The Axial Skeleton Chapter 7. I. Skeletal Divisions (206 bones) A. Axial Skeleton (80 bones) 1....

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Transcript of The Axial Skeleton Chapter 7. I. Skeletal Divisions (206 bones) A. Axial Skeleton (80 bones) 1....

  • The Axial SkeletonChapter 7

  • I. Skeletal Divisions (206 bones)Axial Skeleton (80 bones)Forms longitudinal axis of the body

    Consists of:SkullVertebral columnRibsSternum

  • Appendicular Skeleton (126 bones)Consists ofPectoral girdlePelvic girdleBones of the limbs

  • II. The Skull (22 bones)FunctionsProtects

    Guards entrances to digestive & respiratory systems

  • Cranium (braincase) (8 bones)

  • 1. Occipital Bone (1 bone)Forms posterior & inferior surfaces

  • 2. Parietal Bones (2 bones)Forms superior & lateral surfaces

  • 3. Frontal Bone (1 bone)Forms anterior portion of skull & roof of orbits

  • 4. Temporal Bones (2 bones)Surrounds & protects sense organs of inner ear

  • 5. Sphenoid Bone (1 bone)Cross-brace that strengthens sides of skull (looks like a bat)

  • 6. Ethmoid Bone (1 bone)Forms roof of nasal cavity, part of nasal septum

  • Facial Bones ( 14 bones)

  • 1. Maxillary Bones (2 bones)Supports the teeth

  • 2. Palatine Bones (2 bones)Forms portion of hard palate

  • 3. Lacrimal Bones (2 bones)Forms medial wall of orbits

  • 4. Nasal Bones (2 bones)Supports superior portion of bridge of nose

  • 5. Zygomatic Bones (2 bones)Forms rim & lateral wall of orbits

  • 6. Vomer Bone (1 bone)Forms interior portion of bony nasal septum

  • 7. Inferior Nasal Conchae (2 bones)Creates turbulence in air passing through nasal cavity WHY???

  • 8. Mandible Bone (1 bone)Lower jaw

  • SinusesMakes bones lighterProduces mucus to moisten & clean air in and near the sinuses

  • E. Sutures- Immovable joints connected with dense fibrous connective tissue

    Lambdoidal Suture- between occipital & parietal bones

    Coronal Suture- between frontal and parietal bones

    Sagittal Suture- between parietal bones

  • 4. Squamosal Sutures- between temporal & parietal bones

    5. Fontanels- fibrous area between cranial bones in infants

    a. allow skull to be distorted/squished to ease delivery

    b. the frontal fontanel persists until a child is nearly 2 yrs. old

  • Sutures of the Skull

  • F. Associated Bones of the Skull (7)Auditory Ossicles (6 bones)3 bones per earmalleus, incus & staples

  • Hyoid Bone (1 bone)Supports larynxOnly free standing bone not connected to another bone

  • III. The Vertebral Column- 33 total bones

  • A. Functions of the V.C.Provide a column of support

    Bear the weight of the head, neck & trunk

    Protect the spinal cord

    Helps maintain an upright body position(Sitting/Standing)

  • B. Divisions of the V.C.Cervical Regiona) Made of 7 vertebrae b) Constitutes the neck regionc) Labeled C1-C7 (Superior to Inferior)i. C1 is called the Atlas-holds up the head- Articulates w/ occipital condyles- Allows yes movementii. C2 is called the Axis- Pivots around the Atlas- Allows no movement

  • Thoracic Region

    a) Made of 12 vertebrae b) Constitutes the chest/upper back regionc) Labeled T1-T12 (Superior to Inferior)d) Articulate with the ribs

  • Lumbar Region

    a) Made of 5 vertebrae b) Constitutes the lower back regionc) Labeled L1-L5 (Superior to Inferior)d) Large, weight-bearing bonese) Provides site for muscle attachment

  • 4. Sacrum

    a) Made of 5 fused vertebrae

    b) Constitutes the posterior portion of the pelvis

    c) Provides protection for reproductive, digestive, & urinary organs

  • 5. Coccyx

    a) Made of 3-5 fused vertebrae

    b) Also known as the tailbone

  • 5 Divisions of the V.C.CervicalThoracic


  • C. Spinal Curvatures1) Thoracic Curvature

    2) Sacral Curvature

    - 1) & 2) are known as Primary or Accommodation curves b/c they appear in fetal development

  • 3) Cervical Curvature

    4) Lumbar Curvature

    - 3) & 4) are known as Compensation curves b/c they develop as we learn to walk (help shift weight over legs)

  • 4 Spinal Curvatures

  • IV. The Thoracic CageA. Consists of the thoracic vertebrae, ribs, & sternum

  • B. FunctionsProtects the heart, lungs, thymus & other structures

    Serves as an attachment point for muscles

  • C. The Ribs12 pair of curved, flat bones

    Originate on or between thoracic vertebrae

    End in the wall of the thoracic cavity

  • D. Kinds of RibsTrue/Vertebrosternal Ribs

    a) First 7 pairs, most superior

    b) Connected to sternum by cartilaginous extensions

  • False/Vertebrochondral Ribs

    a) Ribs 8-12

    b) The cartilage on the ends of these ribs fuse together with rib 7

  • 3) Floating Ribs

    a) Last 2 pairs (11th & 12th)

    b) Not connected to sternum at all

  • E. The Sternum (breastbone)Flat bone

    Forms the anterior midline of the thoracic wall

  • F. Divisions of the SternumManubrium

    a) Most superior part of the sternum

    b) Triangular shaped

    c) Articulates w/ the clavicles & the cartilage of the 1st pairs of ribs

  • Body

    a) Tongue shaped

    b) Costal Cartilage from pairs 2-7 attach here

  • Xiphoid Process

    a) Most inferior part of sternum

    b) Smallest part of sternum

    c) The diaphragm & some abdominal muscles attach here

  • The Thoracic Cage