Download cranial nerve ix: glossopharyngeal nerve

CRANIAL NERVE IX: GLOSSOPHARYNGEAL NERVE
Five Functions of Glossopharyngeal Nerve:
1. Innervates Stylopharyngeus Muscle.
2. Special sense of taste to posterior 1/3 of tongue
3. General sensation to posterior 1/3 of tongue, lateral oropharyngeal wall, part of
soft palate
4. Parasympathetic secretomotor to Parotid Gland
5. Visceral Sensation from the Baroreceptors ("blood-pressure" receptors) at the
Carotid Body (Sinus), at the bifurcation of the Carotids.
1. These guys carry special chemoreceptors and stretch receptors. They
provide feedback to the heart to control heart rate and modulate blood
pressure.
GAG REFLEX: Glossopharyngeal can be tested by eliciting a gag reflex. Touch the
posterior 1/3 of tongue or palate region to elicit response.
1. One should also be able to see symmetric raising of the soft palate during
swallowing to verify functionality of the nerve.
OVERALL PATH OF GLOSSOPHARYNGEUS TO PHARYNX:
1. Through JUGULAR FORAMEN
2. Down posterior wall of pharynx to innervate the stylopharyngeus muscle
3. Penetrate gap between Superior and Middle Pharyngeal Constrictors, adhered to
the Stylopharyngeus muscle.
4. Finally, innervation to the posterior 1/3 of tongue.
CRANIAL NERVE X: VAGUS NERVE
Type of Innervation:
1. BRANCHIAL MOTOR (SVE): All muscles of the larynx, pharynx, and palate,
EXCEPT the Stylopharyngeus (IX) and Tensor Palati (V3).
1. In this role, the Vagus is "stealing" some of the innervation from the
Spinal Accessory (XI). Hence in this case the Vagus is actually
innervating striated rather than smooth muscle.
2. VISCERAL MOTOR (GVE): Parasympathetics to the Thoracic and Abdominal
viscera.
1. The Vagus serves no Parasympathetic function in the head and neck
region -- only the thorax and abdomen.
3. VISCERAL SENSORY (GVA): Sensory info from tongue, pharynx and larynx,
heart and lungs, CAROTID SINUS (along with CN IX), stomach and intestine.
4. GENERAL SENSORY (GSA): General sensory from larynx, pharynx, and a
small portion of the outer ear and tympanic membrane.
1. General Sensory innervation may include the eardrum itself. These
individuals may elicit a gag reflex when cleaning their ears -- due to
sensory response from the Vagus!
5. SPECIAL SENSORY (SVA): Maybe a few taste buds carry taste information via
the Vagus.
CRANIAL NERVE XI: SPINAL ACCESSORY NERVE
Two Roots:
1. Spinal Root: Gives SVE (Branchial) innervation to Sternocleidomastoid and
Trapezius muscles.
2. Cervical Root: Quickly joins up with Vagus (and could be considered part of
Vagus) to form the Recurrent Laryngeal Nerve.
CRANIAL NERVE XII: HYPOGLOSSAL NERVE
INNERVATION: All intrinsic and extrinsic musculature of the tongue, EXCEPT the
Palatoglossus which is innervated by the Vagus.
PATH: It exits the posterior cranial fossa through the Hypoglossal Canal, which is
anterior to the Occipital Condyles.