hello guys and welcome back to my channel in this video we will be learning about the thyroid gland to begin with the thyroid gland is an endocrine gland with rich blood supply situated in the lower part of the front and the sides of the neck it regulates the basal metabolic rate stimulates somatic and psychic growth and plays an important role in calcium metabolism the gland consists of right and left lobes that are joined to each other by an Islamist a third law that is a pyramidal law that you see right here we project upwards from the Islamists now looking at the situation and extent of the thyroid gland the gland lies against the c5 to t1 vertebra embracing the upper part of the trachea each lobe extends from the middle of the thyroid cartilage as you can see right here this is the thyroid cartilage and each lobe extends from the middle of the thyroid cartilage to the fourth or fifth track you'll ring as you can see right here the islamists that is an area right here extends from the second to the fourth track you'll ring looking at the dimensions and weight of the thyroid gland each lobe that is the right and the left lobe measures about five centimeter in length to two point five centimeter in breadth and two point five centimeter in thickness and the islamís is one point two centimeters into one point two centimeters on an average the gland weighs about 25 grams it is larger in females than in males further increase in size takes place during menstruation and pregnancy moving on to the capsules of the thyroid gland we have two capsules one is the true capsule that you see right here and the second is the false capsu that you see outside the true capsule right here is the peripheral condensation of the connective tissues of the gland a dense capillary plexus is present deep the true caps you to avoid hemorrhage there is loss of a lot of blood during operations the thyroid is removed along with the true capsule the false capsule that you see right here is the outer layer is derived from the pre trucky layer of the deep cervical fascia now this is a diagram from the posterior aspect this is the ease of figures the trachea and the thyroid gland along with the blood vessel supplying it the false capsule that we were talking about is thin along the posterior border of the lobes this is the left lobe and that is a right lobe and this is a posterior border so it is thin along the posterior border of the loops but thick on the inner surface of the gland where it forms a suspensory ligament that you see right here which is called the Barry's ligament or the suspensory ligament of Barry which connects the loop to the cricoid cartilage present right here this is the suspensory ligament of Barry this is the cricoid cartilage to which the suspensory ligament of Barry attaches to now concisely the important points in detail the thyroid gland is an endocrine gland with rich blood supply situated in the lower part of the front and the sides of the neck it regulates the basal metabolic rate stimulates somatic and psychic growth and plays an important role in calcium metabolism the gland consists of right and left loops that are joined to each other by the islamists a third pyramid elope may be project upwards from the Isthmus now the situation and extent the gland lies against the vertebra c5 to c7 and t1 embracing the upper part of the track eeeh each lobe extends from the middle of the thyroid cartilage to the fourth or fifth track yield ring and the islamists extends from the second to the fourth tracheal ring looking at the dimensions and width each lobe measures about five into 2.5 into two point five centimeters and the islamists 1.2 into one point two centimeters on an average the gland B is about 25 gram it is larger and females than in males and further increase in size during menstruation and pregnancy please moving on to the capsules there is a true capsule and the false capsule the true capsule is the peripheral condensation of the connective tissues of the gland a dense capillary plexus is present deep to the true capsule to avoid hemorrhage during operations the tie rod is removed along with the true capsule moving on to the false capsule it is derived from the pre rocky layer of the deep cervical fascia it is thin along the posterior border of the loops but thick on the inner surface of the gland where it forms a suspensory ligament of Barry which connects the lobe to the cricoid cartilage moving on to the paths and Relations of the thyroid gland each lobe there is a right and the left loops have an apex right here a base three surfaces that is lateral medial and post or lateral which I will be explaining later and two borders anterior and posterior border so the loops are conical in shape they have an fx base three surfaces that is larger medial and postural larger and finally two warders it is anterior and posterior borders now let us learn about it in detail the apex of the thyroid gland is directed upwards and slightly laterally that is away from the median plane it is limited superiorly by the attachment of the sternothyroid muscle right here to the oblique line of the thyroid cartilage that you can see right here which is medial to the epics this is the thyroid cartilage this is the attachment of the sternothyroid muscle and the apex is limited superiorly by the attachment of this muscle the similar thing can be seen clearly on the other lobe this is sister no thyroid muscle this is the apex of the thyroid gland the apex is related to the superior thyroid artery as you can see right here these are the superior thyroid arteries the apex of the thyroid gland is also related to the external laryngeal nerve which is a branch of the superior laryngeal nerve after the apex now moving on to the base the base is at the level with the fourth or the fifth track children it is related to the inferior thyroid artery as you can see right here the base of the lobes are also related to the recurrent laryngeal nerves as you can see right here this is a transverse section through the anterior part of the neck and this is the thyroid gland this is the truck yeah this is the ace of fingers now we are going to learn about the three surfaces there is a lateral median and post-show lateral surface of the lobes this is the lateral surface this is the medial surface that is towards the median plane and this is the posterolateral surface because it comes to the posterior and lateral side so this is the posterolateral surface again this is the lateral surface this is the medial surface and this is the posterolateral surface of the lobes of the thyroid gland looking at the lateral surface or the superficial surface it is convex as you can see and is covered by the sternohyoid muscle the superior belly of the omohyoid muscle the sternothyroid muscle and the sternocleidomastoid muscle similar structures can be seen in relation to the lateral surface of the lobe of the thyroid gland on the opposite side nextly looking at the medial surface it is related to the two tubes that is truck iya and the each of figures two muscles that is the inferior constrictor and the cricothyroid which cannot be seen in this diagram and two nerves that is the external laryngeal and the recurrent laryngeal that I have shown you earlier this is inferior constrictor and this is the pre-code thyroid muscle moving on to the third surface right here there is a post or lateral or the posterior surface it is related to the carotid sheath that you see right here as well as here and it overlaps the common carotid artery moving on to the borders we have two borders it is the anterior border and the posterior border the anterior border is thin and is related to the anterior branch of the superior thyroid artery as you can see right here same on the other side this is superior thyroid artery the anterior branch this is the anterior border this is the anterior border moving on to the posterior view the posterior border of the thyroid gland right here is thick and rounded and separates the medial and the posterior surfaces it is related to the inferior thyroid artery as you can see right here it is related to an anastomosis between the posterior branches of the superior and ascending branches of the inferior thyroid artery it is related to the parathyroid glands which cannot be seen in this diagram and the thoracic duct only on the left side now looking at the features of the islamists the Istres connects the lower parts of the two lobes as you can see right here it has two surfaces that is the anterior and the posterior surface behind it has two borders the superior border and the inferior border now looking at the anterior surface the anterior surface is covered by the right and the left sternothyroid and the sternohyoid muscles on both the sides it is also related to the anterior jugular veins and fascia and skin the posterior surface of the isthmus is related to the second to fourth truckle rings the superior border is related to the anterior branches of the superior thyroid artery of both right and left sides as you can see right here and right here this is a left lateral view of the neck this is the thyroid gland this is the inferior border of the thyroid gland so it is related to the inferior thyroid veins as you can see right here which leave the gland at this border now concisely important points in detail looking at the paths and relations the lobes are conical in shape having an fx a base three surfaces that is lateral medial and post-show lateral surface and two anterior and posterior border the apex is directed upwards and slightly laterally it is limited superiorly by the attachment of the sternothyroid muscle to the oblique line of the thyroid cartilage which is medial to the epics the epics is related to the superior thyroid artery and external laryngeal of the base is at the level with the fourth or fifth truck killed ring it is related to the inferior thyroid artery and recurrent laryngeal nerve the lateral surface of the superficial surface is convex and is covered by the sternohyoid muscle the superior belly of the omohyoid the sternothyroid and the anterior border of the sternocleidomastoid muscle the medial surface is related to two tubes that is a truckie and the east of figures to muscle it is an infinitely inferior constrictor and the cricothyroid - nozzle is an external laryngeal and a recurrent laryngeal nerve the posterolateral or the posterior surface is related to the carotid sheath and overlaps the common carotid artery the anterior border is thin and related to the anterior branch of the superior thyroid artery the posterior border is thick and rounded and separates the medial and posterior surfaces it is related to the inferior thyroid artery anastomosis between the posterior branch of the superior and ascending branch of the inferior thyroid artery the parathyroid glands and the thoracic duct only on the left side the east immerse is a structure that connects the lower part of the two lobes it has two surfaces that is anterior and posterior and two borders that are superior and inferior the anterior surface is covered by the right and left sternal thyroid and sternohyoid muscles the anterior jugular veins and fascia and skin the posterior surface is related to the second or fourth TRUCKING rings the upper border is related to the anterior branches of the right and left superior thyroid arteries and finally the lower border of the isthmus is related to the inferior thyroid veins that leave the gland at this model moving on to the arterial supply of the thyroid gland it is supplied by two arteries that is the superior and the inferior thyroid artery first let's look at the superior thyroid artery right here the superior thyroid artery is the first anterior branch of the external carotid artery that you see right here it runs downwards and forwards and after giving branches it pierces the pre truckle fascia to reach the apex of the lobe where a deviates middle and the upper Pole the artery divides into anterior and posterior branches this is the anterior branch similarly on this side this is the anterior branch the anterior branch descends on the anterior border of the loop and continues along the upper border of the islamists right here to anastomosis with its fellow of the opposite side moving on to the inferior thyroid artery that you see right here it is a branch of the tyro cervical trunk which arises from the subclavian artery it runs first upwards then medially and then finally downwards to reach the base of the gland the thyroid gland the artery then divides into four to five glandular branches which pierces the fascia separately to reach the lower part of the gland concise in the important points are the arterial supply the thyroid gland is supplied by the superior and inferior thyroid artery the superior thyroid artery is the first anterior branch of the external carotid artery it runs downwards and forwards and after giving branches it pierces the pre-travel fascia to reach the apex of the lower and the upper Pole the artery divides into anterior and posterior branches the anterior branch descends on the anterior border of the lobe and continues along the upper border of the islamists to anastomosis with its fellow on the opposite side the posterior branch descends on the posterior border of the lobe and anastomosis with the ascending branch of inferior thyroid artery the inferior thyroid artery is a branch of the thyroid cervical trunk which arises from the subclavian artery it runs first upwards then medially and finally downwards to reach the base of the glut the artery divides into four to five glandular branches which fears the fish separately to reach the lower part of the gland now two extra points are that sometimes in 3% individuals thyroid is also supplied by the lowest thyroid artery that is thyroid iya I'm an artery which arises from the brachiocephalic trunk or directly from the arch of the iota and finally the SS area tyroid arteries also supply the thyroid gland moving on to the venous drainage of the thyroid gland the thyroid is strained by the superior thyroid beam the middle tyroid mean and the inferior thyroid means the superior thyroid mean emerges at the upper Pole and accompanies the superior thyroid artery as you can see right here it ends in the internal jugular vein right here the medial thyroid vein is a short wide channel which emerges at the middle of the lobe and soon enters the internal jugular vein the inferior thyroid beam that you see right here emerges at the lower border of the islamís they form a plexus in front of the trachea and drain into the left brachiocephalic vein as you see right here now concise in the important points under the venous drainage the thyroid is drained by superior middle and inferior thyroid makes the superior thyroid vein emerges at the upper Pole and accompanies the superior thyroid artery it ends in the internal jugular vein the middle thyroid vein is a short wide channel which emerges at the middle of the lobe and soon enters the internal jugular vein the inferior thyroid beam emerges at the lower border of the isthmus the former plexus in front of the truck yya and drain into the left brachiocephalic vein an extra poi that is a fourth beam quarter may emerge between the middle and inferior veins and drain into the internal jugular vein moving on to the lymphatic drainage of the thyroid gland the lymph from the upper part of the gland reaches the upper deep cervical lymph nodes either directly or through the pre laryngeal nodes and lymph from the lower part of the gland drains into the lower deep cervical lymph nodes you see right here directly and also through the pre charcoal and para truckloads concise in the important points lymph from the upper part of the gland reaches the upper deep cervical lymph nodes either directly or through the pre laryngeal nodes and lived from the lower part of the gland drains into the lower deep cervical lymph nodes directly and also through the pre truckin and parrot Rock Hill nodes moving on to the nerve supply the nerves are derived mainly from the middle cervical jangling and partly from the superior and inferior cervical ganglia these are vasoconstrictor nextly looking at the histology of the thyroid gland the thyroid gland is made up of two types of secretory cells first is the follicular cells and second is the pair of ala killer cells the folly killer cells are the ones lining the follicles of the gland and secrete triiodothyronine and the triode thigh Ronin that is thyroxine which stimulates the basal metabolic rate and somatic and psychic growth of the individual whereas the para follicular cells are fewer and light cells these lie in between the follicles they secrete tyro calcitonin which promotes the deposition of calcium salts in the skeleton and other tissues and tends to produce hypocalcemia this is a diagram representing the histology of the thyroid gland finally looking at the clinical anatomy of the thyroid gland any swelling of the thyroid should be palpated from behind the swelling is known as gota removal of the thyroid that is thyroidectomy with true capsule may be necessary in hyperthyroidism during thyroidectomy superior thyroid artery is ligated near the gland to see the external laryngeal nerve hypothyroidism causes cretinous Amane infants and mix edema in others I hope you found this video helpful to get the notes on thyroid gland as well as notes on other topics of anatomy physiology biomechanics psychology and pathology visit my Instagram page the link to which is given in the description below to get the updates on my latest videos click on the subscribe button to get notifications tap on the bear like thank you for watching you