Axial Skeleton: What It Is, Parts And Characteristics
The skeleton or skeletal system is a biological system that provides support, support and protection to soft tissues and muscles in living organisms.
Vertebrates have an internal skeletal system (endoskeleton) made up of bones, while arthropods have chosen the exoskeleton as an evolutionary adaptation, a complex layer composed mainly of chitin, which gives these animals protection, support and the possibility of breathing.
The functions of the skeleton in humans are multiple: mechanical support, production of movement, protection, metabolic storage of substances such as calcium and formation of blood cells. In the bone marrow (which is located inside many bones) are found hematopoietic stem cells, which, when differentiated, give rise to all circulating blood bodies. This includes lymphocytes, platelets and red blood cells, among others.
Thus, the functionality of the skeleton in vertebrates goes far beyond postural maintenance. Today we tell you everything about the axial skeleton the one that makes up the central axis of the human body and allows us to remain upright in three-dimensional space.
The human skeleton is made up of a total of 206 bones, each and every one of them with a different morphology, from the femur of the thigh (the longest in the body) to the stapes (the smallest), which forms the middle ear. . In an adult human being, the skeletal system accounts for 15% of the body weight: if a man has a mass of 75 kilos, 9 of them will correspond solely to bone matter.
Bones are composed of 98% extracellular matter (mainly based on hydroxyapatite and collagen) and only 2% of their tissues are cells themselves, that is, osteoblasts, osteoclasts and osteocytes (responsible for renewing the bone matrix). Due to its percentage of predominantly mineral matter, bone structures store 99% of the body’s calcium
On the other hand, there are 2 parts in the human skeleton:
Thus, following this small list, we could define the axial skeleton as the set of bones that make up the central axis of the human body The term “axial” comes from the Latin word axis, which refers to a central point from which the rest of the structures and formations are distributed in a stable manner. Without this main axis, the limbs would have no points to anchor to, so the name fits this skeletal system like a glove.
Parts of the axial skeleton
The axial skeleton is made up of the skull, vertebral column, ribs, and sternum We show you the particularities of each of these subsystems in the following lines.
1. Skull
The bones of the skull make up a bony box that protects the brain and It gives us the facial structure, which in turn makes it possible to see, breathe, swallow, make sounds and basically perform all the functions that define us as living beings In zoology, we really talk about osteocranium and not just a skull, since other animals have cranial structures analogous to ours that are not completely ossified.
In turn, the cranial bones are divided into 2 large groups based on their functionality: the neurocranium and the splanchnocranium. The first is the one that contains the brain and the cranial meninges, and is composed of the occipital, sphenoid, squamous, mastoid, parietal and frontal bones. Perhaps the frontal bone is the most famous of all, because, as its name indicates, it occupies our forehead and the occipitofrontal muscle is inserted on it, which allows the raising of the eyebrows and the expression of many emotions.
On the other hand, The splanchnocranium refers to the part of the skull that contains the anterior part of the digestive and respiratory systems Also known as the viscerocranium, it has the following bones: ethmoid, lacrimal, vomer, maxilla, zygomatic, tympanic portion, temporal styloid and mandible.
The rib cage is made up of a total of 24 ribs (12 on each side of the body plane) and the sternum, making a total of 25 total bone bodies Costal cartilages are also included in this ultrastructure, although they are not materials made from bone.
The rib cage has an eminently protective function, since it safeguards the most important organs in the entire human body: the heart and lungs. It also provides an anchoring point to the bones of the shoulders (and therefore to the upper extremities), serves as an attachment point to the diaphragm and the muscles of the chest, back, neck and arms. Without a doubt, the physiology of the human being could not be conceived as it is today without the rib cage.
The sternum also deserves special mention, a long, flat, pointed bone that serves as the insertion site for almost all of the ribs (except the last 2 pairs, which are therefore known as floating). In humans, this bone is made up of 3 sections: the handle or manubrium, the body and the xiphoid process or process, which has a very variable shape.
3. Spine
At birth, most human beings come into the world with 33 vertebrae, but throughout development some of these fuse, giving a total of 24 in almost all cases.
Broadly speaking, the spine can be differentiated into several sections: the cervical (7 vertebrae that make up the neck), the thoracic (12 vertebrae) and the lumbar (5 vertebrae). Finally, the sacrum and coccyx are presented, the latter being a “vestigial” remains of the tail of ancestral mammals.
Spinal column provides protection to the spinal cord and nerve roots, which allow communication of all parts of our body with the brain In addition to this, it is also the support base for ligaments, tendons and muscles. On the other hand, the spine is a structural support, allows flexibility and mobility at the level of the trunk and is an excellent center for the storage of minerals and the production of red blood cells.
The axial skeleton summarized in 6 points
If the information previously provided seemed a little confusing to you, don’t worry: it is normal, since the skeletal apparatus stands out for its anatomical complexity. As long as you remember these 6 essential points, you will know the basics of the axial skeleton:
Thus, the axial skeleton has a total of 80 bones, as we indicated at the beginning. Although we have focused on the bony elements that make up the skull, spine and rib cage, you should also not forget that the ear and hyoid bones are also part of this central axis.
If anything can be made clear about the human skeleton, it is that this It is a true work of art of biomechanics Each small bone structure fulfills not just one, but several functions and, no matter how small, it is essential to understand human physiology in all its meanings.
The axial skeleton is made up of a total of 80 bones and 3 large sections, but You should also not forget that the appendicular skeleton exists, with a total of 126 bone structures that enable locomotion and effort, among many other things.
