Bones (Skeletal Tissue)

Long bones

Longer than wide

Contains 2 enlarged ends connected by shaft

All bones located in limbs including finger bones, patella, carpals, and tarsals,

Short Bones

Cube shaped

Ex: 7 Tarsals and 8 Carpels

Flat Bones

Thin, flat, curved

Ex: Scapula, ribs, most skull bones

Irregular Bones

Others that don’t fit into the above categories

Ex: Vertebrae and coxal bones

(Function of bones) Support

Support other bones

Ex: Leg bone connected to…

Support soft tissue (muscles, thoracic wall)

(Function of bones) Protection

Protection of soft tissue/organs

Ex: Skull for brain

Vertebrae for spinal cord

Rib cage for lungs, heart

(Function of bones) Movement

Bones are levers that are moved by skeletal muscles

Tendons connect muscle to bone across joints

Ex: Biceps flexes and antebrachial

Triceps extend antebrachial

Mineral Storage

Minerals are “deposited” or body makes “withdrawals”

This happens continuously (remember parathyroid)

Ex: Calcium and phosphates

Blood cell formation (Hematopoiesis)

Occurs in red bone marrow

Ex: Formed element such as WBC, RBC, platelets

Bone Tissue

Primary tissue found in bones

1. Compact bone - outer and shaft

2. Spongy bone - ends, found inside flat or short bones

Connective Tissue

Articular cartilage

Fibrous that lines cavities

Nerve Tissue

In and on bone

Epithelial tissue

In blood vessels (E)

Muscle tissue

In blood vessels

Diaphysis

Shaft

Medullary Cavity

Hollow middle of diaphysis

In adults, it contains yellow bone marrow (fat)

Epiphysis

Ends of bone

Enlarged most of the time

Articular cartilage

Cover epiphysis

Protects, cushions ends of bones

Epiphyseal Line

Remnant of epiphyseal plate/growth plates

Nutrient Foramen

Holes in shaft for blood vessels, nerves, and lymph vessels

Endosteum

Inner lining of bone lines Medullary cavity

Periosteum

Double-layered membrane covering the long bone

Outer layer of periosteum

Outer layer = Fibrous layer (dense irregular)

Rich in blood vessels, nerves, and lymphatic vessels

Inner layer of periosteum

Inner layer = Osteogenic layer (osteocytes)

Made from osteoblasts (bone forming cells)

And osteoclasts (bone destroying cells)

Yellow Marrow

Fills medullary cavity

Made from fat

Red Marrow

Found in spongy bone

Ends of some long bones and middle of flat bones

Adults, head of femur and humerus, sternum, hip

Osteon system

functional unit of bone

Lamella

Tubes surrounding central canal

Central canal

Middle of osteon

Contains nerves, blood vessels

Perforating Canal

Connect and perpendicular to central canal

Osteocytes

Mature bone cells that divide lamella

Lacunae

Cavity between lamella contains osteocytes

Canaliculi

Canals that connect lacunae

Interstitial lamellae

fill gaps between osteon

Spongy Bone

Trabeculae - Random pattern of cells and tissue

Contains lamellae and osteocytes irregularly placed

Cell and secretions

Osteoblasts

Osteocytes

Osteoclasts

Osteoid

Collagen fibers

Hydroxyapatite

Osteoblasts

Bone forming cell

Osteocytes

Mature bone cells

Osteoclasts

Bone-destroying cells

Osteoid

Ground substance or matrix

Collagen fibers

provide strength

Hydroxyapatite

minerals that make the bone tissue hard

Remodeling of Bone

Each week we recycle 5-7% of our bones

Spongy bone is replaced every 3-4 years, compact bone every 10 years

Growth plate in long bones

Osteporosis - degeneration of the bone - lack of minerals (calcium)

Control of remodeling

Parathyroid hormone- PTH will store (bone deposit) or borrow (bone reabsorption) calcium from bone

This is done by osteoblasts and osteoclasts respectively

Fracture

Break

Nondisplaced break

Ends of bones in alignment

Displaced break

Ends of bones out of alignment

Complete break

Broken across whole bone

Incomplete break

Not broken across whole bone

Linear break

Broken across length wise

Transverse break

Cross section

Open break (compound)

Breaks skin

Closed break (Simple)

Doesn’t break skin

Process of simple fracture repair

Blood, cartilage, spongy, compact

Hematoma formation

Bone breaks

Blood vessels break

Blood clots

Bone cells die

Fibrocartilaginous callus formation

Phagocytic cells clean up debris

Fibroblasts make collagen fibers that connect ends of broken bone

Bony callus formation

Osteoblasts from periosteum and endosteum begin making spongy bone

Begins 3-4 weeks after injury, lasts 2-3 months

Bone remodeling

Form medullary cavity, compact bone in shaft

New linings endosteum and periosteum

Classification of Joints

Fibrous

Cartilaginous

Synovial

Fibrous (synarthrosic) joint

Immovable sutures

Ex: Skull

Cartilaginous (amphiarthrotic) joint

Slightly movable

Ex: Clavicle, vertebrae

Synovial (diathrosic) joint

Freely movable, fluid filled cavity (most joints are this)

Structure of synovial joint

Articular cartilage - covering of bone

Synovial cavity - Space between bones

Articular Capsule - Encloses cavity

Synovial fluid - Lubrication

Ligament - Bone to bone connection

Plane synovial joint

Between ankle bones

Hinge synovial joint

Elbow and knee

Pivot synovial joint

Between vertebrae

Condylar synovial joint

Hand to fingers and foot to toes

Saddle synovial joint

Between wrist and hand

Ball and socket synovial joint

Shoulder and hip