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THE SKELETON

THE SKELETON. CHAPTER 7. Introduction . A strong, yet light, internal support for the human body The skeleton is adapted for the protection, locomotor, and manipulative functions The upright stance increases the ability of the skeletal muscle to resist gravity. Introduction .

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THE SKELETON

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  1. THE SKELETON CHAPTER 7

  2. Introduction • A strong, yet light, internal support for the human body • The skeleton is adapted for the protection, locomotor, and manipulative functions • The upright stance increases the ability of the skeletal muscle to resist gravity

  3. Introduction • The skeleton maintains its upright position through a series of compensating curves • The skeleton accounts for approximately 20% of the body mass • The 206 bones of the body are grouped into the axial and appendicular skeleton

  4. Axial skeleton Forms the long axis of the body 80 bones in three major regions skull vertebral column bony thorax Ribs Sternum Appendicular Bones of upper & lower extremities and girdles 126 bones in three major regions Girdles Shoulder girdle Pelvic girdle upper extremity lower extremity Introduction

  5. THE SKULL SECTION I

  6. The Skull • The skull is the body’s most complex bony structure • It is formed by two sets of bones, the 8 cranial bones and the 14 facial bones • These 22 bones combine to form the cranial cavity and the facial features • In addition, there are 3 bones in each inner ear to assist in sound transmission

  7. The Skull: Introduction • The bones of the skull provide . . . • A case to house the brain, the cranium • A framework for the face • Cavities to house the organs of sight, taste, and smell • Passages for air and food • Attachment sites for the teeth • Attachment sites for muscle

  8. The Skull: Introduction • Most bones of the skull are flat bones • Except for the mandible, all bones are firmly united by interlocking sutures • The major sutures of the skull are . . . • Coronal (Between Frontal & Parietal) • Sagittal (Between Parietal bones) • Squamosal (Between Parietal & Temporal) • Lambdoidal (Between Parietal & Occipital) • Other skull sutures connect facial bones and are named after these structures

  9. ________ ________ ________ Sagittal

  10. Coronal Lambdoid Squamous

  11. Overview of Skull Geography • Facial bones form the anterior aspect • The cranial bones enclose the brain

  12. Vault • The cranial vault or calvaria forms the superior, lateral, and posterior aspects of skull • The cranial base forming the inferior aspect of skull

  13. Cranial Base • Cranial base forms the skull’s inferior aspect • Three prominent ridges divide the base into fossae • The brain rests on these cranial fossae completely enclosed by the cranial vault • The brain occupies the cranial cavity

  14. Cavities of the Skull • In addition to the large cranial cavity there are many smaller cavities • Middle and inner ear cavities • Nasal cavity • Orbits of the eyes • Several bones contain air filled sinuses • Sinuses surrounding the nasal cavity are referred to as the paranasal sinuses

  15. Study Note • As you read about the bones of the skull, locate each bone on the different skull views in Figures 7.2, 7.3, 7.4 • The skull bones and their important markings and features are summarized in Table 7.1 on pages 213-214

  16. Cranium • The 8 cranial bones include; 2 parietal, 2 temporal frontal, occipital, sphenoid, ethmoid • Cranium is self- bracing allowing the bones to be thin, yet strong

  17. Frontal bone • Forms the anterior portion of the cranium, the forehead, roofs of the orbits, and most of the anterior cranial fossa

  18. Frontal bone - landmarks • Frontal squama • Supraorbital margins • Supraorbital foramen • Orbits • Anterior cranial fossa • Glabella • Frontal sinuses

  19. Parietal bones Parietal • Forms most of the superior & lateral aspects of the skull • Articulates with other cranial bones to form four major sutures

  20. Parietal bones - landmarks • The four largest sutures cranial sutures, Coronal, Sagittal, Lambdodial, Squamosal

  21. Occipital bone • Forms most of the posterior wall and base of skull • Articulates with parietal & temporal • Joins w/ sphenoid in the cranial floor • Forms internal walls of posterior cranial fossa

  22. Occipital bone - Ext. landmarks • Foramen magnum, Occipital condyles, External occipital protuberance, Nuchal lines, External occipital crest

  23. Occipital bone - Int. landmarks • Hypoglossal canal, Posterior cranial fossa

  24. Temporal Bone • Forms the infero-lateral aspects of the skull • Parts of the cranial floor • Divided into four regions; squamous tympanic, mastoid, and petrous-(int)

  25. Temporal Bone • The internal petrous region contributes to the cranial base • The petrous region and the sphenoid bone form the middle cranial fossa

  26. Temporal Bone - landmarks • Zygomatic process • Meets the zygomatic bone • Forms the cheek • Mandibular fossa • Receives condyle of mandible

  27. Temporal Bone - landmarks • External Auditory Meatus • Middle and inner ear • Styloid process • Muscle of tongue • Mastoid process • Muscles of neck

  28. Temporal bones - landmarks • Jugular foramen • Entry point for the Jugular artery • Internal acoustic meatus • Entry point for the auditory nerve Jugular Foramen

  29. Temporal bones - landmarks • Stylomastoid foramen • exit for facial nerve • Carotid canal • entrance for the carotid artery which supplies blood to cerebral hemispheres

  30. Sphenoid bone • Bone spanning the width of middle cranial fossa • Articulates as central wedge of all cranial bones • Consists of central body and three processes; greater and lesser wings and pterygoid process (pos. view)

  31. Sphenoid - landmarks • Sella turcica (enclosure for pituitary gland) • Optic foramina (passage of optic nerves) • Superior orbital fissure (Nerves III, IV, V enter orbit) • Foramen rotundum & ovale (Cranial Nerve V to face) • Foramen spinosum (Middle meningeal artery)

  32. Ethmoid bone • Forms most of the area between the nasal cavity & orbits of eyes • Lies between nasal bones & sphenoid • Complex shape gives rise to nasal septum, sinuses and cribiform plate

  33. Ethmoid bone - landmarks • Cribiform plates • Forms roof of nasal cavity • Olfactory formina • Olfactory nerves enter brain • Crista galli • Attachment of the dura mater which secures brain in cavity

  34. Ethmoid bone - landmarks • Perpendicular plate • Forms superior part of nasal septum • Lateral mass • House ethmoid sinuses • Nasal concha • Project into nasal cavity • Orbital plates • Medial walls of orbits

  35. Facial bones • Consists of 14 bones w/ only mandible and vomer unpaired • Others include maxillae, lacrimals, nasals, zygomatics, inferior nasal conchae, and palatines (not pictured)

  36. Mandible • Forms the lower jaw • Largest, strongest bone of the face • It has a body and two upwardly projecting sections called rami • Houses lower dentition

  37. Mandible - landmarks • Mandibular angle • Mandibular notch • Coronoid process • Mandibular condyle • Alveolar margin • Mandible formina • Mental formina • Ramus of mandible

  38. Maxillary bone • Forms upper jaw and central portion of facial skeleton • Fused medially • Articulates with all facial bones except mandible • Upper dentition • Forms 2/3 of hard palate of the mouth Zygomatic process Maxillary bone

  39. Maxillary bones - landmarks • Alveolar margin • Upper dentition • Frontal process • Forms lateral aspects of nose • Zygomatic process • Articulates with zygomatic bone • Maxillary sinuses • (Fig. 7.11)

  40. Maxillary bones - landmarks Palatine Process • Palatine processes • Forms roof of mouth • Incisive fossa • Passage of nerves and blood vessels • Infraorbital foramen • Infraorbital nerve and blood vessel to face

  41. Maxillary bones - landmarks • Inferior orbital fissure • Located deep within the orbit • Permits passage of the zygomatic nerve, maxillary nerve, and blood vessels to reach face

  42. Zygomatic bones • Commonly called the cheekbones • Form prominences of cheeks and inferolateral margins of orbits • Articulate with the Zygomatic process of temporal bone and Zygomatic process of maxallae Zygomatic Process of Temporal Zygomatic bone

  43. Nasal bones • Forms bridge of the nose • Thin, rectangular shape • Fused medially • Articulate with the frontal bone and maxillary bones laterally • Nasal cartilages • (Fig. 6.1)

  44. Lacrimal Bones • Forms part of the medial border of each orbit • Articulates with frontal, ethmoid & maxillae • Forms part of Lacrimal fossa • Permits tears to drain from orbit to nasal cavity

  45. Lacrimal Bones • Lacrimal fossa • Permits tears to drain from orbit to nasal cavity

  46. Palatine bones • The horizontal plates forms the posterior portion of hard palate • Vertical plate forms part of the posterolateral wall of nasal cavity and a small portion of orbit

  47. Palatine bones - landmarks • Horizontal plate • Posterior section of hard palate • Vertical plate • Part of the posteriolateral walls of nasal cavity • Orbital surface • Part of inferior medial aspect of orbit

  48. Vomer • Forms part of the nasal septum • Discussed with the nasal cavity

  49. Vomer - landmarks • Plow shape • Divides nasal septum into right and left parts

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