Lecture 9 - The Nose, Sinuses and Muscles of Facial Expressions Flashcards
The nose: parts
- external nose
- nasal cavity
Nasal cavity: borders
- midline & lateral walls
- roof and floor
Nasal cavity: functions
- humidify, warm and filter air
- facilitate drainage of paranasal sinuses
- secrete mucus
External nose
- projects outwards allowing air to enter the nasal cavity
- made up of bone and cartilage
Bones of the skull: two regions
- neurocranium
- viscerocranium
Neurocranium bones
- frontal bone
- cribiform plate
- ethmoid bone
- sphenoid bone
Viscerocranium bones
- nasal bone
- vomer bone
- maxillary bone
- inferior nasal concha
Bones in the nasal cavity
- frontal bone
- nasal bone
- ethmoid bone
- maxillary bone
- sphenoid bone
- vomer bone
- palatine bone
Nasal septum:
- medial wall
- made up of a bony portion and a cartaliaginous portion
Structures of nasal septum
- ethmoid bone
- septal cartilage
- vomer bone
Conchae and meatuses
- lateral wall
Nasal conchae
- superior and middle nasal conchae are processes of the ethmoid bone
- inferior nasal concha is formed by its own cranial bone
Nasal conchae structures
- ethmoid bone (middle nasal concha)
- inferior nasal concha
Nasal conchae and meatuses
- superior nasal concha/meatus
- middle nasal concha/meatus
- inferior nasal concha/meatus
Nasal conchae functions
- humidify air
- filter air
- warm up air
What is a concha?
a long, narrow, curled shelf of bone that protrudes into the breathing passage of the nose in humans and various animals
Nasal cavity borders
- roof
- floor: palate
- medial wall: nasal septum
What is a meatus?
a natural body opening or canal
Structures of the roof: midsagittal section - medial view
- cribiform plate
- nasal bone
- frontal bone
- sphenoid bone
Structures of the roof: anterior view
- nasal bone
- frontal bone
- sphenoid bone
Structures of the roof: base of skull - superior view
- frontal bone
- cribriform plate
- ethmoid bone
- sphenoid bone
Nose cavity borders: floor
- palatine bone
- maxillary bone
External nose structures
- bony
- cartilaginous
External nose cartilage
- lateral nasal cartilage
- major alar cartilage
- minor alar cartilage
Paranasal sinuses
- cavities (air pockets) found in the skull
- the ethmoid, frontal, maxillary, and sphenoid bones contain paranasal cavities
- parasnasal sinuses are lined with respiratory mucosa and secrete mucous
Which is the largest sinus?
maxillary sinus
Paranasal sinuses: functions
- lighten the weight of the skyll
- humidify/heat/filter air
- secret muscus
Where do the nasal meatuses in the nasal cavity receive drainage from?
the paransal sinuses
Paranasal sinuses drainage
- superior meatus drains the sphenoid and posterior ethmoid sinuses
- middle meatus drains the frontal, anterior ethmoid and maxilary sinuses
- nasal cavity extends to the nasopharynx where the mucus will be swallowed
What nerves innervate tje paranasal sinuses?
- V1 (ophthalmic) and V2 (maxillary) branches of the trigeminal nerve ( CN V)
Muscles of facial expressions: overview
- origniate from facial bones or adjacent muscles
- insert into skin
- superficial (subcutaneous) muscles
- innervated by CN VII (facial nerve)
Muscles of facial expressions: functions
- act as sphincters and dilators
- alter facial expressions
Muscles of facial expressions (7): top to bottom
- frontalis
- corrugator supercilii
- orbicularis oculi
- zygomaticus
- buccinator
- orbicularis oris
- platysma
Frontalis
- epicranial group (occipitofrontalis)
- actions: draws the scalp back, raising the yebrows
- “surprise”
corrugator supercilii
- ortibal group
- action: draw the eybrows together medially and inferiorly (frowning)
orbicularis oculi
- ortibal group
- ortibal parts
- palpebral part
- lacrimal part
- actions:
- ortibal parts: tightly closing the eye
- palpebral part: loosely closing the eye
- lacrimal part: compress lacrimal sac (tears)
orbicularis oris
- oral group
- action: purses and protrudes lips (duck lips)
buccinator
- oral group
- action: pull the cheeks inward and agasint the teeth (blowing)
zygomaticus (minor and major)
- oral group
- action: pull corners of the mouth up and drawing it laterally (smiling)
platysma
- neck group
- action: pull corner of the mouth down (“yikes”)
What nerve innervwates faciual expression muscles?
CN VII (facial nerve)
Facial nerve intracranial pathway
- innervates from brainstem, then goes through…
- internal acoustic meatus then…
- facial canal then…
- medial wall of the middle ear then…
- Stylomastoid foramen
Facial nerve innervation branches: sentence to help rememeber
- “To Zanzibar By Motor Car”
Facial nerve innervation branches
- Tempora branches
- Zygomatic branches
- Buccal branches
- Marginal mandibular branch (does not innervate any facial expression muscles)
- Cervicle branches
Facial nerve innervation: Temporal branches
- orbicularis oculi (upper half)
- corrugator supercilii
- frontalis
Facial nerve innervation: buccal branches
- orbicularis oris
- zugomaticus
- buccinator
Facial nerve innervation: zygomatic branches
- orbicularis oculi (lower half)
Facial nerve innervation: cervical branches
- platysma
