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TMJ and Muscles of Mastication

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Presentation on theme: "TMJ and Muscles of Mastication"— Presentation transcript:

1 TMJ and Muscles of Mastication
Dr Rania Gabr

2 Objectives Identify the parts of the mandible.
Know the type and formation of temporomandibular joint. Understand the attachment of the capsule and ligaments of the temporomandibular joint. Explain the mechanism of movements taking place at temporomandibular joint. Define the stability factors of the joint. Explain the muscles of mastication with their origin, insertion, nerve supply and actions. Discuss maxillary artery.

3 Gross Anatomy This is a synovial joint of condylar variety.
COMPONENTS: Mandibular condyles Articular surfaces of Temporal bone Capsule Articular disc Ligaments

4 ARTICULAR SURFACES- A. Upper part - a) Articular eminence,
b) ant. part of mandibular fossa. B. Inferior surface - head of the mandible.

Fibro cartilaginous tissues Disc divides the compartment into 2: Upper formed by Temporal bone and articular disc (Menisco temporal) Lower formed by mandible and articular disc (Menisco mandibular)

6 CAPSULE Fibrous membrane that surrounds the joint
Covers the joint from all around Thin above the disc and thick below it Encloses the disc Attaches above: to the margins of the mandibular fossa Attaches below: to the neck of the mandible The inner aspect of capsule attaches to disc Above disc – capsule loose Below disc - tight


8 LIGAMENTS Major Ligaments Temporomandibular ligament Lateral ligament
Minor Ligaments Stylo mandibular ligament Spheno mandibular ligament


10 Movements Elevation Depression Retraction Protraction Side to side

11 Movements Side to side – grinding movements
Mandible is alternately protracted and retracted with the two sides moving in opposite directions so that one side is protracted while the other is retracted Actions combined with elevation and depression, rhythmically and alternately. Opening of the jaw (depression) ,is primarily passive or gravity assisted.

12 MUSCLES Messeter Temporalis Medial pterygoid Lateral pterygoid

Auriculo temporal nerve: from the posterior division of the mandibular nerve Messeteric nerve: from the anterior division of the mandibular nerve MOTOR Mandibular division of trigeminal nerve

14 Temporalis Its a fan shaped muscle Covered by temporal fascia Origin: Medial wall of the temporal fossa and temporal fascia Insertion: Anterior margin of coronoid process and anterior border of the ramus of mandible Nerve supply: Deep temporal branch of anterior division of mandibular nerve

15 TEMPORAL FASCIA Attachment: Above: Superior temporal line Below:
It splits into 2 layers and insert into respective borders of zygomatic bone

16 ACTION: ANT - Elevation of the mandible POST – Retraction of mandible Middle fibres - Oblique Anterior fibres – vertical Posterior fibres - Horizontal

17 Masseter It is quadrilateral in shape.
Can be palpated in living subjects on clenching the teeth It consists of 2 layers : Superficial and deep. Origin: Lower margin and deep aspect of zygomatic arch Insertion: Lateral surface of ramus and coronoid process of mandible

18 Protracts the mandible
Nerve supply: Masseteric nerve from the anterior division of mandibular nerve. Action: Elevates the mandible Superficial fibres: Protracts the mandible

19 Pterygoid muscles There are medial and lateral pterygoid muscles.
They extend from the pterygoid plates and insert in the mandible. Lateral pterygoid Partotid duct Buccinator Medial pterygoid

20 Lateral pterygoid It is a short, thick muscle consisting of two parts
I) Upper head II) Lower head Origin: Upper head: Infratemporal surface of greater wing of sphenoid Lower head: Lateral surface of the lateral pterygoid plate Insertion: Pterygoid fovea (depression on the front of the neck of the mandible) Capsule of TMJ Upper head Lower head Some fibres of upper head may insert in the capsule of tempero-mandibular joint

21 Lat. Pterygoid - Attachment
Upper head Infra temporal Sufrace of greater wing of sphenoid Lower head Lateral surface of lateral pterygoid plate Nerve supply: Anterior division of mandibular nerve Action: opening of mouth (Depression of mandible) by pulling forward the head of mandible. Upper head – chewing, Lower head – protrusion. Side to side movements: combined action of medial and lateral pterygoid

22 Medial pterygoid It consists of large deep head and small superficial head. Origin: Deep head: Arises from the medial surface of lat.pterygoid plate Superficial head: Tuberosity of maxilla Insertion: Medial surface of ramus and angle of mandible. Nerve supply: Branch from the trunk of mandibular nerve Deep head Superficial head

23 Deep fibres Superficial fibres Action: Elevation of mandible. Together with lateral pterygoid, it helps in side to side chewing movement.

24 VASCULARISATION Branches of External Carotid Artery
Superficial temporal artery Deep auricular artery Anterior tympanic artery Ascending pharyngeal artery Maxillary artery

25 VASCULARISATION The Blood supply to TMJ is only Superficial, i.e there is no blood supply inside the capsule TMJ takes its nourishment from Synovial fluid

26 Clinical Anatomy Trismus:
Tonic spasm of both masseters is the characteristic symptom of tetanus which produces “lock jaw”


28 Clinical Anatomy (contd...)
Submasseteric space infection: Infection around 3rd molar tooth may seep into the space between the attachment of masseter with mandible which leads to visible swelling and limitation of jaw movements

29 Clinical Anatomy (contd...)
Paralysis of lateral pterygoid muscles causes the jaw to deviate towards the paralysed side on opening the mouth as a result of action of normal muscle.


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