Topic 1.1 Skeletal System

Content 1.1.1-1.1.10

Axial skeleton

Skull, ribs, sternum, vertebral column

Vertebral column

• Cervical- 7 bones

• Thoracic- 12 bones

• Lumbar- 5 bones

• Sacrum- 5 fused as 1

• Coccyx- 4 fused as 1

Appendicular skeleton

Pectoral girdle (scapula and clavicle), humerus, radius, ulna, carpals, metacarpals, phalanges, pelvic girdle (ilium, ischium, pubis), femur, patela, tibia, fibula, tarsals, metatarsals

What are the functions of the axial skeleton?

• Protect vital organs

• Support and maintain posture

• Provide attachment point for muscles

• Storage and release of minerals

• Blood cell production

What are the functions of the appendicular skeleton?

• Provide levers to allow movement

• Provide attachment for muscles to enable movement

• Protect organs

• Store and release minerals

Long bones

• Long cylindrical shaft

• Enlarged at both ends

• Length is greater than width

  • Common for movement

Short bones

• Small short cubes

  • Serves to transfer forces

Flat bones

• Curved surfaces

• Vary from thick to thin

  • Protection and broad surface provide large surface area for muscle attachment

Irregular bones

• Specialized shapes and functions

Epiphysis

• Ends of the long bone

• Made of spongy and compact bone

  • Where blood production occurs

Diaphysis

• Shaft of the bone

• Made of compact bone

  • Envelopes marrow cavity

Spongy bone

• Irregular lattice structure

• Stores red bone marrow

  • Where blood production occurs

Articular Cartilage

Thin layer of cartilage covering the ends of the bones where joints are formed to prevent friction and absorb shock

Compact bone

• External layer of the bone

• Passageways for blood, nerve and lymphatic vessels

  • Important for protection and support

Bone marrow

• Generate blood cells

  • Red bone marrow: produces blood cells

Marrow cavity

• Space in diaphysis

  • Holds yellow bone marrow

Periosteum

• Thin, white shiny membrane

  • Important for bone growth, nutrition, repair and attachment of ligaments/tendons

Blood vessel

• Passes nutrient foramen in the diaphysis

Inferior

Towards the feet

Superior

Towards the head

Anterior

Towards the front

Posterior

Towards the back

Proximal

Towards the body’s mass

Distal

Away from the body’s mass

Medial

Towards the midline of the body

Lateral

Away from the midline of the body

Tendon

• Attaches muscle to bone

• Provides stability in synovial joints

  • Pulls on bone when muscle contracts to move

Ligament

• Bone to bone

• Provides stability in synovial joints

Cartilage

• Bone to bone as cartilaginous joints

• Allows limited movement

Joint

Where two or more bones articulate

Fibrous joints

• No synovial cavity

• No movement

• Held by fibrous connective tissue containing collagen fibers

Cartilaginous joints

• No synovial cavity

• Limited movement

  • Held by cartilage

Synovial joint

• Synovial cavity

• Bones forming joint are united by surrounding articular cartilage

• Free movement

• Synovial fluid inside the synovial membrane

• Common joint type

Articular cartilage

• Smooth tissue covering the ends of the bone at a joint

• Allows bones to glide smoothly over each other

  • Reduces friction and absorbs shock

Synovial membrane

• Lines the inner surfaces of the synovial cavity

• Secretes synovial fluid inside the capsule

Synovial fluid

• Thick fluid inside the capsule

• Lubricating articular surfaces

• Provides nutrients

• Absorbs debris

Bursae

• Tiny sac lined with synovial membrane containing synovial fluid

• Found between bone and soft tissue (tendon/ligaments)

• Reduces friction between structures by preventing wear

Meniscus

• Crescent shaped pad of cartilage

• Helps bones fit together

• Stabilizes and cushions joints

Ligament

• Extension of joint capsule

• Provides strength and stability in synovial joints

• Strong fibrous tissue

Joint cavity

• Articular cavity enclosed by the membrane and articular cartilage

• Containing fluid

Articular capsule

• Strong tissue enveloping the joint

• Blends into periosteum

• Giving joint stability and wanted particles from entering the joint area