The Skeletal SystemBy Kristen Jebulan and Elisha Espino

February 27, 2014Period 3

Skeletal Organization:

The Axial Skeleton

Skull

Cranium

Face

Hyoid

Sternum

Vertebralcolumn

Ribs

Sacrum

Skeletal Organization:

The AppendicularSkeleton

ClavicleScapula

Humerus

Coxa Radius

Ulna

Phalanges

Carpals

Metacarpals

Femur

PatellaTibia

Fibula

TarsalsMetatarsals

Phalanges

Bone Function: Support/Protection• Give shape to structures• Provide support and

protection• Examples: bones of skull

protect eyes, ears, and brain; bones of lower limbs, pelvis, and backbone support body weight

Bone Functions:

Body Movement Blood Cell Formation

Bone Function:Storage of Inorganic Salts• Calcium salts are released

from ECM into blood after osteoclasts are stimulated when blood is low in calcium

• Homeostatic mechanism• Maintains sufficient blood

calcium levels for muscle contraction, nervous impulse conduction, etc.

Differences between

Bones and

Ligaments

Tendons

Cartilage

The Long BoneProximalEpiphysis

Distal epiphysis

Diaphysis

Articular cartilage

Articular cartilage

Spongy bone

Compact boneEndosteum

PeriosteumMedullary cavity

Bone Development

• Osteoblasts• bone-forming cells. Called

“osteocytes” when extracellular matrix (ECM) completely surrounds the osteoblasts.

• Osteoclasts• Large, multinucleated cells

that break down the calcified ECM. • Secrete an acid that dissolves

inorganic component of the calcified matrix

JointsFibrous• Dense connective

tissue• No movement

Cartilaginous • Hyaline

cartilage• Limited

movement

Synovial• Cartilage,

synovium, synovial fluid

• Free movement

Synovial Joint TypesBall-and-socket• All planes; rotation• Ball-shaped with

cup

Condyloid• Variety; no

rotation• Oval condyle and

elliptical cavity

Gliding• Sliding/twisting• Articulating

surfaces; flat/curved

Synovial Joint Types (con.)Hinge• Flexion and extension• Convex surface fits

into concave surface of other

Pivot• Rotation around central

axis• Cylindrical surface of a

bone rotates within a ring

Saddle• Variety of movement• Articulating surfaces

have both concave and convex regions

Types of Joint Movement

Types of Joint Movement (con.)

Bone DiseasesArthritis

• Inflammation in the joint that causes pain• Treatable, but not curable• Can originate from genetic makeup,

constant physical-demanding activity on joint, obesity, etc.

Osteoporosis • Bone become weak and are more likely to

break

• Treatable, but not curable

• Can originate from aging, smoking, drinking, low body weight, gender (women), medication use, etc.