The Skeletal System
Every movement is possible because of
the muscles working with the bones –
skeletal system.
Functions of the Skeletal System:
1. Anchor for body’s movement
2. Provides support
3. Protects soft organs inside the
body.
Classification of Bones
• Long bones – arms and
legs
• Short bones – feet
and hands
• Irregular bones – spine
• Flat bones – ribs and
skull
What are Bones Made Of???
• Bones are made of
soft and hard
material
• Are living tissue
• They have spaces
inside – allow
blood and
nutrients to pass
through
Two Types of Bone Tissue
Compact Bone – Outside of the
bone
Supportive tissue of the
body
Is the part we call the skeleton
Spongy Bone – Tissue inside the
bone
Strong, but lightweight
Marrow and Blood Cells
• Marrow – inside the
spongy bone tissue,
produces blood cells
• The blood brings
nutrients to the
bone cells and
carries waste
materials away.
Two Main Divisions in the
Skeleton
Axial Skeleton –
Central part of the Skeleton
Forms the axis
Provides support and protection
Includes the skull, spinal
column, ribs
Appendicular Skeleton –
Attached to the axis skeleton.
Allows movement
Shoulder, legs, arms, knees, etc.
The Skeleton Changes as
We Grow
• Infancy – Skull is made up of several bones that
have spaces between them – The spaces gradually
grow together.
• Childhood – Bone growth occurs at growth plates, a
flexible, firm connective tissue. The length and
shape of bones is determined by growth plates.
• Adolescence – Bones stop growing at the end of
adolescence – the growth plate becomes hard, then
arms and legs stop growing and the skull plates fuse
together.
• Adulthood – As people age, more bone is broken
down than is formed. Bones become less dense and
can break more easily.
Joints Connect Parts of the Skeletal
System
Joint – A place at which two parts of the
skeletal system meet.
Three Types of Joints:
Immoveable – locks bones together like puzzle
pieces. Ex: bones of skull
Slightly moveable – enables you to flex
slightly. Ex: ribs connected to sternum
Freely Moveable – joints that allow your body
to bend and to move. Ligaments hold the
bones together at moveable joints.
Ligaments & Tendons
• A ligament is a strong,
flexible band.
• A ligament links or
connects bones
together.
• A tendon is a cord
made of tough, white
tissue that attaches
muscles to bones.
• A tendon connects
muscles to bones.
The Skeleton
The Head
• Cranium – Also known
as the skull. Protects
the brain.
• Mandible – Jaw bone,
holds the teeth in
place. Works with the
upper mouth bone
called the maxilla
(mustache bone)
Vertebrae
• Four Sections – Cervical,
Thoracic, Lumber, Sacrum and
Coccyx
• The vertebrae consists of 24
individual bones followed by 5
fused bones of the sacrum and
4 fused bones of the coccyx
Sternum and Ribs
• Sternum - "chest" or breastbone is a long,
flat bone located in the center of the
thoracic (chest). It connects to the rib
bones via cartilage, forming the rib cage
with them, and thus helps to protect the
lungs, heart and major blood vessels from
physical trauma.
• Rib cage- Human ribcage consists of 24
ribs, 12 on each side, the sternum and the
12 thoracic vertebrae and floating ribs.
Clavicle and Arms
• Clavicle – also known as the
collar bone is classified as a
long bone that makes up part
of the shoulder girdle.
Arms
Arm – is also known as the humerus;
upper arm
Forearm - bones are the radius and
ulna; lower arm.
Radius is RAD and connects to your
thumb
Hands
• The hand
- consists of the
carpals, metacarpals, and
phalanges
• There are 8 carpal bones
• There are 5 Metacarpal bones
• There are 15 phalange bones
• They are identified by distal,
middle and proximal. The thumb
only has distal and proximal
phalange bones
Hips
• Hip Bone - is a large,
flattened, irregularly shaped
bone. It consists of three parts,
the ilium, ischium, and pubis
• It is one of the few ball and
socket synovial joints in the
body.
• It meets its fellow on the
opposite side in the middle
line in front, and together they
form the sides and anterior
wall of the pelvic cavity.
• The pelvic cavity also contains
the sacrum and coccyx
Legs
• The anatomy of the leg is similar to
the arm. The 4 bones of the leg are
the femur, the tibia, the fibula and the
patella.
• The femur - is the upper leg bone
which helps form the hip joint by
articulating (fit together) with the
pelvis. It is the largest ball and socket
joint in the body.
• The tibia - in the lower leg, supports
most of the body's weight
• The fibula - provides support for the
ankle and space for muscle
attachments.
• The patella - is the kneecap.
Feet
• The foot - consists of tarsal,
metatarsals and phalange bones
• There are seven tarsal bones, each
one has its own name. Calcaneus,
Talus, Navicular, Medial Cuneiform,
Intermediate Cuneiform, Lateral
Cuneiform, and the Cuboid.
• The Talus (ankle) - articulates with
Tibia and Fibula. Together with the
Calcaneus (Heel bone), they carry
most of the body’s weight.