Podcast
Questions and Answers
What structure does the facial nerve exit through to leave the skull?
Which branch of the facial nerve carries parasympathetic fibers to the submandibular and sublingual glands?
Which of the following muscles is innervated by the temporal branch of the facial nerve?
The zygomatic branch of the facial nerve primarily innervates which area?
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What is the function of the posterior auricular nerve?
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Which branch of the facial nerve supplies the depressor labii inferioris muscle?
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What motor function does the cervical branch of the facial nerve provide?
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The buccal branch of the facial nerve usually splits into how many branches?
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What is the main role of the chorda tympani?
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The mnemonic 'Two Zebras Bit My Cat' helps to remember which aspect of the facial nerve?
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What is the primary function of the motor root of the facial nerve?
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Which gland is innervated by the parasympathetic fibres of the facial nerve?
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In which cranial structure does the facial nerve emerge?
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What is the significance of the greater petrosal nerve?
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Which anatomical part does the facial nerve NOT belong to?
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Which structure is innervated by the chorda tympani branch of the facial nerve?
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The facial nerve's branches outside the cranium primarily serve which regions?
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What does the nervus intermedius primarily convey?
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Which of the following is NOT a muscle controlled by the facial nerve?
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The function of the stapedius muscle is primarily related to which action?
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What is a common symptom associated with damage to the facial nerve?
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Which of the following is NOT a possible cause of extracranial lesions of the facial nerve?
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Which structure is primarily responsible for taste sensation in the anterior two-thirds of the tongue?
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What is one of the parasympathetic functions of the facial nerve?
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What is a common result of parotid gland pathology in relation to the facial nerve?
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Which clinical feature is associated with intracranial lesions affecting the facial nerve?
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In which area does an intracranial lesion occur with regard to the facial nerve?
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Which of the following is NOT a symptom of facial nerve damage?
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What rare cause can lead to damage of the facial nerve?
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Which glands receive parasympathetic innervation from the facial 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 the motor nucleus.
- A smaller root, the nervus intermedius, which carries sensory information.
- The nerve passes into the internal auditory meatus.
Motor Root Functions
- The facial nerve's motor root controls muscles of facial expression.
- It innervates various muscles, including the temporalis, orbicularis oculi, zygomaticus, masseter, buccinator, risorius, and platysma.
- It also controls the stylohyoid muscle and posterior belly of the digastric muscle.
Nervus Intermedius Functions
- This sensory root has special sensory functions related to taste and the external ear.
- It transmits taste sensation from the anterior two-thirds of the tongue.
- It also carries parasympathetic fibers to the submandibular and sublingual salivary glands, as well as lacrimal, nasal, palatine, and pharyngeal glands.
Anatomical Course
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The facial nerve has two main parts: intracranial and extracranial.
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Intracranial: The nerve travels through the cranial cavity.
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Extracranial: The nerve leaves the cranium.
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Three branches emerge before leaving the facial canal:
- Greater petrosal nerve
- Parasympathetic fibers to mucous glands of the nose, paranasal sinuses, palate, and lacrimal gland for tear production.
- Nerve to stapedius
- Motor fibers to the stapedius muscle of the middle ear for dampening loud noises.
- Chorda tympani
- Special sensory fibers to the anterior 2/3 of the tongue for taste. Also parasympathetic fibers to submandibular and sublingual glands.
- Greater petrosal nerve
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The facial nerve then exits the facial canal via the stylomastoid foramen.
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Extracranial branches:
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Posterior auricular 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.
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Branches through the parotid gland, terminates into:
- Temporal Branch
- Zygomatic Branch
- Buccal Branch
- Marginal mandibular Branch
- Cervical Branch
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Damage to the Facial Nerve
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Intracranial lesions occur during the intracranial course, often due to infections of the external or middle ear, or stroke.
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Extracranial lesions can be caused by parotid gland pathology (like tumors or surgery), infections (sometimes viral), or local anesthetic use.
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Symptoms of facial nerve damage may include paralysis or weakness of facial muscles, dry eye, dry mouth, loss of taste, difficulty talking, and reduced salivation.
Examination
- Trigeminal and facial nerve examination is important for diagnosis.
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Description
Explore the anatomy and functions of the facial nerve (VII), including its motor and sensory roots. This quiz covers the nerve's role in facial expressions and taste sensations. Test your knowledge on the innervation of facial muscles and the glands associated with the facial nerve.
