Transcript facial nerve and

ENT related PN
system
DR. MOHAMMAD ALSALEM
Olfactory nerve (I)

Damage can cause an inability to smell (anosmia), a distortion in the sense of
smell (parosmia), or a distortion or lack of taste

Intensely smelling substances, for example ammonia, may lead to the
activation of pain receptors (nociceptors) of the trigeminal nerve that are
located in the nasal cavity

the nerve (actually many small nerve fascicles) travels up through the cribriform
plate of the ethmoid bone to reach the surface of the brain

Located in upper 1/3 of nasal cavity in the posteriodorsal recess (inferior surface
of the cribriform fossa) + superior part of the nasal septum(10mm) &
superiomedial part of superior turbinate

primary olfactory neurons; (olphactory receptor neurons)

bipolar in shape; non-motile cell has single odor receptor (not specialized as other
senses)

Lesions to the olfactory nerve can occur because of "blunt trauma",
such as coup-contra-coup damage, meningitis, and tumors of the
frontal lobe.

Decreases in the ability to smell is a normal consequence of human
aging, and usually is more pronounced in men than in women

Other causes of loss of smell: Upper respiratory tract infection (e.g.,
sinusitis or the common cold, Nasal polyps, Hypothyroidism

Exposure to a chemical that burns the inside of the nose

Radiation therapy to the head and neck

Kallmann syndrome (hypogonadotropic hypogonadism +anosmia)
General features
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Adaptation to odor can occur within 1-5 min
If two odors were mixed the sum of the intensity will be less than the two
individually perceived intensities and is dominated by the stronger
component.
Cross adaptations are present between odors at high concentrations,
whereas cross facilitations occur near threshold values
Odor association tend to stay longer in the memory than the
associations from other senses
Olfaction helps two aspects of eating: the recognition of food types
and the initiation of digestion
Females are better in odor identification than men.
Female sense of odor is more acute at ovulation & less during
menstruation.
Trigeminal Nerve (V)
The sensory function of the trigeminal nerve is to provide tactile, proprioceptive, and
nociceptive afference to the face and mouth. Its motor function activates muscles of
mastication: the masseter, the temporalis and the medial and lateral pterygoids. The
other four muscles are the tensor veli palatini, the mylohyoid, the anterior belly of the
digastric and the tensor tympani
The branch
Foramen
Compartment
Function
Ophthalmic
Superior orbital
fissure
Orbital cavity
Sensation ( somatic afferent); orbit + face
Conveys parasympathetic
• from oculomotor (III) via ciliary branch to ciliary muscles
• through the lacrimal nerve
Maxillary
Foramen
rotundum
Pterygoplatine
fossa
Mandibular
Foramen ovale
Infratemporal
fossa
Sensation : palate + nose + face
Conveys parasympathetic from:
greater petrosal (VII) To the nose + lacrimal gland
Sensation: mandibule + ear
Taste via lingual nerve: anterior 2/3 of the tongue (in
a communication with chorda tympani)
Parasympathetic :parotid gland
Motor: muscles of mastication + floor of mouth + tensors

THE CORNEAL REFLEX
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The afferent limb of the reflex is via the nasociliary nerve
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the efferent limb is via the facial nerve.
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A pointed wisp of cotton wool should be used.

The examiner should ask the patient to look upwards, then resting
the hand on the patient's cheek,

The wisp should be applied to the lower cornea but taking care not
to bring it into vision or a blink reflex will result.

The patient will flinch, the eyeball will roll up and the eye will attempt
to close.
Facial Nerve (VII)

The facial muscles include: Occipitofrontalis muscle, Temporoparietalis
muscle, Procerus muscle, Nasalis muscle, Depressor septi nasi muscle,
Orbicularis oculi muscle, Corrugator supercilii muscle, Depressor supercilii
muscle, Auricular muscles (anterior, superior and posterior), Orbicularis oris
muscle, Depressor anguli oris muscle, Risorius, Zygomaticus major muscle,
Zygomaticus minor muscle, Levator labii superioris, Levator labii superioris
alaeque nasi muscle, Depressor labii inferioris muscle, Levator anguli oris,
Buccinator muscle, Mentalis

Platysma.

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The platysma is innervated by the facial nerve. Although it is mostly in the neck
and can be grouped with the neck muscles by location, it can be considered a
muscle of facial expression due to its common innervation.
The stylohyoid muscle, stapedius and posterior belly of the digastric muscle
Facial Nerve (VII)

The facial nerve is made of 10,000 fibers (7000 mylinated motor,
3000 unmylinated sensory & parasympathetic)
Location of facial nerve related nucleus:
1 Facial Motor nucleus: in the caudal end of
the pons
2 Superior salivatory nucleus
3 Nucleus solitarus: medulla
Note that the facial nerve emerge at the
ponto-medullary junction
The facial nerve is made of:
1. facial nerve proper: input from facial motor nucleus
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special visceral efferent fibers (motor): (efferent)
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Posterior belly of digastrics muscle
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Stylohyoid muscle
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Muscles of facial expressions (including Masseter muscles)
2. nervus intermedius (nerve of wrisberg)
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Gives chorda tympani branch, parasympathetic
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Exists the Brain stem adjacent to the motor branch of the facial nerve
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Joins the VII nerve as it approaches the Internal auditory canal to form the
common Facial nerve
•General Visceral motor: input from Superior salivatory
nucleus (efferent)
•Greater superficial petrosal
•Lacrimal gland
•Nasal glands
•Palatine glands
•Chorda tympani
Submandibular gland
Sublingual gland
Minor salivary gland
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General sensory: input into nucleus
solitarus (afferent)
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Auricular concha
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External auditory canal
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Tympanic membrane
Special Visceral sensory: (input into
nucleus solitarus) (afferent)

Greater superficial petrosal :Taste from
Soft palate

Chordi tympani: Taste from the
anterior 2/3 of the tongue
Pathway
Intracranial part
1-CP <
2-Meatal segment (IAC)
Intratemporal/ intrepetrous part (within the fallopian
canal)
Peri-ganglionic
3-labyrinthine /proximal
segment
4-tympanic/ horizontal
segment
5-mastoid /vertical segment
6-Extracranial part (parotid)
Facial Nerve Paralysis
Ramsay Hunt syndrome /Herpes
zoster oticus
PATHOLOGY
The disease is a reactivated varicella zoster infection (chicken pox)
from dormant viral particles resident in the geniculate ganglion of
the facial nerve and the spiral and vestibular ganglia of VIII
Symptoms:
• Auricular pain: the 1st symptom to appear
• Vesicular Rash:
•location:
1.concha
2.posteriomesial surface of the auricle (postauricular)
3.EUC
4.mucosa of the palate
5.anterior 2/3 of the tongue
• Facial nerve palsy
• VIII may be involved in the form of hearing loss (SNHL), vertigo
and or tinnitus.
Vestibulocochlear (VIII)
Cochlear system
Organ of corti: Specialized epithelium (sensory receptor for sound)
Located within the inner part of the basilar membrane
Hair cells of organ of corti
Number of rows
Total number
Function
Afferent innervations
%
Inner hair cells
1 row
3.000
principal transducer of motion from the
basilar membrane to a nerve impulse
(Send information about hearing to the
brain)
90%
Outer hair cells
3 rows up to 5 in humans
12.000
Cochlear amplifier: amplify motion from the
basilar membrane at the point of maximum
response (which increase sensitivity, frequency
& selectivity)
controlling and fine tuning mechanisms
10%
Summary of the Pathway for sound
 Sound waves in the air enter the outer ear canal.
 Vibration of the tympanic membrane is transmitted through the chain of three (3) ossicles (which amplify the sound
20 X) to the oval window.
 Vibration of the oval window induces pressure waves in the perilymph of the scala vestibuli.
 Vibration of the vestibular (Reissner's) membrane transfers pressure waves from perilymph to the endolymph of the
scala media (cochlear duct).
 Pressure waves of the endolymph induce the basilar membrane to vibrate, induces a shearing of the apical ends of
the hair cells against the tectorial membrane.
 This will bend the bundle of stereocilia on each hair cell resulting in the bending of the bundle of stereocilia and the
opening of mechanically gated ion channels in the membrane of the stereocilia
 Influx of K+ ions, depolarizing the hair cell, which releases neurotransmitters.
 This results in an action potential being propagated along nerve fibers of sensory neurons in the spiral ganglion.
The vestibular system
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Components of the vestibular system
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The semicircular canals are concerned with the rotation
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the saccule and utricle with gravitation (vertical)
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Benign positional vertigo
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One of the most common types of peripheral vertigo
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BPPV occurs because a semicircular canal has otoconia (originating
from the macula of the gravity-sensitive Utricle) either:
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attached to the cupula (cupulolithiasis)
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free floating in the endolymph (canalolithiasis)
The majority of BPPV is due to debris in the posterior canal, but debris
may also enter the horizontal and superior semicircular canals.
ESSENTIALS OF DIAGNOSIS
1.
Sudden vertigo lasting seconds with certain head positions. 10–20 seconds
2.
No associated hearing loss.
3.
Characteristic nystagmus (latent, geotropic, fatigable) with Dix-Hallpike test.

Primary idiopathic endolymphatic hydrops (known as
Ménière’s disease) is of unknown etiology

ESSENTIALS OF DIAGNOSIS
• Episodic vertigo lasting hours.
• Fluctuating hearing loss.
• Tinnitus.
• Aural pressure. (fullness)
Sudden Sensorineural Hearing Loss
(SSNHL)

Definition:

≥ 30 dB SNHL in at least 3 adjacent frequencies that occurs
over ≤ 3 days
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most commonly no etiology found (idiopathic SSNHL) 85%,theories:
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viral infection: atrophy of tectorial membrane

autoimmune
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perilymphatic fistula
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vascular ischemia:reduce O2 tension in stria vascularis
DRUGS
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Temporary vs permenant hearing loss:
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permanent (hearing loss/vestibular dysfunction):
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Anti-neoplastic: cistaplatine/carboplatine
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Amingogylcoside
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vancomycin
temporary (hearing loss):
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Aspirin
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Macrolide: erythromycin
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Quinine
Temporary MAQ
temporary/permanent:
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Permanent CAVe
Diuretics: can cause both; in neonates it cause permanent hearing loss
The main drugs that cause vestibulotoxicity:
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streptomycin
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gentamycin
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minocylcline (tetracycline)
Temporary/Permanent Di
The glossopharyngeal nerve (IX)
Function
Afferent fibers
Somatic sensation
Special sensation
Visceral sensation
Efferent fibers
Visceral
Special visceral (branchiogenic)
Post 1/3 of tongue, tonsils, soft palate
Naso + oropharynx ( pharyngeal plexus)
Ear:
 Ant 1/3 Skin of EUC
 Internal surface of T.M,
 Mucosa of middle ear(tympanic plexus)
 bony part of ET
Taste from the post 1/3 of the tongue
Carotid body
Carotid sinus

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Presynaptic parasympathetic fibers to parotid gland
Motor fibers to stylopharyngeaus muscle
Gag reflex:
Brisk and brief elevation of the soft palate and bilateral
contraction of pharyngeal muscles evoked by touching
the posterior pharyngeal wall, the soft palate or
posterior part of the tongue
It prevents something from entering the throat except
as part of normal swallowing and helps prevent
choking.
Afferent fibers
Nerve
Glossopharyngeal nerve
Efferent fibers
Vagus nerve
Vagus nerve (X) clinical ENT relations
loss of auricular sensation at the
concha & anti helex
auricular
branch
pharyngeal
branch
nasal reguragtaion during
swallowing
external branch
of the superior
laryngeal nerve
Recurrent
laryngeal nerve
deviated Uvula
dysphagia
stridor
horsness of voice
Aphonia
reffered pain from the
laryngeal ca
paralysed v.c
unilateral/ bilateral
Vagus nerve relation to the
pharynx & larynx
Pharyngeal branch which
contributes to the
pharyngeal plexus*)
External branch of the
superior laryngeal nerve
pharyngeal and palate muscles except
tensor palati muscle (trigiminal)
stylopharyngeaus (glossopharyngeal)
Cricothyroid muscle
Recurrent laryngeal nerve
all internsix muscle of the
larynx except the
cricothyroid muscle
1-Pharyngeal muscles:
3 constrictor muscles
salpingopharyngeus
palatoglossus
2-palate muscle:
levator palati muscle
palatoglossus
palatopharyngeus
all intrinsic muscles recieves
unilateral innervation
except interarytenoid
•Somatic motor pathway of the vagus nerve
•Pharyngeal plexus is made up of Vagus & Glossopharyngeal & sympathetic plexus
•Somatic (cutenous sensation):
•Cutenous sensation from the back of the auricle & posterior external auditory canal
•General Visceral Sensation:
•Common sensation from the larynx & pharynx is to the spinal nucleus of the trigeminal
•Special ( taste) Visceral sensation:
•Sensation of taste from the pharynx, vallecula, tongue base, epiglottis
Hypoglossal Nerve (XII)
It receives:
•sympathetic fibres from the superior cervical ganglion
•some fibres from the vagus
•motor roots of Cl and C2 via the ansa cervicalis.
Motor fibres derived from the:
hypoglossal nucleus itself supply intrinsic & extrinsic muscles of the tongue except the
palatoglossus
•The fibres derived from the C 1 components supply Suprahyoid muscles
XIIth nerve lesion
•paralyses one side of the tongue
•the larynx also pulls across to the opposite side on swallowing, because the hyoid
fails to elevate on the paralyzed side.