İKİNCİ FEN · İKİNCİ BÂB · BİRİNCİ FASIL · İkinci Madde
Second Article
Concerning the Skull and its Characteristics.
O beloved! Know that anatomists have stated:
The purpose of all the bones in the skull is to cover the brain, protecting it from dangers.
The fact that the skull consists of many pieces has numerous benefits:
The first benefit is that if a portion of the skull were injured or damaged, the entire skull would not be affected. For if the skull were composed of a single bone, any danger would affect it equally throughout and become a complete calamity. The second benefit is – as the meaning requires – that no bone should possess such contradictory aspects in hardness and softness, size and smallness, thinness and thickness. The third benefit is that it allows thick and dense vapors to escape from the brain. For if it were a solid bone, these vapors could not pass through, and their odor would corrupt the brain. The fourth benefit is that it provides passage and route for the veins and arteries leading into the inner parts of the head.
The natural shape of the skull being circular has two benefits: The first is that the area of a circle and what it contains is greater than that of equal straight-lined shapes. The second is that a circular shape is less affected by external influences and remains more stable, as it is known.
The skull bone has been created in a circular form, corresponding to its length, for the organs of the brain are also elongated. The curved portions extending from its front and back sides are to protect the nerves descending from either side. This shape has three true sutures (derz), and two false ones as well.
The first of the three true sutures resembles a crown (iklîli) or coronal suture, shared with the forehead. Thus:
It is also called the coronal suture.
The second suture is the dividing (sehmî) suture. It is straight and divides the coronal suture lengthwise into two. Thus:
Because it adjoins the coronal suture, it is also called the sagittal (sukûtî) suture.
The third suture is shared between the back of the head and its base (kaide). [114/a] It is shaped like an angle, with the point of the angle adjoining the sagittal suture. Thus:
Because this marking resembles the Greek letter “lambda,” it is called derz-i lâmi.
The two false sutures descend lengthwise parallel to either side of the sehmî suture and do not completely penetrate the bone head; therefore, they are also called kishreyn. They appear in this manner when they adjoin the three true sutures.