Final answer:
The middle layer of the fibrous pouch that encloses the kidney is called the cortex.
Step-by-step explanation:
The middle layer of a fibrous pouch that encloses the kidney and has a layer of fat to protect the kidney is called the cortex.
Externally, the kidneys are surrounded by three layers: the outermost layer is the renal fascia, the second layer is the perineal fat capsule, and the third layer is the renal capsule.
Internally, the kidney has three layers: an outer cortex, the middle medulla, and the inner renal pelvis.