Muskuloskeletal System

Musculoskeletal SystemAs we already mentioned, for movement to happen we

need muscles and we need bones!

There are 206 different bones in the human body!

Musculoskeletal System

Our skeleton provides the body with 5 main functions:

- Movement

- Support

- Protection

- Production of blood cells

- Storage

FunctionsMovement

Bones give structure to our limbs and can therefore

act as levers that the muscles pull on to allow for

movement

FunctionsSupport

Bone’s rigid and sometimes flexible structure gives

our body shape and provides anchor points for our

muscles to attach to

FunctionsProtection

In addition to support, many bones act as hard

barriers to protect fragile internal organs

Ex: the skull protects the brain; the ribs protect the

lungs, heart, etc.

FunctionsProduction of Blood Cells

The bone marrow that is found in some types of bones

is where the blood components such as the RBC,

WBC and platelets are formed

FunctionsStorage

The hard tissues of bones help to store minerals such

as calcium and phosphorous while the internal

cavities store fats.

Bone Types

What is bone?

- A hard solid organ that forms part of the skeleton

- It is the hardest substance in the human body

- Mostly made up of bone cells

- These cells are continuously renewed, even in

adults

Bone Types

There are 2 main types of bone:

- Compact bone

- This type of bone is very dense

- Spongy bone

- This type of bone has lots of little cavities like

the pores in a sponge

The different bones in the body contain varying

amounts of compact and spongy bone

Categories of Bone

The bones in the body come in a number of different

shapes and sizes ranging from the tiny ossicles in the

ear, to the largest bone in the body: the femur.

There are 4 main categories of bone:

- Long bones

- Short bones

- Flat bones

- Irregular bones

Categories of Bone

Long Bones

- These bones are longer than they are wide

- Have a thin shaft called the diaphysis and two

rounded ends called the epiphyses

- Made mostly of compact bone with marrow in the

middle

- Examples: femur, humerus

Categories of Bone

Short Bones

- These bones are almost cubic in shape

- Made mostly of spongy bone

- Found primarily in the wrists and heels

- Examples: carpals

Categories of Bone

Flat Bones

- These bones are thin and flat; sometimes curved

- Like a sandwich: two layers of compact bone with

spongy bone in between

- Examples: skull and ribs

Categories of Bone

Irregular Bones

- Have a shape that does not fall into the other 3

categories

- Examples: vertebrae

Skull

Cervical vertebrae

Sternum

Xiphoid process

Lumbar vertebrae

Ilium

Sacrum

Coccyx

Pubis

Femur

Patella

Orbital cavity

Nasal cavity

Clavicle

Scapula

Rib

Humerus

Ulna

Radius

IschiumCarpals

Metacarpals

Phalanges

Fibula

Tibia

Tarsals

Metatarsals

Body Joints

The different bones of the body are connected in

various ways:

- These bones need to be held together firmly and

also provide mobility where necessary

- This junction between two bones is called the joint

Types of Joints

There are different types of joints depending on the

needs of the bones in question:

- Fixed joints (fibrous)

- Semi-movable (cartilaginous)

- Freely-movable (synovial)

Types of Joints

Fixed joints (fibrous)

- Like the bones in the skull

- The bones are only held together by a ligament

- There is no movement between the bones

Types of Joints

Semi-movable (cartilaginous):

- Like the joints between the vertebrae

- Connected using cartilage

- Provides some flexibility to allow for some

movement but not a lot

Types of Joints

Freely-movable (synovial):

- Allow for a much wider range of motion

- Most joints fall into this category

- There is synovial fluid between the joints to ease

the movement and cartilage on the ends of the

bones to cushion them

Types of Joints

Freely-movable (synovial):

- 4 main types of synovial joints:

- Hinge

- Pivot

- Ball and socket

- Saddle

Types of Joints

Freely-movable (synovial):

- Hinge joint:

- The convex end of one bone moves within the

concave end of another

- Can bend and straighten only

- Think of the hinge on a door

- Example: elbow

Types of Joints

Freely-movable (synovial):

- Pivot joint:

- The rounded part of a bone sits

within a ring

- The bone can rotate within the

ring

- Example: the neck

(vertebrae)

Types of Joints

Freely-movable (synovial):

- Ball and socket:

- The rounded end of a bone fits into the concave

end of another bone

- This allows for the widest range of motion

- Example: the shoulder

Types of Joints

Freely-movable (synovial):

- Saddle:

- Both bones involved have a saddle shape

- Concave in one direction and convex in the

other

- Example: the thumb

Other Connectors

- Ligaments

- Band of very fibrous, tough but flexible tissue that

holds together 2 bones (or cartilage)

- Tendons

- A strong, fibrous and flexible (but not elastic)

cord that attaches muscle to bone

Other Connectors

- Cartilage

- A firm connective tissue that is softer, more

flexible than bone and somewhat elastic

- Often used to keep tubes open (ex: trachea)

- Cushions joints

- Cartilage has no nerves or blood vessels

- Gets nutrition through diffusion

Problems of the Skeletal System

- Fracture

- This is when there is a complete or

partial break in the bone

- It could even be broken in several

places

Problems of the Skeletal System

- Dislocation

- When there is an abnormal

separation of bones at a joint

- Often occurs after a sudden

trauma (fall or impact)

Problems of the Skeletal System

- Sprain

- Damage to the ligaments at a joint

- It could be stretched or even torn

- Strain

- Stretched or torn muscle or tendon

Problems of the Skeletal System

- Arthritis

- Inflammation at the joints

- Osteoarthritis is a result of wear-and-tear to

the cartilage at the joints

- Rheumatoid arthritis is when the body’s

immune system attacks the lining (synovial

membrane) of the joints

Problems of the Skeletal System

- Scoliosis

- A condition where a person’s spine has a

sideways curve

Problems of the Skeletal System

- Osteoporosis

- A disease due to low bone mass and the

deterioration of bone tissue

- Increases the risk of fracture

- The best defense against osteoporosis is to

build strong bones as a child and adolescent!