2.2.2 Structures of Mastication Flashcards
What are the covered parts?
What are the characteristics of the ventral surface of the tongue?
- Ventral surface of tongue is smooth and is attached to floor of mouth by lingual frenulum
- Deep lingual vein courses on either side of the frenulum
- Sublingual caruncles at the base of frenulum provide drainage for the submandibular duct
What are the two types of movement accomplished by the TMJ?
- Hinge: between the mandibular condyle and inferior surface of articular disc
- Gliding: between the superior portion of the disc and the temporal bone
What are the characteristics of the intrinsic muscles of the tongue?
- Allow change in shape and length of tongue
- Do NOT attach to bone
- All innervated by CN XII
- Consist of:
- -Superior & Inferior Longitudinal Bundles
- -Transverse Bundles
- -Vertical Bundles
What are the two compartments of the oral cavity?
1) Vestibule– between teeth and cheeks
2) Oral Cavity Proper – internal to teeth
What structures receive blood from either the 1st, 2nd, or 3rd branch of the maxillary artery?
1st part - Deep Auricular A to ear; Middle Meningeal A to cranial bones; Inf Alveolar A to mandibular teeth
2nd - Muscles of face
3rd - Maxillary teeth; infraorbital artery to face; nose; descending palatine artery to palate
What are the characteristics of the buccinator muscle?
- NOT a muscle of mastication, but rather of facial expression
- Between maxiallar and mandible
- Receives innervation from CNVII
- Keeps food between the occlusal surface of the teeth during chewing
- Pierced by parotid duct as it enters vestibule of oral cavity
What is the origin and insertion of the Temporalis?
Origin - floor of the temporal fossa and the deep surface of the temporal fossa
Insertion - Attaches to the tip of the coronoid process
What are the contents of the oral cavity proper?
- Contents of Oral Cavity Proper
- Hard palate
- Soft palate
- Phalatoglossal arch
- Tongue
- Uvula: separates oral cavity from oral pharynx
What is ankyloglossia?
restricted tongue movement due to short lingual frenulum
What are the characteristics of a dislocated jaw?
- Occurs when there is excess contraction of the lateral pterygoid muscle
- Typically, head of mandible slides too far anteriorly over the articular tubercle
- Corrected by applying downward pressure with fingers in the vestibule of oral cavity
What is the importance of the sphenomandibular lig?
holds mandible to the cranium
spine of sphenoid to lingula, above mandibular foramen
What is the vallecula?
Space between the base of the tongue and the epiglottis
What are the muscles of the soft palate?
Describe the difference between the anterior and posterior dorsum of the tongue.
- Anterior dorsum has papillae for taste sensation
- Posterior dorsum has no papillae but lymphoid tissue known as lingual tonsil
What is the blood supply of the tongue?
external carotid → lingual a → deep lingual, sublingual
What is the function of the Pterygoid plexus?
venous drainage to the fossa
What divides the anterior and posterior divisions of the dorsal tongue?
-Dorsum is divided into anterior 2/3 and posterior 1/3 by the sulcus terminalis
What are the 3 valves to keep food and air separate?
What are the 4 parts of the mandible?
1) Condylar Process: head articulates with temporal fossa
2) Mandibular Notch: where masseteric nerve & vessels enter masseter M
3) Coronoid Process: masseter & temporal m attachment
4) Angle of Mandible: where ramus meets body; insertion for medial pterygoid m
What is the infratemporal fossa?
Irregular space located deep to zygomatic arch and posterior to maxillary bone
What is responsible for the motor nerve supply to the tongue?
- Motor: CN XII innervates all muscles
- Except palatoglossus (CNX)
What are the 4 muscles of mastication?
- Temporalis
- Masseter
- Medial Pterygoid
- Lateral Pterygoid
What are the 4 extrinsic muscles of the tongue?
- Genioglossus: protrudes the tongue
- Hypoglossus: retract and depresses tongue
- Styloglossus: retracts and elevates tongue
- Palatoglossus: elevate posterior tongue and provides structure for palatoglossal arch
What is the point at which the mandible articulates with the cranium?
Temporomandibular joint ( TMJ)
What is the function of the masseter?
-Masseter: powerful elevator of jaw, used for clenching/crushing on molars
What is the tongue anchored to?
-Muscular organ with freely mobile body and base anchored to hyoid bone
What are two important structures within the infratemporal fossa?
- Medial & lateral pterygoid muscles
- Maxillary artery
The medial neck of the mandible serves as?
-lateral pterygoid insertion
What are the characteristics of a broken jaw?
- May occur in several places
- 42% at mandibular angle/body
- 35% at condylar process
- Typically secured with arch bars attached to neck of teeth
- Head of mandible generally receives sufficient blood, even if broken at neck
What are the characteristics of mandibular tori?
- Bony protrusions from the medial wall of the mandible toward the oral cavity
- Most common in males and Asians, affecting 7-10% of the population
What makes up the TMJ?
-Synovial joint whose elements include: mandible, temporal bone, and articular disc
What are some other important aspects of the uvula - pathologies.
What is the origin and insertion of the masseter?
- Origin: Zygomatic arch
- Insertion: Lateral angle of mandible
What carries out the general sensory innervation of the tongue?
- Ant 2/3: lingual nerve from CNV3 (from trigeminal nerve)
- Post 1/3: CN IX
What are the characteristics of a Uvular deviation?
What is the innervation of the 4 muscles of mastication?
Mandibular division of the trigeminal nerve
What is the insertion of the medial pterygoid? Lateral?
Medial - Origin - Medial surface of lateral pterygoid plate
Insertion - Medial surface of the mandible
Lateral - Origin - Infratemporal crest for superior head, lateral pterygoid plate for inferior head
Insertion - Neck of the mandible
What are the most common locations of a mandibular fraction?
What are the characteristics of the Articular Disc that sits in the TMJ?
- Compact, dense, fibrocartilaginous plate
- Between the condylar process of the mandible and the articular surface of the temporal
- Peripherally, fuses with the surrounding joint capsule
Why shouldn’t infants feed on their backs?
What is sleep apnea and what can be some causes of it?
may be due to enlarged tonsils, dropped tongue or enlarged soft palate → blocking normal airflow
What happens to the auditory tube when swallowing?
What is the importance of the mandibular foramen?
-tunnel for inf alveolar nerve
What is circular breathing?
What is Gleeking?
sudden release of saliva from the submandibular ducts as the mylohyoid muscle contracts part of the gland against intrinsic muscles of the tongue
What is the function of the soft palate?
valve to prevent food/fluid from entering nasal cavity
Describe the contents of the vestibule.
- Parotid duct
- Labial frenula: mucosa keeping lips attached to gingiva
- Mucogingival Junction: scalloped line separating the alveolar from gingival mucosa
- -Alveolar Mucosa: loose gingiva covering alveolar processes of maxilla
- -Gingival Mucosa: attached keratinzied stratified epithelium
What are the characteristics of the mandible?
single bone forming lower jaw; horizontal U-shaped body with two vertical rami– is joined from two sites of intramembranous ossification.
What is responsible for the taste nerve supply to the tongue?
- Ant 2/3: CN VII via the chorda tympani
- Post 1/3: CN IX
What are the characteristics of an Inferior alveolar Nerve Block?
anesthetize teeth, near opening of mandibular foramen (feel for lingula)
What is the innervation of the 4 extrinsic muscles of the tongue?
- CN XII: Genioglossus, hypoglossus, styloglossus
- CN X: Palatoglossus
What is the function of the temporalis?
-Temporalis: elevation and retraction of the jaw
What is the function of the medial and lateral pterygoids?
- Medial Pterygoid: elevate jaw, assists with grinding motion
- Lateral Pterygoid: has superior and inferior heads; opens and protrudes jaw
