L1 Anatomy of Kidney (P2 Hard)

The kidney is a bean-shaped organ responsible for filtering waste products from the blood and producing urine. It's vital for maintaining fluid balance and electrolyte levels.

The lateral border of the kidney is convex, curving outwards, while the medial border is concave, curving inwards, and contains the hilum.

The hilum is a notch on the medial border of the kidney where blood vessels, nerves, and the ureter enter and exit.

The kidneys are located in the retroperitoneal space of the abdomen, extending from the T12 vertebra to the L3 vertebra. They are situated behind the peritoneum, the lining of the abdominal cavity.

The right kidney is slightly lower than the left kidney due to its proximity to the liver. This positional difference helps explain why the left kidney is sometimes slightly larger.

The kidneys are covered by three layers: the fibrous capsule, perirenal fat, and renal fascia. These layers provide protection and support to the kidney.

The fibrous capsule is the innermost layer surrounding the kidney. It's a thin, smooth membrane that helps to keep the kidney's shape and protect it from infection.

The renal fascia, also known as Zukercandle fascia, is a sheath of connective tissue outside the perirenal fat. It encloses the kidneys and adrenal glands, playing a crucial role in their structural support.

The renal artery is the main blood supply to the kidney. It branches from the abdominal aorta and divides into five segmental arteries, providing oxygenated blood to the kidney for filtering.

The renal vein carries deoxygenated blood and filtered waste products away from the kidney. It drains into the inferior vena cava, returning blood to the heart for circulation.

The left renal vein receives blood from the left adrenal vein, a branch of the inferior phrenic vein, and the left gonadal vein.

Lymph from the kidney flows through the para-aortic lymph nodes.

A tumor in the left kidney that spreads to the left renal vein can block blood flow in the gonadal veins, causing vein enlargement around the left testicle (varicocele).

Nerves carrying signals to and from the kidney, forming a network around the kidney.

Sympathetic nerves carry signals from the spinal cord to the kidney, located on the 10th to 12th thoracic nerves.

Parasympathetic nerves from the vagus nerve also reach the kidney via the renal plexus.

The renal hilum is located at the level of the transpyloric plane, 5 cm from the midline.

The upper pole of the kidney is 2.5 cm away from the midline and 5 cm above the hilum.

The lower pole of the kidney is 5 cm below the hilum and 7.5 cm from the midline.