Sella turcica
Encyclopedia
The sella turcica is a saddle-shaped depression in the sphenoid bone
of the human
skull
.
. The hypophyseal fossa is located in a depression in the body of the sphenoid bone
. Located anteriorly to the hypophyseal fossa is the tuberculum sellae
.
Completing the formation of the saddle posteriorly is the dorsum sellae
which is continuous with the clivus
, inferoposteriorly. The dorsum sellae is terminated laterally by the posterior clinoid processes
.
, which lies on top of the pituitary, enveloping the pituitary stalk
. Compression of the optic chiasm can lead to bitemporal hemianopsia
, and, when there is no relevant trauma, this clinical finding is pathognomonic
for a pituitary tumor.
to establish the base of the skull in cephalometric analysis
. This is commonly done prior to orthodontic treatment.
Proffit, William R.. Contemporary Orthodontics, 4th Edition. C.V. Mosby, 122006. 6.5.2.1).
vbk:978-0-323-04046-4#outline(6.5.2.1)
Sphenoid bone
The sphenoid bone is an unpaired bone situated at the base of the skull in front of the temporal bone and basilar part of the occipital bone.The sphenoid bone is one of the seven bones that articulate to form the orbit...
of the human
Human
Humans are the only living species in the Homo genus...
skull
Human skull
The human skull is a bony structure, skeleton, that is in the human head and which supports the structures of the face and forms a cavity for the brain.In humans, the adult skull is normally made up of 22 bones...
.
Anatomy
The seat of the saddle is known as the hypophyseal fossa, which holds the pituitary glandPituitary gland
In vertebrate anatomy the pituitary gland, or hypophysis, is an endocrine gland about the size of a pea and weighing 0.5 g , in humans. It is a protrusion off the bottom of the hypothalamus at the base of the brain, and rests in a small, bony cavity covered by a dural fold...
. The hypophyseal fossa is located in a depression in the body of the sphenoid bone
Sphenoid bone
The sphenoid bone is an unpaired bone situated at the base of the skull in front of the temporal bone and basilar part of the occipital bone.The sphenoid bone is one of the seven bones that articulate to form the orbit...
. Located anteriorly to the hypophyseal fossa is the tuberculum sellae
Tuberculum sellae
In the sphenoid bone, behind the chiasmatic groove is an elevation, the tuberculum sellæ .-External links:*...
.
Completing the formation of the saddle posteriorly is the dorsum sellae
Dorsum sellae
In the sphenoid bone, the anterior boundary of the sella turcica is completed by two small eminences, one on either side, called the middle clinoid processes, while the posterior boundary is formed by a square-shaped plate of bone, the dorsum sellæ, ending at its superior angles in two tubercles,...
which is continuous with the clivus
Clivus (anatomy)
The clivus is a part of the cranium, a shallow depression behind the dorsum sellæ that slopes obliquely backward. It forms a gradual sloping process at the anterior most portion of the basilar occipital bone at its junction with the sphenoid bone. On axial planes, it sits just posterior to the...
, inferoposteriorly. The dorsum sellae is terminated laterally by the posterior clinoid processes
Posterior clinoid processes
In the sphenoid bone, the anterior boundary of the sella turcica is completed by two small eminences, one on either side, called the anterior clinoid processes, while the posterior boundary is formed by a square-shaped plate of bone, the dorsum sellæ, ending at its superior angles in two tubercles,...
.
Pathological Significance
Since the sella turcica forms a bony caudal border for the pituitary gland, a pituitary tumor can extend only upward in the rostral direction. This can result in compression of the optic chiasmOptic chiasm
The optic chiasm or optic chiasma is the part of the brain where the optic nerves partially cross...
, which lies on top of the pituitary, enveloping the pituitary stalk
Pituitary stalk
The pituitary stalk is the connection between the hypothalamus and the posterior pituitary....
. Compression of the optic chiasm can lead to bitemporal hemianopsia
Bitemporal hemianopsia
Bitemporal hemianopsia is the medical description of a type of partial blindness where vision is missing in the outer half of both the right and left visual field...
, and, when there is no relevant trauma, this clinical finding is pathognomonic
Pathognomonic
Pathognomonic is a term, often used in medicine, that means characteristic for a particular disease. A pathognomonic sign is a particular sign whose presence means that a particular disease is present beyond any doubt...
for a pituitary tumor.
Clinical significance
Sella turcica is usually used as a reference point with nasionNasion
The nasion is the intersection of the frontal and two nasal bones of the human skull. Its manifestation on the visible surface of the face is a distinctly depressed area directly between the eyes, just superior to the bridge of the nose....
to establish the base of the skull in cephalometric analysis
Cephalometric analysis
Cephalometric analysis is the study of the dental and skeletal relationships in the head. It is frequently used by dentists, often orthodontists in particular, as a treatment planning tool....
. This is commonly done prior to orthodontic treatment.
Proffit, William R.. Contemporary Orthodontics, 4th Edition. C.V. Mosby, 122006. 6.5.2.1).
vbk:978-0-323-04046-4#outline(6.5.2.1)
