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Article Three
Describes the arteries arising from the head.
O, esteemed one! Know that anatomists have said: When the great artery's *sa’id* (arm) portion, which is called the *sebâbeteyn* (carotid arteries), reaches the neck, each has become two branches; one named “front” and the other “back.” The front part then becomes two branches; one descends deeply to reach the tongue. The remainder disperses into the inner muscles of the lower jaw. And a portion is superficial, reaching the ear muscles and cheeks. With their numerous branches, they ascend to the crown of the head, and the arteries coming from the right join with the mouths of the arteries coming from the left in the middle of the head's summit, all uniting there. The posterior part (the branch going towards the head) also divides into two; one small and the other large. Most of the smaller portion rises toward the back, dispersing into the muscles surrounding the head joint. The remainder is directed toward the rear base of the brain, entering through numerous large openings near the *derz-i lâmi* (lamina dura).
The larger part proceeds directly from here, joining the network through the glottis opening located in front of the large opening. There, it has been woven and interlaced like a net upon layers of vessels adhering to one another layer by layer, spreading forward, backward, right, and left from the network. A pair of arteries from the aforementioned network then come together as before, penetrating the brain through the *zar* (membrane), dispersing within that delicate membrane in the parts of the brain. Then, until they reach what they call the ventricle of the brain, the narrow and clustered mouths of its ascending branches enter into the portions where the wide and large mouths of the venous branches descending from the crown of the head have entered and joined. For the Exalted God has made the veins servants (irrigation channels) to the arteries. The most beautiful form of the channel (*zarf*) through which the blood will flow from above downward is when it is in a head-down position.
The spirit arteries only signify the vital spirit. But since the spirit is subtle and mobile, its *zarf* need not be head-down. Perhaps if the spirit’s *zarf* were head-down, it would cause much depletion of the blood near it and make it difficult for the spirit to move from it. For the spirit's movement comes more easily upward. The benefits like warmth necessary for the brain have emerged from the spirit and spread there, sufficient movement and subtlety being present in the spirit. Therefore, the aforementioned network spreads beneath the brain, first allowing arterial blood to pause within it, warming and ripening with the spirit, resembling the temperament of the brain. Afterwards, it gradually comes between the bone and the tough membrane. From there, it enters the brain and disperses among the organs and senses located there. Those who contemplate and recall this arrangement and composition are amazed by it, deriving numerous lessons from it, and knowing that the Creator of this operation is capable of all things. And they know His grace and protection, [the One Who gives to everything the most beautiful forms and appearances] (Musavvir). They turn towards Him with the highest love, remaining in friendship and presence with Him always.