The Skeleton and muscles

The Skeleton and muscles

By Naomi Keddy

The Muscles and skeleton working together to form the musculoskeletal system.

The Function the musculoskeletal system:

 The skeleton provides:

•    Support.
•      Protection of internal organs.
•     Rigid frame for movement.
•      Shape
•       Blood cell manufacture

The human contains 206 bones and it is divided into two parts which are the axial and appendicular skeleton.

The Axial skeleton is made up of the:

•       Skull,
•     Ribs (12 pairs),
•  Sternum (breastbone)

The appendicular skeleton contains the:

•   Pectoral girdle
•    Attached limb (arm)
•      Pelvic girdle
• Attached limb (leg)

  A Vertebrae is an animal with a backbone. The spine is a series of 33 bones (vertebrae).

There are Five Types of Vertebrae:

•   Cervical Vertebra: There are seven of these. The atlas is the first vertebra and supports the skull.
•     Thoracic Vertebra: There are twelve of these that articulate or connect with a pair of ribs.
•  Lumber Vertebra: There are five of these. They have a thick centrum for support and elongated diagonal methods for the attachment of abdominal muscles.
• Sacral Vertebra: There are five of these that are fused to form the sacrum which forms part of the pelvic girdle.
• Coccyx Vertebra: There are four of these that are fused to form the coccyx (tail).

Vertebrae are separated by discs of cartilage.

The twelve ribs are arranged as:

•   The first seven ribs connect with the sternum and are called true ribs.
• The next three ribs connect with the seventh rib and are called false ribs.
•  The last two ribs do not connect at the front and are called floating ribs.

The Composition of Bone:

 The shaft of the bone is called the diaphysis and the head of the bone is called the epiphysis.

Cartilage covers the end of the femur. It protects the ends of bones and allows friction free movement. Cartilage is made of a fibrous protein called collagen. Cartilage has no blood vessels or nerves.

 Types of bones:

• Compact bone is solid bone and is made of bone cells called osteoblasts in a matrix of salts and protein. This gives the bone strength and the protein gives the bone flexibility. Compact bone is found in the diaphysis of the bone.
•   Spongy bone is like compact bone but more porous it is hollow with bone marrow. Spongy bone is found in the epiphyses of the bone

•  Bone marrow is a soft material found in the medullary cavity of the diaphysis.

-Red bone marrow is where blood cells are produced

 -yellow marrow which is inactive and rich in fat.

The Growth of Bone:

• Osteoblasts are bone forming cells that produce the protein collagen. 
•  Growth plates made of cartilage are found between the epiphysis and diaphysis of a bone. Here, cartilage is formed and turned into bone.
• Osteoclasts are large cells that digest bone that lines the medullary cavity.

Arthritis

Cause:

There are many different types of arthritis:

•  Osteoarthritis is the most common, occurring in older people due to the wearing down of cartilage at synovial joints. The underlying bones become large and the joint swells and becomes stiff and sore.
•   Rheumatoid arthritis is an auto-immune disease.

Prevention:

·         Reduce damage to joints,.

Treatment:

•    Anti-inflammatory medication.
•  Rest.
• Weight loss.
•    Replacement of joint by surgery. 

Joints is where bone meet.

Joints

1. Immovable joints:  (Fixed or fused) joints such as the skull.

2. Slightly movable joints: joints such as those between vertebrae

3. Freely movable or synovial joints are joints such as:

·         Hinge Joints – E.g. elbow and knee. They allow movement in one direction only.

·         Ball and Socket Joints – E.g. shoulder and hip. These allow movement in all directions. 

Ligaments join bone to bone.

Tendons join muscle to bone.

There are Three Types of Muscles:

1. Skeletal Muscle: . It is also called striped muscle.. It is also called voluntary muscle.

2. Smooth Muscle: unstriped Muscle. It is also called involuntary muscle.

3. Cardiac Muscle: This is found in the heart. Cardiac muscle is involuntary. Cardiac muscle does not get tired 

An Antagonistic Pair: is two muscles that produce opposite effects.

• The biceps contracts to raise the forearm. it is a flexor.
• The triceps contracts to straighten the forearm. it is an extensor.