A projecting ridge or fin on the bottom of the hull of a boat or ship that improves directional control and is often weighted for added stability. 2. The principal structural member of an aircraft, resembling a ship's keel in shape and function.
The outer, reddish region, next to the capsule, is the renal cortex. This surrounds a darker reddish-brown region called the renal medulla. The renal medulla consists of a series of renal pyramids, which appear striated because they contain straight tubular structures and blood vessels.
On the medial margin of the kidney is concave region called the renal hilus. The renal hilum is the entrance to the renal sinus. Structures such as the renal veins, artery, nerves and lymphatic vessels are located in the renal hilum.The renal sinus is a fat-filled cavity inside the kidney that extends from the hilum.At the hilum the ureters also exit the kidney.The kidney is covered by a fibrous renal capsule.tructures such as the renal veins, artery, nerves and lymphatic vessels are located in the renal hilum. The renal sinus is a fat-filled cavity inside the kidney that extends from the hilum. At the hilum the ureters also exit the kidney. The kidney is covered by a fibrous renal capsule.