Radiological anatomy of the temporo-mandibular joint and mandible.

Dr/ ABD ALLAH NAZEER. MD.

Radiological imaging of temporo-mandibular joint and mandible.

Plain radiography.Ultrasound.Computed tomography.(CT).Magnetic resonance imaging(MRI).Arthrography.

The temporomandibular joint is the joint of the jaw and is frequently referred to as TMJ. The TMJ is a bilateral synovial articulation between the mandible and temporal bone. The name of the joint is derived from the two bones which form the joint : the upper temporal bone which is part of the cranium (skull ), and the lower jawbone or mandible

There are six main components of the TMJ.Mandibular condylesArticular surface of the temporal boneCapsuleArticular discLigamentsLateral pterygoid

Innervation:Sensory innervation of the temporomandibular joint is derived from the auriculotemporal and masseteric branches of V3 or mandibular branch of the trigeminal nerve . These are only sensory innervation. Recall that motor is to the muscles.The specific mechanics of proprioception in the temporomandibular joint involve four receptors. Ruffini endings function as static mechanoreceptorswhich position the mandible. Pacinian corpuscles are dynamic mechanoreceptors which accelerate movement during reflexes. Golgi tendon organs function as static mechanoreceptors for protection of ligaments around the temporomandibular joint. Free nerve endings are the pain receptors for protection of the temporomandibular joint itself.

Blood supply:Its arterial blood supply is provided by branches of the external carotid artery , predominately 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.

TMJ Anatomy The temporomandibular joint (TMJ) or jaw joint is a bi-arthroidal hinge joint that allows the complex movements necessary for eating, swallowing, talking and yawning. Dysfunction of the TMJ can cause severe pain and lifestyle limitation. Temporomandibular disorders are common and sufferers will often seek physiotherapeutic advice and treatment. Good knowledge of the anatomy of the TMJ and related structures is essential to correct diagnosis and appropriate treatment. Joint Capsule - The capsule is a fibrous membrane that surrounds the joint and attaches to the articular eminence, the articular disc and the neck of the mandibular condyle. Articular disc - The articular disc is a fibrous extension of the capsule that runs between the two articular surfaces of the temporomandibular joint. The disc articulates with the mandibular fossa of the temporal bone above and the condyle of the mandible below. The disc divides the joint into two sections, each with its own synovial membrane. The disc is also attached to the condyle medially and laterally by the collateral ligaments. The anterior disc attaches to the joint capsule and the superior head of the lateral pterygoid. The posterior portion attaches to the mandibular fossa and is referred to as the retrodiscal tissue. Retrodiscal tissue - Unlike the disc itself, the retrodiscal tissue is vascular and highly innervated. As a result, the retrodiscal tissue is often a major contributor to the pain of Temporomandibular Disorder (TMD), particularly when there is inflammation or compression within the joint.

Ligaments The ligaments give passive stability to the TMJ. The temporomandibular ligamentis the thickened lateral portion of the capsule, and it has two parts, an outer oblique portion and an inner horizontal portion.

The stylomandibular ligamentruns from the styloid process to the angle of the mandible. The sphenomandibular ligamentruns from the spine of the sphenoid bone to the lingula of mandible.

The oto-mandibular ligaments are the discomalleolar ligament (DML), which arises from the malleus (one of the ossicles of the middle ear) and runs to the medial retrodiscal tissue of the TMJ, and the anterior malleolar ligament (AML), which arises from the malleus and connects with the lingula of the mandible via the sphenomandibular ligament. The oto-mandibular ligaments may be implicated in tinnitus associated with TMD. A positive correlation has been found between tinnitus and ipsilateral TMJ disorder. It has been proposed that a TMJ disorder may stretch the DML and AML, thereby affecting middle ear structure equilibrium. “It thus seems that otic symptoms (tinnitus, otalgia (ear pain), dizziness and hypoacusis) corresponding to altered ossicular spatial relationships (such as conductive middle ear pathologies) can also be produced from masticatory system pathologies.

Muscles and Jaw Movement The jaw can move forward and back, side to side and can open and close. Each of these movements are performed by a number of muscles working together to perform the movement while controlling the position of the condyle within the mandibular fossa. Chewing and talking require a combination of jaw movements in a number of directions. Opening – inferior head of lateral pterygoid, anterior digastric, mylohyoid. Opening is also controlled by eccentric contraction of the closing muscles against gravity. Opening is a complex movement consisting of an early rotary component in the first 2-3cms of movement with a forward glide towards the end of range. The articular disc moves forward with the condyle as it glides forward, effectively extending the superior articular surface of the mandibular fossa. Closing – masseter, anterior and middle temporalis, medial pterygoid, superior head lateral pterygoid. Protrusion – bilateral contraction of the lateral pterygoid. Retrusion – middle and posterior temporalis, possibly helped by deep posterior portion of masseter Laterotrusion (side to side) – ipsilateral middle and posterior temporalis, contralateral inferior head lateral pterygoid.

Temporomandibular Joints (TMJ) Radiographic Anatomy:

Adult Lateral Oblique - Closed Mouth Adult Lateral Oblique - Open Mouth

Adult Temporomandibular Joints - Performed on an OPG Machine.

TMJ open / closed mouth - x-rays.

Adult Mandible - Orthopantogram (OPG)

Adult Mandible - LateralAdult Mandible - PA

Normal CT Anatomy.

Sagittal CT images at the level of the TMJ in a mature camel. (a) Soft tissue window CT image (WW = 4000; WL = 335) and (b) post processing VR muscles-bones CT image (Osiriximaging software). Right lateral view. 1 is temporal muscle; 2 is border of the temporal fossa; 3 is external acoustic meatus; 4 is temporal venous sinus; 5 is zygomatic process of the temporal bone; 6 is articular disc; 7 is retroarticular process; 8 is mandibular condyle; 9 is joint capsule; 10 is articular tubercle; 11 is mandibular notch; 12 is coronoid process of mandible; 13 is ramus of mandible; 14 is digastric muscle; 15 is parotid salivary gland.

CT images at the level of the TMJ in a mature camel. (a) Soft tissue window CT image (WW = 4000; WL = 335) and (b) postprocessing VR muscles-bones CT image (Osirix imaging software). Caudal view. 1 is temporal muscle; 2 is squamous part of the temporal bone; 3 is temporal venous sinus; 4 is zygomatic process of the temporal bone; 5 is articular disc; 6 is mandibular condyle; 7 is joint capsule; 8 is cortical bone; 9 is masseter muscle; 10 is ramus of mandible; 11 is lateral pterygoid muscle; 12 is tensor and levator veli palatini muscles.

Cone Beam CT of TMJ.

Nasal septum curved arrow at (A) and (C), and body of the mandible thin arrow at (A), Ramus of the mandible curved arrow, angle of the mandible thin arrow and TMJ thick arrow at (B) the Symphysis menti Straight arrow at(C).

Bone anatomy and synovial insertion of the two components of the TMJ. Red line: capsular insertion in the temporal bone. Blue line: capsular insertion in the condyle neck. E: Articular eminence; enp: entogolenoid process; t: articular tubercle; Co: condyle; pop: postglenoid process; lb: lateral border of the mandibular fossa; pep: preglenoid plane; Gf: glenoid fossa; Cp: condylar process. (A) Caudal cranial view of the TMJ bone. (B) Caudal cranial view of the TMJ without the condyle. (C) Lateral view of the TMJ bone. (D) Cranial caudal view of the condyle bone without the cranial bone.

Components of the disk. AB: Anterior band; IZ: intermedius zone; PB; posterior band; SPLM: superior pterygoid lateral muscle; RT: retrodiskal tissue; TL: temporal lamina; IL: inferior lamina; JC: joint capsule; Gf: glenoid fossa; E: articular eminence; Co: condylar head of the mandible.

Schematic of the TMJ in a closed mouth position and sagittal projection and (b) sagittal thin section of a closed jaw. 1, Mandibular head; 2, articular eminence; 3, disk (3a, anterior band; 3b, intermediate zone; 3c, posterior band); 4, bilaminar zone; 5, lateral pterygoid muscle with interposed fat tissue (yellow in schematic) (5a, superior head; 5b, inferior head); 6, superior joint space; 7, inferior joint space.

Schematic of the TMJ in a closed mouth position and coronal projection and (b) coronal thin section of a closed jaw. 1, Mandibular head; 2, articular fossa; 3, disk; 4, medial attachment; 5, lateral attachment; 6, superior joint space; 7, inferior joint space; 8, lateral pterygoid muscle.

Schematic of the TMJ in a closed mouth position and sagittal projection. The posterior band of the disk lies within 10° of the 12 o'clock position.

Schematic of the TMJ in an open mouth position and sagittal projection. 1, Mandibular head; 2, articular eminence; 3, superior joint space; 4, inferior joint space; 5, disk (5a, anterior band; 5b, intermediate zone; 5c, posterior band); 6, bilaminar zone; 7, lateral pterygoid muscle with interposed fat tissue (yellow).

Collateral disko-mandibular ligaments of the TMJ; Scl: superficial collateral ligament; Dcl: deep collateral ligament; Gf: glenoid fossa; E: articular eminence; IZ: intermedius zone; IPLM: inferior pterygoid lateral muscle; FN: branches of the facial nerve; ATN: auriculotemporal nerve; MA: maxillary artery; Co: condylar head of the mandible; SFL: sphenomandibular ligament. (A) Schematic view of the TMJ ligaments in the sagittal plane. (B) Schematic view of the TMJ disk and ligaments in the coronal plane. (C) Schematic view of both TMJ muscles and ligaments in the coronal plane.

Schematic view of the TMJ ligaments in the central sagittal plane. SFL: Sphenomandibular ligament; STL: stylomandibular ligament; JC: joint capsule; IAN: inferior alveolar nerve; OG: otic ganglion; LN: lingual nerve; ATN: auriculotemporal nerve; MA: maxillary artery.

Lateral cadaveric specimen view of the TMJ with removal of the condyle and the cygomaticarch. Gf: Glenoid fossa; E: articular eminence; IZ: intermedius diskal zone; RT: retrodiskal zone; SPLM: superior pterygoid lateral muscle; IPLM: inferior pterygoid lateral muscle.

Axial plane of normal anatomy of TMJ, T1 weighted images and cry sectional cadaveric specimen correlation. (A) Cranial plane T1 weighted image. (B) Cranial cry section image. Osseous and articular components: E: Articular eminence. t: articular tubercle. enp: entoglenoid process. pop: postglenoid process. pep: preglenoid plane. Cp: condylar process. Gf: glenoid fossa. Co: mandibular condyle. Capsular disc and articular components. AB: anterior band. IZ: intermedius band. PB: posterior band. 4: anterior recess. 5: posterior recess. IL: inferior lamina. TL: temporal lamina. RT: retrodiscal zone. FC. fibrous capsule. Muscular components: TM: temporal muscle. IPLM: inferior bell of lateral lateral pterygoid muscle. SPLM: superior bell of lateral pterygoid muscle. PMM: medial pterygoid muscle. MM: masseter muscle. Ligaments and vascular components: FN: branches of facial nerve. ATN: auriculotemporal nerve. IAN: inferior alveolar nerve. LN: lingual nerve. OG: otic ganglion. MA: maxillary artery. MV: maxillary vessel. MMA: maxillary artery. STV: superficial temporal vessels. SCL: superficial collateral ligament. DPL: deep collateral ligament. SFL: Sphenomandibular ligament. STL: stylomandibular ligament.

A) Middle plane T1 weighted image. (B) Middle planecryosection image.

(A) Caudal plane T1 weighted image. (B) Caudal plane cryosection image.

Para coronal plane of normal anatomy of TMJ, T1 weightedimages and cryosectional cadaveric specimen correlation. (A) Anteriorplane T1 weighted image. (B) Anterior cryosection image.

(A) Middle plane T1 weighted image. (B) Middle planecryosection image.

(A) Central plane T1 weighted image. (B) Central plane cryosection image.

(A) Posterior plane T1 weighted image. (B) Posterior planecryosection image.

Parasagittal plane of normal anatomy of TMJ, T1 weightedimages and cryosectional cadaveric specimen correlation. (A) Medial sagittal plane T1 weighted image. (B) Medial sagittal cryosectionimage.

A) Middle sagittal plane T1 weighted image. (B) Middlesagittal plane cryosection image.

(A) Lateral sagittal plane T1 weighted image. (B) Lateralsagittal plane cryosection image.

(A) Periferic sagittal plane T1 weighted image. (B) Perifericsagittal plane cryosection image.

a, Sagittal and b, coronal MR images (770/27) of a normal TMJ with the jaw in an open position. Note the bow-tie shape of the disk in the sagittal projection. 1, Mandibular head; 2, articular eminence; 3, disk (3a, anterior band; 3b, intermediate zone; 3c, posterior band) ; 4, bilaminar zone; 5, lateral pterygoid muscle.

T1-Weighted sagittal magnetic resonance images in (a) closed- and (b) open-mouth positions showing normal disc positions (arrows)

Normal anatomy. Sagittal proton density weighted closed mouth and open mouth view of magnetic resonance imaging

Mandibular articular disk position.

TMJ arthrography of normal of normal TMJ disc.

Coronal MR image (400/15) of the pterygoid muscles. The mandibular ramus (1), lateral pterygoid muscle (2), and medial pterygoid muscle (3) are shown.

Axial images of the mandible.

3-dimensional magnetic resonance 3D vibe images of the mandible.

Thank You.