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**Third Article**
[130/a] It describes the remaining five pairs of nerves emanating from the brain.
"O esteemed one! Know that anatomists have stated: Of the brain’s nerves, the third pair emerges from the common boundary in the middle of the brain, traversing through the front, back, and roof of the brain. Initially, it mingles somewhat with the fourth pair, then separates from it, dividing into four branches. The first branch exits through the orifice that the ‘uruk-i sibati’ (a specific structure) will enter, descending through the neck, passing through the diaphragm, and distributing itself to the internal organs located beneath it. The second branch emerges from the opening of the zygomatic bone and joins a nerve separating from the fifth pair, as will be explained later. The purpose of the third branch is for the nerves found on the front of the face; it exits through the orifice from which the second pair originates, not passing through the vacant aperture of the most precious nerve – the optic nerve (first pair) – but rather presses against its cavity, perfectly fitting and closing it. This branch divides into three sub-branches upon separating from that opening.
The first sub-branch inclines towards the outer corner of the eye, toward the ear side; distributing itself to the muscles of the cheekbones, two tear ducts, two eyelids, eyebrows, and forehead. The second sub-branch travels along the inner angle of the eye through the openings (those apertures near the end of the eye), passing into the nose and blending with the skin within the nose. The third sub-branch is a large nerve that descends into the cavity present in the zygomatic bone, dividing into two branches. One branch enters the oral cavity, reaching the upper teeth and the flesh within their roots, branching as it goes.
The other branch spreads to the external organs, such as the cheekbones, nasal tips, and skin of the lips. These are the three parts of the third branch of the third pair. The fourth branch of the third pair passes to the tongue through the opening in the upper jaw, spreading across its surface, and the tongue receives the sense of taste from it. Its excess extends to the flesh within the teeth of the lower jaw and into the inner surface of the lower lip. The fourth branch to the tongue is finer than those going to the eye, so the nerve going to the tongue is firmer than the one going to the eye. And this firmness corresponds with its firmness, being equal in degree.
The origin of the fourth pair is behind the third pair, inclined towards the base of the brain. After mingling somewhat with the third pair, it separates from it and, when it ascends to the palate, it gains a sense of the palate from it. This fourth pair is smaller and firmer than the third pair.
Each nerve of the fifth pair exists as a single pair, emerging from both sides of the brain and attaining form. The first portion of each of these pairs rests upon the membrane within the ear, distributing itself within it; hearing originates from it. The second portion is smaller than the first, penetrating the opening called ‘a’ver’ or ‘a’ma’ in the hyoid bone. Upon exiting that opening, it mingles with the third pair of nerves. And the majority of these two are directed towards the cheek muscle. The remainder spreads between the eye and ear (temples).
The sixth pair originates from the posterior aspect of the brain, adjacent to the fifth pair, emerging through the opening at the end of the ‘derz-i lâmi’ (limbus) and dividing into three parts. One portion reaches the muscles of the throat and the root of the tongue to support the movement of the seventh pair. The second portion is distributed to the shoulder muscles. The third portion is larger than the previous two, rising at the point where the carotid artery rises and attaching to it. [583] From it [130/b], while descending into the internal organs, branches separate when it reaches the level of the hyoid bone, connecting to the muscles that lift the hyoid with its cartilages. As it descends further, branches emerge again when it reaches the level of the hyoid, reaching the muscles covering and opening the third cartilage of the larynx. Therefore, according to medical scholars, its name is ‘asab-i râji’ (the returning nerve).
This nerve does not originate from the spinal cord but descends from the brain, so that it may be found straight and possess strength. This nerve belongs to the sixth pair, because its beginning is soft and its end curved, preventing it from descending firmly and smoothly, thus lacking the capability of emerging and descending. The wisdom in retracting this branch is to grant firmness and strength to the nerve. The strongest of the returning nerves is that which spreads to the muscles covering the larynx. Then, the excess of this nerve descends, its branches going to the diaphragm and the membranes and muscles of the chest; from there it spreads to the heart, lungs, aorta, and arteries. The remainder passes into the coccyx, joining the branches descending from the third pair (mentioned above), spreading to the membranes of the internal organs, and ending in the flat bone called ‘azm-i arîdî’ (hip bone).
The origin of the seventh pair is between the brain and the spinal cord, common to both; many of its branches reach the muscles that move the tongue. From there they branch out and spread to the muscles common to the ‘azm-i derkî’ (thyroid cartilage) and ‘azm-ilam’ (resembling the letter L in the Greek alphabet). A small remaining portion is distributed to the nerves adjacent to them. This wondrous arrangement and intricate intermingling of systems has attained order through the power and wisdom of the All-Powerful Creator (Hâlik and Bârî)."