
This article comes with a self-assessment enabling you to test your knowledge after reading it This article, the fourth in an eight-part series, looks at the adrenal glands. These vessels originate from two lymphatic plexuses – one deep to the capsule, and the other in the medulla.The endocrine system comprises glands and tissues that produce hormones for regulating and coordinating vital bodily functions. Lymph drainage is to the lumbar lymph nodes by adrenal lymphatic vessels. Sympathetic innervation to the adrenal medulla is via myelinated pre-synaptic fibres, mainly from the T10 to L1 spinal cord segments. The adrenal glands are innervated by the coeliac plexus and greater splanchnic nerves. The right adrenal vein drains into the inferior vena cava, whereas the left adrenal vein drains into the left renal vein. Right and left adrenal veins drain the glands.

Zona glomerulosa – produces and secretes mineralocorticoids such as aldosterone.Functionally, the cortex can be divided into three regions (superficial to deep): It secretes two cholesterol derived hormones – corticosteroids and androgens. The cortex and medulla synthesise different hormones. Medulla – derived from the ectodermal neural crest cells.Cortex – derived from the embryonic mesoderm.They are two separate endocrine glands, with different embryological origins: The outer cortex and inner medulla are the functional portions of the gland. The adrenal glands consist of an outer connective tissue capsule, a cortex and a medulla. Veins and lymphatics leave each gland via the hilum, but arteries and nerves enter the glands at numerous sites.
