🥇 ANATOMÍA DE LA GLÁNDULA TIROIDES Y PARATIROIDES. Fácil, Rápida y Sencilla

Anatomy of the Thyroid and Parathyroid Glands

Introduction to the Video

• The video focuses on the anatomy of the thyroid gland and parathyroid glands, dedicated to Andrés Navarro and his family in Venezuela.

Anatomy of the Thyroid Gland

• The thyroid gland is named for its shield-like shape, derived from Greek etymology. It is located centrally in the neck, resembling an "H" or butterfly wings.

• Anatomically positioned between C5 and C7 vertebrae, with some sources suggesting it may extend to D1. The cricoid cartilage at C6 helps locate it.

• The thyroid gland has two protective capsules: an inner fibrous capsule attached directly to the gland and an outer false capsule from the deep cervical aponeurosis (pretracheal lamina).

• Comprised of two lobes connected by a central isthmus covering trachea rings 2, 3, and 4; may also have a pyramidal lobe that varies among individuals.

Structural Features of Each Lobe

• Each lobe has a vertex (top) directed backward, a base (bottom), and three faces: external, internal (medial), and posterior.

• The external face is covered by infrahyoid muscles like sternothyroid and omohyoid; this surface can be observed after sectioning sternocleidomastoid muscle.

Understanding the Thyroid Gland and Its Innervation

Anatomy and Blood Supply of the Thyroid Gland

• The superior laryngeal nerve, particularly its external branch, innervates the thyroid gland. The gland receives blood supply from two main arteries: the superior thyroid artery (a branch of the external carotid artery) and the inferior thyroid artery (from the bicervical scapular trunk).

• The superior thyroid artery has five branches, with glandular branches being most significant. These branches anastomose at the upper edge of the isthmus of the thyroid gland.

• A third, less common vessel known as the middle thyroid artery may also exist; it can originate from either the brachiocephalic trunk or right common carotid artery but is inconsistent in presence.

Venous Drainage and Lymphatic System

• Venous drainage involves three major veins:

• Superior thyroid vein (drains into internal jugular vein)

• Middle thyroid vein (also drains into internal jugular vein)

• Inferior thyroid vein (drains into brachiocephalic veins).

• Lymphatic drainage is categorized by anatomical lobes:

• Lobes drain upward to deep cervical nodes along internal jugular vein.

• Downward drainage occurs to paratracheal ganglia alongside trachea.

• The isthmus drains differently: upward towards pre-laryngeal ganglia in front of larynx and downward towards pretracheal ganglia in front of trachea.

Innervation and Hormonal Function

• The thyroid gland's innervation comes from both sympathetic and parasympathetic systems rather than cervical plexus due to its endocrine function. It produces hormones like T3, T4, and calcitonin.

• Sympathetic innervation arises from cervical sympathetic chain via superior cervical ganglion (along superior thyroid artery) and middle cervical ganglion (along inferior thyroid artery).

• Vagus nerve contributes to sympathetic innervation through recurrent laryngeal nerve and external branch of superior laryngeal nerve.

Surgical Considerations During Thyroidectomy

• In performing a total removal of the thyroid gland (thyroidectomy), surgeons must be cautious about three critical structures:

• Parathyroid glands which are small yet vital for life.

• Recurrent laryngeal nerve that controls most larynx muscles; injury can lead to hoarseness or speech issues.

Understanding the Parathyroid Glands

Overview of Parathyroid Glands

• The parathyroid glands are distinct from the thyroid gland, despite both being endocrine glands that secrete hormones into the bloodstream.

• They produce parathyroid hormone (PTH), which is essential for regulating calcium levels in the body and is crucial for life.

• There is some debate among medical literature regarding blood supply; while some sources state they are supplied solely by the inferior thyroid artery, others suggest that superior parathyroid glands may also receive blood from the superior thyroid artery.

Surgical Considerations

• During thyroidectomy procedures, it is vital to avoid damaging or removing the parathyroid glands, as they can be mistaken for lymph nodes.

• Awareness of their location and function is critical for surgeons to prevent complications related to calcium regulation post-surgery.

Additional Resources

• The speaker encourages viewers to explore more videos on related topics such as neck irrigation through various arteries, enhancing understanding of anatomical relationships.