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Pituitary fossa

The pituitary fossa, also known as the hypophyseal fossa, is a central depression on the superior surface of the sphenoid body that houses the pituitary gland (hypophysis). It forms the core component of the sella turcica, providing bony protection and anatomical support to the pituitary gland and its neurovascular connections.

The pituitary fossa plays a crucial role in the hypothalamic–pituitary axis, accommodating the pituitary gland, pituitary stalk, and surrounding dural reflections. Its size and shape vary with age, sex, and physiological states, but normally maintain well-defined smooth margins.

Synonyms

  • Hypophyseal fossa

  • Sella turcica (central component)

  • Pituitary seat

Location and Structure

  • Position: Midline depression on the superior aspect of the sphenoid body

  • Anterior boundary: Tuberculum sellae

  • Posterior boundary: Dorsum sellae

  • Lateral boundaries: Cavernous sinuses

  • Superior relation: Diaphragma sellae and optic chiasm

  • Inferior relation: Sphenoid sinus

  • Floor: Thin bony plate separating pituitary gland from sphenoid sinus

Relations

  • Superiorly: Diaphragma sellae, optic chiasm, suprasellar cistern

  • Inferiorly: Sphenoid sinus

  • Laterally: Cavernous sinuses and intracavernous internal carotid arteries

  • Anteriorly: Tuberculum sellae and chiasmatic sulcus

  • Posteriorly: Dorsum sellae and posterior clinoid processes

Function

  • Provides a bony housing for the pituitary gland

  • Maintains structural stability for pituitary–hypothalamic connections

  • Protects endocrine structures from mechanical injury

  • Serves as a critical anatomical landmark in skull base imaging and surgery

MRI Appearance

T1-weighted images:

  • Pituitary gland: Intermediate signal intensity, slightly higher than brain parenchyma

  • Posterior pituitary: Intrinsic bright spot due to neurosecretory granules

  • Pituitary stalk: Intermediate signal, centrally located

  • Pituitary fossa bone: Low signal (dark cortex)

  • Surrounding cavernous sinuses: Intermediate signal with flow voids from ICA

T2-weighted images:

  • Pituitary gland: Intermediate-to-slightly hyperintense compared to gray matter

  • Posterior pituitary bright spot: Usually less conspicuous than on T1

  • CSF in suprasellar cistern: Bright

  • Sphenoid sinus (air): Low signal

  • Bony margins of fossa: Low signal cortical outline

STIR:

  • Pituitary gland: Intermediate-to-dark signal

  • Surrounding fat: Suppressed

  • CSF: Bright

  • Bone cortex: Dark

  • Provides clear contrast between gland, CSF, and adjacent soft tissues

T1 Fat-Saturated Post-Contrast:

  • Pituitary gland: Homogeneous enhancement

  • Pituitary stalk: Enhances uniformly

  • Cavernous sinus: Symmetric enhancement

  • Diaphragma sellae: Thin enhancing line

  • Posterior pituitary bright spot may be obscured after contrast

CT Appearance

Non-Contrast CT:

  • Pituitary fossa: Well-defined bony depression in sphenoid body

  • Cortical margins: Smooth, sharply delineated

  • Floor of sella: Thin and intact

  • Sphenoid sinus: Air-filled, low attenuation

  • Cavernous sinuses: Soft tissue density laterally

Post-Contrast CT:

  • Pituitary gland: Homogeneous soft tissue enhancement

  • Cavernous sinuses: Symmetric enhancement

  • Internal carotid arteries: Enhancing tubular structures

  • Bony margins remain sharply defined without erosion

X-ray Appearance

Lateral skull radiograph:

  • Sella turcica visible as a cup-shaped bony depression

  • Anterior wall formed by tuberculum sellae

  • Posterior wall formed by dorsum sellae

  • Floor appears smooth and concave

  • Normal size and contour with sharp margins

X ray image

Pituitary fossa