THE SKELETAL SYSTEM

Overview

There are 206 bones in the body The Skeletal System

Supports and protects the bodyProduces red blood cellsStorehouse for inorganic calcium,

phosphate ions, and fatPermits flexible movement

Parts

BonesSkeleton

CartilagesFlexible connective tissue

JointsWhere two or more bones make contact

Ligaments Connects two bones or cartilages or holds a

joint together

Bones throughout our lives

During the embryos stages, the skeleton is mostly cartilage

As we develop, the cartilage gets replaced by bone

Types of Bone Tissue

Compact: Found on the outside of most bones. Gives the smooth/ white appearance.

Functions include support and protection

Types of Bone Tissue

Spongy: Located inside the bone. Make up large portion of bone.

Contains many open spaces.

Types of Bone Cells

Osteocytes: Mature bone cells

Osteoblasts: Bone-forming cells

Osteoclasts: Bone destroying cells. Break down bone matrix for remodeling and release of calcium

Bone Classification

Short: As wide as they are long. Provide support and stability with little movement.

○ (Carpals)

Bone Classification

Long: Length is greater than width. ○ (Femur, Phalanges, etc.)

Bone Classification

Irregular: Odd shaped that don’t fit any other categories

○ (Pelvis, Vertebrae)

Female Pelvis Male Pelvis

Bone Classification

Flat: Strong, flat, curved plates that provide protection.

○ (Scapula, Sternum, Skull)

Divisions

The Skeletal System is divided into two different sections:Axial Skeleton:

○ Skull, hyoid bone, vertebral column, and thoracic cage

Appendicular Skeleton:○ Limbs and girdle

Axial Skeleton Contains 80 bones Skull (22 bones)

Composed of cranium and facial bones Hyroid bone

U-shaped bone in neckAnchors tongue

Vertebral column (26 bones)Protects the spinal cord

Thoracic cage (27 bones)Protects organs

Axial Skeleton Diagram

Appendicular Skeleton

Contains 126 bones Pectoral Girdles (4 bones) Hands (54 bones) Arm and Forearm (6 bones) Pelvis (2 bones) Feet and Ankles (52 bones) Thigh and Leg (8 bones)

Appendicular Skeleton Diagram

Joints Where two bones come together

Fibrous: No movement, connect bones.○ (Skull and Pelvis)

Cartilaginous: Slightly moveable, bones are attached with cartilage

○ (Spine and ribs)

Synovial: Completely Moveable. Space between bones is filled with

synovial fluid to lubricate and protect the bones

Synovial Joints

Based on shapePlane jointHinge jointPivot JointBall-and-socket jointCondyloid jointSaddle joint

Synovial Joints

Plane jointOnly allows gliding movement(Hands, feet)

Synovial Joints

Hinge jointAllows Extension and retraction of an

appendage(Knee, elbows)

Synovial Joints

Pivot jointOne bone rotates around anotherOnly one pivot joint in body(Where the skull joints with vertebrae)

Synovial Joints

Ball-and-Socket jointAllows movement in almost any direction(Hip, Shoulder)

Synovial Joints

Condyloid jointEgg shaped surface fits into an elliptical

surface(Wrist joint)

Synovial Joints

Saddle jointSurfaces contrast each other in

convex/concave form. (Thumb)