The shape of the human skull in octogenesis undergoes significant changes. During fetal development and in newly born children, the skull is more rounded, due to the fact that the brain is more developed in it and a larger volume of the cranium is required to accommodate it. The shape of the skull changes as teeth grow and chewing muscles become fixed.
Varieties of bones of the facial skull
In the skull there are facial and brain sections. The border lies between the posterior and orbital margins. The bones of the skull are flat. They are connected by sutures, which enable the growth of all cranial bones. After their ossification, growth stops.
The facial part of the skull consists of the nasal and oral cavities. Unpaired include:
- ethmoid bone;
- opener;
- hyoid bone.
From the pair stand out:
- upper jaw;
- nasal bone;
- incisal;
- tearful;
- zygomatic;
- pterygoid;
- palatine bone;
- lower jaw;
- turbinates.
Let's take a closer look at all the bones of the facial skull.
Upper jaw
This bone is a pair. It consists of a body and four processes. The body includes the maxillary sinus, which communicates with a wide cleft and the nasal cavity. The body consists of anterior, infratemporal, orbital and nasal surfaces.
The front surface is concave. On its border is the infraorbital margin, below which is the infraorbital foramen with nerves and vessels. Under it is a depression in the form of a canine fossa. On the medial edge, the nasal notch is well defined, in which the anterior opening of the nasal cavity is noticeable. The lower edge protrudes and creates the nasal spine.
From the orbital surface, the inferior orbital wall is created, which has a triangular smooth concave shape. In the region of the medial edge, it borders on the lacrimal bone, orbital plate and process. In the posterior part, the border runs along the inferior orbital fissure, from where the infraorbital sulcus begins. In front, it transforms into the infraorbital canal.
The infratemporal surface is created from the pterygopalatine and infratemporal fossae. In front, it is delimited by the zygomatic process. The tubercle of the jaw is clearly distinguished on it, from where the alveolar openings originate, passing into the corresponding canals. Vessels and nerves directed to the molars function through these channels.
The surface of the nose is formed by a complex relief. It unites with the bone of the palate and the lower concha of the nose, passing into the upper part of the palatine process. On the surface, a maxillary cleft in the shape of a triangle is clearly visible. Ahead is a well-defined vertical groove, which is connected to the inferior concha of the nose and the lacrimal bone.
Further, the bones of the facial skull continue with the frontal process extending from the body of the upper jaw at the convergence of the nasal, anterior and orbital surfaces. At one end, the process reaches the nasal part of the frontal bone. On the lateral surface lies the lacrimal crest, passing into the infraorbital region, delimiting the lacrimal sulcus. On the medial surface of the process is a cribriform ridge that connects to the zygomatic bone.
The zygomatic process, emerging from the jaw, also converges with the zygomatic bone.
The alveolar process is a thick plate, concave on one side and convex on the other, emerging from the jaw. Its lower edge is an alveolar arch with recesses (dental holes) for 8 upper teeth. The separation of the alveoli is provided by the presence of interalveolar septa. Outside, elevations stand out, especially pronounced in the area of the front teeth.
The sprout of the sky is a horizontal plate. It originates from the nasal surface, from where it passes into the alveolar process. Its surface is smooth from above and forms the lower wall of the nasal cavity. The medial edge bears a raised ridge of the nose, which creates the palatine process,uniting with the coulter edge.
Its lower surface is rough, and palatine furrows stand out on the back. The medial edge is connected to the same process on the other side, whereby a hard palate is created. The anterior edge contains a hole in the incisal canal, and the posterior one is merged with the palatine bone.
Palatine bone
The bones of the facial skull are paired and unpaired. The palatine bone is paired. It includes perpendicular and horizontal plates.
The horizontal plate has four corners. Together with the palatine processes, it makes up the bony palate. The horizontal plate below has a rough surface. The nasal surface, on the other hand, is smooth. Along it and on the process of the upper jaw there is a nasal crest, which passes into the bone of the nose.
The perpendicular plate enters the wall of the nasal cavity. On its lateral surface there is a large furrow of the palate. She, together with the furrows of the upper jaw and the process of the sphenoid bone, creates a large channel of the sky. There is a hole at the end. On the medial surface of the plate there is a pair of horizontal ridges: one is ethmoid, and the other is shell.
The orbital, pyramidal and sphenoid processes depart from the palatine bone of the facial part of the skull. The first runs laterally and forward, the second moves down, back and laterally at the junction of the plates, and the third runs back and medially, connecting to the sphenoid bone.
Opener
The vomer represents the unpaired bones of the facial skull. This is a trapezoidal plate that is located in the nasal cavity and creates a septum. The upper posterior margin is thicker than the other parts. It is divided in two, and the beak and crest of the sphenoid bone pass in the formed groove. The posterior edge separates the choanae, the lower one is connected by the crests of the nose with the palatine bone, and the anterior one - in one part with the nasal septum, and in the other with the plate of the ethmoid bone.
Nose bone
The paired bones of the facial skull are represented by the nasal bone, which creates the bony dorsum. It is a thin plate with four corners, the upper edge of which is thicker and narrower than the lower one. It is connected to the frontal bone, the lateral one - to the frontal process, and the lower one, together with the base of the frontal process, is the boundary of the aperture of the nasal cavity. The anterior surface of the bone has a smooth surface, while the posterior surface is concave, with a ethmoid groove.
Tearbone
These bones of the human facial skull are also paired. They are represented by a rather fragile plate in the form of a quadrangle. With it, the anterior wall of the orbit is formed. Anteriorly, it is united with the frontal process, above - with the edge of the frontal bone, and behind - with the plate of the ethmoid bone, the beginning of which covers its medial surface. On the lateral surface is a lacrimal crest with a lacrimal hook at the end. And ahead is the tear trough.
Chygoma
Another paired bone that unites the bonescerebral and facial skull. It is represented by the orbital, temporal and lateral surfaces, as well as the frontal and temporal processes.
The lateral surface has an irregular quadrilateral shape, the orbital surface forms the wall of the orbit and the infraorbital margin, and the temporal surface forms part of the infratemporal fossa.
The frontal process goes up, and the temporal process goes down. The latter with the zygomatic process forms the zygomatic arch. The bone with the upper jaw is attached to the jagged platform.
Lower jaw
This is the only movable cranial bone. It is unpaired and consists of a horizontal body and two vertical branches.
The body is curved in the form of a horseshoe and has both an inner and an outer surface. Its lower edge is thickened and rounded, and its upper edge creates an alveolar part with dental alveoli, which are separated from each other by partitions.
In front of the chin protrusion is located, expanding and turning into a chin tubercle. Behind there is a chin opening, behind which an oblique line extends.
In the middle of the inner part of the lower jaw, the mental spine is distinguished, on the sides of which there is an oblong 2-abdominal fossa. At the upper edge, not far from the dental alveoli, is the hyoid fossa, under which a weak maxillary-hyoid line originates. And below the line is the submandibular fossa.
The branch of the jaw is a steam room, it has anterior and posterior edges, outer and inner surfaces. Chewing tuberosity is found on the outside, and pterygoid tuberosity is found on the inside.
The branch ends with anterior and posterior processes that go up. Between them there is a notch of the lower jaw. The anterior process is coronal, pointed at the top. The buccal ridge is directed from its base to the molar. And the posterior process, condylar, ends with a head, which continues with the neck of the lower jaw.
Hyoid bone
The bones of the facial part of the human skull end with the hyoid bone, which is located on the neck between the larynx and the lower jaw. It includes the body and two processes in the form of large and small horns. The body of the bone is curved, with the anterior part convex and the posterior concave. Large horns go to the sides, and small ones go up, laterally and back. The hyoid bone is suspended from the cranial bones by means of muscles and ligaments. It is connected to the larynx.
Conclusion
When the bones of the facial skull are studied, anatomy attracts attention primarily with a complex relief on the outer and inner surfaces, which is explained by the fact that the brain, nerve nodes and sensory organs are located here.
The bones are immovable (except the lower jaw). They are securely fastened with various sutures in the skull and face, as well as cartilaginous joints at the cranial base.
