Chapter 7 The Skeletal System The Axial Skeleton

Chapter 7 The Skeletal System: The Axial Skeleton 1

Chapter 7 Skeletal System Gross Anatomy 7 -2

Skeletal System • Provides framework • Without skeleton, muscles couldn’t move body • Components – – Bones Cartilage Ligaments Tendons • Relationships among bones and soft tissues 7 -3

Skeleton • Axial skeleton – Skull – Hyoid bone – Vertebral column – Thoracic (rib) cage • Appendicular skeleton – Limbs – Girdles 7 -4

The Complete Skeleton 7 -5

Anatomic Bone Features • Terms – Body: Main part – Head: Enlarge end – Neck: Constriction between head and body – Margin or border: Edge – Angle: Bend – Ramus: Branch off body – Condyle: Smooth rounded articular surface – Facet: Small flattened articular surface • Projections – Process: Prominent projection – Tubercle: Small rounded bump – Tuberosity: Knob – Trochanter: Tuberosities on proximal femur – Epicondyle: Near or above condyle 7 -6

Anatomic Bone Features • Ridges – Line or linea: Low ridge – Crest or crista: Prominent ridge – Spine: Very high ridge • Openings – – Foramen: Hole Canal or meatus: Tunnel Fissure: Cleft Sinus or Labyrinth: Cavity • Depressions – Fossa: General term for a depression – Notch: Depression in bone margin – Fovea: Little pit – Groove or sulcus: Deeper, narrow depression 7 -7

The Skull or Cranium • Functions – Protects brain – Supports organs of special senses – Provides foundation for structures that take air, food , water into body • Superior view of skull – – Parietal bones Frontal bone Sagittal suture Coronal suture 7 -8

Posterior View of Skull • • Occipital bone Lambdoid suture Sutural bones External occipital protuberance – Ligamentum nuchae: Helps keep head erect – Nuchal lines: Neck muscle attachment points 7 -9

Lateral View of Skull • Squamous suture • External auditory meatus • Mastoid Process • Temporal lines • Sphenoid bone • Zygomatic bones • Maxilla • Mandible 7 -10

Frontal View of Skull • • • Frontal bone Zygomatic bones Maxillae Mandible Orbits – Nasolacrimal canal – Optic foramen 7 -11

Bones of Nasal Cavity 7 -12

Paranasal Sinuses • Functions – Decrease skull weight – Resonating chambers • Names – – Frontal Maxillary Ethmoidal Sphenoidal 7 -13

Inferior View of Skull • • • Foramen magnum Occipital condyles Jugular foramina Styloid processes Vomer bone Hard or bony palate 7 -14

Hyoid Bone • Unpaired • No direct bony attachment to skull • Attachment point for some tongue muscles • Attachment point for neck muscles that elevate larynx during speech and swallowing 7 -15

Vertebral Column • • • Supports weight of head and trunk Protects the spinal cord Allow spinal nerves to exit the spinal cord Provides site for muscle attachment Permits movement of head and trunk 7 -16

Vertebra • • Body Vertebral foramen Vertebral arch Pedicle Lamina Transverse process Spinous process Articular processes 7 -17

Intervertebral Disks • Located between adjacent vertebrae • Functions – Provide support – Prevent vertebrae rubbing • Consist of – Annulus fibrosus – Nucleus pulposus 7 -18

Herniated or Ruptured Disk 7 -19

Spina Bifida 7 -20

Vertebral Column • Regions – – – Cervical (7 vertebrae) Thoracic (12 vertebrae) Lumbar (5 vertebrae) Sacral bone (1) Coccygeal bone (1) • Major Curvatures (4) • Abnormal curvatures – Lordosis – Kyphosis – Scoliosis 7 -21

Cervical Vertebrae • Atlas – First vertebra • Axis – Second vertebra – Dens or odontoid process • Vertebral prominens 7 -22

Thoracic and Lumbar Vertebrae 7 -23

Sacrum and Coccyx 7 -24

Thoracic or Rib Cage • Functions – Protects vital organs – Forms semi-rigid chamber for respiration • Parts – Thoracic vertebrae – Ribs (12 pair) • True or Vertebrosternal • False or Vertebrochondral • Floating or vertebral – Sternum 7 -25

Sternum • Breastbone • Parts – Manubrium – Body – Xiphoid process • Sternal angle – Important landmark for counting ribs to locate areas of the heart 7 -26