Seminar 1 Muscles of mastication, depression elevation

Mastication muscles

1. Presented by – dr.shubham gupta (pg-1St year) Department of oral and maxillofacial SURGERY Muscles of mastication Guided by -Dr satish karandikar (head of department) -Dr bhoopandra singh rajpu t

2. -Introduction -Embryology -classification -applied anatomy -reference Content

3. Introduction Muscles of mastication are muscles that are attach to the mandible and there by produce movement of jaw. Muscles are tissue characterised by aggregation of cell whose primary function is to produce contraction and allow the movement of parts and organs of the body.

4. Classification Primary muscles of mastication Temporalis Masseter Medial pterygoid Lateral pterygoid Secondary muscles of mastication Suprahyoid Digastric. Stylohyoid. Mylohyoid Geniohyoid

5. Primary muscles of mastication Masseter muscles -It has Multipennate arrangement -it has 3 layers Origin Insertion Superficial Layer : zygomatic 2/3 of lower border Lower part of the lateral surface Of zygomatic arch & adjoining of the ramus of the mandible. zygomatic process. Middle Layer : post.1/3 of the lower border Middle of the ramus of the of zygomatic arch. mandible. Deep layer. : Deep surface of the zygomatic Rest of the ramus of the arch. Mandible.

6. RELATIONS On the superficial side below the zygomatic process the duct of parotid gland passes across the surface of the muscle. Superficial part of the parotid gland is also located superficially to the masseter muscle. Along with the parotid gland few more structures found over the lateral side of the muscle. -terminal branches of facial nerve. -facial vein. -facial artery. -zygomaticus major muscle. Anterior to the muscle, buccinator muscle is located.

7. Nerve supply : Masseter Nerve branch of ant erior division of mandibular nerve .

8. Temporalis muscle It is a fan shaped muscle

9. Origin: It arises from the whole temporal fossa except for that part formed by the zygomatic bone together with the deep surface of the temporal fascia. Insertion: Margins and deep surface of the coronoid process. Anterior border of ramus of the mandible.

10. Relations Superficially, the muscles covered by the temporal fascia, masseter muscle , subcutaneous tissue and skin. The auriculotemporal nerve, facial nerve and zygomaticotemporal nerve run across the superficial aspect of the temporalis muscle. Clinical aspects Tension in the temporalis muscle can induce pain in the temporal area. common causes include: -Misalignment of the teeth and jaws -Trauma -Teeth grinding (bruxism)

11. Nerve supply: Two deep temporal branch of anterior division of mandibular nerve. Blood supply: Middle and deep temporal arteries which are branch of superficial temporal & internal maxillary artery respectively.

12. Action: Anterior fibers elevate mandible Side to side grinding movement and retraction of mandible. Palpation: Above zygomatic arch anterior to TMJ run in a vertical direction.

13. Lateral pterigoid muscle It has two head: -Upper head -Lower head

14. Upper head : Lower head : Origin: infratemporal surface Crest of greater wing of sphenoid bone Insertion: pterygoid fovea on the anterior surface of the neck of the condyle. Origin: lateral surface of the lateral pterygoid plate. Insertion: anterior margin of the articular disk and capsules of the TMJ.

15. Relation Lateral pterygoid muscle comprises the medial wall of the infratemporal fossa and is contained with in the masticatory space. The superior margin of the muscle is crossed by the temporal and masseteric branches of mandibular nerve and inferior and lingual branches cross the inferior margin. Maxillary artery and buccal nerve(branch of mandibular nerve) passes between superior and inferior head of lateral pterygoid muscle.

16. Nerve supply: lateral pterigoid is supplied by a branch of anterior division of mandibular nerve. Blood supply: pterigoid branch of 2 nd part of maxillary artery. Action: Depression of mandible. Right Lateral & medial pterigoid turn chin to left side as a part of grinding movement.

17. Medial pterigoid muscle It has thick quadrilateral muscles. It has two head-small: superficial head -large: deep head Origin Small head- Tuberosity of maxilla and adjoining bone Deep head- Medial surface of lateral pterygoid plate Insertion On the medial surface of the angle of mandible. Adjoining part of the ramus of the mandible below the mandibular foramen.

18. Relations Outer surface of the muscles lie against the inner surface of mandible, from which it is separated by the lateral pterygoid muscle, sphenomandibular ligament, maxillary artery and mandibular nerve and its lingual & inferior alveolar nerve branches. Inner surface of the muscle is in relation with the tensor veli palatini and styloglossus muscle. Medial pterygoid muscle is medially related with lateral surface of the submandibular gland the facial artery. Clinical aspect The medial pterygoid muscle can sometime be injured during inferior alveolar nerve block due to it being close proximity to the nerve. This can cause hemorrhage and development of medial pterygoid trismus, this cause inability to completely open mouth.

19. Nerve supply: Medial pterygoid branch of the main trunk of the mandibular nerve. Blood supply: Pterygoid branch of 2 nd part of maxillary artery. Action: Elevate mandible

20. Secondary muscles of mastication Suprahyoid muscles Mylohyoid muscle Digastric muscle Geniohyoid muscle Stylohyoid muscle

21. Mylohyoid : Origin: Mylohyoid lining of the mandible. Insertion: posterior fibers inserted into body of hyoid bone. Anterior and Middle fibers inserted into median raphe that unit right and left muscles. Nerve supply: mylohyoid nerve branch of mandibular nerve. Blood supply: mylohyoid artery branch of inferior alveolar artery. Action: Elevate floor of the mouth. Depression of mandible and elevate hyoid bone.

22. Digastric muscles : Origin: Anterior belly from digastric Fossa of mandible Posterior belly from mastoid notch of temporal bone. Insertion: Both head meet together at an intermediate tendon which is attached to the hyoid bone. Nerve supply: Anterior belly of digastric muscle is supplied by branch of mylohyoid muscle. Post. Belly of digastric muscle is supplied by post. Auricular nerve branch of facial nerve Blood supply: Submental artery branch of facial artery supplied anterior belly and auriculotemporal artery branch of external carotid artery supplied post belly Action: pull mandible backward and dawnward and elevate hyoid bone.

23. Geniohyoid: Origin: From inferior genial tubercle. Insertion Fibers run backward dawnward & in surface of body of hyoid bone. Nerve supply : first cervical nerve fibers passes through hypoglossal nerve Action: elevate hyoid bone and depress mandible.

24. Applied anatomy MPDS ( myofascial pain dysfunction syndrome) Myofascial pain dysfunction syndrome is common pain disorder of muscle. The pain is referred from trigger points from within myofascial structures or from distant area from pain . Etiology: Malocclusion, bruxism, increased pain sensitivity and stress and anxiety. The muscular hyperactivity and dysfunction due to malocclusion are the factors responsible for the pain Clinical presentation: Temporomandibular disorder commonly affects females. Patients may have pain, muscle tenderness, clicking noise in the TMJ and limitation of jaw motion. Sometimes deviation on opening may be present. Pain is usually periauricular radiating to head. Pain may be unilateral or bilateral. The pain is said to be severe during increased stress.

25. References Gargk , Mittal PS, Chandrupatla M.BD Chaurasia’s Human anatomy. CBS publishers; 7 th edition. Snell RS ; Clinical anatomy ; Lippincott Williams & Wilkins; 7 th edition.

26. Thank you