OSTEOLOGY OF SKULL DR.AHA SHIRAHATTI ANATOMY PART 1 CONTENT • State the division of the • Openings in the skull and skull bones the structures that pass through them • Important sutures • Identify the skull bones, the parts and there relevant structures from • Fontanelles different views of the skull – • bony landmarks • 1. Norma verticalis • 2. Norma frontalis • 3. Norma occipitalis INTRODUCTION • Skull- skeleton of the head. • Consists f- 22 / 28 (6 – EAR OSSICLES) several bones joined to gather to form cranium • Composed of a series of flattened or irregular bones which are joined together by immoveable fibrous joints -sutures. CRANIUM • Skeleton of head it is made up of brain case cranium &facial bones • Divided—1)Neurocranium-Bony case for brain. It contains brain, cranial nerve ,blood vessels. Made of 8 (14 , 6 –EAR OSSICLES) bones. • Divided in to skull cap-roof formed by flat bones & cranial base or floor these bones are irregular bones • 2)Viscerocranium (facial skeleton) – • Facial bones.. • These bones surrounds mouth, nose, eyeball etc . Cranial skeleton(8) bones) Paired bones • 1)Parietal bones • 2)Temporal bones Unpairedu • 1)Frontal • 2)Occipital • 3)Sphenoid • 4)Ethmoid • Facial skeleton(14 bones ) • Paired bones 1)Maxilla 2)Zygomatic 3)Nasal 4)Lacrimal 5)Palatine 6)Inferior nasal concha • Unpaired bones 1)Mandible 2)Vomer ANATOMICAL POSITION • Orbitomeatal plane (Frankfort horizontal plane)— Plane passing through inferior orbital margin & sup. margin of external acoustic meatus. Skull can be studied in following ways A)As a whole : 1)Exterior of skull A)Norma verticalis B)Norma occipitalis C)Norma lateralis D)Norma frontalis E)Norma basalis 2)Interior of skull after removing skull cap B)Individual bones of face & skull • Norma frontalis • Norma lateralis • Norma occipitalis • Norma basalis NORMA VERTICALIS • Viewed from above the outline of skull is oval or circular. Three sutures (1) coronal sutures • (2) sagittal sutures • (3)lambdoidal suture, • On either side of the sagittal suture are the parietal eminence and parietal 11 •Parietal bones -Part of the superior and lateral surfaces of the cranium -articulate with each other – sagittal suture -articulate with occipital, frontal, temporal and sphenoid bones • Junction of the sagittal and coronal suture is named the bregma, that of the sagittal and lambdoid sutures, the lambda; • 1. anterior • 2. posterior • 3. 2 antriolateral • 4. 2 posteriolateral CLINICAL SIGNIFICANCE Anterior view: Norma Frontalis Includes: forehead pair of orbits Malar prominence ant nasal aperture teeth bearing upper and lower jaw Maxillary Bones • Upper jaw Alveolar processes • Anterior roof of mouth Maxillary sinuses • Floors of orbits Palatine process • Sides of nasal cavity Largest bone • Floors of nasal cavity • Zygomatic Bones • Cheekbones • Lateral wall of orbit along with sphenoid • Part of zygomatic arch along with part of temporal • Palatine Bones (2) • ‘L’ shaped bones located behind the maxillae • Posterior section of hard palate • Floor of nasal cavity Perpendicular • Lateral walls of portion Coronal section nasal cavity Horizontal portion 18 • Inferior nasal concha – Located in nasal cavity – Increase epithelial surface – Create turbulence in inspired air • Lacrimal bones – Smallest bones in skull – Forms nasolacrimal groove leading to nasolacrimal canal – Delivers tears to nasal cavity Vomer • Vomer – posterior part of nasal septum – Articulates with maxillae and palatines Norma Frontalis Norma occipitalis(Posterior view of the skull • Occipital bone • Part of the base of the skull • articulates with parietal, temporal and sphenoid • Surrounds the foramen magnum • lateral to the FM – hypoglossal canal (12th cranial) • projections = occipital condyles Squamous part of occipital bone. External occipital protuberance –It’s tip is Inion. External occipital crest- Highest nuchal line Superior nuchal line Lambda—junction of lambdoid & sagittal suture . Inferior nuchal line— Mandible • lower jaw • only freely movable bone of the skull • moving articulations with temporal bone MANDIBLE/LOWER JAW • Largest, strongest & movable bone of face. • Parts– Body, Ramus • BODY— • Surfaces- Outer, Inner • Border– Upper ,lower • Features– Outer surface 1)Symphysis menti– Where 2 half meet. 2) Mental protrubarence – triangular. 3) Mental foramen— Mental Vessels & N. • Inner surface— 1) Mylohyoid line 2) Submandibular fossa- Submandibular gland. 3) Sublingual fossa-- Sublingual gland. 4) Genial tubercle-. • Upper border– Alveolar- Socket for teeth. • Lower border– Base. Midline depression- Digastric fossa- • Ramus— Quadrilateral • Surfaces—Lateral ,medial • Borders—Upper, lower, anterior, posterior. • Mandibular foramen– Inferior alveolar vessels and N. • CONDYLAR PROCESS and CORONOID PROCESS AGE RELATED CHANGES • Adult— • Old – • 1.Mental foramen -- • 1.Mental foramen – Nearer midway between upper & upper border. lower border. • 2. The neck of the condyle is • 2.Condylar process lies more or less bent backward. higher than coronoid. • 3.The ramus is oblique in • 3.The ramus is almost direction, the angle vertical in direction, the measures about 140°, angle measuring from 110° to 120° Infantile Skull - OSCE Frontal suture (metopic suture) Frontal bone Anterior fontanel Sagittal suture Posterior fontanel (b) 34 MTF Regarding skull T A Mastoid process is part of occipital bone T B Posterior fontanelle is at lambda F C Maxilla takes part in formation of zygomatic arch F D Nasal bone forms medial wall of orbit F E Optic nerve runs in superior orbital fissure • https://www.youtube.com/watch?v=Nc5IRj3O JhE • https://www.youtube.com/watch?v=WRmNC _yPQZ8 Thank you .