Anatomy and Physiology - Skeletal System

Science Olympiad 2025

Skeletal System

Protects and supports body organs and provides a framework the muscles use to support movement.

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Number of bones in the human body

the cranium

the maxilla

the zygoma

the mandible

the clavicle

the humerous

the ulna

the radius

the carpals

the metacarpals

the phalanges

the scapula

the sternum

the ribs

the vertebral column

the pelvis

the coccyx

the femur

the patella

the tibia

the fibula

the tarsals

the metatarsals

Homeostasis

maintains a balance between the outside body temperature and internal body temperature.

levels of organization in the body

cell, tissue, organ, organ system, human body

Smallest/basic level of organization

cells

Four types of tissue

muscle, connective, nerve, epithelial

muscle tissue

body tissue that contracts and relaxes

connective tissue

Tissue that joins, protects, insulates, supports and cushions.

nerve tissue

tissue that carries messages back and forth between the brain, spinal cord, and every other part of the body

epithelial tissue

Tissue that covers outside of the body and lines organs and cavities inside the body.

Bones

Living organs; store minerals, and produce blood cells

Main parts of the bone

Compact bone, spongy bone, marrow, and periosteum

compact bone

Hard, dense bone tissue that is beneath the periosteum and can resist shock and stress

spongy bone

bone tissue that is porous, provides strength, and aids in making new blood cells

Periosteum

tough membrane covering the bone; ligaments and tendons are attached to it

red marrow

produces red blood cells

yellow marrow

found in the cavities of long bones; stores fat

ligaments

strong band of connective tissue; connects bone to bone

tendon

a tough connective tissue that attaches a muscle to a bone

cartilage

tissue found at ends of bones and acts as a cushion between bones or where joints form

blood vessels

vessels that carry nutrients to the bone and wastes away

bone marrow

A soft tissue inside the bone that produces blood cells

joints

place where two or more bones join together

fixed joint

a joint that does not move; the skull

pivot joint

Allows limited rotation; the neck

ball and socket joint

allows movement in all directions; the hip and shoulder

saddle joint

allows movement in two directions; the thumb

hinge joint

allows movement in one direction; the elbow, knee, or fingers

gliding joint

Allows one bone to slide over another; wrist and ankle

synovial fluid

reduces friction between bones; popping sound is an air bubble

cranium

skull

maxilla

upper jawbone

mandible

lower jawbone

zygoma

cheekbone

clavicle

collarbone

humerous

upper arm bone

ulna

lesser forearm bone (on pinky side)

radius

main forearm bone (on thumb side)

carpals

wrist bones

metacarpals

hand bones

phalanges

finger bones and toe bones

scapula

shoulder blade

sternum

breastbone

ribs

bones surrounding the chest cavity

vertebral column

spine

pelvis

hip bone

coccyx

vestigial structure - the tailbone

femur

upper leg bone or thighbone

patella

kneecap

tibia

shin bone

fibula

calf bone

tarsals

ankle bones

Metatarsals

foot bones

Makes bones strong

calcium

axial skeleton

Portion of the skeletal system that consists of the cranium, sternum, rib cage, and vertebral column

appendicular skeleton

Part of the skeleton that attaches to the axial skeleton and has the limbs attached to it

Functions of the Skeletal System

1. Support

2. Movement

3. Blood cell formation (hemopoiesis)

4. Protection of internal organs

5. Detoxification (removal of poisons)

6. Provision for muscle attachment

7. Mineral storage (particularly calcium and phosphorus)

Axial Skeleton

Consists of 80 bones, in the skull, vertebrae, ribs, sternum, and hyoid bone

Appendicular Skeleton

126 bones, upper and lower extermities plus two girdles. Half of the bones in the body are in the hands and feet

Long Bones

longer than they are wide; shaft and 2 ends. Ex: Humerous

Short Bones

roughly cube shaped. Ex: ankle and wrist bones

Sesamoid Bones

short bones, but with tendons. Ex: Patella

Irregular Bones

odd shapes, do not fit into the other classes. Ex: Vertebrae

Flat Bones

Thin, flat and often curved. Ex: sternum, scapulae, ribs, most skull bones.

cevical vertebrae

7 bones, top of the spine. transverse formina, bifid spinous process, vertebral prominens. Contains Atlas and Axis.

Atlas

Supports the head.

Axis

pivots to turn the head

thoracic Vertebrae

12 bones, middle of the spine. long spinous process, rib facets. Ribs attach here.

Lumbar Vertebrae

5 bones, bottom of the spine. Large bodies, short spinous processes

Saacrum

five saacral vertebrae fused, protects reproductive, excretory, and digestive organs. good cite for muscle attachment in the legs

coccyx

3-5 fused coccyx vertebrae

Ball & Socket join

allows for a full range of motion Ex: hip, shoulder

Pivot

one bone pivots in the arch of another Ex: Axis and Atlas

Saddle

two directional movement between thumb and trapezium carpel Ex: thumb

Hinge

door hinge- bending and extending Ex: elbow, knee, finger joints

Ellipsoid

side to side and back and forth Ex: radius end into carpal bones

Plane or Gliding

least movable- side to side only Ex: between vertebrae