Temporomandibular joint

It is a condylar variety of synovial joint, present in the buccal region. Temporo-mandibular joint helps in chewing.

Bones involved - 

1. Temporal

2. Mandibular

Articular surface - 

A. Upper articular surface is formed by the temporal bone.

1. Articular tubercle of temporal bone.

2. Anterior part of mandibular fossa of temporal bone.

3. Posterior non articular part formed by head of mandible of temporal bone.

B. Lower articular surface is formed by mandible bone.

Note - The articular surfaces are covered with fibrocartilage and the joint cavity is divided into upper and lower parts by an inter articular disc.

Ligaments of TMJ -

1. Fibrous capsule

2. Lateral TM ligament

3. Sphenomandibular ligament

4. Stylomandibular ligament

Relations - 

A. Lateral - 

1. Skin and fasciae

2. Parotid gland

3. Facial nerve (only temporal branch)

B. Medial 

1. Tympanic plate

2. Spine of sphenoid bone

3. Auriculo temporal and chorda tympani nerves

4. Middle meningeal artery

C. Anterior 

1. Lateral pterygoid

2. Masseteric nerves and artery

D. Posterior

1. Parotid gland

2. Superficial temporal vessels

3. Auriculotemporal nerves

E. Superior

1. Middle cranial fossa

2. Middle meningeal vessels

F. Inferior

1. Maxillary artery

2. Maxillary vein

Blood supply of TMJ - 

1. Superficial temporal artery and vein.

2. Maxillary artery and vein.

Nerve supply of TMJ - 

1. Auriculotemporal nerve.

2. Masseteric nerve.

Movements of TMJ - 

1. Depression 

2. Elevation

3. Protrusion

4. Retrusion

5. Lateral or side to side movements (during chewing)

Main muscles producing movements of TMJ - 

1. Depression - 

a. Lateral pterygoid

2. Elevation -

a. Masseter

b. Temporalis

c. Medial pterygoid 

3. Protrusion -

a. Lateral and medial pterygoid

b. Superficial oblique fibres of masseter

4. Retraction - 

a. Posterior horizontal fibres of temporalis

b. Deep vertical fibres of masseter

5. Lateral movements - 

A. Right side movement - 

 

a. Left lateral and medial pterygoid

b. Right temporalis 

c. Right masseter

B. Left side movement -

a. Right lateral and medial pterygoid.

b. Left temporalis

c. Left masseter

Clinical anatomy - 

1. Dislocation of mandible during excessive opening of mouth.

2. During operations of TMJ, facial and  auriculotemporal and mandibular division of trigeminal nerves should be taken care.