Skeletal System Chapter 8/Part II

1. Skeletal SystemChapter 8/Part II Joe Pistack, MS/Ed

2. Divisions of the Skeletal System Skeletal system is divided into two sections: (1)-Axial Skeleton (2)-Appendicular Skeleton

3. The Axial Skeleton The Axial Skeleton includes: • Bones of the skull • Hyoid bone • Bones of the middle ear • Vertebral column • Bony thorax

4. The Appendicular Skeleton The Appendicular Skeleton includes: • Bones of the arms and legs • Bones of the hips • Bones of the shoulder girdles

5. The Cranium Bony structure that encases and protects the brain. Composed of 8 bones: • Frontal 1 • Parietal 2 • Temporal 2 • Occipital 1 • Sphenoid 1 • Ethmoid 1

6. The Cranium Frontal Bone: Forms the forehead and the upper part of the bony structure surrounding the eyes.

7. The Cranium Parietal bones: (2) Form the upper sides of the head and the roof of the cranial cavity.

8. The Cranium Temporal Bones: (2) Located on both sides of the Head close to the ears, commonly called the Temples.

9. The Cranium Important Bone Markings Found on the temporal bones: (1)-External auditory meatus Opening for the ear. (2)-Zygomatic Process-forms part of the cheek-bone. (3)-Styloid Process-sharp projection used as a point of attachment for some of the muscles associated with the tongue and larynx.

10. The Cranium (4) Mastoid Process: Forms a point of attachment for some of the muscles of the neck.

11. The Cranium Occipital Bone: Located at the base of the skull. Foramen magnum-large hole in the occipital bone, allows the brainstem to extend downward as the spinal cord.

12. The Cranium Sphenoid Bone: • Butterfly bone that forms part of the floor and sides of the cranium. Also forms part of the orbits surrounding the eyes. • SellaTurcica-depression in the midline of the sphenoid bone, forms the seat for the pituitary gland. (also called Turk’s saddle)

13. The Cranium Ethmoid Bone: An irregularly shaped bone located between the eye orbits, helps to form the bony structure of the nasal cavity.

14. Facial Bones Facial Bones: (14) • Mandible-lower jaw bone, carries the lower teeth. • Anterior portion of the mandible forms the chin. • Forms the only freely movable joint in the skull. • Temporomandibular joint (TMJ)-depression in front of the ear. Tension or stress cause pain.

15. Facial Bones Maxilla: • Carries the upper teeth. • An extension of the maxilla is the palatine process, this forms the anterior portion of the hard palate (roof) of the mouth. • These bones also form parts of the nasal cavity and the eye orbits.

16. Facial Bones Palatine Bones: (2) • Form the posterior part of the hard palate and the floor of the nasal cavity

17. Facial Bones Failure of the palatine and maxillary bones to fuse causes a condition known as Cleft palate. This makes it very difficult for an infant to suck. Can be surgically repaired.

18. Facial Bnes Zygomatic Bones: • The cheekbones, also form part of the orbits of the eyes.

19. Facial Bones Several other bones complete the facial structure: • Lacrimal bones • The nasal bones • The vomer • The inferior nasal conchae

20. Broken Jaw • Usually the result of trauma or automobile accident. • Cannot cast, must be immobilized by wiring it to the upper jaw. • Patient cannot talk, eat or vomit. • Wire cutters need to be on hand in case of vomiting.

21. Sinuses • Sinuses-air-filled cavities located in several bones of the skull. • Two important functions: (1)-lessen the weight of the skull. (2)-increase the sound of the voice. • Paranasal sinuses- four sinuses that surround and connect with the nasal structures.

22. Sinuses • Four Sinuses: (1)-frontal sinus (2)-ethmoid sinus (3)-sphenoidal sinus (4)-maxillary sinus

23. Sinuses • Sinusitis-a sinus infection characterized by stuffiness and pain in the overlying facial region. • Allergies cause the membranes that line the facial sinuses to over secrete mucous. • Mucous forms a medium for bacterial growth. • As the mucous accumulates, the membranes swell causing pressure and discomfort in the facial region which overlies the sinuses.

24. Sutures Suture- joining of the bones of the skull together, much like a zipper. Major Sutures: • Coronal suture • Lambdoidal suture • Squamosal suture

25. The Infant Skull • Fontanels-soft areas that have not yet been converted to bone. The rhythm of the baby’s pulse can be found in these soft spots. • Two Major Fontanels: (1)-larger, diamond-shaped anterior fontanel. (2)-smaller, posterior, triangular occipital fontanel. • Fontanels are usually closed by the age of two years.

26. The Infant Skull

27. The Infant Skull • Microcephalia-a condition where the sutures of the brain fuse too early, this is characterized by a small skull and impaired intellectual functioning.

28. The Infant Skull • Hydrocephalus-occurs when the skull expands too much from an excessive accumulation of fluid, the bones are forced apart and the skull enlarges.

29. Hyoid Bone Hyoid Bone-U shaped bone located in the upper neck. Anchors the tongue and is associated with swallowing. Often fractured during strangulation.

30. Vertebral Column • Also called backbone- extends from the skull to the pelvis. • Consists of 26 bones called vertebrae. • Vertebrae are stacked in a column.

31. The Vertebral Column • Four Major functions of the vertebral column: • (1) forms a supporting structure for head and thorax. • (2) forms an attachment for the pelvic girdle. • (3) encases and protects the spinal cord. • (4) provides flexibility for the body.

32. The Vertebral Column • Vertebrae are named according to their location in the body. • (C1 to C7)- seven cervical located in the neck region. • Vertebra prominens-C7- used as a landmark in assessing surface anatomy.

33. The Vetebral column C7:-vetebraprominens: Feels like a large bump.

34. Vertebral Column 12 Thoracic Vertebrae (T1 to T 12) Located in the chest region. 5 Lumbar Vertebrae (L1 to L5) Located in the lower back Region. 5 Sacral Vertebrae fuse into one sacrum.

35. The Vertebral Column The sacrum forms the posterior wall of the pelvis. Four small vertebrae fuse Into the tailbone. The tailbone is also called The coccyx.

36. C1 and C2 Atlas-C1: • First cervical vertebrae. • No body (thick solid section that other vertebrae have) but has depressions into which fit the bony projections of the occipital bone of the skull. • Atlas supports the skull and allows you to nod “yes”.

37. C1 and C2 • Axis (C2): • Has a toothlike projection called the dens that fits into the atlas and acts as a pivot or swivel for the atlas. • Allows you to rotate your head from side to side to say “no”.

38. Characteristics of Vertebrae • Vertebrae are irregular bones that contain several distinct structures. • Body of the vertebrae is padded by a cartilaginous disc called an intervertebral disc. • Supports the weight of the vertebrae sitting on top of it.

39. Vertebrae • Vertebral column – also known as the spine. • Vertebrae become larger as the vertebral column descends. • Larger, lower vertebrae carry a heavier load. • Vertebral foramen –opening for the spinal cord.

40. Abnormalities of the Vertebral Column • Spina Bifida –failure of the lamina of the vertebra to fuse during fetal development. • Lamina-bone that forms a protective ring around the vertebrae.

41. Abnormalities of the Vertebral Column • Spina Bifida –defect allows the spinal cord to protrude onto the surface of the back. • Compression of the spinal cord causes paralysis and loss of bladder and bowel control.

42. Abnormalities of the Vertebral Column • Discs may become damaged or may be called a “slipped” disc. • The spinal cord descends from the base of the brain through the vertebral foramen so injury at any point can compress or sever the spinal cord, causing paralysis. • Laminectomy –surgical procedure used to access the intervertebral discs.

43. Curvatures • The vertebral column has four normal curvatures: • (1)-cervical • (2)-thoracic • (3)-lumbar • (4)-sacral • The cervical and lumbar curvatures bend toward the front of the body. • The thoracic and sacral curvatures bend away from the body.

44. Normal Curvatures

45. Abnormal Curvatures • Scoliosis – • Lateral curvature. • Usually involves the thoracic vertebrae. • Severe can compress abdominal organs. • May diminish expansion of the rib cage and impair breathing.

46. Abnormal Curvatures • Kyphosis – • Exaggerated thoracic curvature. • Can impair breathing • Sometimes called hunchback.

47. Abnormal Curvatures • Lordosis – • Exaggerated lumbar curvature. • Sometimes called swayback. • Causes of abnormal curvatures: • (1)-genetic defect. • (2)-response to a disease. • (3)-poor posture

48. Thoracic Cage • The thoracic cage is the bony, cone-shaped cage that surrounds and protects the lungs, heart, large blood vessels, liver and spleen. • Plays a crucial role in breathing and helps to support the bones of the shoulder.

49. Thoracic Cage • Thoracic Cage is composed of: • Sternum • Ribs • Thoracic vertebrae

50. Sternum • Sternum: • Also called breastbone. • Dagger shaped. • Located along the midline of the anterior chest. • Sternum has 3 parts: • (1) manubrium • (2)body • (3) xiphoid process (tip of the sternum).