Anatomy & Physiology Study Guide: Skeletal System and Articulations

Chapter 6 - Bone Tissue

Structures of Bone Tissue

The skeletal system is composed of various types of bone tissue, each with distinct structural and functional properties.

• Compact Bone: Dense, strong tissue forming the outer layer of bones; provides strength and protection.

• Spongy Bone: Porous, lightweight tissue found at the ends of long bones and inside flat bones; contains red bone marrow.

Bone Tissue Cells & Functions

• Osteocytes: Mature bone cells that maintain bone tissue.

• Osteoblasts: Cells responsible for bone formation.

• Osteoclasts: Cells that break down bone tissue during remodeling.

Formation & Remodeling of Bone

Bones are formed and maintained through processes of ossification and remodeling.

• Ossification: The process of bone tissue formation, including intramembranous and endochondral ossification.

• Remodeling: Continuous turnover of bone matrix, involving resorption by osteoclasts and formation by osteoblasts.

Bone Growth & Development

• Epiphyseal Plate: Growth plate where new bone is produced during childhood and adolescence.

• Bone Layers: Periosteum (outer layer), endosteum (inner layer), and compact/spongy bone.

Bone Fractures & Repair

• Common Fractures: Simple, compound, comminuted, greenstick, etc.

• Fracture Repair Process: Hematoma formation, fibrocartilaginous callus formation, bony callus formation, bone remodeling.

Clinical Relevance

• Bone Marrow: Red marrow (hematopoiesis), yellow marrow (fat storage).

• Surface Markings: Projections, depressions, and openings for muscle attachment and passage of nerves/vessels.

• Types of Bones: Long, short, flat, irregular, sesamoid.

Chapter 7 - Axial Skeleton

Axial Skeletal System Overview

The axial skeleton includes bones of the skull, vertebral column, and thoracic cage, providing support and protection for the central nervous system and vital organs.

• Skull: Cranial and facial bones; protects the brain and forms the structure of the face.

• Vertebral Column: Cervical, thoracic, lumbar, sacral, and coccygeal vertebrae; supports the body and protects the spinal cord.

• Thoracic Cage: Ribs and sternum; protects the heart and lungs.

Skull Features

• Fontanelles: Soft spots in infant skulls that allow for growth and flexibility.

• Paired & Unpaired Bones: Examples include paired parietal bones and unpaired occipital bone.

• Unique Bone Structures: Sphenoid bone, vertebrae, etc.

Vertebral Column

• Vertebral Bones: Individual vertebrae classified by region (cervical, thoracic, lumbar, sacral, coccygeal).

• Vertebral Prominens: Notable vertebrae such as C7.

• Bone Articulations: Joints between vertebrae and with ribs.

• Sutures: Immovable joints between skull bones.

Bone Classification & Directional Terms

• Axial vs. Appendicular: Axial includes skull, vertebral column, and thoracic cage; appendicular includes limbs and girdles.

• Directional Terms: Anterior, posterior, lateral, medial, superior, inferior.

Chapter 8 - Appendicular Skeleton

Overview of Appendicular Skeleton

The appendicular skeleton consists of bones of the limbs and girdles, facilitating movement and interaction with the environment.

• Pelvis: Male vs. female pelvis differences (shape, size, angle).

• Ribs & Articulations: Anatomy and connections to vertebrae and sternum.

• Radiology: Imaging techniques for bones and joints.

• Phalanges: Bones of fingers and toes; classified as proximal, middle, distal.

• Calcaneus & Talus: Bones of the ankle and heel.

• Shoulder Girdle: Clavicle and scapula; connects upper limb to trunk.

• Hip Bone, Tibia, Femur: Major bones of the lower limb.

Directional Terms

• Anterior: Toward the front.

• Posterior: Toward the back.

• Lateral: Away from the midline.

• Medial: Toward the midline.

• Superior: Above.

• Inferior: Below.

Chapter 9 - Articulations

Joints and Articulations

Articulations are points where two or more bones meet, allowing for movement and flexibility.

• Joints of Facial Bones: Sutures and other immovable joints.

• Surface Markings: Features that indicate joint locations and muscle attachments.

• Articulating Surfaces: Areas where bones contact each other.

Classification of Joints

• Synovial Joints: Freely movable joints with a synovial cavity (e.g., knee, shoulder).

• Fibrous Joints: Immovable or slightly movable joints (e.g., sutures).

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

Joint Movements

• Adduction: Movement toward the midline.

• Abduction: Movement away from the midline.

• Extension: Increasing the angle between bones.

• Flexion: Decreasing the angle between bones.

Special Joints & Ligaments

• Special Joints: Temporomandibular joint (TMJ), knee, etc.

• Joint & Ligament Connections: Structures that stabilize and support joints.

Additional Information

• Aging: Effects of aging on bone and joint structure and function.

• Directional Terminology: Essential for describing anatomical relationships.

Example Table: Types of Bones

Type	Description	Example
Long	Longer than wide, mostly compact bone	Femur, humerus
Short	Cube-shaped, mostly spongy bone	Carpals, tarsals
Flat	Thin, flattened, usually curved	Sternum, skull bones
Irregular	Complex shapes	Vertebrae, hip bones
Sesamoid	Embedded in tendons	Patella

Key Formula: Bone Remodeling

Bone remodeling is regulated by the balance between osteoblast and osteoclast activity:

$\text{Bone Mass Change} = \text{Osteoblast Activity} - \text{Osteoclast Activity}$

Example: Directional Terms

• Medial: The nose is medial to the eyes.

• Lateral: The ears are lateral to the eyes.

Additional info: This study guide expands on the listed topics with academic context, definitions, and examples to provide a comprehensive review for Anatomy & Physiology students.