The Skeletal System

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JUST FYI

The skeleton on the previous slide was taken from a GRADE 5 science website. It is the VERY MINIMUM you should know.

The Skull

At birth the bones of the skull, or cranium, have spaces between themThis allows them to move and make the baby’s head smaller as it passes through the birth canal

The Skull

Some of these bones fuse in the months following birth, but the rest of the cranium is not completely fused until adolescence (teens)

Spinal Column

To cope with the constant pressure of standing upright, the vertebral column has 2 distinct curves.One is in the neck region (Cervical Curve)

Spinal Column

The other is in the lower back (Lumbar Region)

The S- shape of the spine allows it to carry more weight

Spinal Column

The vertebrae in the lower back are bigger as they carry more weight than those in the neck

The regions of the spine are:

VERTEBRAL COLUMN

Divided into 5 regions(1)Cervical spine (7)(2)Thoracic spine (12)(3)Lumbar spine (5) (4)Sacrum (5)(5)Coccyx (4)

The 5 sacrum vertebrae and 4 coccyx vertebrae are fused to form one solid bone.

The Thorax

The ribs of the chest connect with the vertebral column at the back and the sternum at the front via cartilage

The cartilage allows the chest to expand and contract as we breathe

The Thorax

The lower ribs do not attach at the front, and are known as floating ribs.Their job is to protect the heart and lungs.There are 12 pairs

of ribs in the average adult skeleton

The ShoulderThe connections of the shoulder blade, collar bone, sternum and humerus form the shoulder girdle

This enables the arm to move in a wide circle

The Shoulder

The shoulder blades (scapula) do not meet the vertebral column directly, but are attached to it by strong muscles

The Arm & Hand

The arrangement of bones in the arm allows rotation movements, such as turning a door handleThere are 60 bones in the arms, 54 of these are in the hands

The Arm & HandThe hand is very flexible because the bones in it are so smallThe most significant factor is the position of the thumb on the handIt (the thumb) allows for a larger range of manipulations to occur

The Pelvis

The hips bear the weight of the head, arms and trunkThe Pelvis is actually constructed of three bones fused together: the ilium, ischium and the pubis

The PelvisThe Pelvis is broader in femalesThe joint where the Femur meets the Pelvis is a Ball & Socket joint.The joint is under constant strain as it allows for movement whilst supporting the trunk

Legs & Feet

The largest. Strongest and heaviest bones in the body are the FemursThe leg bones are arranged in a similar fashion to the arms & hand

Legs & FeetThe rotation of the hip is more limited than the shoulderThe Knee joint absorbs more stress than any other part of the bodyThe foot bones are also much more rigid than those in the hand because they bear more weight

Exercise & Bones

By the late teens, skeletal growth is almost completeActivities that are weight- bearing in nature and high impact (gymnastics, running, basketball, etc) are believed to be of the greatest benefit in bone formation

Exercise & Bones

These types of activities help bones form heavier mineral deposits with thicker layers of compact bone

**This reduces the risks of fractures and osteoporosis later in life

Exercise & Bones

Weight / Resistance training can also have positive effects on bone mass through the stress placed upon the bones during muscular contractions

Exercise & Bones

Note: However, irreversible joint damage is known to occur, particularly in young males who have not finished growing when they undergo strenuous weight training…. So be careful!!!