Skeletal System Bones Reading

Overview of the Skeletal System

  • The skeletal system is essential for:

    • Movement

    • Support

    • Organ protection

    • Blood cell production

    • Maintaining electrolyte and acid-base balance

Anatomy of the Skeletal System

  • Components include:

    • Bones

    • Cartilage

    • Ligaments

  • The human skeleton is divided into:

    • Axial Skeleton: Bones of the head, neck, and trunk.

    • Appendicular Skeleton: Bones of the limbs (arms and legs) and girdles (shoulder and pelvic).

Classification of Bones

  • Five bone classifications by shape:

    • Long Bones: Longer than wide (e.g., femur, humerus).

    • Short Bones: Width and length are similar; cube-shaped (e.g., carpals).

    • Flat Bones: Thin and flat (e.g., cranial bones, sternum).

    • Irregular Bones: Doesn’t fit into other categories (e.g., vertebrae).

    • Sesamoid Bones: Develop in tendons (e.g., patella).

Detailed Bone Classifications

  • Long Bones:

    • Characteristics: Chubby ends, longer than wide.

    • Examples: Bones of arms, legs, fingers, and toes.

  • Short Bones:

    • Examples: Wrist bones, cuboid bone in the foot.

  • Flat Bones:

    • Examples: Sternum, cranial bones, ribs.

  • Irregular Bones:

    • Examples: Vertebrae, certain bones in the ear.

  • Sesamoid Bones:

    • Example: Patella, which protects tendons.

The Human Body

  • Approximately 206 bones; number can vary slightly due to sesamoid bones.

Axial Skeleton

  1. Cranial Bones: 8 bones forming the brain case.

    • Example bones: Frontal, parietal, temporal, occipital.

    • Important structures: Foramina for blood vessels/nerves.

  2. Facial Bones: 14 bones providing structure and attachment points for muscles.

    • Important ones include: Nasal, lacrimal, zygomatic, maxilla, mandible.

  3. Spinal Column: 26 vertebrae divided into three regions:

    • Cervical: 7 vertebrae (C1-C7)

    • Thoracic: 12 vertebrae (T1-T12)

    • Lumbar: 5 vertebrae (L1-L5)

    • Sacrum: 1 bone (five fused vertebrae)

    • Coccyx: 1 bone (4-5 fused vertebrae)

  4. Sternum and Ribs: 12 pairs of ribs.

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

    • False ribs (8-12) either share cartilage or are floating ribs.

  5. Hyoid Bone: Unique bone not attached to others, located in the neck.

Abnormal Curvatures of the Spine

  • Scoliosis: Lateral curvature, especially in thoracic region.

  • Kyphosis: Exaggerated thoracic curvature often due to aging.

  • Lordosis: Exaggerated lumbar curvature associated with obesity or pregnancy.

Appendicular Skeleton

  1. Pectoral Girdle:

    • Composed of clavicle and scapula.

    • Connects arms to the trunk.

  2. Bones of Upper Limb:

    • Humerus: Proximal long bone of the arm.

    • Radius and Ulna: Form the forearm.

    • Carpal Bones: 8 wrist bones; arranged in two rows.

    • Metacarpals: 5 bones forming the palm.

    • Phalanges: 14 bones in fingers.

  3. Pelvic Girdle:

    • Formed by ilium, ischium, pubis; connects legs to axial skeleton.

    • Differences between male and female pelvis accommodate childbirth.

  4. Bones of Lower Limb:

    • Femur: Thigh bone, longest in the body.

    • Tibia and Fibula: Form the lower leg.

    • Tarsal Bones: 7 bones in the ankle and foot area.

    • Metatarsals: 5 bones in the middle of the foot.

    • Phalanges: 14 toe bones, similar to fingers.