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What is the primary action of the deep fibers of the masseter muscle?
From where do the fibers of the temporalis muscle originate?
Which artery supplies blood to the masseter muscle?
What is the nerve supply of the temporalis muscle?
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Where is the insertion of the deep fibers of the masseter muscle?
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What muscle primarily aids in the retraction of the head of the condyle?
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How do the upper and lower heads of the lateral pterygoid muscle function?
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What is the action of the anterior fibers of the temporalis muscle?
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Which of the following statements is true about the masseter muscle?
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Which head of the lateral pterygoid muscle is connected to the condyle?
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Which muscle is primarily responsible for the elevation of the mandible during mastication?
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What is the main action of the lateral pterygoid during the process of mastication?
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Which of the following is NOT a movement facilitated by the muscles of mastication?
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What is the innervation of the masseter muscle?
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Which muscle assists in the side-to-side movement of the mandible?
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Which condition might result from excessive clenching or grinding of the teeth?
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What is the blood supply primarily associated with the muscles of mastication?
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What is the role of the temporalis muscle during mastication?
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Which muscle forms the primary bulk of the cheek and assists in forming a seal while chewing?
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During mastication, the term 'retrusion' refers to which action of the mandible?
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Which nerve supplies the posterior belly of the digastric muscle?
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What is the role of the buccinator muscle during mastication?
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From which anatomical structure does the geniohyoid muscle originate?
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Which muscle assists in depressing the mandible while also aiding in deglutition?
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Which artery supplies blood to the anterior belly of the digastric muscle?
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What primary action does the genioglossus muscle perform?
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What happens to the fibers of the buccinator muscle at the corners of the mouth?
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Which nerve supplies the genioglossus muscle?
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What is the main action of the anterior belly of the digastric muscle?
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What is the blood supply for the genioglossus muscle?
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What is the action of the lateral pterygoid muscle during bilateral contraction?
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Which nerve supplies the medial pterygoid muscle?
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Where do some fibers of the lateral pterygoid muscle insert?
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What is the primary function of the medial pterygoid muscle when acting together with the lateral pterygoid muscle?
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Which of the following blood vessels supplies both the lateral and medial pterygoid muscles?
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What structure anchors the intermediate tendon of the digastric muscle?
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From which part of the maxilla does the superficial head of the medial pterygoid arise?
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Which actions are produced by the lateral pterygoid muscles when they act alternately with those of the other side?
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What is the origin of the deep head of the medial pterygoid muscle?
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Which of the following actions is NOT performed by the lateral pterygoid muscle?
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Study Notes
Muscles of Mastication
- Muscles of mastication allow the mandible to move in 5 main ways: forwards, backwards, upwards, downwards, and side to side.
- Movement of the mandible impacts on dental procedures like ID Block (potential bruising and pain), pain during mastication, trismus (difficulty after radiotherapy), and clenching/grinding (stress-related masseter pain).
Masseter
- Thick quadrilateral muscle with two parts: superficial and deep.
- Superficial origin is anterior two-thirds of the lower border of the zygomatic arch.
- Deep origin is posterior third of the lower border and the whole of the medial surface of the zygomatic arch.
- Both parts insert on the outer surface of the ramus of the mandible, with deep part superior to the superficial part.
- Action: Contracts to close the mouth/elevate the mandible.
- Nerve Supply: Masseteric nerve (anterior division of the mandibular nerve).
- Blood Supply: Facial branch of the superficial temporal artery and masseteric branch of the maxillary artery.
- Parotid gland duct, facial nerve and artery pass through the masseter muscle.
Temporalis
- Fan-shaped muscle, located on either side of the head.
- Origin: Arises from the whole of the temporal fossa, bound at the top by the inferior temporal line.
- Insertion: Top and medial surface of the coronoid process and anterior border of the ramus of the mandible.
- Action: Anterior fibers elevate the mandible, posterior fibers elevate the mandible and retract the head of the condyle back into the glenoid fossa.
- Nerve Supply: Anterior and posterior deep temporal nerves (anterior division of the mandibular nerve).
- Blood Supply: Middle temporal branch of the superficial temporal artery and deep temporal branch of the maxillary artery.
Lateral Pterygoid
- Short, thick muscle with two heads: upper and lower.
- Upper head origin is the infratemporal surface and crest of the greater wing of sphenoid bone.
- Lower head origin is the lateral surface of the lateral pterygoid plate of the sphenoid bone.
- Insertion: Merge and insert into the pterygoid fovea on the anterior aspect of the neck of the mandible, some fibers insert into the TMJ.
- Action: Bilateral contraction opens and protrudes the mouth, alternating action between sides produces grinding/side to side movement.
- Nerve Supply: Lateral pterygoid nerve (anterior division of the mandibular nerve).
- Blood Supply: Pterygoid branches of the maxillary artery.
Medial Pterygoid
- Thick quadrilateral muscle with two head: deep and superficial.
- Deep head origin is the medial surface of the lateral pterygoid plate of the sphenoid bone.
- Superficial head origin is from the tuberosity of the maxilla and pyramidal process of the palatine bone.
- Insertion: Passes downwards, backwards and laterally to the medial surface of the ramus and angle of the mandible (below and behind the inferior dental foramen).
- Action: Elevates the mandible and protrudes the mandible in conjunction with the lateral pterygoid muscle.
- Nerve Supply: Medial pterygoid branch of the mandibular nerve.
- Blood Supply: Pterygoid branches of the maxillary artery.
Digastric
- Origin: Posterior belly arises from the digastric notch on the mastoid process of the temporal bone, anterior belly arises from the digastric fossa on the lower border of the mandible.
- Insertion: Both bellies meet above the hyoid bone at the intermediate tendon, anchored by a fibrous sling to the body of the hyoid bone.
- Action: Depresses the mandible, elevates the hyoid bones during chewing and swallowing.
- Nerve Supply: Posterior belly supplied by digastric branch of the facial nerve (VII), anterior belly supplied by the mylohyoid nerve.
- Blood Supply: Posterior belly supplied by the posterior auricular/occipital artery, anterior belly supplied by the submental branch of the facial artery.
Buccinator
- Forms the cheek.
- Origin: Pterygomandibular raphe and buccal alveolar bone (in maxillary and mandibular molar regions).
- Insertion: Fibers run horizontally, blending with the Orbicularis Oris at the corners of the mouth.
- Action: Pulls the corner of the mouth back, compresses the cheek against the buccal surfaces of molars, regulates the vestibular region along with the tongue to keep food between teeth during mastication.
- Nerve Supply: Facial Nerve, buccal branch.
- Blood Supply: Facial and maxillary arteries.
Geniohyoid
- Narrow muscle located above the medial part of the mylohyoid line.
- Origin: Arises from the inferior genial tubercle.
- Insertion: Fibers run downwards and backwards into the body of the hyoid bone.
- Action: Aids in deglutition and opening the mouth by depressing the mandible.
- Nerve Supply: Hypoglossal Nerve.
- Blood Supply: Sublingual branch of the lingual artery.
Genioglossus
- Origin: Arises from the superior genial tubercle on the inner surface of the mandible.
- Insertion: Enters the dorsum of the tongue, forming a fan-shaped muscle, superior fibers pass upwards to the tip of the tongue, inferior fibers insert onto the body of the hyoid bone.
- Action: Depresses the tongue, inferior fibers retract the tongue, 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
Test your knowledge on the muscles involved in mastication, their functions, origins, and innervation. This quiz covers important aspects like the masseter muscle and its role in dental procedures. Explore the movements of the mandible and their implications in oral health.
