Musculoskeletal system

Musculoskeletal system is formed by bones, bones connections, skeletal muscles. Musculoskeletal system ensures movement in space and support of the human body. Bones and the bones connections make passive part of the musculoskeletal system, bones perform the function of levers. Muscles - is an active part the musculoskeletal system, during the muscles contraction, perform body movements (changing the position of the bones). Musculoskeletal system is studied by such sciences as: osteology, myology, and arthrology , that are united in osteoartromiology.

The muscles of the arm and hand

The muscles of the arm and hand are specifically designed to meet the body’s diverse needs of strength, speed, and precision while completing many complex daily tasks. Activities such as lifting weights or heavy boxes require brute strength from the muscles of the arm. Writing, painting, and typing all require speed and precision from the same muscles. Complete athletic activities such as boxing or throwing a ball require arm and hand muscles to be strong, fast, and precise all at the same time.

The muscles of the upper arm are responsible for the flexion and extension of the forearm at the elbow joint. Flexion of the forearm is achieved by a group of three muscles – the brachialis, biceps brachii, and brachioradialis. These flexor muscles are all located on the anterior side of the upper arm and extend from the humerus and scapula to the ulna and radius of the forearm. Additionally, the biceps brachii operates as a supinator of the forearm by rotating the radius and moving the palm of the hand anteriorly. On the posterior side of the upper arm is the triceps brachii, which acts as an extensor of the forearm at the elbow and the humerus at the shoulder. The triceps brachii, as its name indicates, has three heads whose origins are on the scapula and humerus. These three heads merge to insert on the olecranon of the ulna.

The muscles of the abdomen, lower back, and pelvis

The muscles of the abdomen, lower back, and pelvis are separated from those of the chest by the muscular wall of the diaphragm, the critical breathing muscle. Lying exposed between the protective bones of the superiorly located ribs and the inferiorly located pelvic girdle, the muscles of this region play a critical role in protecting the delicate vital organs within the abdominal cavity. In addition to providing protection, these core muscles also function in movement of the trunk, posture, and stability of the entire body.

Extending across the anterior surface of the body from the superior border of the pelvis to the inferior border of the ribcage are the muscles of the abdominal wall, including the transverse and rectus abdominis and the internal and external obliques. Working as a team, these muscles contract to flex, laterally bend, and rotate the torso. The abdominal muscles also play a major role in the posture and stability to the body and compress the organs of the abdominal cavity during various activities such as breathing and defecation.

The muscles of the chest and upper back

The muscles of the chest and upper back occupy the thoracic region of the body inferior to the neck and superior to the abdominal region and include the muscles of the shoulders. These important muscles control many motions that involve moving the arms and head – such as throwing a ball, looking up at the sky, and raising your hand. Breathing, a vital body function, is also controlled by the muscles connected to the ribs of the chest and upper back.

The bones of the pectoral girdles, consisting of the clavicle (collar bone) and scapula (shoulder blade), greatly increase the range of motion possible in the shoulder region beyond what would be possible with the shoulder joint alone. The muscles of this region both allow for this range of motion and contract to stabilize this region and prevent any extraneous motion. On the anterior side of the thoracic region, the pectoralis minor and serratus anterior muscles originate on the anterior ribs and insert on the scapula. These muscles work together to move the scapula anteriorly and laterally during pushing, throwing, or punching motions. In the upper back region, the trapezius, rhomboid major, and levator scapulae muscles anchor the scapula and clavicle to the spines of several vertebrae and the occipital bone of the skull. When these muscles contract, they elevate the pectoral girdle (as in shrugging) and move the scapula medially and posteriorly toward the center of the back (as in rowing). The trapezius also contracts along the back of the neck to extend the head at the neck and hold it upright throughout the day.

The muscles of the head and neck

The muscles of the head and neck perform many important tasks, including movement of the head and neck, chewing and swallowing, speech, facial expressions, and movement of the eyes. These diverse tasks require both strong, forceful movements and some of the fastest, finest, and most delicate adjustments in the entire human body.

The muscles of the face are unique among groups of muscles in the body. While most muscles connect to and move only bones, facial muscles mostly connect bones to skin. These muscles, including the zygomaticus major and orbicularis oris, pull on the skin to produce a seemingly infinite number of facial expressions and to move the lips and cheeks during speech and eating.

Bones of the foot

The metatarsal bones

The metatarsal bones are five long, cylindrical bones in the foot. The bones make up the central skeleton of the foot and are held in an arch formation by surrounding ligaments. The metatarsal bones are joined to the toe bones at the metatarsophalangeal joint, or the knuckles on the toes.

The calcaneus

The calcaneus, or heel bone, is the largest of the ankle bones, or tarsus. It is located below the talus where it projects backward to form the base of the heel. It helps to support the weight of the body and provides an attachment for muscles that move the foot.

The fibula

The fibula is the long, thin and lateral bone of the lower leg. It runs parallel to the tibia, or shin bone, and plays a significant role in stabilizing the ankle and supporting the muscles of the lower leg. Compared to the tibia, the fibula is about the same length, but is considerably thinner. The difference in thickness corresponds to the varying roles of the two bones; the tibia bears the body’s weight from the knees to the ankles, while the fibula merely functions as a support for the tibia.

At the fibula’s proximal end, just below the knee, is a slightly rounded enlargement known as the head of the fibula. The head of the fibula forms the proximal (superior) tibiofibular joint with the lateral edge of the tibia. From the proximal tibiofibular joint, the fibula extends slightly medially and anteriorly in a straight line toward the ankle. Upon reaching the ankle, the fibula swells into a bony knob known as the lateral malleolus, which can be seen and felt protruding from the outside of the ankle joint. At the medial malleolus, the fibula forms the distal (inferior) tibiofibular joint with the tibia and also the talocrural (ankle) joint with the tibia and talus of the foot.

The tibia

The tibia, sometimes known as the shin bone, is the larger and stronger of the two lower leg bones. It forms the knee joint with the femur and the ankle joint with the fibula and tarsus. Many powerful muscles that move the foot and lower leg are anchored to the tibia. The support and movement of the tibia is essential to many activities performed by the legs, including standing, walking, running, jumping and supporting the body’s weight.

The tibia is located in the lower leg medial to the fibula, distal to the femur and proximal to the talus of the foot. It is widest at its proximal end near the femur, where it forms the distal end of the knee joint before tapering along its length to a much narrower bone at the ankle joint. The proximal end is roughly flat with the smooth, concave medial and lateral condyles forming the knee joint with the femur. Between the condyles is the intercondylar region, which includes the tibial spine and provides attachment points for the meniscus and anterior and posterior cruciate ligaments (ACL and PCL) of the knee. At the inferior edge of the lateral condyle is a small facet where the tibia forms the proximal tibiofibular joint with the fibula. This joint is a planar joint, allowing the tibia and fibula to slightly glide past each other and adjust the position of the lower leg.

The patella

The patella

The patella is the technical name for the kneecap, the triangular-shaped bone at the front of the knee joint. The patella is held in place by muscles, the lower end of which surrounds the patella and is then attached to the upper part of the tibia (shin) by patellar tendons. The patella protects the knee joint.

The femur

The femur, or thigh bone, is the longest, heaviest, and strongest bone in the entire human body. All of the body’s weight is supported by the femurs during many activities, such as running, jumping, walking, and standing. Extreme forces also act upon the femur thanks to the strength of the muscles of the hip and thigh that act on the femur to move the leg. The femur is classified structurally as a long bone and is a major component of the appendicular skeleton.