Week 10 Flashcards
Jaw, Jaw and Tongue Muscles, & Ultrasound
What are the two main parts of the jaw?
Maxilla (upper jaw, passive articulator)
Mandible (lower jaw)
What is the only movable part of the jaw?
Mandible, crucial for speech and mastication
How many bones is the mandible?
Two bones fused at the mental symphysis
Fuse together in early years
What/where are the landmarks of the mandible? (5)
Body: Lower horseshoe-shaped, holds the lower teeth
Ramus: Vertical part connecting to the skull
Angle: Where the body and the ramus meet
Condyle (posterior) and coronoid (anterior) process: Two protrusions at the top of the ramus
Mandibular notch: Depression between the two processes
What’s the mental protuberance?
A triangular projection on the anterior part of the mandible located at the midline
Basically your chin
What are mental spines?
Bony projections located in the middle on the inner surface of the mandible
Two inferior and two superior (two pairs)
What do the superior mental spines serve as an origin for?
Genioglossus muscle
What do the inferior mental spines serve as an origin for?
Geniohyoid muscle
What is the temporomandibular joint (TMJ)?
Consists of the condyle of the mandible and the mandibular fossa of the temporal bone
Cushioned by a fibrous articulator disk for smooth movement
What does the temporomandibular joint connect?
Mandible to the temporal bone of the skull
What are the two foramen?
Mandibular foramen
Mental foramen
Where is the mandibular foramen located?
Internal surface of the ramus of the mandible
What is the structure of the mandibular foramen?
An opening serves as an entry point for the inferior alveolar nerve and vessels (vessels provide blood to the lower teeth and surrounding bone)
Where is the mental foramen located?
External surface of the mandible
Near the apex of the mandibular premolar teeth
What is the structure of the mental foramen?
A small opening that allows the passage of the mental nerve and blood vessels
What are the jaw muscles critical for?
Mastication and speech
How are the jaw muscles categorized?
Elevators
Depressors
What muscles elevate the jaw?
Masseter muscle
Temporalis muscle
Medial pterygoid muscles
What is the function of the masseter muscle?
Elevates the mandible (jaw closing)
Divided into deep and shallow heads
Deep head is the shortest muscle in the cranial head
What is the origin and insertion of the masseter muscle?
Origin: Zygomatic arch
Insertion: Ramus and angle of the mandible
What is the temporal fossa?
Shallow depression on the lateral side of the skull
What does the temporal fossa serve as an origin to?
Temporalis muscle
What are the bony boundaries of the temporal fossa? (4)
Frontal bone (inferior lateral part)
Parietal bone (inferior portion)
Temporal bone (squamous part)
Sphenoid bone
What is the function of the temporalis muscle?
Elevates and retracts the mandible (fast closing)