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Questions and Answers
Which muscle primarily allows for the elevation of the mandible during mastication?
Which muscle primarily allows for the elevation of the mandible during mastication?
What is the primary action of the lateral pterygoid muscle in the process of mastication?
What is the primary action of the lateral pterygoid muscle in the process of mastication?
How many main movements can the mandible perform during mastication?
How many main movements can the mandible perform during mastication?
Which muscle of mastication primarily assists in the side-to-side movement of the mandible?
Which muscle of mastication primarily assists in the side-to-side movement of the mandible?
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Why is it important to understand the muscles of mastication in patient management?
Why is it important to understand the muscles of mastication in patient management?
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What is the primary action of the medial pterygoid muscle?
What is the primary action of the medial pterygoid muscle?
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Which nerve is responsible for supplying the lateral pterygoid muscle?
Which nerve is responsible for supplying the lateral pterygoid muscle?
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What is the origin of the large deep head of the medial pterygoid muscle?
What is the origin of the large deep head of the medial pterygoid muscle?
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How does bilateral contraction of the pterygoid muscles affect the mouth?
How does bilateral contraction of the pterygoid muscles affect the mouth?
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What supplies blood to the pterygoid muscles?
What supplies blood to the pterygoid muscles?
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What is the primary action of the deep masseter muscle?
What is the primary action of the deep masseter muscle?
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From where does the deep masseter arise?
From where does the deep masseter arise?
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What is the insertion point for the temporalis muscle?
What is the insertion point for the temporalis muscle?
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Which nerve supplies the lateral pterygoid muscle?
Which nerve supplies the lateral pterygoid muscle?
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What characteristic shape does the temporalis muscle have?
What characteristic shape does the temporalis muscle have?
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Which statement about the action of the temporalis muscle is true?
Which statement about the action of the temporalis muscle is true?
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The masseteric nerve is a branch of which cranial nerve?
The masseteric nerve is a branch of which cranial nerve?
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Which artery is responsible for the blood supply to the deep masseter muscle?
Which artery is responsible for the blood supply to the deep masseter muscle?
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What is the primary action of the posterior belly of the digastric muscle?
What is the primary action of the posterior belly of the digastric muscle?
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Which nerve supplies the anterior belly of the digastric muscle?
Which nerve supplies the anterior belly of the digastric muscle?
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The buccinator muscle helps with which of the following actions?
The buccinator muscle helps with which of the following actions?
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Where does the genioglossus muscle primarily insert?
Where does the genioglossus muscle primarily insert?
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Which artery is the blood supply for the posterior belly of the digastric muscle?
Which artery is the blood supply for the posterior belly of the digastric muscle?
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What is the role of the geniohyoid muscle during mastication?
What is the role of the geniohyoid muscle during mastication?
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What is the blood supply of the genioglossus muscle?
What is the blood supply of the genioglossus muscle?
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Which muscle contributes to regulating the vestibular region of the mouth?
Which muscle contributes to regulating the vestibular region of the mouth?
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Study Notes
Muscles of Mastication
- Muscles of mastication attach to the mandible and facilitate movement like chewing and grinding.
- Mandible can move in 5 ways: Protrusion, Retraction, Elevation, Depression, and Rotation.
Why Knowledge of these Muscles is Important
- To understand potential bruising or discomfort after an injection through a muscle.
- To identify the origins of pain during mastication.
- To explain Trismus, difficulty opening the mouth after radiotherapy.
- To understand clenching and grinding habits that may be stress-related.
Masseter
- It is a thick quadrilateral muscle with a superficial and deep part.
- Superficial part originates from the anterior 2/3 of the zygomatic arch and inserts on the outer surface of the mandible's ramus.
- Deep part originates from the posterior 1/3 of the zygomatic arch and inserts on the ramus above the mandible's angle.
- Action: Elevates the mandible, closing the mouth.
- Nerve Supply: Masseteric nerve
- Blood Supply: Facial branch of the superficial temporal artery and Masseteric branch of the maxillary artery
Temporalis
- Fan-shaped muscle on either side of the head.
- Originates from the temporal fossa, bounded by the inferior temporal line.
- Fibres converge through a gap between the zygomatic arch and the head, becoming a tendon.
- Inserts on the coronoid process and the anterior border of the mandible's ramus.
- Action: Anterior fibres elevate the mandible. Posterior fibres elevate the mandible and retract the condyle.
- Nerve Supply: Anterior and posterior deep temporal nerves
- Blood Supply: Middle temporal branch of the superficial temporal artery and deep temporal branches of the maxillary artery.
Lateral Pterygoid
- Short, thick, triangular muscle with 2 heads.
- Upper head originates from the greater wing of the sphenoid bone and the lower head from the lateral pterygoid plate.
- Inserts into the pterygoid fovea of the mandible's neck.
- Action: Bilateral contraction opens and protrudes the mouth. Alternate contraction on either side produces grinding or side-to-side movement.
- Nerve Supply: Lateral pterygoid nerve
- Blood Supply: Pterygoid branches of the maxillary artery.
Medial Pterygoid
- Thick quadrilateral muscle with 2 heads.
- Deep head originates from the medial surface of the lateral pterygoid plate. The superficial head originates from the maxilla’s tuberosity and palatine bone's pyramidal process.
- Inserts on the medial surface of the mandible's ramus and angle.
- Action: Elevates the mandible and protrudes it together with the lateral pterygoid.
- Nerve Supply: Medial pterygoid branch of the mandibular nerve.
- Blood Supply: Pterygoid branches of the maxillary artery.
Accessory Muscles of Mastication
Digastric
- Two bellies meet at the intermediate tendon above the hyoid bone.
- Anterior belly originates from the digastric fossa of the mandible.
- Posterior belly originates from the mastoid process of the temporal bone.
- Action: Depresses the mandible and elevates the hyoid bone during chewing and swallowing.
- Nerve Supply: Anterior belly - mylohyoid nerve. Posterior belly - digastric branch of the facial nerve.
- Blood Supply: Anterior belly - submental branch of the facial artery. Posterior belly - posterior auricular/occipital artery.
Buccinator
- Muscle that forms the cheek.
- Originates from the pterygomandibular raphae and buccal alveolar bone.
- Inserts into the Orbicularis Oris at the mouth's corners.
- Action: Pulls the mouth’s corners back compressing the cheek against the molars. It helps regulate the vestibular region with the tongue maintaining food between teeth.
- Nerve Supply: Facial nerve, buccal branch.
- Blood Supply: Facial and maxillary arteries.
Geniohyoid
- Located above the mylohyoid line, it is a narrow muscle.
- Originates from the inferior genial tubercle.
- Inserts into the body of the hyoid bone.
- Action: Aids in swallowing and opening the mouth by depressing the mandible.
- Nerve Supply: Hypoglossal nerve.
- Blood Supply: Sublingual branch of the lingual artery.
Genioglossus
- Large fan-shaped muscle on the tongue’s dorsum.
- Originates from the superior genial tubercle on the inner surface of the mandible.
- Inserts into the tongue’s dorsum, with superior fibers reaching the tip and inferior fibers attaching to the hyoid bone.
- Action: Depresses the tongue, the inferior fibers retract the tongue, and the superior fibers protrude the tongue.
- Nerve Supply: Hypoglossal nerve
- Blood Supply: Sublingual branch of the lingual artery and submental branch of the facial artery.
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Description
This quiz covers the anatomy and functions of the muscles responsible for mastication. It explores the masseter muscle in detail, including its origin, insertion, actions, and clinical significance. Understanding these muscles is crucial for recognizing pain sources and jaw dysfunction.
