Exercise 8: Skeletal Overview

Functions of the Skeleton

• Support: Provides a structural framework for the body.

• Protection: Shields vital organs (e.g., skull protects the brain, rib cage protects the heart and lungs).

• Movement: Serves as levers for muscles to act upon, enabling movement.

• Mineral Storage: Stores minerals such as calcium and phosphorus, which can be released into the bloodstream as needed.

• Blood Cell Production: Houses red bone marrow, which produces blood cells (hematopoiesis).

• Triglyceride Storage: Stores fat in yellow bone marrow.

Types of Skeletal Cartilages

• Hyaline Cartilage: Most abundant; provides support with flexibility and resilience. Found in articular surfaces, costal cartilages, respiratory cartilages, and nasal cartilages.

• Elastic Cartilage: Contains more elastic fibers; maintains shape while allowing flexibility. Found in the external ear and epiglottis.

• Fibrocartilage: Highly compressible with great tensile strength. Found in intervertebral discs, pubic symphysis, and menisci of the knee.

Divisions of the Skeleton

• Axial Skeleton: Consists of the skull, vertebral column, and thoracic cage (ribs and sternum).

• Appendicular Skeleton: Includes the bones of the limbs and girdles (pectoral and pelvic) that attach them to the axial skeleton.

Structure of a Long Bone

• Diaphysis: Shaft of the bone; composed of compact bone surrounding a medullary cavity.

• Epiphyses: Ends of the bone; consist of spongy bone covered by compact bone.

• Metaphysis: Region between diaphysis and epiphysis; contains the epiphyseal plate in growing bones.

• Periosteum: Double-layered membrane covering the external surface of bone except at joints.

• Endosteum: Membrane lining the medullary cavity.

Microscopic Structure of Compact Bone (Osteon Model)

• Osteon (Haversian System): Structural unit of compact bone; consists of concentric lamellae around a central canal.

• Lamellae: Layers of bone matrix.

• Central (Haversian) Canal: Contains blood vessels and nerves.

• Lacunae: Small spaces housing osteocytes.

• Canaliculi: Tiny canals connecting lacunae, allowing for nutrient and waste exchange.

Bone Matrix: Inorganic vs. Organic Components

• Inorganic Salts: Mainly hydroxyapatite (calcium phosphate crystals); provide hardness and resistance to compression.

• Organic Proteins: Primarily collagen fibers; provide flexibility and tensile strength.

Epiphyseal Plate Zones and Bone Growth

• Zone of Resting Cartilage: Nearest the epiphysis; anchors plate to bone.

• Zone of Proliferation: Chondrocytes divide rapidly, pushing the epiphysis away from the diaphysis.

• Zone of Hypertrophy: Chondrocytes enlarge and mature.

• Zone of Calcification: Matrix becomes calcified; chondrocytes die.

• Zone of Ossification: New bone forms as osteoblasts deposit bone matrix.

Bone Marking Terminology (Table 9.1)

• Foramen: Round or oval opening through a bone.

• Fossa: Shallow depression.

• Process: Any bony prominence.

• Condyle: Rounded articular projection.

• Trochanter: Large, blunt, irregular surface (femur only).

• Crest: Narrow, prominent ridge of bone.

• Spine: Sharp, slender projection.

• Tubercle/Tuberosity: Small/large rounded projection.

Exercise 9: Axial Skeleton

Skull Bones

• Know the names and locations of all cranial and facial bones.

• Sphenoid Bone: Butterfly-shaped bone at the base of the skull; contains the sella turcica.

• Ethmoid Bone: Located between the eyes; forms part of the nasal septum and the medial wall of the orbit.

Paranasal Sinuses

• Air-filled spaces within the frontal, ethmoid, sphenoid, and maxillary bones.

• Functions: Lighten the skull, enhance voice resonance, and produce mucus.

Vertebral Column

• Cervical Vertebrae: 7 (C1–C7); C1 (atlas) and C2 (axis) are specialized for head movement.

• Thoracic Vertebrae: 12 (T1–T12); articulate with ribs.

• Lumbar Vertebrae: 5 (L1–L5); largest and bear the most weight.

• Sacrum: 5 fused vertebrae.

• Coccyx: 3–5 fused vertebrae (tailbone).

Thoracic Cage and Ribs

• Sternum: Consists of manubrium, body, and xiphoid process.

• Ribs: 12 pairs; true ribs (1–7), false ribs (8–12), floating ribs (11–12).

Fetal vs. Adult Skeleton

• Fetal Skull: Has fontanelles (soft spots) for flexibility during birth and brain growth.

• Major Differences: Proportionally larger cranium, smaller face, and more cartilage in fetal skeleton.

Exercise 10: Appendicular Skeleton

Overview

• Focus on bone names and functional aspects (muscle attachment sites, articulations).

• Be able to determine right vs. left for paired bones.

Pelvis: Male vs. Female Differences

• Male Pelvis: Narrower, heavier, with a more acute pubic arch.

• Female Pelvis: Wider, lighter, with a broader pubic arch to facilitate childbirth.

Carpals and Tarsals

• Carpals: 8 wrist bones arranged in two rows.

• Tarsals: 7 ankle bones, including the talus and calcaneus.

Exercise 11: Articulations and Body Movements

Functional Categories of Joints

• Synarthroses: Immovable joints (e.g., sutures of the skull).

• Amphiarthroses: Slightly movable joints (e.g., intervertebral discs).

• Diarthroses: Freely movable joints (e.g., shoulder, hip).

Structural Categories of Joints

• Fibrous Joints: Bones joined by dense connective tissue; no joint cavity (e.g., sutures).

• Cartilaginous Joints: Bones joined by cartilage; no joint cavity (e.g., symphysis, synchondrosis).

• Synovial Joints: Bones separated by a fluid-filled joint cavity; most movable type.

Types of Synovial Joints (with Examples)

Major Synovial Joints and Their Structures

• Hip Joint: Ball-and-socket; stabilized by acetabular labrum and strong ligaments (iliofemoral, pubofemoral, ischiofemoral).

• Shoulder Joint: Ball-and-socket; stabilized by rotator cuff muscles and glenohumeral ligaments.

• Elbow Joint: Hinge; stabilized by ulnar and radial collateral ligaments, annular ligament.

• Knee Joint: Hinge; stabilized by menisci, cruciate ligaments (ACL, PCL), collateral ligaments (MCL, LCL), and patellar ligament.

Joint Movements Terminology

• Flexion/Extension: Decreasing/increasing the angle between bones.

• Abduction/Adduction: Movement away from/toward the midline.

• Rotation: Movement around a longitudinal axis.

• Circumduction: Circular movement combining flexion, extension, abduction, and adduction.

• Other Movements: Pronation, supination, inversion, eversion, elevation, depression, protraction, retraction.

Ligaments and Supporting Structures

• Know the specific ligaments for major joints (see above).

• Understand the role of cartilage (e.g., menisci in the knee), tendons, and muscle attachments in joint stability and movement.

Additional Study Tips

• Use pre-lab quizzes and post-lab review sheets for practice.

• Practice Anatomy Lab resources online can reinforce identification and understanding.

Additional info: For diagrams and figures referenced (e.g., Fig 8.3, 8.4, 11.1, 11.2, 11.3, 11.5), consult your textbook or lab manual for visual reinforcement. Bone marking terminology and joint types are foundational for further study in anatomy and physiology.