Facial Nerve and Innervation Overview

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Questions and Answers

What condition is indicated by a deviation of the tongue toward the affected side?

  • Hypoglossal nerve damage (correct)
  • Vagus nerve damage
  • Glossopharyngeal nerve damage
  • Facial nerve damage

Which type of hearing loss is indicated by air conduction being better than bone conduction?

  • Mixed hearing loss
  • Conductive hearing loss
  • Central auditory processing disorder
  • Sensorineural hearing loss (correct)

Which cranial nerve is primarily responsible for the sensory component of the gag reflex?

  • Olfactory nerve (Cranial Nerve I)
  • Glossopharyngeal nerve (Cranial Nerve IX) (correct)
  • Accessory nerve (Cranial Nerve XI)
  • Optic nerve (Cranial Nerve II)

Which sinus is unable to be palpated due to its depth?

<p>Sphenoid sinus (C)</p> Signup and view all the answers

What does a problem with the outer or middle ear typically indicate?

<p>Conductive hearing loss (C)</p> Signup and view all the answers

What common condition associated with sound blockage can be attributed to the outer ear?

<p>Earwax impaction (B)</p> Signup and view all the answers

Which nerve's damage can lead to ischemia and necrosis of cartilage in the nasal septum?

<p>Facial nerve (A)</p> Signup and view all the answers

What procedure is indicated for correcting the relationship between maxillary and mandibular jaws?

<p>Orthognathic surgery (D)</p> Signup and view all the answers

Which nerve is responsible for innervating the posterior belly of the digastric muscle?

<p>Facial Nerve (CN VII) (A)</p> Signup and view all the answers

Which of the following statements is true regarding upper motor neuron (UMN) lesions affecting the facial nerve?

<p>Only the lower facial muscles are affected on the contralateral side. (A)</p> Signup and view all the answers

What is the role of the trigeminal nerve (V) in the corneal reflex?

<p>It transmits sensory information from the cornea. (D)</p> Signup and view all the answers

Which cranial nerve innervates the anterior two-thirds of the tongue for taste?

<p>Facial Nerve (CN VII) (C)</p> Signup and view all the answers

Which of the following extraocular muscles is NOT innervated by the oculomotor nerve?

<p>Lateral rectus (D)</p> Signup and view all the answers

What results from pupils not reacting to light?

<p>Possible optic nerve damage (C)</p> Signup and view all the answers

What is accommodation in the context of the eye?

<p>The process of focusing on objects at different distances. (C)</p> Signup and view all the answers

Which of the following describes nystagmus?

<p>Rapid and uncontrollable eye movements. (A)</p> Signup and view all the answers

Which muscle is NOT part of the muscles of mastication?

<p>Sternocleidomastoid (D)</p> Signup and view all the answers

What is the primary function of the thyroid gland?

<p>Produces hormones that control metabolism (A)</p> Signup and view all the answers

What procedure involves making an incision in the cricothyroid membrane?

<p>Cricothyrotomy (B)</p> Signup and view all the answers

Where is the cricoid cartilage located?

<p>Surrounding the trachea (C)</p> Signup and view all the answers

What is the significance of Virchow's node?

<p>Often a clue to abdominal or thoracic malignancy (A)</p> Signup and view all the answers

Which statement about the cricoid cartilage is true?

<p>It is the only complete ring among the laryngeal cartilages (C)</p> Signup and view all the answers

What is the ideal location for a tracheostomy?

<p>2nd and 3rd tracheal rings (D)</p> Signup and view all the answers

What do the parathyroid glands regulate?

<p>Calcium levels in the blood (A)</p> Signup and view all the answers

What characterizes TMJ dislocation?

<p>The condylar head moves anteriorly and superiorly and the patient cannot reposition their jaw (C)</p> Signup and view all the answers

What is a common symptom of TMJ arthritis?

<p>Crepitus during mandibular motion (D)</p> Signup and view all the answers

What does trismus indicate?

<p>A restricted range of motion in mouth opening (A)</p> Signup and view all the answers

What is the primary issue caused by ankylosis of the TMJ?

<p>Abnormal fusion restricting mouth opening (D)</p> Signup and view all the answers

How can you perform a quick check for maximum incisal opening?

<p>Using a single finger to measure the gap (C)</p> Signup and view all the answers

When opening the mouth, what is likely to happen to the mandible on the affected side?

<p>It deviates toward the affected side (B)</p> Signup and view all the answers

What indicates a severely reduced range of motion in the jaw?

<p>One finger fits between the teeth (A)</p> Signup and view all the answers

How can joint tenderness or crepitus in the TMJ be assessed?

<p>Inserting the little finger into the ear canal (D)</p> Signup and view all the answers

Flashcards

Lid lag

A static condition where the upper eyelid is higher than normal during downgaze.

Facial Nerve (Taste)

The nerve responsible for taste sensation in the anterior two-thirds of the tongue.

Glossopharyngeal Nerve (Taste)

The nerve responsible for taste sensation in the posterior one-third of the tongue and gag reflex.

Sensorineural Hearing Loss

Hearing loss caused by damage to the inner ear or auditory nerve.

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Conductive Hearing Loss

Hearing loss caused by a problem in the outer or middle ear.

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Hypoglossal Nerve

Controls tongue movement; paralysis causes tongue deviation to the weak side.

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Sphenoid Sinus

A sinus that cannot be examined clinically due to its deep location.

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Cocaine effect on cartilage

Cocaine causes vasoconstriction, leading to ischemia and necrosis of the cartilage, potentially causing septal perforation.

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Facial nerve innervation of the face

The facial nerve (CN VII) primarily controls facial expressions, innervating muscles of facial expression. The upper facial muscles receive bilateral innervation (from both hemispheres), while the lower face receives contralateral innervation (from opposite hemisphere).

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Posterior digastric innervation

The posterior belly of the digastric muscle is innervated by the facial nerve (CN VII).

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Cranial nerve III

The oculomotor nerve (CN III) controls most extraocular muscles responsible for eye movement, excluding the superior oblique and lateral rectus muscles.

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Upper motor neuron lesions (UMN)

UMN lesions affecting the facial nerve cause weakness or paralysis of the lower face on the contralateral side (opposite).

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Lower motor neuron lesions (LMN)

LMN lesions causing facial nerve issues affect the entire ipsilateral side of the face (same side) which includes both the upper and lower part of the face

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Corneal reflex

Involves the trigeminal nerve (CN V) and the facial nerve (CN VII). This reflex protects the eye.

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Pupillary light reflex pathway

Involves three cranial nerves: the optic nerve (CN II), oculomotor nerve (CN III), and pretectal pathway in the midbrain.

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Taste sensation: cranial nerves

Anterior 2/3 of the tongue - Facial nerve (CN VII); Posterior 1/3 of the tongue - Glossopharyngeal nerve (CN IX); epiglottis and pharynx - Vagus nerve (CN X).

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TMJ Dislocation

The jawbone's condylar head moves too far forward and upward, beyond the articular eminence. A person can't reposition their jaw on their own.

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TMJ Subluxation

The jawbone's condylar head also moves forward and upward, but the person can put their jaw back in place.

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TMJ Arthritis

Creaking or grinding (crepitus) sound in the jaw joint during movement. Rare with myofascial pain syndrome (MPDS).

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Trismus

Limited ability to open mouth due to muscle spasms, inflammation, trauma, or fibrosis of chewing muscles.

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TMJ Ankylosis

Abnormal fusion or stiffening of the jawbone's condylar head to the skull, significantly restricting or preventing jaw opening.

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Mandible Deviation

Jaw moves to one side while opening, often towards the problematic side.

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Maximum Incisal Opening (MIO)

The distance between upper and lower front teeth during maximal mouth opening.

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Jaw Joint Tenderness

Pain or discomfort when touching the area around the TMJ.

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Cricoid Cartilage

The only complete ring-shaped cartilage in the larynx, located below the thyroid cartilage and above the trachea.

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Cricothyroid Membrane

The membrane connecting the cricoid cartilage to the thyroid cartilage.

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What procedure involves making an incision in the cricothyroid membrane?

Cricothyrotomy is a quick emergency procedure to establish an airway by making an incision in the cricothyroid membrane.

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Cricoidectomy

Surgical removal of the cricoid cartilage, either partially or completely.

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Ideal Location for Tracheostomy

The 2nd and 3rd tracheal rings are considered the best location for a tracheostomy.

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Virchow's Node

A swollen left supraclavicular lymph node, often indicating a potential abdominal or thoracic malignancy.

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Thyroid Gland Location

The thyroid gland is located in the neck, below the muscles and wrapping around the trachea near the cricoid cartilage.

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Parathyroid Gland Location

Four small glands situated behind the thyroid gland.

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Study Notes

Differential Diagnoses of Butterfly Rash

  • Systemic Lupus Erythematosus (SLE)
  • Rosacea

Trigeminal Nerve (CN V) Innervation

  • Innervates muscles of mastication
  • Innervates mylohyoid muscle
  • Innervates anterior belly of digastric muscle
  • Innervates tensor tympani and tensor veli palatini

Posterior Belly of Digastric Innervation

  • Innervated by the facial nerve (CN VII)

Facial Nerve Innervation

  • Innervates muscles of facial expression, not muscles of mastication

Mandibular Division (V3) Sensory Branches

  • Meningeal branch
  • Auriculotemporal nerve
  • Long buccal nerve
  • Lingual nerve
  • Inferior alveolar nerve
  • Mylohyoid nerve

Upper Motor Neuron (UMN) Lesions

  • Affect the facial nerve, only the lower face on the contralateral side is affected
  • Upper facial muscles receive bilateral innervation, so the unaffected hemisphere can still supply the forehead muscles on both sides

Lower Motor Neuron (LMN) Lesions

  • Affect the entire ipsilateral side of the face, including both upper and lower face

Corneal Reflex

  • Involves both the trigeminal nerve (CN V) and the facial nerve (CN VII)

Pupillary Light Reflex

  • Involves the optic nerve (CN II), oculomotor nerve (CN III), and ophthalmic nerve (V1)

Cranial Nerves Associated with Taste

  • Anterior two-thirds of the tongue: Facial nerve (CN VII)
  • Posterior one-third of the tongue: Glossopharyngeal nerve (CN IX)
  • Epiglottis and pharynx: Vagus nerve (CN X)

Extraocular Muscles and Innervation

  • Oculomotor nerve (CN III) innervates most extraocular muscles except two
  • Superior rectus: Elevates the eye
  • Inferior rectus: Depresses the eye
  • Medial rectus: Moves the eye medially (adduction)
  • Inferior oblique: Elevates and extorts the eye
  • Lateral rectus: Innervated by the abducens nerve (CN VI)
  • Superior oblique: Innervated by the trochlear nerve (CN IV)

Pupillary Size and Reaction to Light

  • Pupillary response to light can indicate optic nerve damage
  • Drug use can affect pupillary response

Accommodation

  • Process where the eye adjusts its optical power
  • Involves cranial nerves II, III, and V1 branches of the ophthalmic division

Nystagmus

  • Involuntary, rapid eye movements

Taste Sensation

  • Anterior two-thirds of the tongue: Facial nerve (CN VII)
  • Posterior one-third of the tongue: Glossopharyngeal nerve (CN IX)
  • Epiglottis and pharynx: Vagus nerve (CN X)

Gag Reflex

  • Sensory component is mediated by the glossopharyngeal nerve (CN IX)

Hearing Loss (Sensorineural and Conductive)

  • Sensorineural: Inner ear/auditory nerve damage, reduced sound heard through air conduction
  • Conductive: Outer/middle ear damage, weaker sound through air conduction, but stronger bone conduction

Orthognathic Surgery

  • Surgery that corrects the relationship of maxillary and mandibular jaws

Cocaine

  • Vasoconstrictor. Can lead to ischemia and necrosis of the cartilage

Sphenoid Sinus

  • Cannot be palpated or examined clinically

Deviation of the Tongue

  • Deviation towards the side of damage/paralysis. Signifies hypoglossal nerve (CN XII) issue

Temporomandibular Joint (TMJ) Disorders

  • Dislocation: Condylar head moves too far anteriorly and superiorly, patient cannot reposition
  • Subluxation: Similar to dislocation, but patient can reposition
  • Arthritis: Crepitus (grating sound) often heard during mandibular motion
  • Trismus: Restricted range of motion in opening mouth. Caused by inflammation, trauma, or fibrosis

Ankylosis of TMJ

  • Abnormal fusion/stiffening of the condylar head of mandible. Prevents mouth opening.

Deviation of Mandible During Mouth Opening

  • May deviate toward the affected side during opening

Muscles of Mastication

  • Masseter, temporalis, medial pterygoid, lateral pterygoid

Strap Muscles of the Neck

  • Sternohyoid, thyrohyoid, omohyoid, sternothyroid, platysma

Cricoid Cartilage

  • Complete ring surrounding the trachea

Thyroid Gland

  • Located in neck below muscles, wrapping around trachea near cricoid cartilage
  • Produces hormones that control metabolism

Parathyroid Glands

  • Small glands behind the thyroid (top and bottom)
  • Control calcium levels in the blood

Tracheostomy

  • Surgical opening in trachea, ideal location is the 2nd and 3rd tracheal rings

Virchow's Node

  • Left supraclavicular node, can be sign of abdominal/thoracic malignancy

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