Hypoglossal nerve

This video tutorial explores the anatomy and function of the hypoglossal nerve, the 12th cranial nerve responsible for motor innervation of the tongue and infrahyoid muscles. It details the nerve's pathway from the brainstem through the hypoglossal canal, its role in speech and swallowing, and the clinical implications of nerve damage. The tutorial also discusses the innervation of intrinsic and extrinsic tongue muscles and addresses controversies in the innervation of the thyrohyoid muscle.

What is the primary function of the hypoglossal nerve?

• To convey sensory information from the tongue

• To control the majority of the tongue muscles

• To innervate the facial muscles

• To provide blood supply to the tongue

Where does the hypoglossal nerve originate?

• In the thalamus

• In the cerebellum

• In the medulla oblongata

• In the spinal cord

Through which structure does the hypoglossal nerve exit the skull?

• Foramen magnum

• Optic canal

• Jugular foramen

• Hypoglossal canal

What is the ansa cervicalis?

• A blood vessel in the brain

• A branch of the vagus nerve

• A circuit formed by spinal nerves C1 to C4

• A muscle in the neck

Which muscle is NOT innervated by the hypoglossal nerve?

• Hyoglossus

• Palatoglossus

• Styloglossus

• Genioglossus

What is the role of the genioglossus muscle?

• To protrude the tongue

• To retract the tongue

• To elevate the tongue

• To depress the tongue

What symptom might indicate damage to the hypoglossal nerve?

• Inability to close the eyes

• Tongue deviation to one side

• Loss of taste

• Loss of hearing

How can you assess the function of the hypoglossal nerve?

• Ask the patient to smile

• Test the patient's hearing

• Check for pupil dilation

• Ask the patient to stick their tongue out

What might cause lesions in the hypoglossal nerve?

• Infections and neurodegeneration

• Excessive exercise

• High blood pressure

• Dehydration

What is a common result of upper motor neuron damage to the hypoglossal nerve?

• Tongue curves towards the lesion

• Increased saliva production

• Tongue curves away from the lesion

• Loss of taste