Quick Facts
The inner zone of the medulla is the part of the renal medulla farthest in from the cortex, containing the innermost part of the loop of Henle and of the medullary collecting tubule (Dorland, 2011).
Related parts of the anatomy
Structure and/or Key Features
The inner zone of the renal medulla primarily consists of the descending and ascending thin limbs of the nephron loop, medullary collecting ducts, straight arterioles, and peritubular capillary bed. Straight arterioles tend to be absent near the tips of the renal papillae. Proximal and distal straight tubules are typically only found in the outer medulla (Dudek, 2006).
Unlike the striated appearance of the outer medulla, the inner medulla has more of a homogenous appearance, which tapers down to a blunt point before projecting into the pelvis of the ureter (Moffat, 1975).
Anatomical Relations
The inner zone of the renal medulla surrounds the renal pelvis and lies subjacent to the outer zone of the renal medulla.
Function
The hypertonic environment of the inner medulla compared to the glomerular filtrate facilitates the reabsorption of water (Pocock et al, 2013).
References
Dorland, W. (2011) Dorland's Illustrated Medical Dictionary. 32nd edn. Philadelphia, USA: Elsevier Saunders.
Dudek, R. W. (2006) High-yield KidneyLippincott Williams & Wilkins.
Moffat, D. B. (1975) The Mammalian KidneyCambridge University Press.
Pocock, G., Richards, C. D. & Richards, D. A. (2013) Human Physiology, 4 edition. OUP Oxford.
