General principles of autonomic innervation to the structures of the head and neck:
Cranial Nerves with Parasympathetic Functional Componenents 1. Olfactory CN I (SVA) Sensory 2. Optic CN II (SSA) Sensory 3. Oculomotor CN III (GSE, GVE-P) Motor 4. Trochlear CN IV (GSE) Motor 5. Trigeminal CN V (GSA, SVE) Both 6. Abducens CN VI (GSE) Motor 7. Facial CN VII (SVE, GSA, SVA, GVA, GVE-P) Both 8. Vestibulocochlear CN VIII (SSA, SSE) Sensory 9. Glossopharyngeal CN IX (SVE, GSA, SVA, GVA, GVE-P) Both 10. Vagus CN X (SVE, GSA, SVA, GVA, GVE-P) Both 11. Accessory CN XI (GSE) Motor 12. Hypoglossal CN XII (GSE) Motor
Head and Neck Parasympathetics – KEY Points • CN V is the great sensory nerve to structures of the head and provides a ready-made route to all structures which need to be innervated autonomically • The four parasympathetic ganglia [COPS] in the head are “associated” with CN V: • V1 (ciliary) • V2 (pterygopalatine) • V3 (submandibular and otic) • Autonomic fibers of CN III, VII, and IX “hitchhike” along these routes to gain their target organs
Head and Neck Sympathetics – KEY Points • Preganglionic sympathetic axons arise from the IML cell column at T1 – T4 • Enter the sympathetic chain via white rami • Ascend in the sympathetic chain • All preganglionic fibers associate with viscera of the head and neck synapse in the superior cervical sympathetic ganglion • Therefore, THERE ARE NO PRE-GANGLIONIC SYMPATHETIC FIBERS IN THE HEAD
Sympathetic Pathways T1 – T4
Postganglionics leave the Superior Cervical Ganglion as the: External carotid nerve:located on the surface of the external carotid artery; distributes to superficial viscera of the head/neck via branches of this vessel Internal carotid nerve:located on the surface of the internal carotid artery; forms a plexus that contributes branches to the: Glands in the middle ear (caroticotympanic branches) lacrimal gland and mucous glands of the nasal cavity, oral cavity, pharynx [deep petrosal nervejoins the nerve of the pterygoid canal which in turn distribute via branches of maxillary nerve]. Dilator pupillae muscle [cavernous plexusgives rise to the sympathetic root of the ciliary ganglion that distribute by short ciliary nerves].
Parasympathetic Innervation • The ciliary ganglion: • has sensory, sympathetic and motor roots • receives preganglionic parasympathetic axons (from the brainstem/CN III) via the motor root • gives rise to postsynaptic axons that travel in short ciliary nerves to the ciliary muscle and sphincter pupillae
Sympathetic Innervation postganglionic sympathetic fibers arise from the superior cervical ganglion and travel along the cavernous plexus reach the orbit on ophthalmic artery or CN III traverse the ciliary ganglion without synapse Innervates the dilator pupillae muscle and superior tarsal muscle
Parasympathetic Innervation preganglionic parasympathetic fibers course in CN VII (greater petrosal nerve nerve of the pterygoid canal) synapse in the pterygopalatine ganglion postganglionic parasympathetic fibers “hitchhike” along branches of CN V2 to reach the lacrimal, oral, palatal, nasal and pharyngeal mucous glands
Sympathetic Innervation postganglionic sympathetic fibers arise from the superior cervical ganglion and travel in the cavernous plexus forms the deep petrosal nerve and joins the greater petrosal nerve to form the nerve of the pterygoid canal fibers traverse the pterygopalatine ganglion without synapse reach the viscera along branches of the maxillary artery and/or follow branches of CN V
Parasympathetic Innervation preganglionic parasympathetic fibers course in CN VII (chorda tympani) joins the lingual nerve in the infratemporal fossa synapse in the submandibular ganglion postganglionic parasympathetic fibers innervate submandibular, sublingual and lingual salivary glands
Parasympathetic Innervation • preganglionic parasympathetic fibers course in CN IX (tympanic nerve lesser petrosal nerve) • synapse in the otic ganglion • postganglionic parasympathetic fibers travel along CN V3 (auriculotemporal nerve) to innervate the parotid gland
Sympathetic Innervation • postganglionic sympathetic fibers arise from the superior cervical ganglion and travel in the external carotid plexus • travel on the facial artery • reach the viscera along branches CN V3
Autonomic innervation of the smooth muscle and glands in the pharynx and larynx:
Parasympathetic Innervation • preganglionic parasympathetic fibers course in CN X (pharyngeal branches, internal laryngeal nerve, recurrent laryngeal nerve) • enter pharynx and larynx to synapse in intramural ganglia
T1 – T4 Sympathetic Innervation • preganglionic sympathetic fibers arise in the IML cell column (T1 – 4) • synapse in the sympathetic chain • laryngopharyngeal branches
A 24-year-old female presents to the emergency room 5-days after a bar fight with the chief complaints of a “messed up hand and funny eye”. Physical examination reveals the images below. • Where is the injury? • What is the diagnosis? • What other signs would most likely be present on PE?
Horner’s Syndrome also occurs in: • cervical spinal cord injury • Brainstem strokes • apical lung tumors A 54-year-old male presents to the emergency room with the chief complaints of headache and hoarseness. Physical examination reveals a weak gag reflex and the image below. • Where is the injury? • What is the diagnosis?