Podcast
Questions and Answers
Which of the following is NOT a function of the motor root of the facial nerve?
Which of the following is NOT a function of the motor root of the facial nerve?
Which of the following structures does the facial nerve NOT pass through?
Which of the following structures does the facial nerve NOT pass through?
The nervus intermedius is responsible for which of the following functions?
The nervus intermedius is responsible for which of the following functions?
Which of the following is not innervated by the Facial Nerve?
Which of the following is not innervated by the Facial Nerve?
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Which branch of the Facial nerve supplies the muscles of the lower lip?
Which branch of the Facial nerve supplies the muscles of the lower lip?
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Which branch of the facial nerve carries special sensory fibers for taste?
Which branch of the facial nerve carries special sensory fibers for taste?
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What is the primary function of the stapedius muscle?
What is the primary function of the stapedius muscle?
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The Chorda Tympani nerve travels with which other cranial nerve?
The Chorda Tympani nerve travels with which other cranial nerve?
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Which of the following muscles is not innervated by the Facial Nerve?
Which of the following muscles is not innervated by the Facial Nerve?
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Why is the facial nerve relevant to dentistry?
Why is the facial nerve relevant to dentistry?
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Which of the following is NOT a location where the facial nerve provides parasympathetic innervation?
Which of the following is NOT a location where the facial nerve provides parasympathetic innervation?
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Which branch of the Facial Nerve is responsible for supplying the Auricular muscles, Frontalis, and Orbicularis Oculi?
Which branch of the Facial Nerve is responsible for supplying the Auricular muscles, Frontalis, and Orbicularis Oculi?
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The Facial Nerve exits the skull via which foramen?
The Facial Nerve exits the skull via which foramen?
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Which of the following statements regarding the intracranial course of the facial nerve is TRUE?
Which of the following statements regarding the intracranial course of the facial nerve is TRUE?
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Which of the following correctly describes the innervation of the posterior belly of the digastric muscle?
Which of the following correctly describes the innervation of the posterior belly of the digastric muscle?
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What is the function of the Cervical branch of the Facial Nerve?
What is the function of the Cervical branch of the Facial Nerve?
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Which of the following symptoms is NOT associated with damage to the facial nerve?
Which of the following symptoms is NOT associated with damage to the facial nerve?
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What is a potential cause of intracranial lesions affecting the facial nerve?
What is a potential cause of intracranial lesions affecting the facial nerve?
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Which structure is primarily innervated by the facial nerve for parasympathetic functions?
Which structure is primarily innervated by the facial nerve for parasympathetic functions?
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What is the role of the facial nerve in relation to taste?
What is the role of the facial nerve in relation to taste?
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What is the impact of extrinsic infections like herpes on the facial nerve?
What is the impact of extrinsic infections like herpes on the facial nerve?
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Flashcards
Facial Nerve Function
Facial Nerve Function
The Facial nerve (VII) supplies muscles for facial expressions, taste, and gland secretions.
Motor Root of Facial Nerve
Motor Root of Facial Nerve
The main motor root controls muscles of facial expression and some other muscles.
Nervus Intermedius Functions
Nervus Intermedius Functions
The smaller root that handles sensory, taste, and parasympathetic functions.
Branches of Facial Nerve
Branches of Facial Nerve
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Greater Petrosal Nerve
Greater Petrosal Nerve
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Chorda Tympani
Chorda Tympani
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Intracranial Course
Intracranial Course
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Extracranial Course
Extracranial Course
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Intracranial Lesions of Facial Nerve
Intracranial Lesions of Facial Nerve
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Symptoms of Facial Nerve Damage
Symptoms of Facial Nerve Damage
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Extracranial Lesions of Facial Nerve
Extracranial Lesions of Facial Nerve
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Parotid Gland Pathology
Parotid Gland Pathology
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Stylomastoid foramen
Stylomastoid foramen
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Temporal branch
Temporal branch
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Zygomatic branch
Zygomatic branch
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Buccal branch
Buccal branch
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Mandibular branch
Mandibular branch
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Cervical branch
Cervical branch
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Posterior auricular nerve
Posterior auricular nerve
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Study Notes
Facial Nerve (VII)
- The facial nerve (VII) emerges from the brain between the pons and medulla.
- It has two roots:
- A larger motor root originating from a motor nucleus.
- A smaller root, called the nervus intermedius, which is considered sensory.
- The nerve enters the internal auditory meatus.
Motor Root Functions
- Supplies muscles of facial expression (e.g., temporalis, orbicularis oculi, zygomaticus, masseter, buccinator, risorius, platysma) and associated muscles such as stylohyoid, posterior belly of digastric muscle, stapedius.
- The function of the motor root is to innervate, or control, the facial muscles required for expression.
Function - Nervus Intermedius
- Provides special sensory function involving taste to the anterior two-thirds of the tongue.
- Supplies sensory information from the external ear.
- It provides parasympathetic efferents, innervating:
- Submandibular and sublingual salivary glands.
- Lacrimal glands.
- Nasal, palatine, and pharyngeal mucous glands.
Anatomical Course
- The facial nerve's course can be divided into intracranial and extracranial parts.
- The intracranial portion refers to its pathway within the skull, the extracranial portion refers to its movement outside the skull.
Intracranial
- The facial nerve originates in the brainstem's pons area.
- It has two roots: a larger motor root and a smaller sensory root (nervus intermedius).
- The roots travel through the internal acoustic meatus, entering the facial canal.
Branches before leaving facial canal
- The greater petrosal nerve:
- Has parasympathetic fibres that innervate mucous glands in the nose, paranasal sinuses, palate, and lacrimal glands.
- The nerve to stapedius:
- Carries motor fibres that innervate the stapedius muscle (within the middle ear) which controls the dampening of loud noises.
- The chorda tympani:
- Contains special sensory fibres that innervate the anterior two-thirds of the tongue (taste).
- Also carries parasympathetic fibres that innervate the submandibular and sublingual salivary glands.
- After these branches, the facial nerve exits the facial canal (skull) via the stylomastoid foramen.
Extracranial
- The facial nerve emerges from the stylomastoid foramen, located on the lateral aspect of the skull base.
- It then passes through the parotid gland, dividing into five main branches.
- These branches are:
- Temporal branches
- Zygomatic branches
- Buccal branches
- Marginal mandibular branches
- Cervical branches
Posterior Auricular nerve
- Motor nerve.
- Ascends in front of the mastoid process.
- Innervates the intrinsic and extrinsic muscles of the outer ear and the occipital part of the occipitofrontalis muscle.
Nerves to digastric and stylohyoid Muscle
- Specific nerves associated with these muscles (digastric and stylohyoid) are mentioned.
- Diagrammatic representations of these muscles are provided.
Facial Branches
- A mnemonic device ("Two Zebras Bit My Cat") is used to remember the order of the five main branches of the facial nerve emerging from the parotid gland.
Muscles of Facial Expression
- A list and diagram showing several muscles of facial expression that are innervated by the facial nerve are listed.
Temporal Branch
- Originates from the superior surface of the parotid gland.
- Crosses the zygomatic arch to reach the forehead.
- Supplies specific muscles on the forehead and surrounding areas.
Zygomatic Branch
- Typically has 2 branches: the upper and lower.
- Upper branch supplies the frontal belly of the occipitofrontalis muscle & orbicularis oculi.
- Lower branch supplies lower part of orbicularis oculi and some muscles in the upper lip & nose.
Buccal Branch
- Usually composed of two branches.
- Supplies muscles of the mouth including the orbicularis oris, buccinator, and zygomaticus.
- Contributes to innervation of muscles in the upper lip and nose.
Mandibular Branch
- Arises from the lower border of the parotid gland.
- Runs close to the inferior border of the mandible.
- Supplies the muscles of the lower lip including depressor labii inferioris, depressor anguli oris, and mentalis.
Cervical Branch
- This branch descends from the lower border of the parotid gland.
- It supplies the platysma muscle.
- This muscle helps with facial expressions involving the mouth and neck.
Damage to the facial nerve
- Intracranial lesions:
- Occur during the intracranial course.
- Potential causes may include infections of external/middle ear, stroke.
- Extracranial lesions:
- Likely causes include parotid gland pathologies (tumors, parotitis, or surgery), nerve infections (maybe herpes virus), and local anesthetic use.
- Symptoms often involve paralysis/weakness of facial muscles.
Trigeminal and facial nerve examination
- These examinations are mentioned as important assessments of these nerves.
Summary
- The facial nerve primarily controls facial expression muscles.
- It plays a sensory role in taste and has parasympathetic functions for the glands previously mentioned.
Quiz
- A quiz is scheduled at the end of the presentation.
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Description
Explore the structure and functions of the facial nerve (VII) in this quiz. Understand its motor and sensory roots, and learn how it innervates facial muscles and provides taste sensations. Test your knowledge on the anatomical pathways and functions of this crucial cranial nerve.
