Overview
This lecture covers the core structures and functions of the integumentary, skeletal, muscular, and cardiovascular systems, with an emphasis on anatomical organization, tissue types, development, clinical relevance, and key terminology.
Integumentary System and Fascia
- The integumentary system consists of epidermis, dermis, hair follicles, sebaceous, and sweat glands.
- Skin functions in protection, containment, thermoregulation, sensation, and vitamin D production.
- Subcutaneous tissue beneath the dermis stores most body fat.
- Deep fascia envelops the body beneath subcutaneous tissue and extends to divide muscles and form bursae.
Skeletal System
- The axial skeleton includes bones of the head, neck, and trunk; the appendicular skeleton contains limb bones.
- Cartilage provides flexibility; bones provide support, protection, movement, storage, and blood cell production.
- Bone types: long, short, flat, irregular, sesamoid.
- Periosteum surrounds bones; perichondrium surrounds cartilage.
- Bone markings such as foramina, processes, and ridges are sites for ligament, tendon, and vessel attachment.
Bone Development and Growth
- Bones form via intramembranous or endochondral ossification.
- Long bones grow at epiphysial plates until adult size; fusion creates an epiphysial line.
- Bones are supplied by nutrient, metaphyseal, and epiphysial arteries; periosteum is essential for bone survival.
- Clinical: fractures heal through callus formation; osteoporosis is age-related bone loss; bone age is assessed radiographically.
Joints
- Joints unite bones and can be fibrous (limited movement), cartilaginous (slight movement), or synovial (freely movable).
- Synovial joints have a capsule, synovial fluid, and are classified by movement: plane, hinge, saddle, condyloid, ball and socket, pivot.
- Joints are supplied by articular arteries, veins, and nerves (sensory/proprioceptive).
- Clinical: degenerative joint disease (osteoarthritis), joint infection, and neonatal fontanelles.
Muscle Tissue and Muscular System
- Muscle types: skeletal (voluntary, striated), cardiac (involuntary, striated), smooth (involuntary, unstriated).
- Skeletal muscles are grouped by shape (flat, pennate, fusiform, etc.) and function (prime mover, fixator, synergist, antagonist).
- Muscle contraction: isotonic (concentric/eccentric) produces movement; isometric maintains position.
- Motor units consist of a neuron and the muscle fibers it controls.
- Clinical: muscle testing, EMG, atrophy, soreness, and regeneration (limited in skeletal and cardiac muscle; smooth muscle can undergo hyperplasia).
Cardiovascular System
- The heart, arteries, veins, and capillaries circulate blood through pulmonary and systemic circuits.
- Arteries (elastic, muscular, arterioles) carry blood from the heart; veins return blood and have valves to prevent backflow.
- Capillaries permit exchange of gases and nutrients.
- Collateral circulation occurs via arterial anastomoses; end arteries have limited collateral supply.
- Venous return is aided by musculovenous and arteriovenous pumps.
Key Terms & Definitions
- Epidermis — outermost layer of the skin.
- Dermis — deeper layer of skin with connective tissue.
- Fascia — connective tissue sheet beneath the skin.
- Epiphysial plate — growth plate in long bones.
- Synovial joint — freely movable joint with a fluid-filled cavity.
- Isotonic contraction — muscle changes length to produce movement.
- Isometric contraction — muscle contracts without change in length.
- Motor unit — neuron plus all muscle fibers it innervates.
- Osteoporosis — reduction in bone mass leading to fragility.
- Anastomosis — connection between blood vessels.
Action Items / Next Steps
- Review diagrams of bone markings, muscle shapes, and joint types.
- Practice identifying bone types and markings on skeletal models.
- Complete assigned reading on ossification and joint classifications.
- Prepare for muscle testing demonstrations in lab.