7938279 bone-of-the-cranial-cavity


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7938279 bone-of-the-cranial-cavity

  1. 1. Bones of the Cranial Cavity Nyra E. Montera Nov. 11, 2008
  2. 2. • Important Landmarks on the Skull • Fossae and Foramen at the base of the skull => external aspect => internal aspect
  3. 3. Landmark Shape and Location Pterion (G. wing) Junction of the greater wing of the sphenoid, squamous temporal, frontal, and parietal bones; overlies course of anterior division of middle meningeal artery Lambda (G. the letter L) Point on calvaria at junction of lambdoid and sagittal sutures Bregma (G. forepart of the head) Point on calvaria at junction of coronal and sagittal sutures Vertex (L. whirl or whorl) Superior point of neurocranium in the midline with skull oriented in anatomical (orbitorneal or Frankport) plane Asterion (G. asterios, starry) Star-shaped; located at junction of three sutures; parietomastoid, occipitomastoid, and lambdoid Glabella (L. smooth, hairless) Smooth prominence, most marked in males, on the frontal bone superior to the root of nose; most anterior projecting part of forehead Nasion (L. nose) Point on skull where frontonasal and internasal sutures meet Inion (G. back of head) Most prominent point of external occipital protuberance
  4. 4. glabella
  5. 5. External Aspect of the Base of the Skull
  6. 6. Internal Aspect of the Base of the Skull
  7. 7. Anterior cranial fossa Posterior cranial fossa Middle cranial fossa
  8. 8. ⇒the shallowest of the three fossae. ⇒formed by the anteriorly: frontal bone middle: the ethmoid bone, posteriorly: the body and lesser wings of the sphenoid. ⇒The greater part of this fossa is formed by the ridged orbital parts of the frontal bone which support the frontal lobes of the brain and form the roofs of the orbits Anterior cranial fossa
  9. 9. Anterior Cranial Fossa Contents Foramen cecum Nasal emissary vein (1% of the population) Foramina in cribriform plate Axons of olfactory cells in olfactory epithelium that form olfactory nerves Anterior and posterior ethmoidal foramina Vessels and nerves with same names
  10. 10. Middle cranial fossa ⇒butterfly-shaped ⇒Posteroinferior to the anterior cranial fossa ⇒The bones forming the fossa are: laterally: greater wings of the sphenoid bone posteriorly: the petrous parts of the temporal bones ⇒Supports the temporal lobes of the brain
  11. 11. Middle Cranial Fossa Contents Optic canal Optic nerves (CN II) and ophthalmic arteries Superior orbital fissures Ophthalmic veins, ophthalmic nerve (CN V1 ), CN III, IV, and VI, and sympathetic fibers Foramen rotundum Maxillary nerve (CN V2 ) Foramen ovale Mandibular nerve (CN V3 ) and accessory meningeal artery Foramen spinosum Middle meningeal artery and vein and meningeal branch of CN V3 Foramen lacerum Internal carotid artery and its accompanying sympathetic and venous plexuses Groove or hiatus of greater petrosal nerve Greater petrosal nerve and petrosal branch of middle meningeal artery
  12. 12. Posterior cranial fossa ⇒the largest and deepest of the three fossae ⇒Lodges the cerebellum, pons and medulla oblongata ⇒Anteriorly: it extends to the apex of the petrous temporal. Posteriorly: it is enclosed by the occipital bone. Laterally: portions of the squamous temporal and mastoid part of the temporal bone form its walls.
  13. 13. Posterior Cranial Fossa Contents Foramen magnum Medulla and meninges, vertebral arteries, spinal roots of CN XI, dural veins, anterior and posterior spinal arteries Jugular foramen CNs IX, X, and XI, superior bulb of internal jugular vein, inferior petrosal and sigmoid sinuses, and meningeal branches of ascending pharyngeal and occipital arteries Hypoglossal canal Hypoglossal nerve (CN XII) Condylar canal Emissary vein that passes from sigmoid sinus to vertebral veins in neck Mastoid foramen Mastoid emissary vein from sigmoid sinus and meningeal branch of occipital artery
  14. 14. Special thanks to: Dalley and Moore, clinically oriented anatomy 5th edition,(lippincott williams and wilkins, 2000), 841-847.
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