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Osteology of Human Skull.pptx
- 1. Osteology of theSKULL By: Dr Prasanna Kumar P
- 2. Content 1. Introduction 2. Functions 3.Divisions- • Norma frontalis—the anterior view • Norma lateralis—the lateral view • Norma occipitalis—the posterior view • Norma basalis—the inferior view • Norma verticalis—the superior view
- 3. The Skull • Theskull is composed of several separate bones (28 bones) united at immobile joints called sutures. • The connective tissue between the bones is called a sutural ligament Introduction
- 4. • The upperpart of the cranium is The vault • The base of the skull is the lowest part of the cranium • The skull bones are made up of External and internal tables of compact bone separated by a layer of spongy bone called the diploic bones • The bones are covered on the outer and inner surfaces with periosteum. • Only one moveable bone, the mandible which is united to the skull by the mobile Temporomandibular Joint The bones of the skull can be divided into: • Bones of the cranium (contain the brain) • Bones of the face (facial skeleton)
- 5. Cranial skeleton, consistingof 8 bones: Paired bones • Parietal • Temporal • Incus • Malleus • stapes Unpaired bones • Frontal • Occipital • Sphenoid • Ethmoid Facial skeleton, consisting of 14 bones: Paired bones • Maxilla • Zygomatic • Nasal • Lacrimal • Palatine • Inferior nasal concha Unpaired bones • Mandible • Vomer The skull The skull is made up of 28 bones.
- 6. Skull Joints • Thejoints in the skull are mostly sutures, a few primary cartilaginous joints and three pairs of synovial joints. • Sutures are: 1. Plane – internasal suture 2. Serrate – coronal suture 3. Denticulate – lambdoid suture 4. Squamous – parietotemporal suture
- 7. Anatomical position ofthe skull 1. Reid’s base line is a horizontal line obtained by joining the infraorbital margin to the center of external acoustic meatus, i.e. auricular point. 2. The Frankfurt’s horizontal plane of orientation is obtained by joining the infraorbital margin to the upper margin of the external acoustic meatus
- 8. Bones of skull •Frontal bone • Parietal bone • Occipital bone • Temporal bone • Sphenoid bone • Lacrimal bone • Nasal bone • Zygomatic bone • Ethimoid bone • Vomer • Inferior nasal concha • Palatine bone • Maxilla • Mandible
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- 26. • Superior –Norma verticalis • Posterior – Norma occipitalis • Anterior – Norma frontalis • Lateral – Norma lateralis • Inferior – Norma basalis Exterior of the skull The external features of the skull are studied from five different aspects Methods of study of the skull
- 27. Exterior of theskull The external features of the skull are studied from five different aspects
- 28. Exterior of theskull The external features of the skull are studied from five different aspects Inferior – Norma basalis
- 29. Study of skullas a whole from inside after removing skull cap
- 30. Study of skullas a whole
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- 32. NORMA VERTICALIS • Ovalin shape • Wider posteriorly than anteriorly • Bones 1. Upper part of frontal bone -anteriorly. 2. Uppermost part of occipital bone- posteriorly. 3. A parietal bone-on each side. • Sutures – coronal, sagittal, lambdoid, metopic
- 33. Norma Verticalis Superior aspectof the skull Frontal: Frontal eminences Parietals: • parietal foramens • parietal eminences Sutures: - Coronal ↓Bregma - Sagittal - Lambdoid ↓Lambda Occipital Norma Verticalis
- 34. Bones and Sutures Thebones are frontal, parietal, and occipital • Frontal bone (squamous part) anteriorly. • Parietal bones (paired) on each side of midline. • Occipital bone (squamous part) posteriorly. These bones are united by three sutures. • Coronal suture (L. = a crown), between frontal and two parietal bones. It crosses the cranial vault from side-to side. • Sagittal suture (L. = an arrow), between two parietal bones. It lies in the median plane. • Lambdoid suture, between occipital and two parietal bones. It is shaped like the letter lambda. Norma Verticalis
- 35. Anatomical Features • Bregma:It is the point at which the coronal and sagittal sutures meet. It is the site of anterior fontanelle in new born skull. • Parietal eminence: It is the area of maximum convexity of parietal bone, seen on each side. • Vertex: It is the highest point of the skull. It lies on the sagittal suture, near its middle and is situated a few centimeters behind the bregma. • Lambda: Point at which the sagittal and lambdoid sutures meet is named as lambda. • Parietal foramen: A small foramen is seen in each parietal bone near the sagittal suture, 3 to 4 cm in front of lambda. • Temporal lines: A pair of temporal lines, one superior and one inferior are seen. They are present antero posteriorly on lateral side of each parietal emenience. They are better described in norma lateralis. Norma Verticalis
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- 38. Calvaria • Emissary foramen:small, inconsistent (not always present) foramina for passage of emissary veins. • Bregma: is the landmark formed by the intersection of the sagittal and coronal sutures. • Lambda: is the landmark formed by the intersection of the sagittal and lambdoid sutures. Norma Verticalis
- 39. Infant calvaria • AnteriorFontanelle: (soft spot) is the future site of the bregma • By about 18 months the surrounding bones fuse together and is no longer palpable. • Posterior Fontanelle: is triangular and marks the future site of the lambda • Fusion of surrounding bones occurs by about 6 months Fontanelles- membranous gaps (soft spots) in skull that permit growth Norma Verticalis
- 40. Inner calvaria • Frontalbone • Parietal bone • Coronal suture • Sagittal suture • Frontal sinus • Groove for superior sagittal sinus • Groove for middle meningeal artery • Granular foveolae Norma Verticalis
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- 42. Norma Occipitalis (Post. Aspect) Bones: •Occipital • Parietals • Mastoid process Landmarks: • External occipital protuberance • Superior and inferior nuchal lines • External occipital • Mastoid foramen Sutures: • Lambdoid suture • Occipitomastoid suture • Parietomastoid suture Norma Occipitalis
- 43. Bones and sutures Theback of skull is composed of posterior part of parietal bones, occipital bone and mastoid part of temporal bones. • Parietal bones, superiorly one on each side. • Occipital bone (squamous part), inferiorly. • Mastoid part of temporal bone, inferolaterally on each side. The sutures which unite these bones are: • Lambdoid suture, between occipital and two parietal bones. • Occipitomastoid suture, between occipital and mastoid part of temporal bone. • Parietomastoid suture, between parietal and mastoid part of temporal bone. Norma Occipitalis
- 44. • Lambda: Itis the point at which sagittal and lambdoid sutures meet. • External occipital protuberance: It is a median bony projection seen midway between the lambda and the foramen magnum. The most prominent point of the prominence is called inion. • Superior nuchal lines: These are curved bony ridges passing laterally, on each side, from the external occipital protuberance. • External occipital crest: Is a median, vertical ridge passing vertically downwards from the external occipital protuberance to the posterior margin of foramen magnum. • Inferior nuchal lines: These are curved bony ridges passing parallel to and below the superior nuchal lines, laterally on each side from the middle of external occipital crest. Anatomical Features Norma Occipitalis
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- 47. Norma Frontalis (Anterior aspectof the skull) Regions (cavities): - Nasal - Orbit - Oral Bones: - Frontal - Zygomatic - Maxillae - Mandible - Nasal Norma frontalis
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- 49. It presents: • Frontalbone, forms the forehead. • Right and left nasal bones, form the bridge of nose. • Right and left maxillae, form the upper jaw. • Right and left zygomatic bones, form the malar prominences. • Mandible, forms the lower jaw. Bones and sutures Norma frontalis
- 50. • Forehead: Itis formed by the frontal bones. On each side of median plane, the frontal bone articulates with the nasal bone at the root of nose. • Frontal prominence: It is a low, rounded elevation seen above each of the supraciliary arch. • Supraciliary arches: These are rounded bony elevations forming an arch above each of the superior orbital margins. • Glabella: It is a median elevation between the supraciliary arches. • Orbits: These are two bony cavities in which the eyes are located. • Bony external nose: Is formed by the nasal bones above and the maxillae laterally. • Anterior nasal aperture: It is a piriform shaped aperture seen in the center of norma frontalis. Anatomical Features Norma frontalis
- 51. • Anterior nasalaperture: It is a piriform shaped aperture seen in the center of norma frontalis. It is bounded by nasal bones above and maxillary bones laterally and inferiorly. • Root of nose: It is a slightly depressed area seen above the nasal bones where they meet the frontal bone at the frontonasal sutures. • Nasion: It is a median point at the root of nose where the internasal and frontonasal sutures meet. • Prominence of the cheek: It is formed by the body of zygomatic bone. • Anterior surface of maxilla: It presents on each side (Nasal notch, medially, Infraorbital foramen, 1 cm below the infraorbital margin, Incisive fossa above the incisor teeth, Canine fossa lateral to canine eminence produced by the root of canine tooth). Anatomical Features Norma frontalis
- 52. • Upper jaw:It is formed by the alveolar processes of the two maxillae and bears the upper teeth. • Lower jaw: The lower jaw is formed by mandible. The upper border, also called alveolar arch of mandible, carries the lower teeth. • Anterior surface of body of mandible: (Symphysis menti, Mental protuberance, Mental point (gnathion), Mental foramen, Oblique line on body of mandible). Norma frontalis Anatomical Features
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- 57. Norma Occipitalis (Post. Aspect) Bones: •frontal • parietal • occipital • temporal • sphenoid • zygomatic • mandible • Maxilla • nasal Sutures: • Coronal suture • Parietosquamosal suture • Lambdoid suture Norma lateralis
- 58. It presents: • Above:Nasal, frontal, parietal and occipital bones. • In middle: Maxilla, zygomatic, sphenoid and temporal bones. • Below: Body and ramus of mandible. The sutures which unite these bones are: • Coronal suture • Parieto-squamosal suture, between parietal bone and squamous part of temporal bone. • Parietomastoid suture, between parietal bone and mastoid part of temporal b. • Occipitomastoid suture, between occipital bone and mastoid part of temporal bone. • Lambdoid suture Bones and sutures Norma lateralis
- 59. • Temporal lines:These are two in number, one superior and one inferior temporal line. • Zygomatic arch: A horizontal bar of bone formed by the union of temporal process of zygomatic bone and zygomatic process of temporal bone is seen in centre anteriorly. • Temporal fossa: It is the area bounded above and posteriorly by the temporal line and below by the zygomatic arch and frontal process of zygomatic bone. • Pterion: It is the region in the anterior part of temporal fossa where the 4 bones forming floor of temporal fossa meet. • Infratemporal fossa: It is the region on the side of skull below the zygomatic arch. • Lateral or external surface of ramus of mandible: The ramus projects upwards from posterior part of body of mandible. Anatomical Features Norma lateralis
- 60. • External acousticmeatus: It is the external aperture of bony ear canal. • Suprameatal triangle (triangle of McEven): It is a small depression present postero-superior to the external auditory meatus. • Tympanic plate of temporal bone: It is a thin plate of bone forming the anterior and inferior wall of external acoustic meatus. • Mastoid process: It is a conical process seen extending down from the mastoid part of temporal bone, behind the external acoustic meatus. • Styloid process: It is a thin long bony process of temporal bone lying anteromedial to the mastoid process. • Asterion: It is the meeting point of parietomastoid, occipitomastoid and lambdoid sutures. Anatomical Features Norma lateralis
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- 62. Osteology of thehead Norma lateralis
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- 68. Norma Basalis • Normabasalis or inferior surface of cranium extends from alveolar arch in front to the superior nuchal lines behind. • It is studied in three parts namely, anterior, middle and posterior. • Anterior part is formed by the alveolar arch and hard palate. • The middle part extends from posterior margin of hard palate to anterior margin of foramen magnum and the posterior part lies behind a transverse line passing through the anterior margin of the foramen magnum.
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- 70. • Alveolar arch •Hard palate Anatomical features in the anterior part of norma basalis Norma Basalis
- 71. Norma Basalis -Anterior • Alveolar process of maxilla • Palatine process of maxilla • Horizontal plate of palatine bone • Incisive foramen • Greater palatine foramen • Lesser palatine foramen
- 72. The median area •Posteriorborder of vomer •Broad bar of bone The lateral area •Pterygoid process •Infratemporal surface of the greater wing of sphenoid •Sulcus tubae (groove for auditory tube) •Inferior surface of the petrous temporal bone •Downward edge of tegmen tympani Anatomical features in the middle part of norma basalis Norma Basalis
- 73. Norma Basalis -Middle • Vomer • Pharyngeal tubercle • Pterygoid process of sphenoid bone Medial & Lateral plates / Fossa / Hamulus
- 74. Norma Basalis -Middle • Foramen ovale • Foramen spinosum / Spine of sphenoid • Foramen lacerum • Carotid canal
- 75. The median area •Foramenmagnum •External occipital crest •External occipital protuberance The lateral area •Occipital condyles •Hypoglossal canal •Condylar fossa •Jugular process of occipital bone •Jugular foramen •Tympanic canaliculus •Stylomastoid foramen Anatomical features in the posterior part of norma basalis Norma Basalis
- 76. Norma Basalis -Posterior • Occipital condyles • Styloid process of temporal bone • Mastoid process • External occipital protuberance (inion) • Nuchal lines • Superior • Inferior
- 77. • Foramen magnum •Jugular foramen • Stylomastoid foramen • Condylar canal • Mastoid foramen Norma Basalis - Posterior
- 78. Female Male Thinner and lighter Thickerand heavier Bones Less More Cranial capacity Not well-marked Well-marked, hence seen prominently Muscular markings and ridges Not prominent Prominent Superciliary arches Less prominent Prominent Mastoid process Prominent Less prominent Frontal and parietal tubers Differences between male and female skulls
- 79. Mandible • The mandible,or the lower jaw, is the largest and the strongest bone of the face. • It develops from the first pharyngeal arch. • It has a horseshoe-shaped body which lodges the teeth, and a pair of rami which project upwards from the posterior ends of the body.
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- 84. • Maxilla (cheek)is the second largest bone of the face, the first being the mandible • The two maxillae form the whole of the upper jaw, and each maxilla forms a part each in the formation of face, nose, mouth, orbit, the infratemporal and pterygopalatine fossae • Each maxilla has a body and four processes—the frontal, zygomatic, alveolar and palatine.
- 86. References • B dchaurasia’s human anatomy (volume 3) • Netter’s head and neck anatomy for dentistry • Human osteology for dental students inderbir singh • Gray’s Atlas of Anatomy 3rd edition
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