Kinesiology
Understand how structure becomes movement
Lesson 5 of 16
Head and face: mastication
Muscles of facial expression and chewing occupy a sensitive, highly communicative region. The muscles of mastication move the mandible at the temporomandibular joints, while facial muscles commonly attach into skin. Work only with clear consent and appropriate training, avoiding pressure that provokes jaw pain or headaches.
Key points
- Masseter and temporalis are major jaw elevators during closing.
- Medial and lateral pterygoids contribute to jaw movement in multiple directions.
- The lateral pterygoid assists protrusion and helps coordinate opening with other structures.
- Facial expression muscles often blend with the skin rather than inserting on bone.
- Ask before touching the face or jaw; a client can decline any area.
- Refer persistent jaw locking, significant pain, or neurological symptoms to an appropriate clinician.
Key terms
- Masseter
- O: zygomatic arch; I: lateral ramus and angle of mandible; A: elevates mandible.
- Temporalis
- O: temporal fossa and fascia; I: coronoid process of mandible; A: elevates and retracts mandible.
- Medial pterygoid
- O: pterygoid region and maxilla; I: medial mandibular ramus; A: elevates and assists protrusion.
- Lateral pterygoid
- O: sphenoid and lateral pterygoid plate; I: mandibular neck and TMJ disc/capsule; A: protrudes and assists jaw opening.
- Orbicularis oculi
- O: medial orbital margin and nearby tissues; I: tissues around eyelids; A: closes eyelids.
Memory tip
Jaw relaxation is often better supported by slow pacing and client-led breathing than by stronger pressure.
Clinical note
Do not perform intraoral techniques unless specifically trained, legally permitted, and separately consented to.
Unit checkpoint
Lock it in: match the terms, then test yourself.