Week 2

• Paranasal sinuses


  Paired, air-filled cavities in bones, lined with a mucous membrane
• Paranasal sinuses


  • Frontal Sinuses
  • Sphenoidal Sinuses
  • Ethmoidal Sinuses
  • Maxillary Sinuses

  
• Paranasal sinuses


  • Communication with the nasal cavity through OSTIA in the lateral nasal walls
  • To lighten the skull bones
  • Sound resonators
  • Provide mucous for the nasal cavity

  
• Sinusitis


  Mucous membrane of the sinuses can become inflamed and congested with mucus
• Sinusitis symptoms


  • Headache near the sinus that's involved
  • Foul smelling nasal or pharyngeal discharge
  • Systemic infection possible fever and weakness
  • Skin over sinus tender, hot, red
• Chronic sinus infection lies in the nasal mucus, therefore, surgeons have moved towards removing the mucus and enlarging the OSTIA
• An infection in one sinus can spread to another
• Maxillary sinuses are close to the posterior maxillary teeth, therefore, any infection present in these teeth can create clinical problems in the sinus aka. secondary sinusitis (infection from another source)

  
• Perforation


  An abnormal hole in the wall of the sinus due to inflammatory process and an infection can occur
• Frontal sinuses


  • Paired
  • Located in frontal bone superior to nasal cavity
  • Asymmetrical (2-3CM in diameter)
  • Divided by a septum
  • Communicates and drains into the nasal cavity by a constricted canal frontonasal duct to the middle nasal meatus

  
• Sphenoidal sinuses and ethmoidal sinuses cannot be palpated
• Maxillary sinuses


  • The largest, paired, pyramid-shaped
  • Located body of maxilla
  • Posterior to maxillary canines and premolars; maxillary posterior periodontium may be in direct contact with mucous of maxillary sinus
  • Discomfort with primary sinusitis can mimic discomfort of a periodontal infection
  • With age may extend to maxillary posterior teeth and margins to the body of the zygomatic bone

  
• Maxillary sinuses have an apex, 3 walls, a roof, and a floor

  
• Orantral communication


  Fistula from an extraction
• Temporal fossa

  • Paired, flat, fan shaped depression
  • Formed by 5 different bones: zygomatic, frontal, sphenoid, temporal, parietal
  • Contains: body of the temporalis muscle; blood vessels and nerves
• Infratemporal fossa


  • Paired depression; inferior to anterior of temporal fossa
  • Contains: maxillary artery and middle meningeal artery, inferior alveolar artery, posterior alveolar artery, pterygoid plexus of veins and muscles, mandibular nerve of C5 (trigeminal)
• Pterygopalatine fossa


  • Cone shaped, paired depression
  • Deep into infratemporal fossa and posterior to maxilla
  • Communicates via fissures and foramina's in the walls to the cranial, infratemporal fossa, orbit, nasal cavity, and oral cavity
  • Contains: maxillary artery including the infraorbital and sphenopalatine arteries, maxillary nerve C5 (trigeminal) and pterygopalatine ganglion

  
• Superior view of external skull: 4 cranial bones, sutures: coronal, sagittal and lambdoidal

  
• Anterior view of external skull: frontal bone, ethmoid bone, vomer, sphenoid bone, mandible, lacrimal (2), nasal (2), inferior nasal conchae (2), zygomatic (2), maxillae (2)

  
• Orbit


  • Protects eyeball
  • 4 walls, 1 apex
  • Orbital apex: deepest part of orbit, made up of the lesser wing of the sphenoid bone (base) and the palatine bone (small inferior part)
  • Orbital walls: frontal bone plate (roof), ethmoid bone plate (medial), lacrimal bone (ant. medial, orbit maxilla, floor), zygomatic bone (anterior lateral), greater wing of sphenoid bone (posterior lateral), maxilla (floor)
• Optic canal


  • Opening in orbital apex; between the lesser wings; C2 (optic nerve) and ophthalmic artery passes to reach the eye
• Superior orbital fissure


  • A curved slit; between greater and lesser wing. Connects the orbit with cranial cavity. C3 (oculomotor nerve), C4 (trochlear nerve); C6 (abducens) and ophthalmic nerve and vein all travel through this fissure
• Inferior orbital fissure


  • Between greater wing and maxilla. Connects orbit with infratemporal fossa and pterygopalatine fossa
• Orbit


  • Protects eyeball
  • 4 walls, 1 apex
  • Orbital apex: deepest part of orbit, made up of lesser wing of sphenoid bone (base) and palatine bone (small inferior part)
• Orbital walls


  • Frontal bone plate (roof)
  • Ethmoid bone plate (medial)
  • Lacrimal bone (anterior medial, orbit maxilla, floor)
  • Zygomatic bone (anterior lateral)
  • Greater wing of sphenoid bone (posterior lateral)
  • Maxilla (floor)

  
• Optic canal


  Opening in orbital apex; between the lesser wings; C2 (optic nerve) and ophthalmic artery passes to reach the eye
• Fissures


  • Superior orbital fissure: curved slit; between greater and lesser wing. Connects orbit with cranial cavity. C3 (oculomotor nerve), C4 (trochlear nerve); C6 (abducens) and ophthalmic nerve and vein all travel through this fissure.
  • Inferior orbital fissure: between greater wing and maxilla. Connects orbit with infratemporal fossa and pterygopalatine fossa. Infraorbital, zygomatic nerves and infraorbital artery enter orbit through this fissure.
• The shape of the orbit is a pyramid
• Orbital rim


  • Base of pyramid; rectangular; discontinuous at the lacrimal fossa
  • Supra orbital rim: superior rim
  • Infraorbital rim: inferior rim
  • Frontal, zygomatic, and maxilla bones contribute to rim; protection; strong bones
  • Zygomaticomaxillary suture: notch, midpoint of infraorbital rim; between zygomatic and maxilla
• Nasal cavity


  • Superior part of respiratory tract; located between the orbits
  • Lateral walls, floor, both anterior and posterior openings
  • Made up of bone and cartilage
• Nasal bones


  Bridge of nose
• Nasion


  Junction of frontal and nasal bones

  
• Piriform aperture


  Anterior opening; large; triangular; anchors midline cartilage (nasal septum); lateral cartilaginous alae; nares (nose openings)
• Posterior nasal aperture


  Large deeper posterior opening
• Floor of nasal cavity


  • Palatine processes of maxillae anteriorly and horizontal plates of the palatine bones posteriorly

  
• Lateral walls of nasal cavity


  • Mainly made up of maxilla; each wall is made up of 3 conchae (turbinates) and nasal meatus
  • Medial side of conchae: increases surface area and helps direct inspired airflow
  • Nasal meatus: helps protect conchae and has openings in the paranasal sinuses/the nasolacrimal duct communicates with the nasal cavity
• Nasal septum


  Anterior is formed by a perpendicular plate of ethmoid and inferiorly the nasal septal cartilage. Posterior formed by vomer bone.

  
• Cranial bones


  • Occipital, frontal, parietal, temporal, sphenoid, and ethmoid

  
• Skull sutures


  • Coronal, lambdoidal, squamous

  
• Skull lines


  • Superior temporal line and inferior temporal line, both cross frontal and parietal bones