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norma basalis.pptx

25. Mar 2023
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norma basalis.pptx

  1. Faculty of dentistry T H E F U T U R E S T A R T S H E R E S p r i n g 2 0 2 2
  2. Dr. Waleed Nasr Norma basalis . Dr. Rehab Tolba
  3. Foramen magnum Anterior part Middle part Posterior part Norma Basalis Externa
  4. Anterior part • Formed by the Bony Palate • The anterior ¾ of the palate is formed by the palatine processes of both maxillae (separated by the intermaxillary suture) • The posterior ¼ is formed by the horizontal plates of both palatine bones (separated by the interpalatine suture) Palatine processes of maxillary bones Horizontal plates of palatine bones Interpalatine suture Intermaxillary suture Incisive fossa
  5. Features of the anterior part • Alveolar arch, formed by the alveolar processes of both maxillae • Palato-maxillary suture, separates the parts forming the hard palate. • Incisive fossa, an anterior median depression. • Greater palatine foramen (one on each side), on the posterior and lateral part of the bony palate. It leads to the greater palatine canal • Lesser palatine foramina (two small foramina) behind the greater palatine foramen. • Posterior nasal spine, a median projection from the posterior border of the bony palate • Maxillary tuberosity :a rough prominence behind the last molar tooth Incisive fossa Alveolar arch Greater palatine foramen Lesser palatine foramina Posterior nasal spine Interpalatine suture Palato-maxillary suture Intermaxillary suture Cruciform suture Palatine crest
  6. • Body of sphenoid bone • Basilar part of occipital bone • Pterygoid process of sphenois • Greater wing of sphenoid • Petrous part of temporal bone • Tympanic part of temporal bone • Mastoid part of temporal bone • Mandibular fossa Body of sphenoid bone Petrous part of temporal bone Groove for cartilagenous part of auditory tube Tympanic part of temporal bone Styloid process Mandibular fossa Mastoid part of temporal bone Middle part Extends from the posterior margin of hard palate to the anterior margin of foramen magnum
  7. Features: •Vomer, a median bone forming the posterior part of the nasal septum •Posterior nasal apertures •Pterygoid process, formed of lateral & medial plates with the pterygoid fossa in between. •Pterygoid Hamulus •Pterygomaxillary fissure •, Infratemporal surface of greater wing of sphenoid •Pharyngeal tubercle, a small elevation on the basilar part occipital bone Pterygoid hamulus Posterior nasal apertures Vomer Medial pterygoid plate Lateral pterygoid plate
  8. Foramina to be identified: • Foramen ovale, on the infratemporal surface of greater wing of sphenoid • Foramen spinosum, behind the foramen ovale • Foramen lacerum, at the apex of petrous temporal bone • Carotid canal • Stylomastoid foramen, between the styloid and mastoid processes. Foramen ovale Foramen spinosum Foramen lacerum Carotid canal Stylomastoid foramen Groove for cartilagenous part of auditory tube
  9. Posterior part Formed mainly by the different parts of the occipital bone, surrounding the foramen magnum Bones to be identified: • Condylar parts, one on each side of foramen magnum • Squamous part, behind the foramen magnum Features: •Occipital condyles, on each side of foramen magnum •Condylar fossa, behind the occipital condyles •External occipital protuberance •External occipital crest •Inferior nuchal lines •Superior nuchal lines Basilar part Squamous part Foramen magnum Pharyngeal tubercle Occipital condyles (condylar part) External occipital protuberance Condylar fossa Condylar canal External occipital crest Inferior nuchal lines Superior nuchal lines
  10. Foramina: • Foramen magnum, the largest in the skull • Jugular foramen, between the occipital and petrous temporal bones • Hypoglossal canal, above the occipital condyle • Condylar canal Foramen magnum Jugular foramen Jugular fossa Condylar canal Mastoid foramen
  11. Norma Basalis Interna Divided into; anterior, middle and posterior cranial fossae Features of the anterior cranial fossa • Frontal crest, a median ridge on the inner aspect of frontal bone • Cribriform plate of ethmoid bone, in the median region of the fossa, forming the roof of the nasal cavity. It shows a median projection called the crista galli • Orbital plate of frontal bone, on each side of the cribriform plate of ethmoid. • Body of sphenoid bone, behind the cribriform plate • Lesser wing of sphenoid, on each side of the sphenoid bone. • Anterior clinoid process The medial end of the lesser wing Frontal crest Cribriform plate of ethmoid Orbital plate of frontal bone Body of sphenoid bone Lesser wing of sphenoid Crista galli Anterior clinoid process Anterior cranial fossa Bound posteriorly by the lesser wings of sphenoid
  12. Foramina: • Foramen cecum, between the crista galli and frontal crest • Antherior ethmoidal canal, on the lateral margin of the cribriform plate of ethmoid • Posterior ethmoidal canal, at the posterolateral angle of the cribriform plate of ethmoid. Foramen cecum Antherior ethmoidal canal Posterior ethmoidal canal
  13. Middle cranial fossa • Bound anteriorly by the lesser wings of sphenoid and posteriorly by the upper border of petrous temporal bone • Narrow in the middle and expands greatly laterally Bones to be identified; • Body of sphenoid, in the median region • Greater wing of sphenoid • Squamous part of temporal bone • Anterior surface of petrous temporal bone Body of sphenoid Greater wing of sphenoid Squamous part of temporal bone Petrous part of temporal bone F. magnum
  14. Features of the middle cranial fossa Tegmen tympani Acruate eminence Trigeminal impression Groove for ICA Hypophyseal fossa Posterior clinoid process Foramen lacerum Sulcus for optic chiasma Anterior clinoid process • Hypophyseal fossa (sella turcica), a median depression on the body of sphenoid. Bound anteriorly by the tuberculum sellae and posteriorly by the dorsum sellae. The upper end of the dorsum sellae forms two projections (the posterior clinoid processes) • Groove for Internal Carotid Artery, on the lateral aspect of the body of sphenoid • Trigeminal impression, a depression at the apex of petrous temporal bone • Acruate eminence, an elevation on the anterior surface of petrous temporal bone • Tegmen tympani (roof of the middle ear) lies lateral to the arcuate eminence.
  15. Foramina and openings in the middle cranial fossa; • Superior orbital fissure, a fissure between the greater and lesser wings of sphenoid • Foramen rotundum, behind the medial end of superior orbital fissure, leads to the pterygopalatine fossa • Foramen ovale, behind the foramen rotundum. • Foramen spinosum, behind the foramen ovale • Foramen lacerum, at the apex of petrous temporal bone Superior orbital fissure Foramen rotundum Foramen ovale Foramen spinosum Foramen lacerum Groove for greater petrosal nerve Groove for lesser petrosal nerve
  16. Posterior cranial fossa Boundaries: posterior clinoid process, upper border of petrous temporal bone, groove for transvers sinus, internal occipital protuberance Bones to be identified; • Basilar part of occipital bone, in front of F magnum. Together with the basilar part of sphenoid they form the clivus. • Condylar part of occipital bone, on each side of F magnum. • Squamous part of occipital bone, behind F magnum. • Posterior surface of petrous temporal bone, lateral to the occipital bone • Mastoid part of temporal bone, behind and lateral to the petrous part. Basilar part of occipital bone Basilar part of sphenoid Squamous part of occipital bone Petrous temporal bone Clivus Condylar part of occipital bone Mastoid part of temporal bone
  17. Features of the posterior cranial fossa • Internal occipital protuberance, a median elevation on the squamous part of occipital bone • Internal occipital crest, a median ridge extending from the internal occipital protuberance to the F. magnum • Groove for transverse venous sinus, extends from the internal occipital protuberance to the mastoid part of temporal bone • Sigmoid sulcus, an S-shaped sulcus extending from the end of the groove for transverse sinus to the jugular foramen • Groove for superior petrosal sinus, running along the upper border of petrous temporal bone • Groove for inferior petrosal sinus, running along the ptrosphenoidal fissure (between petrous bone and occipital bone) Internal occipital protuberance Internal occipital crest Groove for transverse venous sinus Sigmoid sulcus Groove for superior petrosal sinus Groove for inferior petrosal sinus
  18. Foramina to be identified: • Foramen magnum • Jugular foramen, between the occipital and petrous bones • Hypoglossal canal, above the occipital condyle • Condylar canal, connects the codylar fossa (seen on the norma basalis externa) with the sigmoid sulcus • Mastoid foramen, on the line of the occipito-mastoid suture (opens into the sigmoid sulcus) • Internal acoustic meatus, on the posterior surface of petrous bone Foramen magnum Jugular foramen Hypoglossal canal Condylar canal Mastoid foramen Internal acoustic meatus Foramen spinosum Foramen ovale Foramen rotundum Foramen lacerum
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