Thyroid Gland Flashcards
Thyroid gland is an endocrine gland. True or false
True
Thyroid gland develops from where
Foramen cecum (of Morgagni)
Describe the anatomy of the thyroid gland
Thyroid gland is located in front of the neck. It consists of 2 lobes(left and right) in front of the second , third and fourth or 5th tracheal rings united by the isthmus
What muscles cover the thyroid gland on the lateral sides of the pharynx and larynx
Sternothroid and sternohyoid muscles
Functions of thyroid gland
- Regulates nasal metabolic rate
- Important in calcium metabolism
- Stimulate psychic growth
The isthmus extents from what trachea ring to what tracheal ring
2nd to 3rd
The lower pole of the thyroid gland can extend up to what tracheal ring
6th
Which gender has larger thyroid gland
Females
Average weight of the gland
25g
The upper pole of the thyroid gland cannot normally rise above the level of the oblique line of the thyroid cartilage. True or false
True
What is the dimension of the thyroid gland
5 X 2.5 X 2.5 cm
Components are the components of thyroid gland
2 lobes (left and right)
Isthmus
Pyramidal lobe
Functions of thyroid gland
-They help in the overall growth, development, and differentiation of all the body cells.
-They regulate the basal metabolic rate (BMR).
-They play an essential role in calcium metabolism
-They help in the overall development and function of CNS in children.
-They stimulate somatic and psychic growth.
-They stimulate heart rate and contraction.
-They help in the deposition of calcium and phosphate in bone and make the bones strong.
-They decrease the level of calcium in the blood.
-They regulate carbohydrate, fat, and protein metabolism.
-They also help in the metabolism of vitamins.
-They control the body temperature.
-They help degrade cholesterol and triglycerides.
-They maintain the electrolyte balance.
-They support the process of RBC formation.
-They enhance mitochondrial metabolism.
-They increase the oxygen consumptions by the cells and tissues.
-They influence the mood and behavior of a person.
-They stimulate gut motility.
-They also enhance the sensitivity of the beta-adrenergic receptors to catecholamines.
Dimensions of the isthmus
1.2 X 1.2cm
Why does the thyroid gland increase during menstruation and pregnancy
Check WhatsApp group
What are the 2 capsules of the thyroid gland
- True (deeper capsule): peripheral condensation of CT of the gland
- False capsule: formed from the pretracheal layer of the deep cervical fascia
The false capsule is —— along the posterior border of the lobes and ——- in the inner surface of the lobe
Thin
Thick
What ligament does the false capsule form and what’s the function of the ligament
Suspensory ligament of Berry
It connects the thyroid lobe to the cricoid cartilage
Shape of the thyroid lobes
Conical
It has a base, an apex and 3 surfaces
What are the 3 surfaces of the thyroid gland
Anterolateral
Posterolateral
Medial
Relation of the anterolateral border of the thyroid gland
-Strap muscles
> Sternohyoid
> sternothyroid
> superior belly of omohyoid muscles
- SCM muscle
Relation of the posterolateral border of the thyroid gland
Carotid sheath
Relation of the medial border of the thyroid gland
Law of twos
2 tubes
- trachea in front
- oesophagus behind
2 muscles
- inferior constrictor
- cricothyroid
2 nerves
- external laryngeal
- recurrent laryngeal
Diagram of the thyroid gland and it’s relations
Check note and google
You must know this wella
The apex of the thyroid gland is limited superiorly by
The attachment of the sternothyroid muscles to the oblique line of thyroid cartilage
How many border and surface does the isthmus have? name them;
2 borders
> superior
> inferior
2 surfaces
> anterior
> posterior
Relation of the anterior border of the isthmus
- Right and left sternohyoid and sternothyroid muscle
- the anterior jugular veins and fascia
Relation of the posterior border of the isthmus
2nd and 3rd tracheal rings
What is the arterial supply of the thyroid gland
> Superior thyroid artery (1st branch of the external carotid artery). Supplies upper part of the lateral lobes of the thyroid gland and the isthmus
Inferior thyroid artery (from thyrocervical trunk). Supplies the lower part of the lobe.
Thyroidea ima artery (only present in about 10% of the population). It’s a single artery i.e it’s not paired
Why nerve closely is related to the superior thyroid artery?
External laryngeal nerve
Why nerve is related to the inferior thyroidal artery?
Recurrent laryngeal nerve
Course of superior thyroid artery
Check that 55 pages slide (it’s on page 21-22. You should know this by heart)
Course of inferior thyroid artery
Check that 55 pages slide (it’s on page 22-25. You should know this by heart )
Venous drainage of the thyroid gland
Superior, middle, and inferior, a fourth thyroid vein of Kocher thyroid veins (check slide, page 26-27)
Location of thyroid vein of Kocher
May between the inferior and middle thyroid veins and drains into IJV
Inferior thyroid veins drains into where
Left brachiocephalic vein
Deficiency of iodine causes what
Goiter
The right recurrent laryngeal nerve loops around —— and the left recurrent laryngeal nerve loops behind around——
Subclavian artery (that’s why in subclavian vascular anomaly, the recurrent laryngeal nerve do not longer “REOCCUR”, instead it proceeds in a more transverse direction from the vagus nerve to the larynx).
Arch of aorta
Lymph drainage of the thyroid gland
> Prelaryngeal nodes to the upper cervical lymph nodes (Upper part part of the gland)
> Preteacheal and paratracheal nodes to the lower cervical lymph nodes (Upper part part of the gland)
Nerve supply of the thyroid glandn
Middle cervical ganglion (main)
Superior and Inferior cervical ganglion
Theses ganglions are secretomotor
What are the 2 types of secretory cells that makes up the thyroid gland
- Follicular cells
- Parafollicular cells
What hormones do the follicular cells secrete
Tri-iodothyronin
Tetra- iodothyronin (throxin)
This hormones stimulate basic metabolic rate, somatic and psychic function of an individual.
What lines the follicles of the thyroid gland
Follicular cells
Location of the parafollicular cells
Between the follicles
What is the hormone that parafollicular cells secrete and what’s the function?
Thyrocalcitonin
Promote deposition of calcium salts in skeletal, muscular tissues. Tends to produce hypocalcemia.
Parathormone effects are opposite of the throcalcitonin
Where does the thyroid gland develop from
The median endordermal thyroid diverticulum (check slide to learn this by heart)
Remnant of the thyroglossalnduct may form
Thyroglossal cyst or fistula
Sure that thyroid gland am an be found in (anomaly)
Lingual
Suprahyoid
Infrahyoid
Retrohyoid
Retrosternal
Hypothyroidism causes —— in infants and —— in adults
Cretinism
Myxoedema
The false capsule is attached to hat structures
Hyoid bone
Thyroid cartilage
Cricoid cartilage
The nerves related to the superior and inferior thyroid arteries, how are they ligated?
Check page 19-23 of the 39 pages slide
Where can the thyroidae ima artery arise from
Brachiocephalic trunk, left common carotid artery or directly from arch of aorta
Clinical correlation relating to thyroidea ima artery
Page 25 of the 39 pages slide
The superior thyroid veins drain into where
UJV or facial vein
Middle thyroid veins drains where
IJV
Clinical correlation of inferior thyroid vein (check)
Page 28-29 of the 39 pages slide
What type of gland is the parathyroid gland?
Endocrine gland
Location of parathyroid gland and size
Posterior to the thyroid gland between its capsule and fascial sheath.
O.5cm X 0.8cm ovoids.
Size of a small pea
Function of parathyroid gland
Plays important role in calcium metabolism. Secrets parathormone that mobilizes bone calcium to blood and increases the absorption of calcium from gut and kidneys
The position of superior parathyroid gland is more constant than that of the inferior, true or false
True
Blood supply of the parathyroid gland
Superior and inferior thyroid arteries
