2. ANATOMY OF MASTICATION
• Mastication or chewing is the process by
which food is crushed and ground by teeth. It
is the first step of digestion, and it increases
the surface area of foods to allow more
efficient break down by enzymes.
• During the mastication process, the food is
positioned by the cheek and tongue between
the teeth for grinding.
3.
4.
5.
6.
7.
8. Actions Muscles
Depression (Open mouth)
Elevation (Close mouth)
Protrusion (Protrude chin)
Retrusion (Retrude chin)
Side-to-side movements
(grinding and chewing)
Lateral pterygoid
Suprahyoid
Infrahyoid
Temporalis
Masseter
Medial pterygoid
Masseter (superficial
fibres)
Lateral pterygoid
Medial pterygoid
Temporalis
Masseter (deep fibres)
Temporalis on same side
Pterygoid muscles of
opposite side
Masseter
9.
10.
11.
12.
13.
14. Lateral pterygoid
• FEATURES
• Due to its relations, the lateral pterygoid is
considered to be the main muscle of the
infratemporal zone.
• The lower head of lateral pterygoid travels in the
middle of the two heads of the medial pterygoid
muscle.
• Lateral pterygoid is the only masticatory muscle,
which opens the mouth.
• Developmentally, the articular disc of
temporomandibular joint is a part of tendon of
lateral pterygoid muscle.
15. Lateral pterygoid
• SUPERFICIAL
1. Ramus of the mandible.
2. Tendon of temporalis.
3. Superficial head of medial pterygoid.
4. Maxillary artery along with its temporal and masseteric
branches.
• DEEP
1. Mandibular nerve.
2. Middle meningeal artery.
3. Sphenomandibular ligament.
4. Deep head of medial pterygoid muscle.
16. Lateral pterygoid
• Structures emerging at the upper border
– Deep temporal nerves (two).
– Masseteric nerve.
• Structures emerging at the lower border
– Inferior alveolar nerve and artery.
– Lingual nerve.
– Middle meningeal artery (deep towards the lower
border).
17. Lateral pterygoid
• Structures Passing Through the Gap Between the
Two Heads
–Maxillary artery enters the gap in order to
connect with the pterygopalatine fossa via
pterygomaxillary fissure.
–Buccal nerve which is a branch of mandibular
nerve. It emerges via the aperture in order to
supply sensory innervation towards the skin
along with mucus membrane of the cheek.
