The SkeletonThe Skeleton

FactsFacts• Without your skeleton Without your skeleton

you would be a you would be a shapeless sack of flesh.shapeless sack of flesh.

• It consists of 206 It consists of 206 bones, held together at bones, held together at joints by strong fibres joints by strong fibres called ligaments.called ligaments.

• The bone that sticks The bone that sticks out at the bottom of out at the bottom of your spine is the your spine is the remains of your tail and remains of your tail and is called the coccyx.is called the coccyx.

Your SkeletonYour Skeleton

Functions Of The Functions Of The SkeletonSkeleton•The skeleton has four main roles:The skeleton has four main roles:

– SupportSupport– ProtectProtect– MovementMovement– Blood ProductionBlood Production

SupportSupport• It forms a It forms a

framework to framework to support your support your body and give it body and give it strength.strength.

• It performs a It performs a similar role to similar role to steel girders in a steel girders in a tall building.tall building.

ProtectionProtection• Some parts of your Some parts of your

body are delicate body are delicate and can get easily and can get easily damaged.damaged.

• Your cranium Your cranium protects your brain.protects your brain.

• Your ribs and Your ribs and sternum protect sternum protect your heart and your heart and lungs.lungs.

MovementMovement• Your muscles are Your muscles are

firmly attached to firmly attached to your skeleton.your skeleton.

• Muscles work by Muscles work by contracting or contracting or getting shorter.getting shorter.

• When they contract When they contract they pull on bones.they pull on bones.

• This makes the This makes the bones move.bones move.

Blood ProductionBlood Production• Some bones Some bones

contain red bone contain red bone marrow.marrow.

• This makes red This makes red cells, white cells cells, white cells and platelets for and platelets for blood.blood.

• The ribs, vertebrae, The ribs, vertebrae, humerus and femur humerus and femur all have some red all have some red bone marrow.bone marrow.

Types of bonesTypes of bones•Four types of bones in your skeleton.Four types of bones in your skeleton.•Your bones are different shapes and Your bones are different shapes and

sizes because they have different sizes because they have different jobs to do.jobs to do.

•They are divided into four groups:They are divided into four groups:– LongLong– ShortShort– FlatFlat– IrregularIrregular

Long BonesLong Bones• They have a They have a

diaphysis, epiphyses diaphysis, epiphyses and a hollow centre.and a hollow centre.

• Your height, shoe size Your height, shoe size and glove size depend and glove size depend on long bones.on long bones.

• Examples:Examples:• Upper and lower arm, Upper and lower arm,

collar bone, ribs, collar bone, ribs, metacarpals and metacarpals and phalanges.phalanges.

Short BonesShort Bones• These are small and These are small and

squat.squat.• These are spongy These are spongy

bones covered with bones covered with a thin layer of a thin layer of compact bone.compact bone.

• They are light and They are light and very strong.very strong.

• Examples:Examples:• Carpals and tarsals.Carpals and tarsals.

Flat BonesFlat Bones• These are also These are also

spongy bones spongy bones between two layers between two layers of compact bone.of compact bone.

• They have a large They have a large surface area.surface area.

• Examples:Examples:• Scapula, pelvis and Scapula, pelvis and

cranium.cranium.

Irregular BoneIrregular Bone• These are spongy These are spongy

bones inside and bones inside and compact outside.compact outside.

• They are specially They are specially shaped to suit the shaped to suit the job they have to do.job they have to do.

• Examples:Examples:• Patella and the Patella and the

vertebrae.vertebrae.

The Vertebral ColumnThe Vertebral Column• Down the back of your skeleton is the Down the back of your skeleton is the

backbone or vertebral column.backbone or vertebral column.• It has several jobs to do.It has several jobs to do.

– It must be able to bend and twist. So it is It must be able to bend and twist. So it is made up of 34 small bones instead of one long made up of 34 small bones instead of one long one called vertebrae.one called vertebrae.

– It must be strong, to support your body parts. It must be strong, to support your body parts. So it is curved. Therefore it is stronger. (Think So it is curved. Therefore it is stronger. (Think of arches in bridges)of arches in bridges)

– It must protect the spinal cord, the bundles of It must protect the spinal cord, the bundles of nerves running down from your brain. They nerves running down from your brain. They have a hole for this in their design. have a hole for this in their design.

Parts of the vertebral Parts of the vertebral columncolumn

• The vertebrae are The vertebrae are divided into five divided into five groups, each with groups, each with a different job.a different job.

• Cervical Cervical • ThoracicThoracic• Lumbar Lumbar • Sacrum Sacrum • CoccyxCoccyx

Cervical VertebraeCervical Vertebrae

•This supports the neck and the This supports the neck and the head.head.

• It allows the most movement.It allows the most movement.• It allows you to bend and tilt your It allows you to bend and tilt your

head and look over your shoulder.head and look over your shoulder.•There are 7 bones in this part of There are 7 bones in this part of

the spine.the spine.

Thoracic VertebraeThoracic Vertebrae

•Your ribs are connected to these.Your ribs are connected to these.•They do not move much.They do not move much.•This is because its main job is to This is because its main job is to

protect your heart and lungs and protect your heart and lungs and stop them from getting squashed.stop them from getting squashed.

•There are 12 bones in this part of There are 12 bones in this part of the spine.the spine.

Lumbar VertebraeLumbar Vertebrae•These are big bones.These are big bones.•Their job is to support the rest of Their job is to support the rest of

the spinal column.the spinal column.• Its design allows plenty of twisting Its design allows plenty of twisting

and turning.and turning.•Powerful back muscles attach to the Powerful back muscles attach to the

wings at each side.wings at each side.•There are 5 bones in this part of the There are 5 bones in this part of the

spine.spine.

SacrumSacrum

•The bones in this part are fused The bones in this part are fused together to make one.together to make one.

• It is then fused to the pelvic girdle.It is then fused to the pelvic girdle.•This makes a solid base for the This makes a solid base for the

trunk and legs.trunk and legs.•There are 5 bones in this part of There are 5 bones in this part of

the spine.the spine.

CoccyxCoccyx

•Once again all the bones are Once again all the bones are fused together to make one.fused together to make one.

• It is the remains of a tail that It is the remains of a tail that you we once had when we were you we once had when we were apes.apes.

•There are 5 bones in this part of There are 5 bones in this part of the spine.the spine.

Other Bones of the Other Bones of the SkeletonSkeleton• The cranium or brain case is made of 8 flat The cranium or brain case is made of 8 flat

bones.bones.• The lower jaw bone is hinged so you can The lower jaw bone is hinged so you can

chew.chew.• You have 12 pairs of ribs. All are joined to You have 12 pairs of ribs. All are joined to

your vertebrae at the back. Ten pairs are your vertebrae at the back. Ten pairs are joined to your sternum at the front and the joined to your sternum at the front and the bottom two do not attach at the front and bottom two do not attach at the front and are called floating ribs.are called floating ribs.

• The patella is not attached to any other The patella is not attached to any other bone.bone.