Semester 1 Essays

Page 1: Bone as an Organ

• Mature Bones

  • Referred to as osseous (bone) tissue or an organ.

  • Consists of:

    • Osseous tissue

    • Nervous tissue

    • Epithelial and muscle tissue (blood vessels)

Osseous Tissue

• Composed of:

  • Cells

    • Osteoblasts: Build bone density

    • Osteoclasts: Break down bone tissue

    • Osteocytes: Mature bone cells in lacunae

  • Extracellular Matrix: Includes ground substance and fibers

  • Living tissue capable of growth and repair

Types of Bone Tissue

1. Compact Bone

   • Layers (lamellae) organized into concentric circles

   • Contains Haversian canals

   • Osteon: Functional unit of compact bone

   • Osteocytes in lacunae connected by tunnels (canaliculi)

2. Spongy Bone

   • Porous and light

   • Composed of trabecular rods and plates

   • Contains red bone marrow

Functions of the Skeleton

• Definition: Framework of the body

• Function:

  • Support for the body

  • Protective cavity for vital organs

  • Movement (attachment for muscles)

  • Mineral storage (calcium and phosphorus)

  • Blood cell formation (hematopoiesis)

Types of Bones

1. Long Bones

2. Short Bones

3. Flat Bones

4. Irregular Bones

5. Sesamoid Bones

Page 2: Bone Development and Growth

• Ossification: Process of bone formation.

• Two Types of Ossification Processes:

  1. Intramembranous Ossification

  2. Endochondral Ossification

• Skeleton forms from fibrous membranes and hyaline cartilage.

• Continues through adulthood for repair and remodeling.

Intramembranous Ossification

1. Formation of spongy bone tissue begins at centers of ossification.

2. Osteoblasts migrate and deposit bony matrix.

3. Osteoblasts in matrix turn into osteocytes.

4. Red marrow forms followed by compact bone formation.

Endochondral Ossification

1. Periosteum forms around hyaline cartilage (bony collar).

2. Cavity formation and ossification occurs in the center.

3. Vascular invasion leads to elongation of the bone.

4. Secondary ossification centers develop at the epiphyses.

5. Epiphyseal plates and articular cartilage remain.

Page 3: Bone Growth and Factors

Growth Factors

• Nutritional Factors: Vitamins A, C, D.

• Hormonal Influences: Thyroid, pituitary hormones.

• Exercise: Stimulates bone adaptation and growth.

Increase in Length

• Growth occurs at the epiphyseal plate.

• Cartilage growth continues until the early twenties.

Increase in Width

• Appositional Growth: Bones grow in thickness.

• Osteoblasts form compact bone while osteoclasts reduce bone mass internally.

Page 4: Joints Between Bones

Types of Joints

1. Fibrous Joints

   • Sutures: Immovable joints in the skull.

   • Gomphoses: Teeth to sockets.

   • Syndesmoses: Slightly movable.

2. Cartilaginous Joints

   • Synchondrosis: Immovable, connected by hyaline cartilage.

   • Symphyses: Slightly movable, connected by fibrocartilage.

3. Synovial Joints

   • Movable joints with synovial fluid.

Examples of Synovial Joints

• Hinge, Saddle, Plane, Pivot, Condyloid, Ball-and-Socket.

Page 5: Structure of Synovial Joints

• Synovial Capsule: Secretes synovial fluid for lubrication.

• Articular Cartilage: Reduces friction.

• Bursae: Fluid-filled sacs to reduce friction (e.g. in the knee).

Page 6: Vertebral Column

Structure

• Composed of 33 vertebrae: cervical, thoracic, lumbar, sacral, and coccygeal.

• 24 presacral vertebrae allow movement.

Function

• Protection: Shields the spinal cord.

• Support: Weight bearing for the upper body.

• Movement: Facilitates posture and motion.

Page 7: Joints of the Vertebral Column

• Facet Joints: Allow gliding; strengthened by ligaments.

Biomechanics

• Movement includes flexion, extension, lateral flexion, and rotation.

Page 8: Skeleton of the Thorax

• Ribs: Protects organs; assists in breathing.

• Sternum: Articulates with ribs via cartilage.

• Thoracic Joints: Contributes to biocompatibility and movement.

Page 9: Joints Between the Vertebrae and Skull

• Atlanto-Axial and Atlanto-Occipital Joints: Allow for rotation and nodding of the head.

Page 10: Joints of the Shoulder Girdle

Structure & Movement

• Includes sternoclavicular, acromioclavicular, and scapulothoracic joints.

Shoulder Joint

• Ball-and-socket joint allowing extensive movement.

Page 11: Elbow Joint

Characteristics

• Hinge joint connecting arm to forearm.

• Articulating surfaces: humerus, ulna, and radius.

Page 12: Pelvic Girdle

Structure

• Consists of hip bones, sacrum, and coccyx.

Functions

• Weight transfer, muscle attachment, protection of viscera.

Page 13: Hip Joint

Overview

• Ball-and-socket joint between femur and acetabulum.

Movements

• Flexion, extension, abduction, adduction, medial and lateral rotation.

Page 14: Knee Joint

Articulating Surfaces

• Tibiofemoral and patellofemoral joints.

Ligaments & Movements

• Cruciate and collateral ligaments stabilize joint.

Page 15: Joints of the Foot

Overview

• Includes tarsals, metatarsals, and phalanges.

Movements

• Dorsiflexion, plantarflexion, inversion, eversion, abduction, adduction.