Thyroid (Human Anatomy): Image, Function, Definition, Location in our Body, and More

The gland known as the thyroid was given its name because of its resemblance to the shields that were often used in ancient Greece. It is the most significant endocrine gland in the human body.

During the third week of intrauterine life, the thyroid gland first begins to grow as an endodermal thickening in the midline of the floor of the pharynx immediately beneath the tuberculum impar. This thickening will soon cause a depression below the surface, which will result in the formation of a diverticulum known as the thyroglossal duct.

The thyroid gland's capsule is attached to the laryngeal cartilages and the hyoid bone, both of which move up and down during swallowing. As a result, the thyroid gland also moves up and down during this process. As a result, thyroid swellings can be differentiated from other swellings in the region of the neck through clinical examination.

The thyroid gland can be found on the front and side of the lower part of the neck, directly opposite the C5, C6, C7, and T1 vertebrae.

The thyroid consists of two lobes on either side, which are joined together by a bridge (called an isthmus) in the middle. It is not possible to detect the thyroid when it is at its normal size.

The thyroid has a colour that is somewhere between brown and red, and it is packed with blood vessels. Additionally, nerves that are significant to the quality of one's voice travel through the thyroid.

Triiodothyronine (T3), tetraiodothyronine (T4; also known as thyroxine), and calcitonin are the hormones that are secreted by the thyroid gland. These hormones serve a variety of purposes, including the following:

• Maintain proper control of the resting metabolic rate.
• Encourage the body's psychosomatic expansion through exercise.
• Play a significant role in the process of calcium metabolism.
• The proper amount of thyroid hormone is essential for proper brain development throughout infancy and childhood.

• Goiter: Goitre refers to any enlargement of the thyroid gland, with the exception of those that occur during menstruation and lactation. It is possible that either hypofunction or hyperfunction of the gland is associated with it.
• Thyroiditis: Inflammation of the thyroid gland, also known as thyroiditis, is most frequently brought on by either an autoimmune condition or an infection brought on by a virus. If you have thyroiditis, it's possible that you won't even feel a thing despite having the condition.
• Hyperthyroidism: The overproduction of T3 and T4 hormones is what causes hyperthyroidism, also known as thyrotoxicosis. Symptoms of thyrotoxicosis that can be observed in a patient include tremors, tachycardia, and a systolic bruit. The increased basal metabolic rate is the primary cause of the effects.
• Hypothyroidism: Hypothyroidism develops when there is an inadequate production of the thyroid hormones T3 and T4. The increased production of TSH is a consequence of the decreased levels of T3 and T4.In children, hypothyroidism can cause cretinism, while in adults it can cause myxoedema.
• Graves disease: A form of autoimmune disease in which the thyroid is inappropriately stimulated, leading to hyperthyroidism.
• Thyroid cancer: Thyroid cancer is an unusual form of the disease and is typically treatable. Thyroid cancer can be treated with a variety of approaches, including surgery, radiation, and hormone therapy.
• Thyroid nodule: A benign growth or lump that can sometimes be found in the thyroid gland. There is a very high incidence of thyroid nodules. Very few of them are cancerous. They might produce an excess of hormones, leading to hyperthyroidism, or they might not cause any problems at all.
• Thyroid storm: it is A rare form of hyperthyroidism characterised by abnormally high levels of thyroid hormone in the blood that can lead to severe illness.
• Retrosternal goitre: The downward expansion that can be seen behind the sternum is referred to as a retrosternal goitre. It can cause the trachea to become compressed, which can result in dangerous dyspnea. It is also possible for it to cause severe venous compression, which can then lead to venous congestion.
• Thyroglossal cyst/fistula: It is possible for the thyroglossal duct to remain, which would result in the formation of a thyroglossal cyst and a fistula.Ectopic thyroid: It is possible to find the thyroid gland (thyroid tissue) in an abnormal position anywhere along the course of the thyroglossal duct.
• Lingual thyroid: In the condition known as lingual thyroid, the mass of thyroid tissue is located within the tongue just beneath the foramen caecum. If the mass is particularly large, it can make it difficult for an infant to swallow.
• Retrosternal thyroid: The thyroglossal duct may descend further than its definitive position in the neck, all the way down to the superior mediastinum.
• Aberrant thyroid: It is possible for thyroid tissue to be located in areas that deviate from the typical path of the thyroglossal duct. These areas include the pericardium, the mediastinum, and the carotid sheath.
• Ligation of thyroid arteries during thyroidectomy: Near the apex, the superior thyroid artery and the external laryngeal nerve both branch off in different directions; however, the artery is located superficially, whereas the nerve is located more deeply. As a result of this, when performing a thyroidectomy, the superior thyroid artery should be ligated in a location that is as close to the apex of the thyroid lobe as is practically possible in order to prevent damage to the external laryngeal nerve.
• Benign tumours: The neighbouring structures can become compressed or displaced when benign tumours are present, but malignant growth has a tendency to invade the neighbouring structures of the thyroid gland.

• Anti thyroid peroxidase antibodies: Proteins incorrectly assault the thyroid peroxidase enzyme, which is used by the thyroid in the process of producing thyroid hormones. This results in autoimmune thyroid disease.
• Thyroid scan: In order to get pictures of the thyroid gland, a trace quantity of radioactive iodine is taken orally and administered. There is a high concentration of radioactive iodine within the thyroid gland.
• Thyroid biopsy: A small amount of thyroid tissue is removed, usually to look for thyroid cancer. Thyroid biopsy is typically done with a needle.
• Thyroid stimulating hormone (TSH): Secreted by the brain, TSH regulates thyroid hormone release. A blood test with high TSH indicates low levels of thyroid hormone (hypothyroidism), and low TSH suggests hyperthyroidism.
• T3 and T4 (thyroxine): The primary forms of thyroid hormone, checked with a blood test.
• Fine needle aspiration cytology: for this test a fine needle is inserted into the gland which is suspected to be infected from any parasitic or non parasitic infection and the fluid or substance inside the gland is aspirated which is then evaluated under a microscope by using different diagnostic methods
• Pet scan: The scan is a positron emission tomography (PET) scan, and it works by injecting a radioactive isotope into the gland and then using a camera and a computer to identify and evaluate any abnormalities. In detecting organ carcinogenic activity, it is quite sensitive.
• Serum calcium: it is a specific type of scan for evaluating levels of calcium present in the blood which can be bounded through different proteins and transporting molecules it is helpful in determining the thyroid levels as they are directly or indirectly proportional to the levels of TSH T3 and T4
• Anti thyroid peroxidase antibodies1: this lab laboratory diagnostic test is an important factor in evaluating the levels of lipids which can be high density lipoprotein low density, lipoproteins or triglycerides. which is directly involved with the metabolism hence important for evaluating thyroid disorders
• Anti thyroid peroxidase antibodies3: The thyroid produces this chemical, which can be utilised as a diagnostic tool for thyroid cancer. Thyroid cancer patients often have their levels checked as part of their follow-up care. If the readings are high, the cancer has returned.
• Contrast enhanced computed tomography: It stands for contrast enhanced computed tomography, in which high resolution images are produced using a 3 dimensional flow of X-rays around the organs. It is a gold standard diagnostic technique for many of the disorders of the thyroid, spleen, brain, kidneys and other vital organs.
• Anti thyroid peroxidase antibodies5: It stands for magnetic resonance imaging, for which high resolution imaging is done by using a super magnetic conductor and a central processing unit, which involves resizing and impartial diagnosis of disorders of thyroid gland, heart, spleen, kidney and other vital organs.
• Anti thyroid peroxidase antibodies7: A blood test can tell you how much vitamin D is in your body, so you can make sure you have an ideal amount for your health. Vitamin D status refers to the quantity of this essential vitamin that a Calcium, a mineral crucial to bone development, is regulated in the body in a roundabout way.

• Thyroid surgery (thyroidectomy): A surgeon removes all or part of the thyroid in an operation. Thyroidectomy is performed for thyroid cancer, goiter, or hyperthyroidism.
• Radioiodine Ablation: It is a type of treatment in which radioiodine pigment is injected into the infected part of the thyroid tissue which can be done by fine needle insertion or by thyroid surgery, particularly this type of treatment is used for prevention of thyroid surgery
• Lobectomy or thyroidectomy: Thyroidectomy refers to the removal of all or part of the thyroid gland, which may be necessary in cases of thyroid cancer. thyroid condition in addition to thyroid abscess, or any of the several thyroid illnesses. Surgical intervention is required.
• Chemoradiation: It refers to the method of cancer treatment in which chemotherapy and radiation therapy are both administered, either one after the other or in a series, depending on the specific needs of the patient being treated for carcinoma. it is one of the useful methods for treating thyroid cancer
• External beam radiotherapy: It is a type of radiotherapy in which an external beam of radiation is aimed at the part of cancer. It is highly precise and poses less risk in terms of being treated by chemo radiation. It is a better method than localised chemotherapy, which involves more exposure and more complications related to the chemo radiation.
• Minimally invasive video assisted thyroidectomy: It entails endoscopic treatments that are carried out using probes. The aesthetic results of this technique for thyroid surgery are superior, and it is no longer regarded as an unique surgical procedure.

• Antithyroid medications for hyperthyroidism: In patients with hyperthyroidism, the overproduction of thyroid hormone can be treated with medication. Methimazole and propylthiouracil are two antithyroid medications that are often used.
• Thyroid hormone pills for hypothyroidism: A therapy taken on a daily basis that restores the quantity of thyroid hormone that your body is no longer able to produce. Hypothyroidism may be treated with thyroid hormone tablets, and these medicines are also used to help prevent thyroid cancer from returning once it has been treated.
• Betablockers for thyoiditis: Beta blockers are used when there is a condition of thyroiditis, thyroid cancer, or any other chronic or acute sickness of the thyroid in order to maintain blood flow into the thyroid gland. Other conditions that may require the use of beta blockers include: Atenolol, propranolol, and metoprolol are a few examples of end-stage medications.
• Recombinant human TSH for thyroid carcinoma: The administration of this thyroid-stimulating drug by injection has the potential to improve the diagnostic clarity of thyroid cancer