Muscles of facio-maxillary region Flashcards
functions of facial muscles:
- sphincters + dilators of orifice of face
structure of facial muscles (how they are + origin + innervation):
- subcutaneous
- origin = fascia or bone
- insertion = into the skin
- innervation = facial nerve (CN VII)
muscles of temporal branche (le truc des 5 doigts sur la face):
- frontalis
- orbicularis oculi
- corrugator supercilii
muscles of zygomatic branches:
orbicularis oculi
muscles of buccal branches:
- orbicularis oculi
- buccinator
- zygomaticus
muscles of marginal mandibular branches:
- mentalis
- depressor labii inferioris
- depressor anguli oris
muscles of cervical branches:
platysma
muscles of the scalp:
occipito-frontalis
muscles of the eyelid:
- orbicularis oculi
- corrugator supercilia
- levator palpebrae superioris
muscles of the nose:
- nasalis
- procerus
- depressor septi
- ## dilator naris posterior
muscles of the mouth:
- orbicularis oris
- buccinator
- levator anguli oris
- depressor anguli oris
- depressor labii inferioris
- mentalis
- risorius
- zygomaticus
- levator labii superioris
- levator labii superioris alaeque nasi
muscles of the ear:
- anterior auricular
- posterior auricular
- superior auricular
action of frontal belly:
wrinkles forehead, raises eyebrows, draws scalp backwards
the orbicularis has 2 major parts which are:
- orbital + palpebral parts
action of the orbicularis oculi:
sphincter muscle of the eyelid
- orbital part = closes voluntarily + forcefully + produces wrinkles in forehead
- palpebral part = involuntarily + softly
action of cogurrator supercilli:
draws eyebrows medially and downward, causing vertical wrinkles above the nose and active when frowning
action of levator palpebrae superioris:
(most superior muscle in the orbit)
contraction of the muscle raises the eyebrow
action of nasalis:
- transverse part: compresses nasal aperture
- alar part: draws cartilage downward and laterally opening nostril
action of procerus:
Draws down the medial angle of eyebrows, producing transverse wrinkles over the bridge of the nose.
- It can also contribute to an expression of anger
action of dilators of nose (depressor spt nasi + dilator naris)
Depressor septi nasi:pulls the nose inferiorly, assisting the alar part of the nasalis in opening the nares.
- The Dilator naris muscle is a part of the nasalis muscle. It is divided into posterior and anterior parts:
Dilatator naris posterior
Dilatator naris anterior
Action: enlarge the aperture of the nares. Their action in ordinary breathing is to resist the tendency of the nostrils to close from atmospheric pressure.
action of the orbicularis oris:
Contraction of the orbicularis oris narrows the mouth and closes the lips. Its function is apparent when ‘pursing’ the lips as during whistling.
lower oral muscles:
DEPRESSOR ANGULI ORIS
DEPRESSOR LABII INFERIORIS
MENTALIS
action of Buccinator:
The Buccinators compress the cheeks so that, during the process of mastication, the food is kept under the immediate pressure of the teeth. When the cheeks have been previously distended with air, the Buccinator muscles expel it from between the lips, as in blowing a trumpet.
It aids in whistling and smiling, and in neonates, it is used to suckle
action of mentalis:
raises and protrudes the lower lip as it wrinkles the skin of the chin; helps position the lip when drinking from a cup or when pouting.
upper oral muscles:
Risorius
Zygomaticus major
Zygomaticus minor
Levator labii superioris
Levator labii superioris alaeque nasi
Levator anguli oris
action of levator labii superioris:
retracts + everts upper lip
action of levator labii superioris alaeque nasi:
dilates nostril + elevates wing of nose and upper lip
action of levator anguli oris:
raises the angle of the mouth while smiling
action of risorius:
The risorius retracts the angle of the mouth to produce a smile, albeit an insincere-looking one that does not involve the skin around the eyes. Compare with a real smile, which raises the lips with the action of zygomaticus major and zygomaticus minor muscles and causes “crow’s feet” (A name for wrinkles in the outer corner of the eyes as the result of aging resembling crow’s feet) around the eyes using the orbicularis oculi muscles
zygomaticus major and minor actions:
- zygomaticus major: Draws the corner of the mouth upward and laterally.
It raises the corners of the mouth when a person smiles. Variations in the structure of this muscle may cause dimples. - zygomaticus minor: Draws the upper lip upward
action of levator labii superioris:
Raises upper lip; helps form nasolabial furrow, may assist in flaring the nares
action of levator angulis oris:
it elevates the corner of the mouth and may help deepen the furrow between the nose and the corner of the mouth during sadness
the articular components of the temporomendibular joint:
- mandibular fossa
- articular tubercle of temporal bone
- mandibular condyle
what is the articular surface of the bones of the TMJ composed of ?
The articular surface of the bones is covered byfibrocartilage, not hyaline cartilage
the 3 extracapsular ligaments that stabilize the TMJ:
Lateral ligament– runs from the beginning of the articular tubule to the mandibular neck. It is a thickening of the joint capsule and prevents posterior dislocation of the joint.
Sphenomandibular ligament– originates from the sphenoid spine and attaches to the mandible.
Stylomandibular ligament–a thickening of the fascia of the parotid gland. Along with the facial muscles, it supports the weight of the jaw.
muscles of mastication and the hyoid muscles produce movements at this joint, the 2 divisions and their functions:
- Protrusion and Retraction: The upper part of the joint allows for the mandible’s protrusion and retraction–the jaw’s anterior and posterior movements.
- Elevation and Depression: The lower part of the joint permits elevation and depression of the mandible, which opens and closes the mouth. Depression is mostly caused bygravity.
nerve supply of temporalis and masseter:
branches of mandibular division of trigeminal nerve
action of temporalis:
elevates and retracts the mandible
action of the masseter:
elevates and protrudes the mandible
action of lateral pterygoid:
- bilateral: protracts mandible
- unilateral: pushes mandible to the opposite side
action of the medial pterygoid:
- bilateral: pushes mandible forward
- unilateral: pushes mandible to the opposite side
- elevates the mandible
some important relations to the TMJ:
Anteriorly: The mandibular notch and the masseteric nerve and artery
Posteriorly: The tympanic plate of the external auditory meatus
Laterally: The parotid gland, fascia, and skin
Medially: The maxillary artery and vein and the auriculotemporal nerve
Superiorly: middle cranial fossa with the Temporal lobe
