1. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Human Anatomy & Physiology, Sixth Edition Elaine N. Marieb PowerPoint ® Lecture Slides prepared by Vince Austin, University of Kentucky 7 The Skeleton Part A

2. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings The Skeleton  The skeleton (“dried up body” or mummy)  It is strong, yet light, and almost perfectly adapted for the protective, locomotor and manipulative functions it perform  Composed of bones, cartilages, joints and ligaments, accounts for about 20% of body mass.  The skeleton is divided into Axial and Appendicular

3. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings The Axial Skeleton  This part of skeleton supports the head, neck and trunk and it protects the brain, spinal cord and the organs in the thorax  Eighty bones segregated into three regions  1.- Skull  2.- Vertebral column  3.- Bony thorax

4. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings The Skull  The skull, the body’s most complex bony structure, is formed by the cranium and facial bones  Cranium – protects the brain and is the site of attachment for head and neck muscles  Facial bones  Supply the framework of the face, the sense organs, and the teeth  Provide openings for the passage of air and food  Anchor the facial muscles of expression

5. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Anatomy of the Cranium  The cranium can be divided in : 1.- cranial vault (calvaria) 2.- cranial base (floor)  Eight cranial bones – two parietal, two temporal, frontal, occipital, sphenoid, and ethmoid  Cranial bones are thin and remarkably strong for their weight

6. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Frontal Bone  Forms the anterior portion of the cranium  Articulates posteriorly with the parietal bones via the coronal suture  The most anterior part of the frontal bone is the vertical frontal squama, commonly called the forehead  Major markings include the supraorbital margins, the anterior cranial fossa, and the frontal sinuses (internal and lateral to the glabella)

7. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Skull: Anterior View Figure 7.2a

8. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Skull: Posterior View Figure 7.2b

9. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Parietal Bones and Major Associated Sutures  They are curved, rectangular bones. Form most of the superior and lateral aspects of the skull Figure 7.3a

10. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Parietal Bones and Major Associated Sutures  Four sutures mark the articulations of the parietal bones  1.- Coronal suture – articulation between parietal bones and frontal bone anteriorly  2.- Sagittal suture – where right and left parietal bones meet superiorly  3.- Lambdoid suture – where parietal bones meet the occipital bone posteriorly  4.- Squamosal or squamous suture – where parietal and temporal bones meet

11. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Occipital Bone and Its Major Markings  It articulates anteriorly with the paired parietal and temporal bones via the lambdoid and occipitomastoid sutures.  It also joins with the sphenoid bone in the cranial floor via a plate called the pharingeal tubercule.  Forms most of skull’s posterior wall and base  Major markings include the posterior cranial fossa, foramen magnum, occipital condyles, and the hypoglossal canal Figure 7.2b

12. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Occipital Bone and Its Major Markings Figure 7.4b Internally, the occipital bone forms the walls of the posterior cranial fossa which supports, the cerebellum of the brain. The foramen magnum connect the brain with the spinal cord

13. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Temporal Bones  Form the inferolateral aspects of the skull and parts of the cranial floor  Divided into four major regions – squamous, tympanic, mastoid, and petrous  Major markings include the zygomatic, styloid, and mastoid processes, and the mandibular and middle cranial fossae  Major openings include the stylomastoid and jugular foramina, the external and internal auditory meatuses, and the carotid canal

14. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Temporal Bones Figure 7.5 Between the styloid and mastoid processes exist the stylomastoid foramen that allow cranial nerve VII to leave the skull. The mastoid region of the temporal bone exhibits the conspicuous mastoid process, an anchoring site for some neck muscles

15. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Homeostatic Imbalance  The mastoid process is full of air cavities, “the mastoid sinuses or “air cells”. Because it position behind the middle ear cavity (high risk area for infections spreading from the throat) put it at risk for infection itself.  A mastoid sinus infection is difficult to treat

16. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Sphenoid Bone  Butterfly-shaped bone that spans the width of the middle cranial fossa  Forms the central wedge that articulates with all other cranial bones  Consists of a central body, greater wings, lesser wings, and pterygoid processes  Major markings: the sella turcica, hypophyseal fossa, and the pterygoid processes  Major openings include the foramina rotundum, ovale, and spinosum; the optic canals; and the superior orbital fissure

17. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Sphenoid Bone Figure 7.6a, b

18. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Ethmoid Bone  Like the temporal and sphenoid bones, the ethmoid bone has a complex shape  Most deep of the skull bones; lies between the sphenoid and nasal bones  Forms most of the bony area between the nasal cavity and the orbits  Major markings include the cribriform plate, crista galli, perpendicular plate, nasal conchae, and the ethmoid sinuses

19. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Ethmoid Bone Figure 7.7 Allow the olfatory nerves to pass from the smell receptors in the nasal cavites to the brain

20. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Wormian Bones (sutural bones)  Tiny irregularly shaped bones that appear within sutures more often in the lambdoid suture. Structurally unimportant.

21. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Facial Bones  Fourteen bones of which only the mandible and vomer are unpaired  The paired bones are the maxillae, zygomatics, nasals, lacrimals, palatines, and inferior conchae  As a rule the facial skeleton of men is more elongated than that the women, therefore, women’s faces tend to be rounder and less angular

22. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Mandible and Its Markings  The U-shaped mandible (lower jawbone) is the largest, strongest bone of the face  It has a body, which forms the chin, and two upright rami (branches)  Its major markings include the coronoid process, mandibular condyle, the alveolar margin, and the mandibular and mental foramina  Each ramus meets the body posteriorly at a mandibular angle

23. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Mandible and Its Markings Figure 7.8a

24. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Maxillary Bones (or maxillae)  Medially fused bones that make up the upper jaw and the central portion of the facial skeleton  Facial keystone bones that articulate with all other facial bones except the mandible  Their major markings include palatine, frontal, and zygomatic processes, the alveolar margins, inferior orbital fissure, and the maxillary sinuses

25. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Maxillary Bone Figure 7.8b The anterior nasal spine allows the infraorbital nerve and artery to reach the face

26. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Zygomatic Bones  Irregularly shaped bones (cheekbones) that form the prominences of the cheeks and the inferolateral margins of the orbits

27. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Other Facial Bones  Nasal bones – thin medially fused bones that form the bridge of the nose  Lacrimal bones (fingernail shaped) – contribute to the medial walls of the orbit and contain a deep groove called the lacrimal fossa that houses the lacrimal sac  Palatine bones – two bone plates that form portions of the hard palate, the posterolateral walls of the nasal cavity, and a small part of the orbits

28. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Other Facial Bones  Vomer – plow-shaped bone that forms part of the nasal septum  Inferior nasal conchae – paired, thin-curved bones in the nasal cavity that form part of the lateral walls of the nasal cavity. They are the largest of the three pairs of conchae.

29. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Anterior Aspects of the Skull Figure 7.2a

30. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Posterior Aspects of the Skull Figure 7.2b

31. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings External Lateral Aspects of the Skull Figure 7.3a

32. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Midsagittal Lateral Aspects of the Skull Figure 7.3b

33. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Inferior Portion of the Skull Figure 7.4a

34. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Inferior Portion of the Skull Figure 7.4b