The organism of the living beings of the animal kingdom is constituted by four main parts, the head, the trunk and the extremities; The latter in turn are divided into anterior or superior and posterior or inferior, depending on whether they are animals or humans, in which the fact of managing to evolve to standing has led to a more advanced level of evolution of structures such as the hands. And feet.
The limbs are elements that allow carrying out important actions such as maintaining posture, changing position, as well as walking, jumping or running.
Superior limbs
The upper limbs are joined to the trunk through the glenohumeral joint or shoulder joint, which is formed by the union of three bones: the clavicle forward, the scapula back and the humerus on the outside, these three bones form what is known as the shoulder girdle.
The upper extremities are made up of several segments, the arm, the forearm, the wrist, and the hand.
Arm. The arm is the segment between the shoulder and the elbow, it contains a single bone, the humerus and a group of muscles responsible for flexing and extending the forearm over the arm.
Forearm. It is located between the elbow and the wrist, it consists of two bones, the ulna and the radius, it is capable of rotating movements that allow the palm of the hand to be placed up or down, which is known as supination and pronation respectively.
Wrist and hand. The wrist comprises a series of 8 bones that form the carpus, a structure that joins the ulna and radius to form this joint. The hand, on the other hand, is a very complex structure that ends in five appendages known as fingers, it constitutes the quintessential tool of human beings since it allows us to eat, do our different activities and even thanks to them the blind can read and identify objects and dumb communicate.
Lower extremities
The lower limbs are attached to the trunk by its lower part or pelvis, through the hip joint, in which the iliac bone and the femur intervene. Like the upper limb, the lower one is made up of segments:
Thigh. It is located between the hip and the knee, the bone that gives it its shape is the femur, there are inserted several very powerful muscles that are necessary both for walking and for standing.
Leg. It is located between the knee and the ankle. It is made up of two bones, the tibia and the fibula, to which are attached a group of muscles that allow the foot to be extended or flexed; the leg is attached to the latter through the ankle joint.
Foot. Just as the hand is a very complex structure that involves several bones, muscles and ligaments to stabilize these structures, the foot also has a soft tissue distributed throughout the plantar region that acts as a cushion to cushion the impact when moving.
Photos: iStock - NKS_Imagery / Eraxion
