Action of digastric muscle:

 # Following is the action of digastric muscle:

A. Elevates the mandible and depresses the hyoid bone

B. Elevates the hyoid bone and depresses the mandible

C. Depresses the mandible as well as hyoid bone

D. Elevates the mandible as well as hyoid bone

The correct answer is B. Elevates the hyoid bone and depresses the mandible.

Digastric muscle depresses the mandible when the mouth is opened widely or against resistance and elevates the hyoid bone.

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Temporalis muscle originates from:

 # Temporalis muscle originates from:

A. Side of the skull

B. Zygomatic process

C. Ramus of the mandible

D. Pterygopalatine fossa

The correct answer is A. Side of the skull.

Temporalis muscle arises from temporal fossa and temporal fascia and inserts into deep surface of coronoid and anterior border of the ramus of mandible. 

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WATCH THIS VIDEO TO KNOW ABOUT ORIGIN AND INSERTION OF ALL THE MUSCLES OF MASTICATION:

Medial pterygoid muscle is attached to:

 # Medial pterygoid muscle is attached to:

A. Medial surface of lateral pterygoid plate

B. Lateral surface of medial pterygoid plate

C. Medial surface of medial pterygoid plate

D. Lateral surface of lateral pterygoid plate

The correct answer is A. Medial surface of the lateral pterygoid plate

Deep head of the medial pterygoid muscle arises from medial surface of lateral pterygoid plate and palatine bone. The lateral pterygoid muscle arises from lateral surface of lateral pterygoid plate.

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Lymphatic drainage of TMJ:

 # Lymphatic drainage of TMJ is mainly to:

A. Submandibular nodes

B. Submental nodes

C. Deep cervical nodes

D. Parotid nodes

The correct answer is D. Parotid nodes.

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Nerve supply of Capsule of TMJ:

 # Which of the following supplies capsule of TMJ?

A. Facial nerve

B. Auriculotemporal nerve

C. Branch of maxillary nerve

D. First cervical nerve

The correct answer is B. Auriculotemporal nerve.

Sensory nerve supply: Sensory innervation of the TMJ is derived from the auriculotemporal and masseteric branches of V3 (otherwise known as the mandibular branch of the trigeminal nerve).

Blood supply of TMJ: Its arterial blood supply is provided by branches of the external carotid artery, predominantly the superficial temporal branch. Other branches of the external carotid artery, namely, the deep auricular artery, anterior tympanic artery, ascending pharyngeal artery, and maxillary artery, may also contribute to the arterial blood supply of the joint.

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Dynamic receptors of the TMJ joint:

 # Which of the following are dynamic receptors of the TMJ joint?

A. Ruffini endings

B. Pacinian corpuscles

C. Golgi tendon

D. Free nerve endings

The correct answer is B. Pacinian corpuscles

Pacinian corpuscles  are dynamic mechanoreceptors which accelerate movement during reflexes. 

The receptors for specific mechanics of proprioception:

Ruffini endings- static  mechanoreceptors which position the mandible

Pacinian corpuscles- Dynamic mechanoreceptors which accelerate movement during reflexes

Golgi tendon organs- Static mechanoreceptors for protection of ligaments around the temporomandibular joint

Free nerve endings- Pain receptors for protection of the temporomandibular joint itself

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Articular disc of TMJ is

 # Articular disc of TMJ is:

A. Fibrocartilaginous

B. Bony

C. Hyaline cartilage

D. Elastic cartilage

The correct answer is A. Fibrocartilaginous

The unique feature of the TMJ is the articular disc. The disc is composed of fibrocartilaginous tissue which is positioned between the two bones that form the joint. There is neither innervation nor vascularization within the central portion of the articular disc. Articular disc is oval fibrous plate with concavoconvex superior surface and concave inferior surface. It divides joint into upper and lower compartments. Upper compartment permits gliding and lower permits gliding as well as rotatory movements. 

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