates pharyngeal arch 2 muscles (Name them!) • Special Sensory: taste from the anterior 2/3 of the tongue – Via the chorda tympani branch Dr. Valerie O'Loughlin 22 CN VII (Facial) • Has special sensory (taste), somatic motor and parasympathetic motor components • Leaves posterior cranial fossa and enters internal acoustic meatus • In petrous part of temporal bone – gives off greater petrosal nerve (preganglionic parasympathetic) • Facial nerve continues as: – Somatic motor (through stylomastoid foramen) – Chorda tympani Dr. Valerie O'Loughlin 23 CN VII (Facial) • Greater Petrosal: travels through middle cranial fossa – Connects up with deep petrosal nerve (sympathetics) and becomes nerve of pterygoid canal • Nerve of pterygoid canal enters pterygopalatine fossa, goes to pterygopalatine ganglion – Synapse occurs! – Postganglionic parasympathetics travel with branches of CN V2 to lacrimal gland, glands of nose & palate Dr. Valerie O'Loughlin 24 CN VII (Facial) • Chorda tympani – Enters tympanic cavity, and exits temporal bone – Travels with lingual nerve (branch Of CN V3) to submandibular ganglion • Synapses here • Postganglionic parasympathetic axons go to submandibular, sublingual glands – Receives taste from anterior 2/3 of tongue Dr. Valerie O'Loughlin 25 CN VII (Facial) • Somatic motor portion of facial nerve exits via stylomastoid foramen – Splits into 5 terminal branches that innervate the muscles of facial expression – Also innervates: • Stapedius • Stylohyoid • Posterior belly of digastric Dr. Valerie O'Loughlin 26 CN VII: Parasympathetic Innervation of Submandibular and Sublingual Glands Review temporal fossa notes Dr. Valerie O'Loughlin 27 CN VIII: Vestibulocochlear • Sensory only • Hearing and equilibrium • Q: this nerve exits the posterior cranial fossa through which foramen? McKinley/O’Loughlin/Pennefather‐O’Brien – Human Anatomy 5e © 2017 Dr. Valerie O'Loughlin 28 Review and Integrate: CN IX (Glossopharyngeal) • Innervates pharyngeal arch 3 structures (e.g., stylopharyngeus) • (Baroceptor) info from carotid sinus to CNS • (Chemoreceptor) info from carotid body to CNS • Parasympathetic motor to parotid salivary gland • Question: through what foramen does CN IX exit the skull? Dr. Valerie O'Loughlin 29 CN IX (Glossopharyngeal) • Supplies pharyngeal arch 3 structures • Leaves skull through jugular foramen • General sensory to much of pharynx*, palatine tonsil, carotid sinus, carotid body, middle ear • Receives touch/taste information from posterior 1/3 of tongue • Parasympathetic motor to parotid gland • Somatic motor to stylopharyngeus *Except nasopharynx, which is innervated by V2 Dr. Valerie O'Loughlin *Part of laryngopharynx innervated by CN X 30 CN X (Vagus) • Supplies pharyngeal arch 4 and 6 structures • Q: Leaves skull through which foramen? • General sensory from external acoustic meatus, tympanic membrane, part of laryngopharynx, larynx and tiny part of posterior tongue • Visceral sensory info from most thoracic/abdominal organs Dr. Valerie O'Loughlin 31 CN X (Vagus) • Somatic motor to all muscles of larynx – External laryngeal innervates cricothyroid m. – Recurrent laryngeal innervates all other laryngeal muscles • Somatic motor to pharynx (pharyngeal plexus) – Innervates constrictors, most of soft palate muscles • Parasympathetic motor to thoracic, most abdominal organs Dr. Valerie O'Loughlin 32 Review and Integrate: CN XI (Accessory) • Somatic motor to trapezius, SCM • Q: Leaves skull through? • Travels through anterior and lateral cervical regions to reach muscles • Question: do you recall what OTHER structures travel through the jugular foramen? Dr. Valerie O'Loughlin 33 CN XII (Hypoglossal) • Q. Leaves skull through which foramen? • Somatic motor only • Innervates most extrinsic and intrinsic tongue muscles McKinley/O’Loughlin/Pennefather‐O’Brien – Human Anatomy 5e © 2017 Dr. Valerie O'Loughlin 34 Review and Integrate: Sensory Innervation of Scalp, Face, Neck • CN V – face, anterior scalp • Greater occipital (post ramus of C2) – posterior scalp/posterior neck • Posterior rami of C3, C4, C5 – posterior neck • Cutaneous branches of Cervical plexus (ant rami of C2‐C4) – anterior and lateral neck – Lesser Occipital – Great Auricular – Transverse Cervical – Supraclavicular Dr. Valerie O'Loughlin 35 Cranial Nerves summarized Dr. Valerie O'Loughlin McKinley/O’Loughlin/Pennefather‐O’Brien – Human Anatomy 5e © 2017 36.