Sella turcica

The pituitary gland lies deep within the cranial vault, connected to the brain by the infundibular stalk (a downward extension of the floor of the third ventricle) and protected by an indentation of the sphenoid bone called the sella turcica (see Fig. 50-1). The pituitary gland, a small, gray rounded structure, has two parts ... 

The pituitary gland is situated in sella turcica or hypophyseal fossa of the sphenoid bone attached to the brain by a stalk which is continuous with the part of brain i.e. hypothalamus and there is a communication between the hypothalamus and the pituitary gland by means of nerve fibres and a complex of blood vessels. Pituitary gland consists of three parts - anterior lobe or adenohypophysis, posterior lobe or neurohypophysis and middle lobe or pars intermedia. 

The control of metabolism, growth, and reproduction is mediated by a combination of neural and endocrine systems located in the hypothalamus and pituitary gland. The pituitary weighs about 0.6 g and rests at the base of the brain in the bony sella turcica near the optic chiasm and the cavernous sinuses. The pituitary consists of an anterior lobe (adenohypophysis) and a posterior lobe (neurohypophysis) (Figure 37-1). It is connected to the overlying hypothalamus... 

The pituitary gland is a small, pea-shaped structure located within the sella turcica at the base of the brain. The pituitary lies inferior to the hypothalamus and is attached to the hypothalamus by a thin stalk of tissue known as the infundibulum. The structural and functional relationships between the hypothalamus and pituitary gland are briefly discussed later in this section. A more detailed presentation of the anatomic and physiologic functions of the hypothalamus and pituitary gland can be found in several sources.8,14,32... 

A 42-year-old Spanish man took cabergoline (up to 3 mg/day) for a large prolactinoma causing hypopituitarism and symptomatic chiasmal compression (112). After 18 months there was only a minimal tumor remnant on the floor of the sella turcica, but there was chiasmal herniation. However, there were no clinical effects of this, and in particular the visual fields were normal. 

The pituitary gland (hypophysis) is located at the base of the skull (Figure 50-1) in a bone cavity called the sella turcica (Turkish saddle). The gland is small—1 cm or less in height and width and weighs approximately 500 mg. As discussed previously, the gland is anatomically divided into the anterior (adenohypophysis) and the posterior (neurohypoph-ysis) lobes. A third lobe (the intermediate lobe) is present in most vertebrates and in the human fetus this lobe is rudimentary in the adult human. 

The pituitary gland, also referred to as the hypophysis, is located at the base of the brain in a cavity of the sphenoid bone known as the sella turcica. The pituitary is separated from the brain by an extension of the dura mater known as the diaphragma sella. The pituitary is a very small gland, weighing between 0.4 and 1 g in adults. It is divided into two distinct regions, the anterior lobe, or adenohypophysis, and the posterior lobe, or the neurohypophysis (see Fig. 75-1). 

Within the cranial vault, 95% of primary germ cell tumors are found along the midline in the pineal and suprasellar regions, especially the former. About 10% involve both regions, and 25% arise in the suprasellar cistern. The mixed germ cell tumor and lymphoma (ger-lymphoma) has only been seen in the sella turcica. Germ cell tumors rarely involve spinal cord or peripheral nerve. ... 

The pituitary gland Figure 4.1) is a bilobed structure located in the sella turcica, immediately below the median eminence area of the hypothalamus. The 2 lobes are derived embryologically from different sources. The anterior lobe or adeno-hypohysis, which is differentiated into 3 distinct zones, the pars distalis, pars intermedia and the pars tuberalis, is derived from ectodermal tissue of the oral... 

It is now firmly established that the synthesis and release of the hormones of the adenohypophysis are controlled by substances released from nerve endings in the hypothalamus and conveyed to the anterior pituitary gland via the portal vessels. The evidence which demonstrated the fundamental importance of the hypothalamus and the hypothalamo-hypophysial portal vessels came mainly from experiments which involved transection of the pituitary stalk, transplantation of the pituitary gland to a site remote from the sella turcica or electrical stimulation of the hypothalamus. 

The simple experiment of removing the pituitary and from the sella turcica to another site of the body also demonstrated the role of the hypothalamus in the control of anterior pituitary function. When the transplanted tissue is placed in a site remote from the sella turcica, for example, the anterior chamber of the eye, the kidney capsule or temporal lobe of the brain, partial or complete atrophy of the ovaries, testes, reproductive tracts, thyroid gland and adrenal cortices is observed together with a reduction in the rate of body growth. When, however, the transplanted tissue is placed in the vicinity of the hypothalamus and pituitary stalk, regeneration of the hypophysial portal vessels occurs and anterior pituitary function is restored as shown by the maintenance of reproductive, thyroid and adrenocortical activity [5]. 

The hypophysis is a small, bean-shaped organ (0.6-0.65 g) located in the sella turcica at the base of the skull. On close examination of the gland, an anterior yellowish and a posterior more fibrous and whitish part can be distinguished. The two parts are separated by a pars intermedia, a lamellar structure, grayish and fibrous in appearance. The gland is attached to the floor of the third ventricle by a hollow pedicle, the stalk of the hypophysis. 

Fig. 8-1. A case of acromegaly with large skull hypertrophy of the cortex, enlargement of the frontal sinuses, and, most relevant, enlargement of the sella turcica (box) as a result of tumoral growth of the hypophysis. (From J. Collins)...

Dural membranes fold or form a sac to form three important structures. The diaphragma sel-lae is a small fold of dura that covers the hypophyseal fossa of the sella turcica of the sphenoid,... 

The bilaterally paired cavernous sinuses are found lateral to the sella turcica and extend from the sphenoidal fissure to the apex of the petrous portion of the temporal bone. Cranial nerves III, IV, VI, the ophthalmic division of V, and the internal carotid artery are all found in relation to the cavernous sinuses. The sinuses are fed by ophthalmic veins, and drain to the superior and inferior petrosal sinuses, the sigmoid sinus, and then to the internal jugular vein. Dysfunction at the tip of the petrous portion of the temporal can interfere with the outflow of the cavernous sinus into the narrow petrosals. 

---