Study Guide: Integument, Osteology, Skeletal Anatomy & Articulations

Osteology

Skeletal Cartilages

Cartilage is a resilient, semi-rigid form of connective tissue that provides support and flexibility in the skeletal system.

• Types of Skeletal Cartilage: Hyaline (most abundant, found in joints, ribs, nose), Elastic (external ear, epiglottis), and Fibrocartilage (intervertebral discs, menisci).

• Functions: Provides support, flexibility, and smooth surfaces for joint movement.

• Growth: Cartilage grows by appositional growth (new layers added to the surface) and interstitial growth (expansion from within).

Bone Classification

Bones are classified by their shape and structure.

• Long bones: Longer than they are wide (e.g., femur, humerus).

• Short bones: Cube-shaped (e.g., carpals, tarsals).

• Flat bones: Thin, flattened, and usually curved (e.g., sternum, skull bones).

• Irregular bones: Complicated shapes (e.g., vertebrae, hip bones).

Functions of Bone

• Support: Framework for the body.

• Protection: Protects vital organs (e.g., skull protects brain).

• Movement: Acts as levers for muscles.

• Mineral Storage: Reservoir for calcium and phosphate.

• Blood Cell Formation: Hematopoiesis in red marrow.

• Triglyceride Storage: Fat storage in yellow marrow.

Bone Anatomy

• Gross Anatomy: Diaphysis (shaft), epiphyses (ends), metaphysis, medullary cavity, periosteum, endosteum.

• Microscopic Anatomy: Osteons (Haversian systems), lamellae, lacunae, canaliculi, osteocytes, osteoblasts, osteoclasts.

• Chemical Composition: Organic (cells, osteoid) and inorganic (hydroxyapatite crystals) components.

Bone Markings

Bone markings are features on bones where muscles, tendons, and ligaments attach, and where blood vessels and nerves pass.

• Projections: Tuberosity, crest, trochanter, line, tubercle, epicondyle, spine, process.

• Depressions/Openings: Foramen, groove, fissure, notch, fossa, meatus, sinus.

Bone Development (Ossification)

Ossification is the process of bone tissue formation.

• Intramembranous Ossification: Bone develops from fibrous membrane (e.g., flat bones of skull).

• Endochondral Ossification: Bone forms by replacing hyaline cartilage (e.g., long bones).

Bone Growth

• Interstitial Growth: Lengthening of bones at the epiphyseal plate.

• Appositional Growth: Increase in bone thickness by addition of bone to the surface.

Hormonal Regulation of Bone Growth

• Growth hormone: Stimulates epiphyseal plate activity.

• Thyroid hormone: Modulates growth hormone activity.

• Sex hormones: Promote growth spurts and epiphyseal plate closure.

Bone Deposition and Remodeling

• Bone Deposition: Addition of new bone by osteoblasts.

• Bone Resorption: Removal of bone by osteoclasts.

• Remodeling: Continuous process of bone renewal and repair.

Wolff’s Law

Bone grows and remodels in response to the forces placed upon it.

• Example: Bones are thicker in dominant limbs or in response to exercise.

Bone Repair/Fracture Repair

• Steps:

  1. Hematoma formation

  2. Fibrocartilaginous callus formation

  3. Bony callus formation

  4. Bone remodeling

Homeostatic Imbalances

• Osteoporosis: Decreased bone mass and increased fracture risk.

• Osteomalacia/Rickets: Softening of bones due to vitamin D deficiency.

• Paget’s Disease: Disorganized bone remodeling.

Skeletal System

Axial Skeleton

The axial skeleton forms the central axis of the body and includes the skull, vertebral column, and thoracic cage.

• Skull: Cranial bones (protect brain) and facial bones (form face structure).

• Vertebral Column: Cervical (7), thoracic (12), lumbar (5), sacrum, coccyx.

• Thoracic Cage: Sternum, ribs, thoracic vertebrae.

Landmarks and Features

• Skull: Foramen magnum, orbits, nasal cavity, zygomatic arch, mastoid process, etc.

• Vertebrae: Body, spinous process, transverse process, vertebral foramen, intervertebral discs.

• Thoracic Cage: True ribs (1-7), false ribs (8-12), floating ribs (11-12).

Neonatal Fontanelles

Fontanelles are soft spots on a baby's skull that allow for growth of the brain and skull during infancy.

• Major fontanelles: Anterior, posterior, mastoid, sphenoidal.

Spinal Curvatures

• Primary curves: Thoracic and sacral (present at birth).

• Secondary curves: Cervical (develops as baby lifts head), lumbar (develops as baby walks).

Appendicular Skeleton

The appendicular skeleton includes the limbs and girdles that attach them to the axial skeleton.

• Shoulder Girdle: Clavicle and scapula; landmarks include acromion, coracoid process, glenoid cavity.

• Pelvic Girdle: Ilium, ischium, pubis; landmarks include iliac crest, acetabulum, obturator foramen.

• Female vs Male Pelvis: Female pelvis is wider, shallower, and has a larger pelvic inlet/outlet for childbirth.

• Arches of the Foot: Medial longitudinal, lateral longitudinal, and transverse arches provide support and flexibility.

Articulations

Joint Classifications

Joints (articulations) are classified by structure and function.

• Structural Classification:

  • Fibrous Joints: Bones joined by dense connective tissue; little or no movement (e.g., sutures, syndesmoses, gomphoses).

  • Cartilaginous Joints: Bones joined by cartilage; limited movement (e.g., synchondroses, symphyses).

  • Synovial Joints: Bones separated by a fluid-filled cavity; freely movable (e.g., shoulder, knee).

• Functional Classification: Synarthroses (immovable), amphiarthroses (slightly movable), diarthroses (freely movable).

Features of Synovial Joints

• Articular cartilage, joint (synovial) cavity, articular capsule, synovial fluid, reinforcing ligaments, nerves, and blood vessels.

Subcategories and Classifications of Joints

Joint Type	Example	Movement
Suture (fibrous)	Skull sutures	Immovable
Gomphosis (fibrous)	Teeth in sockets	Immovable
Syndesmosis (fibrous)	Distal tibiofibular joint	Slightly movable
Synchondrosis (cartilaginous)	Epiphyseal plate	Immovable
Symphysis (cartilaginous)	Pubic symphysis	Slightly movable
Plane (synovial)	Intercarpal joints	Gliding
Hinge (synovial)	Elbow	Flexion/extension
Pivot (synovial)	Proximal radioulnar joint	Rotation
Condyloid (synovial)	Metacarpophalangeal joints	Flexion/extension, abduction/adduction
Saddle (synovial)	Thumb (1st carpometacarpal)	Flexion/extension, abduction/adduction
Ball & Socket (synovial)	Shoulder, hip	All movements

Hilton’s Law

Nerves supplying a joint also supply the muscles moving the joint and the skin covering their attachments.

Specific Named Joints and Ligamentous Support

• Upper Extremity: Shoulder (glenohumeral), elbow, wrist joints; supported by ligaments such as the glenohumeral, ulnar collateral, and radial collateral ligaments.

• Lower Extremity: Hip, knee, ankle joints; supported by ligaments such as the iliofemoral, anterior cruciate, posterior cruciate, and deltoid ligaments.

Joint Pathologies

• Osteoarthritis: Degeneration of articular cartilage.

• Rheumatoid Arthritis: Autoimmune inflammation of synovial membrane.

• Sprains: Ligament injury.

• Dislocations: Bones forced out of alignment.

Additional info: This guide expands on the review topics with definitions, examples, and context to support exam preparation in anatomy and physiology (A&P) college courses.