The TMJ Flashcards
💪 What is the function of the masseter muscle
Elevates 🔼 and protrudes ➡️ the mandible.
🧠 What are the actions of the temporalis muscle?
Anterior fibres: Elevate the mandible 🔼
Posterior fibres: Retract the mandible ⬅️
🔁 What does the superior head of the lateral pterygoid do?
Pulls the capsule & disc forward ⏩ during opening
Stabilises the condyle while chewing 🍴
🔽 What does the inferior head of the lateral pterygoid do?
Depresses 🔽 and protrudes ➡️ the mandible
Controls lateral ↔️ and medial movement of the mandible
✊ What is the function of the medial pterygoid?
Elevates the mandible 🔼
Assists with side-to-side movements
🧠 What nerve innervates the muscles of mastication?
: Trigeminal nerve (CN V3) 🧠
📍 Where do the pterygoid muscles attach?
Both lateral & medial attach to the lateral pterygoid plate of the sphenoid bone
Lateral pterygoid: attaches to the outside of the plate
Medial pterygoid: attaches to the medial (deep) surface
⚙️ What kind of joint is the TMJ?
Complex synovial joint with a fibrous capsule 🧃
🧽 What is the articular disc made of, and what is its function?
Made of fibrocartilage 🧽
Cushions the joint and separates it into upper and lower cavities
🌀 What happens in the inferior and superior TMJ cavities?
Inferior cavity: Rotation occurs 🔄
Superior cavity: Translation (gliding) occurs 🧊
📐 What movements occur at the TMJ?
Rotation (hinge) 🔄: depression/elevation
Translation (glide) 🧊: protrusion/retraction
Side-to-side grinding (chewing) ↔️
🧩 What bones form the TMJ?
Mandibular condyle fits into the mandibular fossa of the temporal bone
Articular disc sits between them
🔒 What does the joint capsule do?
Encloses the TMJ
Attaches to the temporal bone superiorly and neck of mandible inferiorly
: 📏 What is the role of the lateral ligament (temporomandibular ligament)?
Prevents posterior displacement of the mandible
Has two parts:
Inner Horizontal Part (IHP): prevents excessive backward movement
Outer Oblique Part (OOP): limits downward rotation, guiding condyle forward
🏗️ What does the sphenomandibular ligament do?
Connects spine of sphenoid ➡️ lingula of mandible
Supports TMJ as an accessory ligament
Prevents excessive inferior displacement ⬇️
🧵 What does the stylomandibular ligament do?
From styloid process ➡️ posterior mandible
Separates parotid and submandibular glands
May limit excessive protrusion ➡️
😮 What happens during normal jaw opening?
Inferior head of lateral pterygoid pulls condyle forward
Disc slides forward
Rotation in lower cavity first, then translation in upper
: 😌 What happens during closing?
Superior retrodiscal lamina pulls disc back
Superior head of lateral pterygoid contracts to guide disc
Inferior head relaxe
🎧 What causes TMJ clicking?
Disc is out of position
As the jaw opens, the condyle snaps back onto the disc = Click
As the jaw closes, disc may slip again = Click
🔒 What happens in TMJ locking?
A:
Condyle is stuck behind the disc
Disc is too far forward
No clicking — jaw can’t open fully
🧠 What is the myotatic (jaw jerk) reflex?
Keeps the jaw in resting position
Stretching the jaw → contraction of muscles of mastication 💪
😣 What is the nociceptive reflex?
Protective reflex due to pain
Masticatory muscles relax
Digastric contracts to open the mouth and reduce harm 🛡️
