Facial Nerve medium

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Questions and Answers

What is the most common cause of intracranial lesions of the facial nerve?

Tumors in the parotid gland

Idiopathic causes

Stroke

Infection related to external or middle ear (correct)

Which symptom is NOT typically associated with damage to the facial nerve?

Dry mouth

Loss of taste on the anterior 2/3 of the tongue

Difficulty in vision (correct)

Reduced lacrimal function

What happens when the extrinsic facial nerve is damaged after exiting the stylomastoid foramen?

Sensory and motor functions are lost

Only sensory function is affected

Only motor function is affected (correct)

No function is affected

Bell's palsy is usually diagnosed when:

No identifiable cause can be found Signup and view all the answers

What might cause damage to the facial nerve due to pressure?

Forceps delivery during childbirth Signup and view all the answers

Which of the following symptoms would indicate reduced lacrimal function?

Dry eye Signup and view all the answers

What function remains unaffected by an extracranial lesion of the facial nerve?

Sensory feedback from the face Signup and view all the answers

What is a common symptom of intracranial facial nerve damage?

Hyper sensitivity to sound Signup and view all the answers

Which of the following conditions is likely to affect the chorda tympani branch of the facial nerve?

Infection of the middle ear Signup and view all the answers

Which statement about Bell's palsy is accurate?

It may occur with an unknown cause. Signup and view all the answers

What muscle is responsible for raising the hyoid bone?

Posterior belly of digastric muscle Signup and view all the answers

Which branch of the facial nerve crosses the zygomatic arch to reach the forehead?

Temporal branch Signup and view all the answers

Which branch of the facial nerve supplies the muscles of the upper lip and nose?

Buccal branch Signup and view all the answers

What is the main function of the cervical branch of the facial nerve?

Supplies the platysma muscle Signup and view all the answers

The buccal branch supplies which of the following muscles?

Orbicularis oris Signup and view all the answers

What does the temporal branch NOT supply?

Orbicularis oris Signup and view all the answers

Which facial nerve branch emerges from the lower border of the parotid gland?

Mandibular branch Signup and view all the answers

Which of the following muscles does the mandibular branch innervate?

Mentalis Signup and view all the answers

What is a key characteristic of the zygomatic branch?

Controls the orbicularis oculi Signup and view all the answers

Which of the following is true regarding the facial branches?

They provide motor function to facial muscles Signup and view all the answers

What type of nerve fibers does the greater petrosal nerve carry?

Parasympathetic fibers Signup and view all the answers

Which structure does the chorda tympani innervate for taste sensation?

Anterior 2/3 of the tongue Signup and view all the answers

What is the function of the nerve to stapedius?

Dampens loud sounds Signup and view all the answers

Which of the following branches of the facial nerve emerges after it exits the stylomastoid foramen?

Cervical branch Signup and view all the answers

Which muscle is innervated by the posterior auricular nerve?

Occipital part of the occipitofrontalis muscle Signup and view all the answers

What is the primary function of the facial nerve's branches after passing through the parotid gland?

Motor function to facial muscles Signup and view all the answers

Which function is primarily associated with the motor root of the Facial nerve?

Muscle movement for facial expressions Signup and view all the answers

Which structure does the facial nerve originate from?

Pons Signup and view all the answers

What is a primary function of the nervus intermedius branch of the Facial nerve?

Efferent connections to submandibular glands Signup and view all the answers

Which anatomical regions does the Facial nerve primarily supply?

Muscles of the facial expression and several glands Signup and view all the answers

The parasympathetic fibers carried by the chorda tympani are directed to which glands?

Sublingual and submandibular glands Signup and view all the answers

What is the anatomical distinction of the Facial nerve's course?

Divided into intracranial and extracranial parts Signup and view all the answers

Which cranial opening does the facial nerve use to exit the skull?

Stylomastoid foramen Signup and view all the answers

What type of fibers does the chorda tympani carry in addition to taste sensation?

Parasympathetic fibers Signup and view all the answers

What type of gland does the Facial nerve NOT innervate?

Parotid salivary glands Signup and view all the answers

Which structure is NOT innervated by the Facial nerve?

The temporalis muscle Signup and view all the answers

What is a cranial nerve associated with the second pharyngeal arch?

Facial nerve (VII) Signup and view all the answers

Where does the Facial nerve emerge from the brain?

Between the pons and medulla Signup and view all the answers

What type of function does the Facial nerve provide to the muscles of facial expression?

Motor Signup and view all the answers

Which of the following is NOT a function of the Facial nerve?

Auditory processing Signup and view all the answers

Study Notes

Facial Nerve

The facial nerve (VII) is a cranial nerve
It's associated with the second pharyngeal arch
It emerges from the brain between the pons and medulla
It has two roots:
- A larger motor root from the motor nucleus
- A smaller root, called the nervus intermedius
It passes into the internal auditory meatus

Intended Learning Outcomes

Describe the function of the facial nerve
Outline the anatomical regions the facial nerve supplies
Explain the relevance of the facial nerve to dentistry

Why do I need to know this?

The facial nerve transmits information to and from facial structures
Its branches allow sensation to oral and facial structures
It produces saliva via the submandibular and sublingual salivary glands

Resources

AnatomyTV
Netter's Head and Neck Anatomy for Dentistry
Acland's Video Atlas of Human Anatomy
TeachMe Anatomy

Intracranial Course

The facial nerve arises in the pons, an area of the brainstem
It starts as two roots: a large motor root and a small sensory root
The two roots travel through the internal acoustic meatus into the facial canal

Three Branches before Leaving Facial Canal

Greater petrosal nerve: parasympathetic fibers to mucous glands of nose, paranasal sinuses, palate, and lacrimal gland for tear production
Nerve to stapedius: motor fibers to stapedius muscle of the middle ear for dampening loud noises.
Chorda tympani: special sensory fibers to the anterior 2/3 of the tongue (taste function) and parasympathetic fibers to the submandibular and sublingual glands

Chorda Tympani

Innervates the anterior 2/3 of the tongue with the special sense of taste
Travels with the lingual nerve (branch of trigeminal nerve)
Carries parasympathetic fibres to the submandibular and sublingual glands

Extracranial Course

The facial nerve exits the cranium via the stylomastoid foramen
Extracranial branches:
- Posterior auricular nerve
- Posterior belly of the digastric muscle
- Stylohyoid muscle
Passes through the parotid gland and terminates into 5 branches:
- Temporal branch
- Zygomatic branch
- Buccal branch
- Marginal mandibular branch
- Cervical branch

Posterior Auricular Nerve

A motor nerve
Ascends in front of the mastoid process
Innervates the intrinsic and extrinsic muscles of the outer ear
Supplies the occipital part of the occipitofrontalis muscle

Nerves to Digastric and Stylohyoid Muscle

Innervates the posterior belly of digastric muscle, responsible for raising the hyoid bone
Innervates the stylohyoid muscle

Facial Branches

Two Zebras Bit My Cat
- Temporal
- Zygomatic
- Buccal
- Mandibular
- Cervical

Muscles of Facial Expression

Frontalis
Temporalis
Orbicularis oculi
Zygomaticus
Masseter
Buccinator
Risorius
Platysma

Temporal Branch

Leaves the superior surface of the parotid gland
Crosses the zygomatic arch to reach the forehead
Supplies auricular muscles, frontalis, orbicularis oculi, and corrugator supercilii muscles

Zygomatic Branch

Usually has two branches (upper and lower)
Upper branch passes above the orbit to supply the frontal belly of the occipitofrontalis and orbicularis oculi muscles
Lower branch passes below the orbit to supply the lower part of the orbicularis oculi muscle and contributes to innervation of the upper lip and nose muscles

Buccal Branch

Usually has two branches
Supplies the orbicularis oris, buccinator, and zygomaticus muscles
Contributes to innervation of the muscles of the upper lip and nose

Mandibular Branch

Emerges from the lower border of the parotid gland
Runs near the inferior border of the mandible
Supplies the depressor labii inferioris, depressor anguli oris, and mentalis muscles of the lower lip

Cervical Branch

Passes downwards from the lower border of the parotid gland
Supplies the platysma muscle
Raises the skin of the neck and forms noticeable vertical and horizontal ridges and depressions
Can pull the corners of the mouth downward when a person grimaces

Damage to the Facial Nerve - Intracranial Lesions

Intracranial lesions occur during the intracranial course of the facial nerve, proximal to the stylomastoid foramen
Causes:
- Infection related to the external or middle ear
- Stroke

Damage to the Facial Nerve - Extracranial Lesions

Paralysis or severe weakness of muscles of facial expression
Causes:
- Parotid gland pathology (e.g., tumor, parotitis, surgery)
- Nerve infection, particularly by the herpes virus
- Local anesthetic (rare)

Parotid Gland Tumor and Surgery

Can cause facial nerve damage/weakness after surgery

Trigeminal and Facial Nerve Examination

Examination for both nerves

Summary

Motor supply to muscles of facial expression
Minor sensory role
Taste to the anterior two-thirds of the tongue
Parasympathetic innervation to submandibular and sublingual salivary glands, nasal, palatine, pharyngeal mucous glands, and lacrimal glands

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Description

Explore the intricacies of the facial nerve (VII) in this quiz, including its anatomical path and functions. Learn how this cranial nerve impacts sensation and saliva production in facial and oral structures. Master the relevance of the facial nerve in dentistry through detailed descriptions and key concepts.