2.1 Skeletal System Functions and Bone Tissue

Functions of the Skeletal System

• Supports the body by using legs and the pelvic girdle
• Protects soft body parts
  • Skull protects the brain
  • Ribcage protects the heart and lungs
  • Vertebrae protect the spinal cord
• Produces blood cells in red bone marrow
• Stores minerals (calcium and phosphorus) and fat
• Allows for movement by attaching muscles

Types of Bone Tissue

• Compact bone
  • Highly organized, made of osteons with central canals containing blood vessels
  • Densest and toughest near the external surface
  • Makes up the bulk of the shaft in long bones
  • Provides protection, support and resistance to stressors
• Spongy bone (Trabecular bone)
  • Appears unorganized with strong light weight steel beams
  • Found in the epiphysis (ends) of long bones

Bone Homeostasis

• Bone is constantly changing
  • Repairing minor cracks
  • Responding to stress, such as weight training and bearing
• Recycling 5-7% bone mass each week
  • Spongy bone is replaced roughly every 3-4 years
  • Compact bone is replaced roughly every 10 years

Important Cells in Bone Growth, Remodeling, and Repair

• Osteoblasts - bone-forming cells
• Osteoclasts - breaking down cells
• Osteocytes - mature bone cells maintaining bone structure derived from osteoblasts
• Sensers of change

Blood Made in Bones

• Blood cells live 180 days
• New blood formation occurs in red bone marrow

The Bones of the Skeleton

• Axial skeleton - midline of the body
• Appendicular skeleton - limbs and their girdles
  • Bones in green = axial skeleton
  • Bones in red = appendicular skeleton

The Vertebral Column

• Commonly known as the spine
• Functions of the vertebral column are not specified
• Number of vertebrae is 7-12-5 (data unclear)
• Separated by intervertebral discs
• Functions of the discs are not specified
• Herniated/slipped disc description is not given

Parts of a Typical Vertebra and Their Function

• Vertebral body
• Vertebral arch
• Vertebral foramen
• Transverse process
• Spinous process
• Articulating processes and facets

Types of Vertebra

• Thoracic vertebra is detailed, showing components like spinous process, lamina, neural arch, pedicle, transverse process, vertebral foramen, centrum (body), superior articular process.

Sacrum

• Description of different parts and features, including:
  • Superior articular facet
  • Sacral canal
  • Sacral ala
  • Spinous tubercles
  • Dorsal sacral foramina
  • Sacral hiatus
  • Coccyx (tail bone)
  • Iliac bone
  • Sacroiliac joint
  • Symphysis pubis

Thorax

• Sternum, including its components (manubrium, body, xiphoid process, jugular notch)
• Ribs (true, false, floating)

Appendicular Skeleton

• Clavicle
• Scapula

Upper Limb

• Arm - humerus
• Forearm - radius & ulna
  • Humerus components: head, anatomical neck, greater and lesser tubercle, bicipital groove, deltoid tuberosity, medial and lateral epicondyles, coronoid fossa, olecranon fossa, capitulum, trochlea
  • Radius components : head & styloid process
  • Ulna components: olecranon process, & styloid process

The Hand

• 8 carpals, 5 metacarpals, 5 digits, 14 phalanges

Ilium, Ischium, and Pubis

• Details on the structural components of the pelvic girdle

Pelvic Girdle

• Features of the pelvic girdle
  • Iliac crest
  • Sacroiliac joint
  • Anterior superior iliac spine
  • Anterior inferior iliac spine
  • Ischial spine
  • Acetabulum
  • Pubic tubercle
  • Obturator foramen
  • Pubic symphysis
  • Posterior superior iliac spine
  • Pelvic inlet
  • Sacrum
  • Ilium
  • Coccyx
  • Pubis
  • Ischium
  • Os coxae
  • Subpubic angle (pelvic angle)

Lower Limb

• Thigh - Femur
• Leg - Tibia & Fibula
  • Femur features include : head, neck, greater and lesser trochanter, gluteal tuberosity, medial & lateral condyles, intercondylar fossa
  • Tibia features include medial & lateral condyles, intercondylar eminence, tibial tuberosity, anterior border, medial maleolus
  • Fibula features include head, lateral maleolus

The Foot

• 7 tarsals (talus and calcaneus), 5 metatarsals, 14 phalanges

Joints

• Functions of joints: holding bones together and allowing for mobility
• Two ways to classify joints: structurally and functionally

Ligaments

• Short bands of tough, flexible tissue
• Connect most bones in the body
• Hold bones steady during movement
• Basic building blocks are collagen fibers
• Fibers are strong, flexible, and get stronger with use
• Arranged in parallel bundles

Articular Cartilage

• Smooth surface (9 times smoother than ice on ice)
• Low friction during movement, in tandem with synovial fluid
• Spreads load like a yoga mat, over a larger surface area

Synovial Joints

• Features that distinguish them: articular cartilage, articular capsule, synovial membrane, joint cavity, reinforcing ligaments, movement by muscles.

Joint Injuries

• Dislocation: painful tear of joint structures, displaces the joint, often requires repositioning
• Subluxation: painful tear of ligaments, joint is less stable, but does not fully displace the joint and leave the socket

Common Forms of Arthritis

• Osteoarthritis: Chronic inflammation due to injury/irritation; commonly related to aging
• Rheumatoid arthritis: Autoimmune disease where immune system attacks joint tissue, less common than osteoarthritis

Surgery Videos

• Provided links to YouTube and Physiopedia for related videos

Explore the skeletal system's support, protection, and movement functions. Learn about compact bone, spongy bone, and bone homeostasis, including the skeletal system's constant change and repair processes. Understand bone remodeling and calcium regulation.