Details of Your Structural System
Can you visualize a human body without a structural system? Like the jellyfish, your body without a supporting structure would be a mass of jelly-like shapeless form. But, with the skeletal system, your body holds together to form an erectile moving form.
What is the Structural System?
The structural system consists of a body framework of bones with joints and cartilages that make up the skeleton. The system also contains skeletal muscles, connective tissues (ligaments and tendons), and synovial bursa to initiate body motions.
The structural system, therefore, is composed of skeletal and muscular structures. Both of these structures complement one another to cause body movements. They also maintain body position, whether sitting, standing, or sleeping.
The Skeletal Structure
In childhood, the skeletal structure consists of 270 bones. Later in life, some of the bones fuse, and the number of bones reduces to about 206. On the other hand, the number of muscles is above 600, which taking the best part of your body space and weight.
The main features of the skeletal structure are the bones and cartilages.
Every bone in the body is divided into two sections, the dense or compact part, which is the outer part of the bone, and the spongy-like part inside the bone.
The location and the shape of the bones determine the density of both the outer and inner parts of the bones. The nearer the surface, the thicker and sturdy the bone can be.
Since the compact bones are dense, the spongy bones balance the skeleton weight by their lightness.
Unlike other parts of the body, the bones continue forming for the best part of your lifetime, with the formation rate reducing after puberty. The bone formation and resorption go hand in hand to balance the capacity of your skeleton for a specified period.
After 25 years, the rate of resorption further increases against the rate of formation leading to the loss of bone density.
The bones in the skeletal structure are grouped into two main sections, the axial and the appendicular skeleton.
The Axial Skeleton
The axial skeleton is a collection of bones of the head and the vertebrate trunk.
Bones of the head - The bones of the head are the skull, middle ear ossicles, and the hyoid bone. The skull protects your brain and other tissues inside your head while shaping your head and facial structure.
The vertebrate trunk - It contains the breastbone (sternum), the rib cage (rib bones), and the vertebral column. The vertebrate trunk also protects the inner body organs from injuries.
The axial skeleton contains a total of 80 bones of crania, facial, ossicles, hyoid, thorax, and the vertebrae (sacrum and coccyx).
The Functions of the Axial Skeleton
The axial skeleton is the cover of the vital organs in its region. The bones of the axial skeleton protect the brain, the spinal cord, nerves, the heart, and other internal organs. The structural system cannot be complete without the axial skeleton. It contributes to the shaping and support of the structural system.
The axial skeleton provides an area for the attachment of your head, neck, and trunk muscles and bones. It also provides a surface for the attachment of muscles that move the head, neck, and trunk.
It is the axial skeleton that stores the body salts such as calcium. It also produces blood cells in the red bone marrow and stores fat as yellow bone marrow. While it provides part of your body posture, it is the basis for the upper body mechanical motions.
The Appendicular Skeleton
The appendicular skeleton consists of the pectoral girdle, the pelvic girdle, the upper, and the lower limbs.
The four parts of the appendicular skeleton also consist of other bones as per the following details:
The pectoral girdle, also known as the shoulder girdle is the connection between the upper limb and the axial skeleton. Bones of the pectoral girdle are:
Clavicles - The clavicle, which is also the collarbone, is a bone lying horizontally below your neck. You have two clavicles, one on the right and the other on the left. The clavicle bone connects the breastbone or the pectoral girdle with the shoulder blade or scapula.
Scapula - The scapula can also be called the shoulder blade, shoulder bone, blade bone, or even the wing bone. You have two scapulas on both sides of your shoulders. The triangular-shaped bone is located at the back of your shoulder. It connects the upper limb to the clavicle for support.
The Upper Limbs
The upper limbs are made up of several bones joined together to form the upper limb skeleton. The bones are:
Humerus. The humerus is one single bone of the arm that elongates from the shoulder joint to the elbow joint.
Forearm bones. Your forearm has two bones, the radius, and the ulna. The radius bone is the shorter of the two forearm bones. It articulates with the elbow joint on the upper end and the wrist section at the thumb side on the other end.
The ulna bone is the other piece of the two forearm bones. It is longer than the radius and slightly curved. It joins the humerus at the elbow joint on the upper side, and the wrist section. It articulates with the carpus (wrist) and the radius on the lower side of the pinky finger.
Hand bones. The hand skeleton has three sections, the carpus (wrist bones), metacarpus (palm bones), and phalanges (bones of the fingers).
The Pelvic Girdle. The pelvic girdle consists of three bones, which are ischium, ilium, and pubis. The pubis is the anterior bone of your pelvic girdle. The ilium is above the pubic bone and the most significant bone of the pelvic girdle, which shapes your hips. The ilium joins the sacrum to create a pelvic cavity wall.
The ischium is another bone in the pelvic girdle, located below the ilium and the pubis bones. It completes the 'wing' shape of the ilium bone.
The Lower Limb. The lower limb has three sections, thigh, leg, and foot. The entire lower limb has 30 pieces of bones. Get a closer look at the lower limb's three sections and all the bones that make up the lower limb right here below:
The Thigh (Upper Part). The thigh is the section that articulates the hip joint at the upper end and the knee joint on the lower end. It has only one large bone, the femur, which is the largest and the sturdy bone in the human body. The bone is sturdy enough to resist the pressure of up to 2,500 pounds.
The femur articulates with the hip bone by the ball-and-socket to create the hip joint. On the lower side, the bone articulates the kneecap and the tibia at the patella surface, forming the knee joint.
The Leg (Lower Part). The leg starts from the knee joint to the ankle joint. It contains two pairs of bones, the tibia, and the fibula.
Tibia. It is a larger and more substantial bone and the one that bears the body weight compared to the fibula. It comes second to the femur, which is the largest bones in the body. Tibia is nearer to the skin that you can quickly feel it.
Fibula. Fibula is the smaller bone of the two of your lower leg. It is connected to the tibia on the upper side and the ankle bone and tibia on the lower side, forming the ankle projection. It is lighter, smaller, and slender compared to its pairing bone.
The Foot. The foot has three sections which are:
Forefoot - The forefoot is the part that bears the five toes or phalanges and hence having the five metatarsals bones that precede the phalanges. Metatarsals are longer than the phalanges. The phalanges are bones that form the toes.
Midfoot - From the forefoot, the foot extends to the midfoot. The midfoot contains five bones that form the pyramid-like foot arch. The bones are three cuneiform bones, the navicular, and the cuboid bone.
Hindfoot - The hindfoot, also known as the rear foot, makes up the ankle and the heel. The talus is the ankle bone, which also articulates with the tibia and fibula and hence supporting them. The calcaneus is the largest bone in all the foot bones. It is the heel bone that articulates with the midfoot bones, talus and cuboid to create a joint called subtalar.
Cartilage is a fibrous and rubber-like connective tissue. It is a smooth tissue that covers the end of the long bones and some joints such as the ankles knees and elbows.
The rib bones have cartilage as well. The seven pairs of the rib cage, also known as the 'true ribs,' have cartilages at the meeting point with the breastbone or sternum. Some other bones that have cartilages are the ankles, knees, and elbows.
The bones of a developing embryo are in cartilage form, which later changes and becomes the typical compact/spongy type.
Cartilages are in three different types:
Elastic. The type of cartilage is in the larynx, epiglottis, and the external ear.
Fibro. It is part of the joint capsules, intervertebral discs, and ligaments structures.
Hyaline. The most common cartilage is the precursor bones of an embryo. It is also found at the ribs joints, nose, trachea, and larynx.
Cartilages play different roles depending on their locations, for instance:
Shock absorber. The cartilage cushion bones and prevent causing stress on each other, especially during strenuous activities such as weight-lifting or joints of heavy-weight people.
Smooth motions. It provides a lubricated surface for bones to glide on one another without causing damage during bone movement.Enter your text here ...
A joint is a point of articulation between two bones. While most bone joints enable bone movements, others have immovable joints such as the skull plate joints.
Different Categories of Movable Joints
You have 360 bone joints altogether, both movable and immovable. The movable joints are further categorized to differentiate them from one another according to their activities:
Fibrous. The fibrous joints are immovable (synarthrodial). Although they are held together by ligaments, you cannot move the joints. As we had mentioned, the plates of your skull are immovable joints known as sutures. Another example of this kind of bone joint is the tooth, which joins its bony socket.
Cartilaginous. The cartilaginous joint is a slightly movable (synchondroses) joint held together by cartilages. The two joining bones have cartilages at their point of articulation. Examples of a cartilaginous joint are the manubrium joint that articulates the clavicle and the sternum joint that articulates the ribs.
Synovial. The synovial are the prevalent joints in your body. The name originates from the synovial fluid in the joints. The bone joints that contain a synovial capsule with synovial fluid are entirely moveable. Synovial joints have a type of cartilage known as hyaline cartilage at the joint's point of articulation to provide flexibility.
Synovial joints are further classified into six categories, considering how they move and their shape.
- Hinge Elbow, knee, fingers, and toes are hinge joints. They move in one direction, also called the flexion movement.
- Ball/socket The joint has a ball-shaped articulation point that fits into a bone with a cup-like end. Examples of such a joint are the hip and shoulder joints.
- Pivot It is a joint with rotational movement with one bone rotating on the other. An example of such a bone joint is the atlas and axis joint at the top of the neck.
- Condyloid The type of joint has flexion and extension or abduction and adduction type of movement. An example is the joint of the wrist, which articulates with the carpal bones.
- Saddle The movement of the joint is flexion and extension or abduction and adduction. The joint has a saddle-like appearance with one bone resting on the other one. An example of such a joint is your thumb.
- Gliding Just like the name, the joints have gliding movement. The bones connect at almost plane-like flat surfaces to glide in different directions. An example of such a joint is the intervertebral joints while articulating with one another.
A ligament is a connective tissue of tough and coarse fibrous band that fastens a bone to another at the joint. The connective fibrous band of a ligament is composed of some fibrocytes (cells of connective tissue that produce collagen) and collagenous fibers.
Ligaments are elastic and stretchable fibers that allow bones flexibility during movement. As you age, your ligaments can stiffen, grow short, or lose collagen hence causing stiff joints.
The Muscular Structure
The bones are rigid and cannot make any movement or motion without the muscular structure. Muscles have significant functions in your body, such as assisting body parts in moving.
Despite causing movement, the muscles also play other significant roles in our bodies, such as enabling the heart to pump blood.
Every muscle in the body has a unique role it plays to the adjacent body part attached to it. It is the location of the muscle tissue that defines its purpose and category.
Three Muscles Categories
All the muscles in your body are classified into three categories.
Visceral Muscle. Visceral muscles are smooth muscles and are not striated, and neither are they banded as compared to the next two kinds.
The unconscious part of the brain controls the visceral muscles, which makes them involuntary muscles. The examples of such muscles are the muscles in your blood vessels that help the blood circulation, stomach muscles, and intestines muscles that both help in digestion.
The functions of the visceral muscles are not intense compared to other muscle tissues and hence being the weakest muscles.
Cardiac Muscle. The cardiac muscle is the muscle of the heart, also known as the heart muscle. Just like the visceral muscles, the cardiac muscle contraction is involuntary. The cardiac muscle enables your heart to pump non-stop.
The heart muscle has rhythmic contraction regulated by the natural heart's pacemaker in the heart called the sinoatrial node. The sinoatrial node responds to an autonomic nervous system for the control of heart rate speed.
Skeletal Muscles. The skeletal muscles are voluntary muscles under the control of your somatic nervous system. The brain sends signals to your nervous system to initiate your muscle's actions. Most of the skeletal muscles are banded with crossed long and fine fibrous forming regular patterns.
Every muscle, just like any other body tissue, gets blood circulation services through arteries, veins, and capillaries.
Most muscles differ in sizes and shapes due to what they do and their location.
Shape - Some muscles have a distinctive shape from others. An example is the shoulder muscle known as the deltoid muscle, which has a triangular-rounded form. Another unique type of muscle is the serratus muscle that moves and rotates the shoulder blade. It attaches the shoulder blade to some of the ribs giving it a saw-like shape.
Size - Some of the muscles from the same region can only be told apart by their sizes — for instance, the three muscles of the gluteal region. The gluteus maximus is the large muscle of the three muscles and the most massive muscle in your body. The gluteus medius is the medium size muscle, and the gluteus minimus is the smallest of the three.
Three Major Functions of Skeletal Muscles
The skeletal muscles have various functions in your body. Three of its services are:
Movement. One of the significant tasks of your skeletal muscles is to move your movable body parts. The muscles contract and relax using tendons attached to the bones to cause movement.
Maintain Position and Posture. The skeletal muscles do not always contract to cause movement. In some cases, a muscle can contract to maintain body position and posture. For instance, the head muscles contract to hold the head still. Also, the abdomen and pelvis muscles contract to keep the abdominal and other organs in position.
Maintaining Body Temperature. The muscular system maintains body temperature. When your muscles contract, they generate about 85 percent of your entire body heat. Shivering is as a result of muscles contracting to generate heat during low body temperature.
Your smooth muscles of the blood vessels also relax to allow more blood flow to regulate the heat on the skin.
For the muscles to initiate activities, they attach to the bones by use of some connective tissues called tendons.
At each end of a muscle, there is a tendon. Tendons are connective tissues connecting a muscle to the bone and are distributed in all of your entire body. Some of the tendons are small, while others are large ones.
The largest tendon in your body is the Achilles tendon. It is the tendon of the calf muscle that attaches to your heel bone.
The tendons are primarily a mass of strong parallel collagen fibers that can resist damage from any strenuous pulling during heavy activities. However, some of the strenuous activities can cause friction between a tendon and its bone and hence the need for lubricating fluid from a bursa.
A bursa is a sac-like cavity filled with some fluid at the bone joints similar to the white of a raw egg. The number of bursae in your body is more than 150. Frequent movement activities between bone to bone, tendons to bones, and muscles to bones can cause friction on the gliding surfaces.
The fluid from the bursa provides smooth movement by lubricating the area the tissues rub against one another.
The bursae have size variations due to their locations. For instance, the largest bursa in your body is the iliopsoas bursa located at the hip joint.
There are four types of bursae, synovial, adventitious, subcutaneous, and submuscular bursae. A synovial bursa is the most common bursa in most parts of your body.
The Structural System Diseases
Your structural system, like any other body system, is susceptible to diseases that can affect its proper performance in your body.
Some of the disorders are:
Arthritis Arthritis is the disease of the joints. It can cause swelling and tenderness to your bone's joints. Although it can occur at any age, it is most common among aged persons. There are two types of arthritis, osteoarthritis, and rheumatoid arthritis.
Osteoarthritis It is a form of arthritis that affects more people than any other type. The disease gradually wears and breaks down the cartilage. The most affected joints by osteoarthritis are the hips, knees, hands, and the spine. It is a progressive disease that worsens over time. Age, genetics, and obesity are some of the risk factors of osteoarthritis.
Rheumatoid Arthritis It is a disease that causes inflammation on the joints and can also affect other areas of your body, such as the skin and the lungs. Rheumatoid arthritis is an autoimmune disease that affects your bone lining and can erode your joints.
Over time, the disease can degenerate to cause joint deformities such as deforming the fingers, the knees, and other joints. Various infections can trigger the autoimmunity, which can attack your joint lining (synovium) to wear it down and hence cause friction among the articulating bones.
Tendinitis Tendinitis, like its name, affects your tendons. It causes inflammation and tenderness to the tendons. The disease mostly affects the joints on your shoulders, elbows, wrists, knees, and also the heels.
Repetitive motions on one joint while doing certain activities can strain the tendons and hence cause tendinitis.
Bursitis Bursitis is the inflammation of your bursa. The disease mostly affects the shoulder joints, elbows, and knees. Seek medical attention when you hurt on the joints after walking or performing activities. The condition can also affect your heels or any other most active joint.
Osteoporosis Osteo means bones, and hence osteoporosis is the disease of the bones. Like its name, the bones become porous and fragile, exposing them to fractures. Osteoporosis is a progressive disease that wears down the bones to the extent of reducing bone density.
You may not notice the existence of the disease until your bones get more porous and weaken to the extent of breaking without a substantial reason. Some of the osteoporosis symptoms are back pain as an effect of a collapsed or broken vertebra and gradual loss of height due to bones wearing down.
Muscular Dystrophy Muscular dystrophy is a disease that progressively weakens the muscles by loss of muscle mass. The disease most common in childhood can be caused by mutation of abnormal genes, which can affect protein production for muscle development.
Muscle stiffness, delayed growth, walking on toes, large calf muscles are some of the symptoms of muscular dystrophy.
Your structural system helps you to make movements and perform other activities. Any circumstance that can deny you mobility is the worst thing and most regrettable that can happen to you.
It is, therefore, imperative to keep watch on your health to maintain your structural system to its best state for effective performance.
You can prevent some of the disorders that can affect your structural system. Eating healthily and being active can maintain your bones and muscles. Don't forget to include sunshine and calcium in your diet to strengthen your bones.
Reach us at Island Healthworks Natural Health Clinic by dialing our number +250.468.7685 for all your structural system concerns or any other questions. We offer an on-telephone consultation if you are unable to visit our clinic.
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Editor: Yvonne Dollard Perc
Research Assistant: Elizabeth Njuguna
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This article is intended for educational purposes and the information contained within is not intended to treat, diagnose or cure any disease or health problem. Please seek appropriate medical attention for any health complaints. We cannot take responsibility for your health care decisions. Our intent is only to offer health information to help you with your search for better health.