The pituitary gland sits at the base of your brain, behind the bridge of your nose and directly below a brain region called the hypothalamus. Despite being only about the size of a pea, it controls hormone production throughout your body, which is why its exact position matters for understanding everything from pregnancy changes to tumor symptoms.
Exact Position Inside the Skull
The pituitary gland rests inside a small, saddle-shaped pocket of bone called the sella turcica. This bony compartment is part of the sphenoid bone, a butterfly-shaped bone that stretches across the base of your skull roughly behind your eyes and nasal passages. The sella turcica wraps around the gland on three sides, giving it a protected seat deep within the skull.
A thin sheet of tissue called the diaphragma sellae stretches over the top of this bony pocket like a roof, separating the gland from the brain above. A narrow stalk called the infundibulum pierces through this tissue roof to physically connect the pituitary to the hypothalamus. This stalk carries both blood vessels and nerve fibers, allowing the hypothalamus to send chemical and electrical signals that tell the pituitary which hormones to release and when.
What Surrounds the Gland
The pituitary’s neighbors are what make its location clinically important. Directly above the gland, just a few millimeters away, lies the optic chiasm, the crossing point where the optic nerves from each eye meet before heading to the back of the brain. This tight proximity explains why a pituitary tumor growing upward can press on those nerve fibers and cause vision problems, particularly loss of peripheral vision on both sides, blurred vision, or difficulty seeing colors.
On either side of the pituitary sit the cavernous sinuses, channels of venous blood that also carry major nerves controlling eye movement and facial sensation. The internal carotid arteries, major blood suppliers to the brain, run through these sinuses as well. When pituitary tumors grow sideways, they can push into the cavernous sinus, potentially compressing these arteries and nerves. This is one reason surgeons pay close attention to the lateral boundaries of the gland on imaging scans.
Two Lobes in One Gland
The pituitary is actually two distinct structures fused together. The front portion, called the anterior lobe, makes up roughly 80% of the gland and produces hormones that regulate growth, thyroid function, stress responses, and reproductive cycles. The back portion, the posterior lobe, doesn’t manufacture its own hormones. Instead, it stores and releases hormones made by the hypothalamus, including one that controls water balance in your kidneys and another that triggers contractions during labor.
These two lobes even develop from different tissues during fetal growth. The anterior lobe forms from tissue in the roof of the developing mouth, while the posterior lobe grows downward from brain tissue. They meet and fuse together early in development, but they retain separate blood supplies and different relationships to the hypothalamus throughout life.
How the Gland Changes Size
The pituitary isn’t a fixed structure. Its volume shifts measurably across life stages. In non-pregnant adults, the gland measures roughly 300 cubic millimeters on MRI. During pregnancy, the anterior lobe enlarges progressively as it ramps up production of the hormone that prepares the body for breastfeeding. By the third trimester, the gland’s volume can reach about 700 cubic millimeters, more than double its usual size. It gradually shrinks back over several months after delivery.
The gland also tends to shrink with age, and its volume can increase slightly during puberty. These normal fluctuations matter because radiologists need to know what size is expected for a given patient before flagging anything as abnormal on a brain scan.
Why Location Matters for Surgery
The pituitary’s position behind the nasal passages is actually convenient for surgeons. When a pituitary tumor needs to be removed, the most common approach is transsphenoidal surgery, a procedure that reaches the gland through the nose rather than opening the skull. A surgeon passes a thin endoscope through the nostril, travels along the nasal septum, and enters the sphenoid sinus, the hollow air space directly in front of the sella turcica. From there, a small piece of the sella turcica bone is removed to expose the gland.
This route works because the sphenoid sinus sits immediately in front of the pituitary, separated by only a thin wall of bone. The entire path from nostril to gland is essentially a straight line through air-filled cavities, avoiding any need to move brain tissue aside. Most patients go home within a few days, and because no external incision is made, there’s no visible scar.
How to Picture It
If you placed your finger on the bridge of your nose and imagined pushing straight back about three inches into your skull, you’d arrive roughly at the pituitary gland. It sits almost exactly at the geometric center of your head when viewed from the front, tucked into its bony cradle just below the brain. For such a small structure, its central, well-protected position reflects how essential it is: a hormonal command center wired directly to the brain, shielded by bone, and surrounded by some of the most critical blood vessels and nerves in the body.