Oral Cav And Skull Flashcards
Commissure
corner of the mouth
Vermillion zone
red part of lip where lip mucosa meets the skin
Nasolabial groove
the groove running downward on each side of the nostrils
Vestibule
space between the cheeks or lips and teeth
Oral cavity proper
space between the teeth and palatine tonsils, bounded by the hard palate superiorly and the floor of the mouth inferiorly
The Skull
o 28 individual bones make up the skull
▪ 11 are paired
▪ 6 are single
o Function
▪ To protect the brain is the most important
▪ Protects 5 organs of special sense
• Olfaction, vision, gestation, vestibular function, auditory)
Two major ways to divide the skull
▪ Regionally • Cranium • Mandible ▪ Developmentally • Neurocranium – portion of the skull that protects the brain
Bones of the neurocranium
4 single, 2 paired
Sphenoid
forms the majority of the middle portion of the cranial base and forms the posterior part of the eye socket.
Frontal
forms the majority of the forehead and the roof of the eye socket. Contains the paranasal sinuses
Occipital
forms posterior part of cranial vault. Provides articulating surfaces between skull and vertebral column
Ethmoid
porous bone that forms the major portion of the middle part of the face between the two orbits. Made up from a cribiform plate, orbital plate, perpendicular plate, middle nasal concha
Temporal
forms the base and lateral walls of the skull. Houses the vestibular and auditory apparatus. Location of the mandibular fossa of the TMJ
Parietal
forms the roof and sides of the cranial vault
Maxilla
made up of a central body and four processes (frontal, zygomatic, alveolar, palatine).
Maxillary sinuses
one of four sinuses that surround the nasal passages (frontal, ethmoid, sphenoid)
Maxillary sinuses Func
to lighten the skull, give resonance to voice, warm the air we breathe, moisten the nasal cavity
Mandible
largest and strongest bone of the skull
▪ Made up of a horizontal body and two vertical rami, each of which has a coronoid process and condylar process
Exterior body of the mandible
- Extends from the chin to the ascending ramus
- Houses the inferior alveolar nerve and artery – a branch of which exits the mental foramen
- External oblique ridge
Interior Body of Mandible
- Temporal crest – ridge extending downward from a coronoid process to the third molar region
- Internal oblique line is inferior ¼ of this crest
- Mylohyoid ridge
Ascending Ramus of the Mandible
- Coronoid process – the temporalis muscle inserts here
* Condylar process – forms the inferior part of the TMJ; the lateral pterygoid muscle inserts here
Vomer
plow shaped. Forms posterior and inferior parts of the nasal septum
Palatine
forms the posterior ¼ of the hard palate when it fuses anteriorly with the palatine process of the maxilla
Zygomatic
forms majority of the cheek bone (provides origin of the masseter) (second most commonly broken face bone
Nasal
forms bridge of nose (most commonly broken face bone)
Lacrimal
forms a small portion of medial wall of the orbit
Inferior nasal concha
curved bone that forms part of the lateral wall of the nasal cavity
Temperomandibular Joint
It’s the area where the mandibular condyle articulates with the base of the cranium with the temporal bone
o Proper functioning has profound effects on the contacts of teeth
Tmj aka
ginglymoarthroidal joint
ginglymoarthroidal joint bc?
o Provides a hinging motion in one plane = ginglymoid joint and,
o Provides for gliding movements = arthroidal joint
Anterior view Condyle
▪ It has two projections, the medial pole and the lateral pole
▪ The medial pole extends well beyond the neck of the condyle and is more prominent
Posterior view Condyle
▪ The articular surface of the posterior aspect of the condyle is greater than on the anterior surface
Occlusal View Condyle
▪ The condyles are NOT parallel to the transverse axis of rotation
▪ They are directed medially and anteriorly from the axis
Temporal Bone and tmj
o The condyle fits into the mandibular fossa (aka glenoid fossa, or articular fossa)
o Articular eminence – the convex bony prominence anterior to the mandibular fossa
Mandibular fossa
o STF = squamotympanic fissure
o Posterior roof of the fossa is very thin
o The degree of convexity of the articular eminence is variable from person to person
The condyle is separated from the mandibular fossa by
the articular disc
Tmj is classified as compound bc
Classified as a compound joint (requires 3 bones) because the disk acts as a non-ossified bone
Articular Disc Sagittal view
▪ Composed of dense fibrous CT
▪ Intermediate zone – thinnest and has no blood supply
▪ Moves with the head of the condyle in function
▪ Retrodiscal tissue (bilaminar zone) – region of loose CT that is highly vascularized, innervated, and has elastic fibers that attach the disc to the tympanic plate of bone and to the capsule
▪ Anteriorly the disc is attached to the fibrous capsule superiorly and in between to the superior head of the lateral pterygoid muscle
Intermediate zone Articular Disc
thinnest and has no blood supply
Retrodiscal tissue (bilaminar zone)
region of loose CT that is highly vascularized, innervated, and has elastic fibers that attach the disc to the tympanic plate of bone and to the capsule
Articular Disc Anterior View
▪ Disc is thicker medially than laterally and can adapt to the functional demands of the articular surfaces
▪ Disc is attached by discal ligaments to the lateral and medial borders of the condyle
Functions of the Articular Disc
o Partitioning the TMJ into functional compartments
o Stabilizing the condyle
o Helps to lubricate the TMJ – it is smooth and slippery
Fibrous capsule
Sheet, sac, or tube of tissue that encloses the TMJ like a tube
Fibrous capsule Inner layer
Secretes synovial fluid
Fibrous capsule Outer layer
thick fibrous tissue that protects the joint and helps to limit movement
Supporting ligaments
Fibrous capsular ligament Temperomandibular ligament Stylomandibublar ligament Sphenomandibular ligament do not actively participate in normal joint function
Temperomandibular ligament
attaches to the zygomatic arch and lateral and posterior aspect of the condyle
▪ Prevents posterior and lateral displacement
Stylomandibublar ligament
tenses when the mandible protrudes
Sphenomandibular ligament
restricts opening of the mandible
Muscles of Mastication func
▪ Have major control over all movements of the mandible
▪ The MoM are aided by the digastrics muscles, the supra- and infrahyoid muscles, and the muscles of the neck and shoulders
Bones that form origins of the MoM
- Temporal bone – forms the mandibular fossa of the TMJ
- Sphenoid bone – has 2 of the 4 origins of the MoM
- Zygomatic bone – origin of the masseter
Masseter
- Origin: zygomatic bone
- Insertion: angle of the mandible
- Function: elevate (close) the mandible
Temporalis
- Origin: temporal fossa
- Insertion: coronoid process of the mandible and anterior border of the ramus
- Function: anterior fibers elevate the mandible; posterior fibers retrude the mandible
Medial Pterygoid
- Origin: medial surface of the lateral pterygoid plate of the sphenoid
- Insertion: medial angle of the mandible
- Function: elevate (close) the mandible
Lateral Pterygoid (upper head)
- Origin: infratemporal surface of the great wing of the sphenoid bone
- Insertion: mainly into the articular disc, but also into the condyle
- Function: pull articular disc forward during opening of the mandible and lateral movements of the mandible
Lateral Pterygoid (lower head)
• Origin: lateral side of lateral pterygoid plate of sphenoid
• Insertion: neck of the condyle
• Function: symmetrical: (opening, depressing) and protrusion
Asymmetrical: lateral movement of the mandible
Lower Compartment tmj
▪ Condyle disc responsible for the rotational movements of the mandible
▪ The disc is attached tightly to the condyle medially and laterally
Upper compartment tmj
▪ Condyle-disc complex functioning against the mandibular fossa and articular eminence
▪ Responsible for translational movements of the mandible
