Autonomics of the head Flashcards
The following structures of the head require autonomic innervation
- Blood vessels, sweat glands, arrector pili
- Mucous-secreting glands of head
- Lacrimal gland
- Parotid gland
- Submandibular gland
- Sublingual gland
- Intraocular eye muscles (sphincter and dilator pupillae; ciliary muscle)
- Superior tarsal muscle of eye
general sympathetic innervation
B. Sympathetic innervation arises from the upper thoracic spinal cord and ascends the sympathetic chain to the superior cervical ganglion. From here, postganglionic fibers travel with the external carotid artery (external carotid nerve) to get to superficial structures and the internal carotid artery (internal carotid nerve) to get to deeper structures of the head.
general parasympathetic innervationa.
Parasympathetic innervation arises from 4 cranial nerves and 4 cranial ganglia.
- Cranial Nerves
a. Oculomotor nerve
b. Facial nerve
c. Glossopharyngeal nerve
d. Vagus nerve
4 ganglia: Ciliary Pterygopalatine Submandibular Otic
Ciliary ganglion
- Location – orbit; between optic nerve and lateral rectus.
- Sensory root – from nasociliary branch of V1
- GVE-P root – from oculomotor nerve
- GVE-S root – from internal carotid nerve (via cavernous branch)
Pterygopalatine ganglion
- Location – pterygopalatine fossa
- Sensory root – from pterygopalatine branches of V2
- GVE-P root – from greater petrosal nerve of pterygoid canal (CN VII).
- GVE-S root – from deep petrosal nerve of nerve of pterygoid canal.
Submandibular ganglion
- Location – oral cavity
- Sensory root – from lingual nerve of V3
- GVE-P root – from chorda tympani nerve of CN VII.
- GVE-S root – from external carotid nerve.
Otic ganglion
- Location – infratemporal fossa
- Sensory root – from V3
- GVE-P root – from lesser petrosal branch of CN IX.
- GVE-S root – from external carotid nerve.
The trigeminal nerve is associated with all 4 parasympathetic ganglia of the head.
CN V does not carry parasympathetic fibers of its own, but suspends each ganglion and distributes parasympathetic, sympathetic, and sensory fibers to their target structures.
a. V1 suspends the ciliary ganglion and distributes fibers to the eye.
b. V2 suspends the pterygopalatine ganglion and distributes fibers to the lacrimal gland, nasal cavities, paranasal sinuses, and palate.
c. V3 suspends the submandibular ganglion and distributes fibers to the submandibular and sublingual glands.
d. V3 suspends the otic ganglion and distributes fibers to the parotid gland.
II. Parasympathetic innervation of head
A. Oculomotor nerve (CN III)
- Pathway of innevation to intraocular muscles.
a. Preganglionic parasympathetic cell bodies – Edinger Westphal nucleus
b. Preganglionic parasympathetic fibers – CN III (inferior division)
c. Postganglionic parasympathetic cell bodies – ciliary ganglion
d. Postganglionic parasympathetic fibers – short ciliary branches of V1 - Distribution and Function
a. Sphincter pupillae muscle – miosis (constriction of pupil)
b. Ciliary muscle – accommodation - Dysfunction
a. Sphincter pupillae muscle – loss of pupillary light response; dilated pupil
b. Ciliary muscle – loss of accommodation
Parasympathetics: Facial nerve – greater petrosal branch
- Pathway for innervation to mucous-secreting glands of head and lacrimal gland.
a. Preganglionic parasympathetic cell bodies – salivatory nucleus
b. Preganglionic parasympathetic fibers – CN VII (greater petrosal n)
c. Postganglionic parasympathetic cell bodies – pterygopalatine ganglion
d. Postganglionic parasympathetic fibers – various branches of V2 to mucous-secreting glands of nasal cavity, paranasal sinuses, and palate.
e. Postganglionic parasympathetic fibers – zygomatic branch of V2 and lacrimal branch of V1 to lacrimal gland. - Distribution and Function
a. Lacrimal gland – increases lacrimation
b. Mucous-secreting glands – increase mucous secretion to lubricate mucosa. - Dysfunction
a. Lacrimal gland – dry, red eye due to deceased lacrimal fluid production
b. Mucous-secreting glands – dry, irritated mucous-membranes
Parasympathetics: C. Facial nerve – chorda tympani branch
- Pathway for innervation to submandibular and sublingual glands.
a. Preganglionic parasympathetic cell bodies – salivatory nucleus
b. Preganglionic parasympathetic fibers – CN VII (chorda tympani n)
c. Postganglionic parasympathetic cell bodies – submandibular ganglion
d. Postganglionic parasympathetic fibers – lingual branch of V3 to submandibular and sublingual glands. - Distribution and Function
a. Submandibular gland – increases gland secretion
b. Sublingual gland – increases gland secretion
c. NOTE: also carries SVA (taste to anterior 2/3 of tongue) - Dysfunction
a. Submandibular gland - xerostomia (dry mouth) due to decreased salivation.
b. Sublingual gland - xerostomia (dry mouth) due to decreased salivation.
Parasympathetics: glossopharyngeal nerve
- Pathway for innervation to parotid gland.
a. Preganglionic parasympathetic cell bodies – salivatory nucleus
b. Preganglionic parasympathetic fibers – CN IX (lesser petrosal n)
c. Postganglionic parasympathetic cell bodies – otic ganglion
d. Postganglionic parasympathetic fibers – auriculotemporal branch of V3 to parotid sublingual gland. - Distribution and Function
a. Parotid gland – increases gland secretion - Dysfunction
a. Parotid gland - xerostomia (dry mouth) due to decreased salivation.
Parasympathetics: Vagus
- This is the pathway for innervation of smooth muscle, glands, blood vessels of the neck, thorax, and most of the abdomen.
- Specific named branches involved: Pharyngeal branches, laryngeal branches, cardiac and pulmonary branches, visceral branches to gut.
Sympathetic innervation of head
A. Preganglionic sympathetic neurons
- Cell bodies for the entire head originate in the IMLCC at T1-T4
- Preganglionic fibers enter sympathetic chain via white rami and ascend to the superior cervical ganglion (SCG).
B. Postganglionic sympathetic neurons
1. Cell bodies for the entire head originate in the SCG.
2. Postganglionic fibers follow two primary routes to the head:
Internal carotidd nerve
Deep petrosal nerve
Pathway of sympathetics: internal carotid
a. Internal carotid nerve
1. Distribute via branches of the internal carotid artery to deep structures of head.
2. Provides the following specific nerves:
a. Cavernous sinus nerve
1. Follows internal carotid artery through the cavernous sinus.
2. Forms sympathetic root to ciliary ganglion.
3. Provides innervation to superior tarsal and dilator pupillae muscles.
4. Superior tarsal muscle
a. Assists (CN III) with elevation of the upper eyelid.
b. Dysfunction – ptosis
5. Dilator pupillae muscle
a. Dilates pupil to allow more light to enter eye.
b. Dysfunction – constricted pupil; loss of pupillary dilation