norma lateralis
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The Lateral View of the Skull
Norma Lateralis
The Bones Involved in Norma Lateralis
1. Temporal Bone2. Parietal Bone3. Occipital Bone4. Frontal Bone5. Zygomatic Bone6. Maxilla7. Mandible8. Nasal Bone9. Sphenoid Bone10. Lacrimal Bone.
The Two Divisions of the Skull in Norma Lateralis
1. Cerebral Portion - located above the zygomatic arch.
2. Facial Portion- located below the zygomatic arch.
THE CHARACTERISTIC FEATURES OF THE CEREBRAL PORTION
1. Temporal Lines2. Supramastoid Crest3. Temporal Fossa4. Zygomatico-
temporal foramen5. Zygomatic arch6. Infratemporal fossa7. Suprameatal triangle8. Pterion9. Asterion.
Pterion
- the thinnest part of the lateral wall of the skull.
- an important area because it overlies the anterior division of the middle
meningeal artery and vein.
- point where the posteroinferior angle of the parietal bone meet the occipital bone and the mastoid part of the temporal bone.
Asterion
THE CHARACTERISTIC FEATURES OF THE FACIAL PORTION
1. Zygomatic arch2. Articular tubercle3. External acoustic
meatus4. Mandibular fossa5. Styloid process6. Mastoid temporal7. Mastoid process8. Mastoid foramen9. Gonion.
10. Pterygo-maxillary fissure11.Pterygo-palatine fossa12.Spheno-palatine foramen.
THE TEMPORAL BONE
• 1. Squamous part
• 2. Mastoid part
• 3. Tympanic part
• 4. Petrous part
Four Parts of the Temporal Bone
THE THREE FOSSAE IN NORMA LATERALIS
1. Temporal Fossa
2. Infratemporal Fossa
3. Pterygopalatine Fossa
THE TEMPORAL FOSSA
A flat, fan-shaped depression on the lateral surface of the skull.
Bones involved:1. Zygomatic Bone2. Frontal Bone3. Greater Wings of
Sphenoid4. Temporal Bone5. Parietal Bone
BOUNDARIES OF THE TEMPORAL FOSSA
Boundaries Structure
Superior Inferior Temporal Line
Anterior Frontal Process of Zygomatc Bone
Medial Surface of parietal bone,Temporal Bone, frontal bone and GWS
Lateral Zygomatic ArchInferior Infratemporal Crest of
Sphenoid BonePosterior Inferior Temporal line
1. Temporalis muscle is attached to its floor.
2. Pterion – a small circular area where the frontal, parietal, sphenoid, and temporal bones are close together.
Contents of the Temporal Fossa
THE INFRATEMPORAL FOSSA
- A paired depression that is inferior to anterior part of the temporal fossa.
- Divided from the temporal fossa by the crest of the greater wings of sphenoid.
BOUNDARIES OF THE INFRATEMPORAL FOSSA
Boundaries Structure
Superior Greater wings of sphenoid
Anterior Maxillary tuberosity
Medial Lateral pterygoid plate
Lateral Mandibular ramus and zygomatic arch
Inferior No borderPosterior No border
1. The mandibular division of the trigeminal nerve,
2. Contains pterygoid plexus and the pterygoid muscles,
3. Maxillary artery and its branches, middle meningeal artery,
4. Inferior alveolar artery, 5. Posterior alveolar artery.
Contents of the Infratemporal Fossa
THE PTERYGOPALATINE FOSSA
A cone-shaped depression, deep into the infratemporal fossa.
It is located between the pterygoid process and the maxillary tuberosity near the apex of the orbit.
BOUNDARIES OF THE PTERYGOPALATINE FOSSA
Boundaries Structure
Superior Inferior surface of the body of the sphenoid
Anterior Maxillary tuberosity
Medial Vertical plate of the palatine bone
Boundaries Structure
Lateral Pterygomaxillary fissure
Inferior Pterygopalatine canal
Posterior Pterygoid process of the sphenoid bone
1. Maxillary artery and its branches,
2. Pterygopalatine ganglion,
3. Maxillary nerve.
Contents of the Pterygopalatine Fossa
The Temporomandibular Joint
- is a complex articulation of the movable mandible and the base of the skull.
Articulation takes place in two areas:
1. Between maxillary and mandibular teeth ( interjaw dental occlusion ), and
2. Between the mandibular condyle and the temporal bone.
Bones Involved in the TMJ
1. Condylar process or condyle of the mandible
2. Mandibular fossa3. Articular
emminence of the temporal bone
COMPONENTS OF THE TMJ
1. Articular or Fibrous Capsule
2. Temporo-mandibular (lateral) Ligament
3. Articular Disc
4. Joint Cavities
1. ARTICULAR OR FIBROUS CAPSULE
- encloses the joint surfaces like a sleeve that runs from the temporal bone superiorly, to the condyle of the mandible inferiorly. The enclosed space between the articular surfaces is the joint cavity
Superior attachment :
area surrounding the mandibular fossa and articular eminence of the temporal bone.
Inferior attachment:
periphery of the mandibular condyle.
2. TEMPOROMANDIBULAR (LATERAL) LIGAMENT
- is a lateral thickening of the
joint capsule and is similar to
the collateral ligaments of
other joints.
- It prevents posterior and
inferior displacement of the
condyle but allows limited
anterior movements of the
condyle.
3. ARTICULAR DISC
- it is composed of dense fibrous tissues and lies within the joint
capsule, intervening between the condyle and the mandibular fossa.
- It is a biconcave disc that serves to provide reciprocal articular
surfaces between its inferior surface and the condyle, and its superior
surface and the mandibular fossa and eminence.
Three zones of the articular disc:
1. Posterior thickening – sits atop the condyle and fills the mandibular fossa above when the mandible is at rest.
2. Anterior thickening - lies just below the posterior slope of the articular eminence.
3. Intermediate zone - lies between the two previous zones.
4. JOINT CAVITIES
The disc effectively divides the joint cavity into two distinct upper and
lower compartment that allow two types of joint movements.
These cavities are also filled with synovial fluid which nourishes the
articular disc.
Joint Cavities
ACCESSORY LIGAMENTS
Two accessory ligaments span the joint but do not significantly limit mandibular movements:
1. Sphenomandibular ligament - it runs from the spine of the sphenoid bone to the lingula of the mandible.
2. Stylomandibular ligament- it runs from the styloid process of the temporal bone to the angle of the mandible.
THE SYNOVIAL MEMBRANE
A layer of synovium lines the inner aspects of the joint capsule. This relatively dense membrane does not line the actual articular surfaces of the joints because synovial joints are generally weight-bearing joints.
The pressure in the TMJ is provided by the occluded maxillary and mandibular teeth.
Synovium secretes synovial fluids for lubrication and nourishment of the opposing articular surfaces.
1. An intimal cellular layer- contains type A cells which are phagocytic, and type B cells which synthesize hyaluronate found in synovial fluid.
2. A vascular subintimal layer- Contains blood vessels, and lymphatics
within the loose connective tissue matrix.
Two Layers of the Synovial Membrane
NERVE SUPPLY OF THE TMJ
1. Branches of the temporalis N.
2. Branches of the auriculotemporal N.
3. Branches of the masseteric N.
BLOOD SUPPLY OF THE TMJ
1. Superficial temporal artery
2. Muscular branches of the maxillary artery
TEMPOROMANDIBULAR JOINT IN ACTION
MUSCLES ACTING ON THE TMJ
1. Masseter2. Temporalis3. Lateral Pterygoid4. Medial Pterygoid
Protrussion:
1. Lateral pterygoid m.
2. Medial pterygoid m.
Retraction
1. Temporalis M.
Synergists:a. Massetersb. Digastricc. Geniohyoid
Elevation
1. Temporalis2. Masseter 3. Medial
pterygoid
Depression
1. Lateral pterygoid
Synergists:2. Digastric3. Geniohyoid4. Mylohyoid
Lateral movements
1. Medial pterygoid m.
2. Lateral pterygoid m.
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