What Is the Sella Turcica Its Structure and Function in the Sphenoid Bone
The Sella Turcica, a bony pocket that supports the pituitary gland, is a cranial base developmental boundary that separates notochord-dependent posterior development from neural crest cell migration-driven anterior development.
The pituitary gland is housed in the Sella Turcica ("Turkish saddle"), a concave, midline depression in the basisphenoid (also called the hypophysis). The anterior clinoid processes of the lesser sphenoid wing and the tuberculin Sellae constitute Sella's anterior boundaries, while the dorsum Sellae forms the posterior boundary. Understanding Sella Turcica anatomy is vital to get a complete understanding of its function. The pituitary gland and the distal section of the pituitary stalk are housed in the Sella Turcica, a midline depression in the sphenoid bone. A dural reflection protects the Sella. The supraclinoid internal carotid arteries, pituitary stalk, optic nerves, chiasm, and tracts are all in the suprasellar cistern. The cavernous sinuses, which contain the carotid arteries, are located to the side of the Sella Turcica.
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One of the most widely utilized landmarks in cephalometrics is the Sella point, located in the middle of the Sella Turcica. In a radiographic examination of neurocranial and craniofacial complex nature, the Sella Turcica is an essential structure. The locations of the maxilla and mandible in respect to the cranium and themselves are measured using such markers found inside the craniofacial area.
Sella Turcica Anatomy
The sphenoid bone's Sella Turcica is a bony depression. The cavernous sinuses border the Sella laterally, the diaphragma Sellae (dural fold) superiorly, the sphenoid sinus anteroinferiorly, and the pontine cistern posteriorly. Usually, the pituitary gland is found within the Sella. An anterior lobe, middle (vestigial) lobe, and posterior lobe make up the gland.
The Sella Turcica function is to form the bony seat for the human body's pituitary gland. The adenohypophysis, which makes up about 75–80% of the overall gland, is a hub for hormone production, including thyroid-stimulating hormone, adrenocorticotropic hormone (ACTH), along with prolactin. The pituitary stalk connects the posterior lobe, hypothalamus, neurohypophysis, and the pituitary stalk receives hormones from the hypothalamus.
What is the Sphenoid Bone Sella Turcica?
Sphenoid bone Sella Turcica plays a vital role in the human body. The sphenoid bone is a part of eight bones forming the cranium, which encloses and helps in protecting the brain. The sphenoid bone is supposed to be developed like a butterfly. It is made up of a body, two pterygoid processes, and paired larger and lesser wings.
The sphenoid bone is divided into three sections: a core body with the Sella Turcica, two bigger wings, and two lesser wings laterally. The front regions of both middle fossae are made up of bigger wings, whereas the posterior portion of the anterior cranial fossae is made up of smaller wings.
The medial and lateral pterygoid muscles connect to the medial and lateral pterygoid processes on the sphenoid bone, facilitating jaw movement. The pterygoid or Vidian's canal can be seen inferomedial to the foramen rotundum when looking at the sphenoid bone from the front.
Empty Sella Syndrome
In many cases, Sella Turcica ends up facing issues; one such is the Empty Sella syndrome. The disorder known as empty Sella syndrome or the Sella Turcica pituitary gland occurs when the pituitary gland shrinks. The pituitary gland is a tiny gland that sits right under the brain. The pituitary stalk connects it to the bottom of the brain. The pituitary is housed in the Sella Turcica, a saddle-like compartment in the skull. On an MRI scan, the pituitary gland shrinks or flattens, and it is not visible. This gives the pituitary gland's location the appearance of an "empty Sella."
However, the Sella isn't empty. It's frequently stuffed with cerebrospinal fluid (CSF). The fluid that surrounds the brain and spinal cord is known as CSF. CSF has spilled into the Sella Turcica, placing pressure on the pituitary in empty Sella syndrome. The gland shrinks or flattens as a result of this. One can view this flattening through the Sella Turcica radiography system and analyze the syndrome.
The Sella Turcica radiology also showcases the size of the Turcica. The size of the Sella Turcica may be determined using radiographs in several ways, including linear measures and different area and volume measurements. The vertical size varies typically from 4 to 12 mm, whereas the anteroposterior dimension typically ranges from 5 to 16 mm.
Sella Turcica is an important portion of the human body and should be learned carefully to understand its uses.
FAQs on Sella Turcica Anatomy and Role in the Skull
1. What is the sella turcica?
The sella turcica is a saddle-shaped depression in the sphenoid bone of the skull that houses the pituitary gland. It is located in the middle cranial fossa at the base of the brain and provides protection and structural support to the pituitary. The name means “Turkish saddle” because of its shape. It is an important anatomical landmark in neuroanatomy and endocrinology.
2. Where is the sella turcica located in the human skull?
The sella turcica is located in the body of the sphenoid bone at the base of the skull, in the middle cranial fossa. It lies:
- Inferior to the hypothalamus
- Superior to the sphenoid sinus
- Between the two cavernous sinuses
3. What is the function of the sella turcica?
The main function of the sella turcica is to house and protect the pituitary gland. It:
- Provides a bony enclosure for the pituitary
- Stabilizes the gland within the skull
- Allows passage of the infundibulum (pituitary stalk) to connect the pituitary to the hypothalamus
4. What structures are found in the sella turcica?
The primary structure found in the sella turcica is the pituitary gland (hypophysis). It also includes specific anatomical parts:
- Tuberculum sellae (anterior boundary)
- Hypophyseal fossa (central depression holding the pituitary)
- Dorsum sellae (posterior boundary)
5. Why is the sella turcica important in endocrinology?
The sella turcica is important in endocrinology because it contains the pituitary gland, the body’s “master endocrine gland.” The pituitary secretes hormones such as:
- Growth hormone (GH)
- Thyroid-stimulating hormone (TSH)
- Adrenocorticotropic hormone (ACTH)
- Luteinizing hormone (LH) and FSH
6. What is the hypophyseal fossa?
The hypophyseal fossa is the central depression within the sella turcica that directly holds the pituitary gland. It forms a protective bony cavity and is precisely shaped to fit the gland. This fossa ensures that the pituitary remains securely positioned at the base of the brain.
7. What is empty sella syndrome?
Empty sella syndrome is a condition in which the sella turcica appears empty on imaging because the pituitary gland is flattened or reduced in size. It occurs when cerebrospinal fluid fills the sella and compresses the gland. It can be:
- Primary (due to a defect in the diaphragma sellae)
- Secondary (after surgery, radiation, or pituitary disease)
8. How does the sella turcica develop during embryology?
The sella turcica develops from the cartilaginous neurocranium during embryonic skull formation. Specifically:
- The sphenoid bone forms by endochondral ossification
- The pituitary gland develops from Rathke’s pouch (oral ectoderm) and the neural ectoderm
9. What is the relationship between the sella turcica and the cavernous sinus?
The sella turcica is bordered laterally by the cavernous sinuses, which are venous channels on either side of the pituitary gland. These sinuses contain:
- The internal carotid artery
- Cranial nerves III, IV, V1, V2, and VI
10. How is the sella turcica seen in medical imaging?
The sella turcica is clearly visualized using MRI and CT scans of the skull. On imaging:
- MRI is best for evaluating the pituitary gland and soft tissues
- CT scans show the bony structure of the sphenoid bone
