p'es of the fourth ventricle

Two prolongations of the pia situated on the roof of the fourth ventricle near the median line. They are covered by a layer of epithelium, p. of the obturator nerve. A p. formed by the union of a branch of the obturator nerve, the nerve of the sartorius muscle, and the internal saphenous nerve, p. omental is. Sympathetic fibers in the omenta, p. ophthalmic us. A p. made up of sympathetic fibers and branches of the ciliary nerves surrounding the ophthalmic artery and optic nerve, p. simplici imus. An anastomosis between two nerves by the transfer of one bundle of fibers to the other. p. thyroideus impar. A venous p. derived from the inferior thyroid veins, and situated beneath the isthmus of the thyroid gland, p. thyroideus inferior. A p. formed of branches of the middle cervical ganglion which surround the external carotid and inferior thyroid arteries and are distributed to the larynx, pharynx, and thyroid gland.