Thyroid

Introduction

The thyroid gland is one of the most important parts of the Endocrine system where it plays a major role in different metabolic pathways along controlling different paths in the human body. And before speaking about it I would like to share the below videos from youtube where it speaks about the Anatomy & of the Thyroid Glands

Location & structure

The Thyroid gland is located in the Anterior Neck (Butterfly shaped structure) on the Trachea just inferior to the Larynx as shown in the figure below where it can be described as being located at the front & the sides of the neck

It is composed of 2 lateral lobes where they are connected to each other across the middle line through a Median tissue mass called the ISTHMUS as shown below in the figure; Where it connects the lower third of each lateral lobe & it measures around half an inch in breadth & depth

The lobes are conical in shape in which the apex of each being directed upward & outward; The base in general looks downward and on a level with the 5′th or 6′th tracheal ring; The external or superficial is convex & covered by the skin.

There is a third lobe of conical shape called the PYRAMID which arises from the upper part of the isthmus or from the adjacent portion of either lobes but most commonly the left ; There are also small detached parts of the thyroid tissue which are sometimes found above the isthmus & their presence is readily explained by the reference to the manner by which the gland was developed

The Thyroid gland is the largest pure Endocrine organ in the human body in which the weight is normally variable between individuals but as an average it weights around one ounce (Around 28.34 grams) ; It is somehow heavier in females compared to males since it also becomes enlarged through menstruation & pregnancy; The gland is provided by a very rich blood supply through 2 major arteries which are as the below

1- The Superior Thyroid Artery
2- The Inferior Thyroid Artery

Internally the Thyroid Gland is composed of FOLLICLES which are a hollow spherical cells in which their walls are formed of cuboidal or squamous epithelial cells called FOLLICLE CELLS ; The follicle cells produces theTHYROGLUBULIN which is the famous Glycoprotein of the Thyroid Gland; Inside these follicle cells there is a hollow central cavity lumen which contains the COOLLOID which is an amber colored sticky material made of the same thyroglobulin molecules attached to IODINE; The Thyroid hormone is derived from this Iodinated-Thyroglobulin molecules; follicles are shown below

There is also another collection of cells in the Thyroid gland tissue called the Para-Follicular cells which produces CALCITONIN and those cells lies between the follicular epithelium but protrude into the soft connective tissue that separates & surrounds the thyroid follicles

It’s worth it to mention that there are other structures called the Para-Thyroids which are located near the thyroid gland & we’ll discuss them in a later article.