16.5 Musculoskeletal System

The muscles and bones allow for movement.

The weight of the body is supported by the bones of the skeleton.
The muscles of the muscular system contract and pull on the bones, allowing for a wide range of movements.

It can be very difficult to deal with an injury or disease.

Malnutrition can affect the development and maintenance of bones and muscles.

Other diseases affect the joints, such as arthritis, which can make movement difficult and, in advanced cases, completely impair mobility.

Joint replacement surgery in the hips and knees is the most common surgery for artificial joints.

Replacement joints for shoulders, elbows, and fingers are also available.

There are 206 bones in the human skeleton.

The body's internal structure is more similar to that of insects.
The skeleton provides support to the body, storing minerals and lipids, producing blood cells, protecting internal organs, and allowing for movement.
The bones of the animal's body are divided into two parts, the axial skeleton and the appendicular skeleton.

You can view the following digital 3D sculpturing.

The bones of the skull, ossicles of the middle ear, hyoid bone, and vertebral column are shown in blue.

The skeleton of the appendix is shown in red.

The skull is made of bones.

The head and neck muscles are attached to the brain by the cranial bones.
In the adult they are tightly jointed and there is no movement of the adjoining bones.

There are two malleus bones, two incus bones, and two stapes on each side of the auditory ossicles.

The sense organs of the eyes, mouth, and nose are provided by facial bones.

It acts as a base for the tongue and is connected to other muscles.

The airway and gut are controlled by the mandible.

The bones are the 24 vertebrae, the sacrum, and the coccyx.

Each body has a large hole in the center through which the spine goes down.
The hole contains nerves that exit from the back of the neck.
There is a notch on each side of the hole through which the nerves can exit.

The spine is 70 cm in length in adults and can be seen from a side view.

There are intervertebral discs between the second and the sacrum.

The discs act as a cushion to absorb shocks from movements such as walking and running.

The heart and lungs are protected by the thoracic cage.

It provides support for the shoulder girdles and upper limbs and serves as the attachment point for the muscles of the back, chest, neck, and shoulders.
The breastbone is a flat bone in the chest.
The skull is formed from many bones in the embryo.
The ribcage is made of 12 pairs of long curved bones that curve toward the front of the body.
The anterior ends of most ribs are connected by Costal Cartilage.

The upper and lower limbs are attached to the body through the pectoral, shoulder, and pelvic girdles.

The collarbones and the shoulder blades are in the anterior.

The upper limb has bones of the arm, forearm, and hand.

The longest bone in the upper limb is the humerus.
It has a joint at the elbow and at the shoulder.
The forearm extends from the elbow to the wrist.
The bones of the hand include the wrist, palm, and fingers.

Since it is responsible for carrying the weight of the body and for being able to walk, the Pelvis is attached to the skeleton by strong ligaments.

It has deep sockets and strong ligaments that attach to the femur.
There are two large hip bones in the pelvic girdle.
The pubic symphysis is where the hip bones join together in the anterior of the body.

The lower limb includes the thigh, leg, and foot.

The bones of the lower limbs are stronger than those of the upper limbs to support the weight of the body.
The thighbone is the strongest bone in the body.
The shinbone and kneecap form the knee joint at its other end.

The movement of limbs and the stability found in the bones of the skull are caused by joints.

Depending on their structure or function, there are two ways to classify joints.

Depending on the material of the joint and the presence or absence of a cavity in the joint, the joints are categorized into three groups.
Most fibrous joints are only capable of minor movements because there is no space between the bones.

The so-called "disks" of the spine are found at the joints between the back of the neck.

Very little movement is allowed by cartilaginous joints.

The joint cavity is filled with fluid.

The fluid lubricates the joint.
The ends of the bones are covered by a capsule.
The joints are able to move the most.
synovial joints include knees, elbows, and shoulders.

Different types of movements can be produced by the wide range of movement allowed by the synovial joints.

The angle between the bones of a joint can change.
Flexion occurs when the angle between the bones decreases.
The forearm can be moved upward at the elbow.
The angle between the bones of a joint is called extension.
The movement of a bone is called rotational movement.
The movement of the head is an example of rotation.

Medical doctors who specialize in the diagnosis and treatment of disorders of the joints, muscles, and bones are called rhumatologists.

They diagnose and treat a variety of diseases, including arthritis, osteoporosis, and ankylosing spondylitis.

Rheumatoid arthritis affects the joints of the hands, feet, and spine.

Affected joints become stiff and swollen.
Although it is known that the body's immune system mistakenly attacks healthy tissue, the exact cause of the disease is not known.
Immune cells from the blood can enter joints and cause inflammation.
The bones rub against each other causing pain.
The age of onset for RA is between 40 and 50 years for women and between 40 and 50 years for men.

Symptoms such as joint inflammation and pain, x-ray, and blood tests can be used to diagnose RA.

A contrast agent, such as a dye that is opaque to x-rays, is used in arthroscopy.
The soft tissue structures of joints can be visualized.
The surface of soft tissues lining the joint is different from a regular x-ray.
Changes in joint cartilage can be detected before bones are affected.

rheumatologists have a number of treatment options to choose from.

Treatments that reduce the symptoms of the disease and those that reduce the damage to bone and cartilage are the ones that are divided.

It is possible to treat early stages with rest of the affected joints through the use of a cane.
Exercise can be used to strengthen the muscles around the joint when inflammation is low.
If joint damage is more extensive, medications can be used to relieve pain.
Aspirin, pain killers, and injections are some of the anti- inflammatory drugs that may be used.
In cases of severe joint damage, surgery may be required.
Doctors are using drugs to reduce the damage to bones caused by the disease.
The drugs all act to reduce the impact of the autoimmune response by reducing the number of T lymphocytes, a cell of the immune system.

Muscles allow for movement and facilitate bodily processes.

There are three types of muscle in the body.

Skeletal muscle cells are long and cylindrical, they have multiple nuclei, and the small, dark nuclei are pushed to the center of the cell.

Smooth muscle cells have a single nucleus at each end.
Cardiac muscle cells are short and cylindrical.
The nucleus of the cell can be found in the center of the cell.

Voluntary muscle is also called skeletal muscle because it can be controlled.

Skeletal muscle tissue has a striped or striated appearance when viewed under a microscope.
The arrangement of the proteins inside the cell leads to this appearance.
The cells of skeletal muscle are long and have multiple nuclei.

Smooth muscle has no striations and is not under control.

There is a single nucleus in smooth muscle cells.

The muscles of the heart pump blood throughout the body.

Cardiac muscle is striated, but unlike skeletal muscle, it can't be consciously controlled.
The cells of cardiac muscle are connected to each other through intercalated disks.

Skeletal muscle fiber is a cell in the body.

The entire length of the muscle fiber is run by myofibrils.
The sarcolemma is surrounded by a muscle fiber.
There are many fibrils in a muscle fiber.
The cell's striated appearance is due to the orderly arrangement of the proteins in each unit.

The striated appearance of muscle tissue is caused by repeating bands of the actin and myosin.