Module 10: Special Senses Flashcards
- Contains vestibulocochlear organ
- Consists of 3 main parts: External, Middle, Internal
- 2 functions: Balance and hearing
Ear
• Composed of
- Auricle (collects sounds)
- External acoustic meatus (conducts sounds to tympanic membrane)
External Ear
- Shell like part
- Consists of single elastic cartilage which is continuous with cartilage of external acoustic meatus
- Contains: hair,sweat/sebaceous glands
- Shape varies
- Lobule – no cartilage, can be pierced for earring
Auricle
• Auditory passage • Extends from concha to tympanic membrane (TM) • S-shaped, 2.5cm long • Composition: o Lateral 1/3: Cartilage o Medial 2/3: Bony • Infants: PURE cartilage
EXTERNAL ACOUSTIC MEATUS (EAM)
• Lined with skin • Contents: o Hair follicles o Sebaceous glands o Ceruminous glands – produce cerumen
EXTERNAL ACOUSTIC MEATUS (EAM): Lateral Part
- Lined with thin skin
- Isthmus – constricted part
*This is where most foreign bodies gets lodged or impacted (ex. Ipis)… killed the insect with baby oil, water or hydrogen peroxide,
EXTERNAL ACOUSTIC MEATUS (EAM): Medial Part
EXTERNAL ACOUSTIC MEATUS (EAM): Arterial supply
- Post-auricular branch of External carotid artery (ECA)
- Deep auricular branch of Maxillary artery
- Auricular branch of Superficial temporal artery
EXTERNAL ACOUSTIC MEATUS (EAM): VENOUS DRAINAGE
- External jugular vein (EJV)
- Maxillary vein
- Pterygoid plexus
EXTERNAL ACOUSTIC MEATUS (EAM): NERVE SUPPLY
- Auricotemporal nerve (from CN V)
- Tympanic plexus (from CN VII)
- Auricular branch (from CN X)
(Clinical Anatomy)
• When doing otoscopic exam, know the anatomy of EAM
- Directed anteriorly and medially
* Pull the ear superiorly, posteriorly, and laterally
- Thin, semitransparent, oval membrane
- Medial end of EAM
- Separates external from middle ear
- Oblique and slopes inferomedially
- Pearly gray and shiny
TYMPANIC MEMBRANE
- Concavity toward the EAM with a central depression called umbo, formed by the handle of malleus
- From umbo, bright area emanates called cone of light
- Moves in response to air vibrations that pass to it
- Vibrations are transmitted from TM by auditory ossicles through the middle ear to the internal ear
TYMPANIC MEMBRANE
TYMPANIC MEMBRANE: Arterial Supply
Maxillary artery
o Deep auricular artery
o Posterior auricular artery
o Tympanic branch
TYMPANIC MEMBRANE: Venous Drainage
• External jugular vein
TYMPANIC MEMBRANE: NERVE SUPPLY
• Auriculotemporal nerve (from CN V3)
Clinical Anatomy: Tympanic Membrane
• Perforation of TM
o Deafness
o Etiology: Foreign bodies, Infection, Excessive pressure as in scuba diving
• During PE, pull the auricle superiorly, posteriorly, and laterally
• Narrow cavity in petrous part of temporal bone • Contents: o Auditory ossicles o Stapedius o Tensor tympani o Chorda tympani nerve
MIDDLE EAR
MIDDLE EAR: Connections
o Anterior: Nasopharynx
o Posterosuperior: Mastoid antrum
Middle Ear
When the plane descends, you experience some type of ear pain. That is because of your ear being equalized. If you have difficulty equalizing, the pain will persist for a couple of days hanggang sa maging infection na siya. That is what we refer to as para-trauma of your middle ear.
WALLS OF MIDDLE EAR
• ROOF or TEGMENTAL
Formed by tegmen tympani
Separates middle ear from dura
• FLOOR or JUGULAR
Formed by bone Separates middle ear from IJV (Internal Jugular Vein)
• LATERAL or MEMBRANOUS
Formed by TM (Tympanic Membrane)
WALLS OF MIDDLE EAR: MEDIAL or LABYRINTHINE
• Semicircular ducts and cochlea • Separates middle ear from inner ear • 2 small windows: 1. Fenestra vestibule o Closed by base of stapes o Through this window, vibrations of stapes are transmitted to inner ear
- Fenestra cochlea
o Closed by a secondary TM
o Allows perilymph to move in response to impulses
WALLS OF MIDDLE EAR: POSTERIOR or MASTOID
- Leads to mastoid antrum via an opening, aditus
- Pyramidal eminence
- Contains the stapedius muscle
WALLS OF MIDDLE EAR: INFERIOR or CAROTID
2 openings which connects:
• With canal occupied by tensor tympani
• With nasopharynx through auditory tube
- Otherwise known as your Eustachian / Pharyngotympanic tube
- Funnel-shaped
- Connects nasopharynx to middle ear
- 3.5-4 cm long
- 1/3: Bone; 2/3: Cartilage
- Function: Equalizes pressure in middle ear with atmospheric pressure
AUDITORY TUBE
What happens when you’re not able to equalize as the plane descends?
Your Eustachian tube will have a dysfunction. It is not able to open up. That is why you are instructed to do a Valsalva maneuver. Or you can pinch your nose and swallow.
AUDITORY TUBE: Arterial Supply
- Ascending pharyngeal artery
- Middle meningeal artery
- Artery of pterygoid canal
AUDITORY TUBE: VENOUS DRAINAGE and NERVE SUPPLY
VENOUS DRAINAGE: Pterygoid plexus
NERVE SUPPLY: Tympanic plexus (CN VII and IX
- Ear bones
- Form a chain across middle ear
- From Tympanic Membrane to oval window
- Function: Increase the force but decrease amplitude of vibrations transmitted from tympanic membrane
- Consists of: Malleus, Incus, Stapes
AUDITORY OSSICLES
Malleus / Hammer (Parts)
Head
o Rounded superior part
o Lies in epitympanic recess
o Articulates with incus
Neck
o Lies vs flaccid part of TM
o Where chorda tympani nerve crosses
Handle
o Embedded in TM
o Where tendon of tensor tympani inserts
Incus (Parts)
Body: Articulates with head of malleus
Long Process: Articulates with stapes
Short Process: Connected to tympanic cavity by a ligament
Lenticular Process: Articulates with head of stapes
Stapes (Parts)
- Smallest bone
- Base – fits into oval window
- Head – articulates with lenticular process of incus
- 2 cm long Origins -cartilaginous part of auditory tube - greater wing of sphenoid bone - petrous part of temp bone Insertion: Handle of malleus NS: Mandibular n [CN V3] Action: - pulls handle of malleus thus tenses TM - reduces amplitude of oscillations - prevents damage to int ear when exposed to loud sounds
TENSOR TYMPANI
Origin: pyramidal eminence Insertion \: Neck of stapes NS: Nerve to stapedius [CN VII] Action - Reduces oscillatory range - Prevents excessive movement of stapes
STAPEDIUS
- Contains the vestibulocochlear organ
- Concerned with reception of sound and maintenance of balance
- In petrous part of temporal bone
- Consists of sacs and ducts of membranous labyrinth
- Membranous system contains endolymph and end organs for hearing and balance (these are specialized neuro-epithelial structures)
INTERNAL EAR
- Surrounded by perilymph
* Suspended within bony labyrinth
Membranous Labyrinth
• Composed of:
- Cochlea
- Vestibule
- Semicircular canals
Bony Labyrinth
- Shell-like
* Contains the cochlear duct
Cochlea
Cochlea: Parts
o Cupula – apex
o Osseous spiral lamina – shelf of bone
o Basilar membrane – attached to ossicles
o Spiral ganglion
o Organ of corti – concerned with auditory perception
o Scala vestibule – opens into vestibule
o Scala tympani – related to tympanic cavity at fenestra cochlea
• Oval bony chamber • About 5 mm • Contains utricle and saccule, which are parts of balancing apparatus • Continuous: o Anteriorly with cochlea o Posteriorly with semicircular canals
Vestibule
- Bony canals which open into vestibule
- Set at right angles to each other
- Three: Anterior, Posterior, Lateral
- Forms 2/3 of a circle
- About 1.5 mm diameter except at swelling called ampulla (this ampulla correspond to your organ of Corti which contains your specialized neurons)
Semicircular Canals
• Sacs and ducts in cavities of bony labyrinth
• Follows the form of bony labyrinth but smaller
• Contains watery fluid, endolymph
• Consists of 3 parts:
1. Utricle and Saccule
2. 3 Semicircular ducts
3. Cochlear duct
MEMBRANOUS LABYRINTH
• Dilatations
• With a specialized area of sensory epithelium, macula
• Macula
o Static organs for signaling position of the head in space
o Macula utriculi – in utricle
o Macula sacculi – in saccule
Utricle and Saccule
- Each duct has an extension containing sensory area called Crista ampullaris
- Sensors of movement
- Hairs of cristae are supplied by primary sensory neurons whose cell bodies are in vestibular ganglion
Semicircular Ducts
- Spiral
- Blind tube firmly fixed to cochlear canal by spiral ligament
- Roof: Vestibular membrane
- Floor: Basilar membrane
- Spiral organ of Corti
Cochlear Duct
• Receptor of auditory stimuli
• Contains hair cells that respond to vibrations induced in the endolymph by sound waves
• It is in this area where the hydronium energy coming from the vibration or wave process called by the stimulation of the fluid inside the inner ear, area where it is converted to the air impulse by hair cells»_space; the electric impulses are conducted by auditory nerve going to auditory center in
the brain (temporal lobe). The brain is responsible for processing these electric impulses.
Spiral organ of Corti
Bony»_space; Membranous»_space; Sensory Organ
Cochlea»_space; Cochlear duct»_space;Organ of Corti
SC canal»_space; SC duct»_space; Crista terminalis
Vestibule Utricle/Saccule»_space; Macula
• Narrow canal
Runs laterally for about 1 cm
Within petrous part of temporal bone
• Closed laterally by a thin, perforated plate of bone that separates it from internal ear
• Through his plate pass CN VII, VIII
• CN VIII – divides near lateral end of IAM into anterior cochlear portion and posterior vestibular portion
INTERNAL ACOUSTIC MEATUS (IAM)
Pathway of Sound Conduction
Auricle >> External acoustic meatus >> Tympanic membrane >> Ossicles [malleus,incus,stapes] >> Perilymph vibrations >> Cochlea >> CN VIII >> Brain
- Formation of spongy bone around stapes and fenestra vestibuli
- May stop movement of base of stapes
- Causes deafness
- Not common among Filipinos
OTOSCLEROSIS
- Inflammation of middle ear
- May spread to tegmen tympani
- Causes inflammation of meninges
- Common among Filipinos
OTITIS MEDIA
- Inflammation of EAM
* Movement of tragus causes pain because cartilage in it is continuous with EAM
OTITIS EXTERNA
- Forms a route through which infections pass from nasopharynx to middle ear
- Blocked by swelling of its mucous membrane
- Residual air in the tympanic cavity is absorbed into the mucosal blood vessels
- Lowering of pressure in tympanic cavity, retraction of tympanic membrane
- Hearing reduced
- Magkakaroon ng transmutation of fluid from your intravascular space going to your middle ear (high pressure
AUDITORY TUBE
- Tympanic muscles have protective action
- Dampen large vibrations of tympanic muscles from loud noises
- Paralysis of stapedius (lesion of CN VII) results in excessive hearing
- Results from uninhibited movement of stapes
HYPERACUSIA
- Spherical sinus
- At temporal bone
- Connected to tympanic cavity by aditus
- Separated from middle cranial fossa by tegmen tympani
- Very sensitive to sound
MASTOID ANTRUM AND CELLS
- Results from infection of middle ear
* During surgery, ENT should not injure the CN VII
Mastoiditis
- Persistent exposure to loud sounds
- Causes degenerative changes in spiral organ at base of cochlea
- Drill handlers, machine operators, tractor drivers
HIGH TONE DEAFNESS
- Injury to ear by an imbalance in pressure between surrounding air and air in middle ear
- In fliers, divers, parachuters
OTIC BAROTRAUMA
- Projects from the face
* Vary in size and shape because of differences in nasal cartilage
EXTERNAL NOSE
EXTERNAL NOSE (Parts)
o Root – superior angle o Apex – tip o Nares – 2 piriform openings o Alae – lateral boundaries o Nasal septum – middle structure which separates 2 nares o Vestibule – with stiff hairs
EXTERNAL NOSE (Skeletal Part)
- Nasal bones
- Frontal process of maxilla
- Nasal part of frontal bone
EXTERNAL NOSE (Cartilaginous Part)
- 2 lateral cartilages
- 2 alar cartilages
- 1 septal cartilage
• Divides the chamber of the nose into 2 nasal cavities
• Components:
o Perpendicular plate of ethmoid
Forms superior part of the nasal septum
o Vomer – thin flat bone that forms the posteroinferior part of the nasal septum
o Septal cartilage – articulates with bony septum
NASAL SEPTUM
- Open posteriorly into the nasopharynx thru the choanae
* Mucosa lines the nasal cavities except for vestibule (lined with skin)
NASAL CAVITIES
Nasal Mucosa
Olfactory area
o Superior 1/3
o Contains organ of smell
Respiratory area
o Inferior 2/3
o Where air is warmed and moistened before it goes to respiratory tract
• 3 scroll-shaped elevations • Superior, middle, inferior • Divide the nasal cavity into 4 passages: o Sphenoethmoidal recess o Superior meatus o Middle meatus o Inferior meatus
NASAL CONCHA
Nasal Passage (1)
Sphenoethmoidal Recess: Sphenoidal sinus
Superior Meatus: Posterior ethmoidal sinus
Nasal Passage (2)
Middle Meatus:
Interior/Middle ethmoidal sinus
Frontal sinus
Maxillary sinus
Inferior Meatus: Nasolacrimal duct
Nose (Arterial Supply)
Branches of:
- Sphenopalatine artery
- Anterior and posterior ethmoidal artery
- Greater palatine artery
- Superior labial artery
- Lateral nasal branches of facial artery
- Anterior
- Where all arteries anastomose
- Where nose bleeding occurs
- Most common site of epistaxis
- Other name: Little’s area
Kiesselbach’s area
Nose: VENOUS DRAINAGE
- Sphenopalatine veins
- Facial veins
- Ophthalmic veins
NOSE: NERVE SUPPLY
NERVE SUPPLY (Nasal Septum):
- Nasopalatine nerve
- Greater palatine nerve
- Anterior ethmoidal nerve
- Posterior ethmoidal nerve
NERVE SUPPLY (Smell): Olfactory nerve; Olfactory bulb (forebrain)
• Air-filled extensions of the respiratory part of the nasal cavity into the following cranial bones: o Frontal o Ethmoid o Sphenoid o Maxillary
PARANASAL SINUSES
- Between outer and inner tables of frontal bone
- Detectable by 7 years old
- Drains through frontonasal duct into ethmoidal infundibulum which opens into semilunar hiatus of middle meatus
- Nerve supply: Branch of supraorbital nerves (from CN V1)
FRONTAL SINUS
• Comprise several ethmoidal cavities – ethmoidal cells
• At ethmoid bone
Parts:
o Anterior – drain into middle meatus
o Middle – form ethmoidal bulla; drain into middle meatus
o Posterior – drain into superior meatus
• Nerve supply: Nasociliary nerve (from CN V1)
ETHMOIDAL SINUS
- Unevenly divided
- Body of sphenoid
- Separated by thin plates of bone from optic nerve and chiasma, ICA, pituitary gland
- Opens into sphenoethmoidal recess
- Nerve supply: Posterior ethmoidal nerve
SPHENOIDAL SINUS
• Largest
• Pyramidal shaped
• Parts:
o Apex – into zygomatic bone
o Base – inferior part of lateral wall of nasal cavity
o Roof – formed by floor of orbit
o Floor – formed by alveolar part of maxilla
• Drains via maxillary ostium into middle meatus
• Nerve supply: Superior alveolar nerves (from CN V2)
MAXILLARY SINUS
• Fibromuscular tube
• Extends from the base of the skull to the lower border of the cricoid cartilage (at which point it becomes the esophagus)
• Portions of the pharynx lie posterior to:
o Nasal cavity»_space;Nasopharynx
o Oral cavity»_space; Oropharynx
o Larynx»_space; Laryngopharynx
• Behind nasal cavities, mouth, and larynx
• Funnel-shaped
• Musculo-membranous wall
PHARYNX
- Continuous with nasal cavity, mouth, larynx and tympanic cavity
- UPPER: ciliated columnar epithelium
- LOWER: stratified squamous epithelium
Pharynx: Mucous membrane
- ABOVE: thicker, stronger, connected to base of skull
* BELOW: continuous with submucous coat of esophagus
Pharynx: Fibrous layer
The muscular walls of the pharynx are comprised of an outer layer made up of 3 circularly disposed muscles, the __. They are logically named (from superior most to inferior most) the SUPERIOR, MIDDLE and INFERIOR PHARYNGEAL CONSTRICTORS
CONSTRICTORS
Consists of:
- superior constrictors
- middle constrictors
- inferior constrictors
Fibers:
- circular fashion
- stylopharyngeus ms.
- salpingopharyngeus ms.
Pharynx: Muscular Layer
Origin:
- medial pterygoid plate
- pterygoid hamulus
- pterygomandibular ligament
- mylohyoid line
Insertion:
Upper - pharygeal tubercle; Middle – median fibrous raphe
Nerve supply: pharyngeal plexus
Action: contract and pull post pharyngeal wall forward during swallowing aid soft plate in closing off nasopharynx
Superior Constrictor Muscle
Origin: stylohyoid ligament lesser and greater cornua of hyoid
Insertion: median fibrous raphe
Nerve supply: pharyngeal plexus
Action: contracts and propels food bolus down into esophagus
Middle Constrictor Muscle
Origin: thyroid cartilage; cricoid cartilage Insertion: superior fibers – MCM lower fibers – esophagus median fibrous raphe
Nerve supply: pharyngeal plexus
Action: propel bolus of food into esophagus cricopharyngeus muscle – sphincteric effect
Inferior Constrictor Muscle
Origin: styloid process, temporal bone
Insertion: between SCM and MCM
Nerve supply: glossopharyngeal nerve
Action: elevate larynx and pharynx during swallowing
Stylopharyngeus Muscle
Origin: lower part, auditory tube
Insertion: blend with palatopharyngeus
Nerve supply: pharyngeal plexus
Action: assists in elevating pharynx
Salpingopharyngeus
The__ takes origin, as the name suggests, from the soft palate, and runs down the length of the pharynx, intermingling with fibers of the stylopharyngeus below the inferior border of the superior constrictor
PALATOPHARYNGEUS
NASOPHARYNX (Roof, Floor, Anterior Wall)
Roof:
- body of sphenoid
- basilar part of occipital bone
- pharyngeal tonsil
Floor:
- soft palate
- pharyngeal isthmus
Anterior wall: posterior nasal apertures
NASOPHARYNX (Posterior and Lateral Wall)
Posterior wall: anterior arch of atlas
Lateral wall:
- auditory tube
- tubal elevation
- salpingo pharyngeal fold
- pharyngeal fold
- tubal tonsil
- A vertical fold of mucous membrane that extends inferiorly from the medial end of the pharyngotympanic tube
- It covers the salpingopharyngeus muscle
SALPINGOPHARYNGEAL FOLD
OROPHARYNX (Roof and Floor)
Roof: Soft palate; Pharyngeal isthmus
Floor:
- 1/3 tongue and epiglottis
- Lingual tonsil
- Median glossoepiglottic fold
- 2 lateral glossoepiglottic fold
- Vallecula
OROPHARYNX (Anterior Wall, Posterior Wall and Lateral Wall)
Anterior Wall: Mouth; Tongue
Posterior Wall: C2, C3
Lateral Wall:
- Palatoglossal and palatopharyngeal arches/folds
- Palatine tonsils
- Upper epiglottis and cricoid
- Anterior wall: Inlet of pharynx
- Posterior wall: C3-C6
- Lateral wall: Thyroid cartilage
- Pyriform fossa
LARYNGOPHARYNX