Axial skeleton

Skeletal System

  • Functions

    • Body Support: Provides structure, with bones held together by ligaments.

    • Organ Protection: Protects vital organs like the brain and heart.

    • Movement: Facilitates movement of the body through joints.

    • Mineral Storage: Acts as a reservoir for minerals like calcium, phosphorus, and fats.

    • Blood Cell Production: Produces blood cells in bone marrow.

Axial and Appendicular Skeleton

  • Axial Skeleton

    • Composed of 80 bones including:

      • Skull

      • Vertebral Column

      • Rib Cage

      • Hyoid Bone

      • Ossicles (inner ear)

  • Appendicular Skeleton

    • Composed of 126 bones including:

      • Shoulder girdle (scapula and clavicle)

      • Arms, Hands

      • Pelvic girdle (hip bones)

      • Legs, Feet

Energy and Mineral Storage

  • Bone Matrix:

    • Serves as a reservoir for calcium and phosphorus; can be released into the bloodstream.

  • Bone Marrow:

    • Yellow Marrow: Stores adipose tissue for energy.

    • Red Marrow: Site of hematopoiesis (production of red blood cells, white blood cells, and platelets).

Calcium Homeostasis

  • Blood Calcium Levels:

    • Low Levels: Osteoblast activity stimulated by parathyroid hormone leads to:

      • Activation of vitamin D.

      • Reduced calcium loss in urine.

      • Increased intestinal absorption of calcium.

    • Normal Levels: Stimulates release of calcium from the bone.

Classification of Bones

  • Types of Bones:

    • Long Bones:

      • Examples: Arms (humerus), legs (femur), hands, and feet.

    • Short Bones:

      • Cuboidal in shape, e.g., carpals and tarsals.

    • Flat Bones:

      • Examples: Skull, scapula, and ribs.

    • Irregular Bones:

      • Examples: Vertebrae and facial bones.

    • Sesamoid Bones:

      • Examples: Patella, small bones found in tendons.

Bone Structure

  • Diaphysis:

    • Tubular shaft between proximal and distal ends; contains medullary cavity with yellow marrow.

  • Epiphysis:

    • Ends of the bone, filled with spongy bone; includes epiphyseal plate (growth plate).

      • Replaced with osseous tissue at maturity (epiphyseal line).

  • Periosteum:

    • Outer covering that nourishes the compact bone; contains blood vessels, lymph, and nerves.

  • Articular Cartilage:

    • Covers ends of bones forming joints, providing a friction and shock absorber.

Axial Skeleton Anatomy

  • Purpose:

    • Protection of vital organs and provides attachment for muscles and tendons.

Skull Anatomy

  • Cranial Bone Composition:

    • Made up of 22 bones:

      • 8 cranial bones (immovable)

      • 14 facial bones

      • 6 ear bones (ossicles)

  • Cranial Bones Include:

    • 1 Occipital, 1 Sphenoid, 1 Ethmoid, 1 Frontal, 2 Parietal, 2 Temporal.

    • The mandible is the only movable bone apart from the ossicles.

  • Facial Bones Include:

    • Mandible, vomer, maxillae, palatine bones, nasal bones, nasal conchae, zygomatic bones, and lacrimal bones.

Vertebral Column/Spine

  • Composition:

    • Composed of 24 movable vertebrae and fused vertebrae.

    • Divisions:

      • 7 Cervical

      • 12 Thoracic

      • 5 Lumbar

      • Sacrum and Coccyx.

Vertebrae Anatomy

  • Vertebrae Increase in Size:

    • As body weight increases.

  • Parts of Vertebra:

    • Body, vertebral arch, and processes.

    • Vertebral Foramen: Houses the spinal cord.

  • Intervertebral Foramen:

    • Openings for nerve roots to exit the spinal column.

Ligaments of the Spine

  • Includes:

    • Anterior and posterior longitudinal ligaments, interspinous ligaments, and ligamentum flavum.

Sacrum and Coccyx

  • Fused vertebrae allowing passage for nerves and blood vessels.

Sternum and Rib Cage

  • Sternum Structure:

    • Composed of 3 parts:

      • Manubrium: Attachment for clavicles and 1st ribs.

      • Body: Junction at sternal angle, attaching 2nd rib.

      • Xiphoid Process: Sensitive area (solar plexus).

  • Rib Cage Composition:

    • 12 pairs of ribs:

      • True ribs (1-7): Attach directly to sternum.

      • False ribs (8-12): Indirectly attach via cartilage.

Bone Health

  • Importance of Exercise:

    • Increases bone density, particularly through resistance training.

  • Calcium Intake:

    • Must be acquired through diet (dairy, greens, fatty fish).

    • Vitamin D is essential for calcium absorption.

    • Other supporting nutrients: Vitamin K, Magnesium, Fluoride.

  • Hormonal Influences:

    • Hormones play a crucial role in bone health and development.