In this article, you can find out what the areas of the head are, how this part of the body is arranged and why did it even appear during evolution? The article begins with the simplest - basic information about the organization.
What is meant by the skeleton of the head or, more simply, the skull? This is a collection of many bones, paired or not, spongy or mixed. The skull contains only two large sections:
- cerebral (the cavity in which the brain is located);
- facial (this is where some systems originate, such as the respiratory or digestive systems; in addition, more sense organs can be found here.)
As for the brain department, it is worth mentioning that this area is also divided into two:
- crani;
- its foundation.
Evolution
It is important to know that vertebrates did not always have such a large head. Let's dive a little into the past. This part of the body appeared in ancient vertebrates during the fusion of the first three segments of the spine. Prior to this phenomenon, the samesegmentation. Each vertebra had its own pair of nerves. The nerves of the first vertebra were responsible for smell, the second - for vision, the third - for hearing. Over time, the load on these nerves increased, it was necessary to process more and more information, which led to a thickening of these segments responsible for these sensory organs. So they merged into the brain, and the union of the vertebrae formed a brain capsule (like a skull). Please note that the head of even a modern person is still divided into segments from which it was formed.
What is the average size of an adult human head? Length - 17-22 cm, width - 14-16 cm, height - 12-16 cm, circumference - 54-60 cm. The length of the head, as a rule, is greater than the width, so it is not round, but elliptical. It is also very interesting that the numbers (length, width and height) are not constant, they either increase or decrease. And it all depends on the location of the person.
Brain
Before moving on to the study of the areas of the head, it is worth saying that the head is not just considered the most important part of the body. After all, it is here that they are located:
- brain;
- visual organs;
- hearing organs;
- organs of smell;
- organs of taste;
- nasopharynx;
- language;
- chewing apparatus.
Now we will learn a little more about the brain. What is it and how is it arranged? This organ is made up of nerve fibers. Neurons (these are brain cells) are able to control the work of the entire human body by producingelectrical impulse. In total, twelve pairs of nerves can be observed that control the functioning of organs. The signals given by the brain reach their destination through the spinal cord.
The brain is in fluid all the time, which prevents it from contacting the cranium when the head moves. In general, our brain has pretty good protection:
- hard connective tissue;
- soft connective tissue;
- choroid;
- liquor.
The fluid in which our brain "floats" is called cerebrospinal fluid. The pressure of this fluid on the organ is considered to be intracranial pressure.
It is also important that the work of the brain and organs located on the head requires large energy costs. For this reason, we can observe intense blood circulation in this area. This is:
- Nutrition: carotid and vertebral arteries.
- Outflow: internal and external jugular veins.
So at rest, the head consumes about fifteen percent of the body's total blood volume.
Skull and muscles
The skeleton of the head (skull) has an equally complex structure. Its main function is to protect the brain from mechanical damage and other external influences.
The entire human cranium is made up of 23 bones. They are all motionless except for one - the lower jaw. As mentioned earlier, two departments can be distinguished here:
- brain;
- front.
The bones related to the facial region (there are 15 in total) canbe:
- paired - upper jaw, palatine bone, lacrimal, inferior nasal concha;
- unpaired - lower jaw, vomer, hyoid.
Paired bones of the medulla:
- parietal;
- temporal.
Unpaired:
- occipital;
- frontal;
- wedge;
- lattice.
The entire brain section consists of eight bones in total.
The cervical region, to which the skull is attached, allows the head to move. Movement is provided by the muscles of the neck. But on the head itself there are also muscle fibers that are responsible for facial expressions, one exception is the masticatory muscles, which are considered the strongest in this area.
Head areas
The whole head is conditionally divided into 13 areas. There are also distinguished paired and unpaired. And so, six of them are classified as unpaired areas.
- The frontal region of the head (the focus is on it in the next section of the article).
- Parietal (detailed information will be presented to your attention later).
- Occipital (discussed in more detail in a separate section of the article).
- Nasal, which fully corresponds to the contour of our nose.
- Oral, also matches the contour of the mouth.
- Chin, which is separated from the mouth with the help of the chin-labial groove.
Now let's move on to listing the seven paired areas. These include:
- Buccal region separated from the nose and mouth by the nasolabial sulcus.
- Parotid chewing (contours of the parotid gland and muscles responsible for the chewing reflex).
- Temporal region of the head (the contours of the scales of the temporal bone, located below the parietal region).
- Orbital (eye socket contour).
- Infraorbital (below the eye sockets).
- Zygomatic (cheekbone contour).
- Mastoid (this bone can be found behind the auricle, which, as it were, covers it).
Forehead region
Now we turn to a detailed examination of the frontal region of the head. The boundaries of the anterior section are the nasolabial suture, the supraorbital edges, the posterior section is the parietal region, the sides are the temporal region. This section even captures the scalp.
As for the blood supply, it is carried out through the following arteries:
- superblock;
- supraorbital.
They depart from the ophthalmic artery, which is a branch of the carotid. In this area, there is a well-developed venous network. All vessels in this network form the following veins:
- superblock;
- supraorbital.
The latter, in turn, partially flow into the angular and then into the facial vein. And the other part goes into the eye.
Now briefly about the innervation in the frontal region. These nerves are branches of the ophthalmic and are named:
- superblock;
- supraorbital.
As you might guess, they pass together with the vessels of the same name. Motor nerves - branches of the facial nerve, which have the name - temporal.
Parietal area
This area is limited by the contours of the bones of the crown. You can imagine it if you draw projection lines:
- before - coronal seam;
- rear - lambdoid seam;
- sides - temporal lines.
Blood supply is facilitated by arterial vessels, which are processes of the parietal branches of the temporal artery. Outflow - parietal branch of the temporal vein.
Innervation:
- before - terminal branches of the supraorbital nerve and frontal;
- sides - ear-vessel nerve;
- butt - occipital nerve.
Occipital region
The occipital region of the head is below the parietal, and is limited to the back of the neck. So, borders:
- top and sides - labd seam;
- bottom - the line between the tops of the mastoid processes.
Arteries contribute to the blood supply:
- occipital;
- back ear.
Outflow - occipital, and then - vertebral vein.
Innervation is carried out by the following types of nerves:
- suboccipital (motor);
- large occipital (sensitive);
- small occipital (sensitive).
Nervous system
The article briefly talks about the nervous system of some areas of the human head. See the table for more details. In total, the head contains 12 pairs of nerves that are responsible for sensations, the release of tears and saliva, the innervation of the muscles of the head, and so on.
| Nerve | Short explanation |
| Olfactory | Affects the nasal mucosa. |
| Visual | It is represented by a million (approximately) tiny nerve fibers, which are the axons of neurons in the retina. |
| Oculomotor | Protrudes like muscles that move the eyeball. |
| Block | Deals with nerves of the oblique muscle of the eye. |
| Threesome |
This is the most important nerve located on our head. It innervates:
|
| Diverter | Innervation of the rectus eye muscle. |
| Front |
Innervation:
|
| Vericochlear | It is a conductor between the receptors of the inner ear and the brain. |
| Glossopharyngeal |
Engaged in innervation:
|
| Wandering |
Has the mostwide area of innervation. Engaged in innervation:
|
| Extra | Motor innervation of the pharynx, larynx, sternocleidomastoid and trapezius muscles. |
| Sublingual | Due to the presence of this nerve, we can move our tongue. |
Circulatory system
Studying the anatomy of the head, one cannot ignore such a complex but very important topic as the circulatory system. It is she who provides blood circulation to the head, thanks to which a person can live (eat, breathe, drink, communicate, and so on).
For the work of our head, or rather for the brain, you need a lot of energy, which requires a constant flow of blood. It has already been said that even at rest, our brain consumes fifteen percent of the total volume of blood and twenty-five percent of the oxygen that we receive when breathing.
What arteries feed our brain? Basically it is:
- vertebrates;
- sleepy.
The same should happen and its outflow from the bones of the cranium, muscles, brain and so on. This is due to the presence of veins:
- internal jugular;
- external jugular.
Arteries
As already mentioned, vertebrates and sleepy animals are engaged in the nutrition of the human head.arteries, which are presented in pairs. The carotid artery is the basis of this process. It is divided into 2 branches:
- outer (enriches the outer part of the head);
- internal (passes into the cranial cavity itself and branches, providing blood flow to the eyes and other parts of the brain).
Blood flow to the muscles is carried out by the external and internal carotid arteries. About 30% of brain nutrition is provided by the vertebral arteries. Basilar provides work:
- cranial nerves;
- inner ear;
- medulla oblongata;
- cervical spinal cord;
- cerebellum.
The blood supply to the brain varies depending on the condition of the person. Mental or psychophysiological overload increases this indicator by 50%.
Veins
Considering the anatomy of the human head, it is hard to pass by a very important topic - the venous structure of this part of the body. Let's start with what the venous sinuses are. These are large veins that collect blood from the following parts:
- skull bones;
- head muscles;
- meninges;
- brain;
- eyeballs;
- inner ear.
You can also find their other name, namely, venous collectors, which are located between the sheets of the brain membrane. Leaving the cranium, they pass into the jugular vein, which runs next to the carotid artery. You can also distinguish the external jugular vein, which is slightly smaller and located in the subcutaneous tissue. This is where the blood collectsfrom:
- eye;
- nose;
- mouth;
- chin.
Generally speaking, everything that is listed above is called superficial formations of the head and face.
Muscles
To put it very briefly, all the muscles of our head can be divided into several groups:
- chewable;
- mimic;
- calvarium;
- sense organs;
- upper digestive system.
You can guess about the functions performed by their names. For example, chewing makes the process of chewing food possible, but mimics are responsible for human facial expressions and so on.
It is very important to know that absolutely all muscles, regardless of their main purpose, are involved in speech.
Skull
The entire skull, formed by the bones of the head, is divided into two sections:
- front;
- brain.
The first is located between the eye sockets and the chin, and forms the initial sections of some body systems (more specifically, the digestive and respiratory). In addition, the facial region is the site of attachment of some muscle groups:
- chewing;
- mimic.
What is located in this department:
- eye sockets;
- nasal cavity;
- oral cavity;
- tympanic cavity.
Special attention should be paid to the zygomatic bone, which is the place of attachment of the bulk of the muscles of the face. It is located below the orbit and performs an importantfunction - protecting the eye and nose from mechanical damage.
It is important to note the jaw, represented by the upper paired bone and the lower unpaired. The lower jaw is the only movable bone to which strong chewing muscles are attached.
Let's pay attention to the intermaxillary region, which is also called the deep part of the face. Restrictions:
- outer part - lower jaw branch;
- inner part - tubercle of the upper jaw;
- top - the lower surface of the greater wing of the sphenoid bone.
Briefly about the brain department, which is designed to protect the brain and other structures that are associated with it. The department is formed by 8 bones, the main ones are:
- occipital;
- parietal;
- frontal;
- temporal.
It is important to note that the skull is not solid, it has sinuses and openings that allow nerves and blood vessels to enter the brain. At the base of the skull of the human head is the foramen magnum, which connects the cranial cavity and the spinal canal.
