The thyroid gland is an endocrine gland located in the front of the neck below the larynx. It produces thyroid hormones that regulate metabolic processes throughout the body. The thyroid gland has two lobes connected by an isthmus. It has a rich blood supply from three main arteries and is composed of follicles containing thyroid epithelial cells that absorb iodine and produce thyroid hormones, as well as parafollicular cells. The thyroid gland receives nerve fibers from cervical ganglia via branches of the vagus nerve.

1. ANATOMY OF
THYROID GLAND
By:
Waqas Nawaz
11-arid-975
DVM 2nd sem.

2. THYROID GLAND
 An endocrine gland that produces thyroid
hormones that regulate many metabolic
processes in the body.
 Metabolic processes are activities that occur
in cells, involving the release of energy from
nutrients or using energy to create other
substances.
 Thyroid hormones are important in the
maintenance of normal, healthy activity
levels of many different organs in the body.

3. LOCATION
•In front of the neck
•below the larynx (voice box)
•The thyroid gland consists of two
lobes, one on each side
•It starts cranially at the oblique line on the
thyroid cartilage (just below the laryngeal
prominence, or 'Adam's Apple'), and
extends inferiorly to approximately the fifth
or sixth tracheal ring, windpipe
•each gland is deeply buried in the soft
tissues of the neck that surround the voice
box.

5. GENERAL STUCTURE
 Elongated
 Dark red gland
 size is variable
 Depending on the breed and individual animal.
 It is shaped like a "bow tie," having two halves
or lobes.
 A normal thyroid gland may or may not be
palpable (felt in the neck with fingertips); this
varies in certain breeds of dog.

6.  Two cone-like lobes or wings, lobus dexter
(right lobe) and lobus sinister ( left
lobe), connected via the isthmus.
 larger endocrine glands, weighing 2-3 grams
in neonates and 18-60 grams in adults, and
is increased in pregnancy.

7. HISTOLOGICAL STRUCTURE
thyroid gland is composed of three parts….
1. Follicles.
spherical follicles that selectively absorb
iodine (as iodide ions) from the blood for
production of thyroid hormones, but also for
storage of iodine in thyroglobulin.
2. Thyroid epithelial cells
(or "follicular cells")
3. Parafollicular cells
(or "C cells")

9. THE BLOOD SUPPLY
 5ml/gram of tissue.
 This makes the blood supply almost twice as
rich as that of the kidney.
 When the thyroid is very large, the massive
blood flow to the gland is audible as a noise
(bruit).

10.  There are three main arteries supplying the
thyroid gland:
 1) Superior thyroid artery
2) Inferior thyroid artery
Veins
 1) Superior thyroid vein
2) Middle thyroid vein
3) Inferior thyroid vein

12. NERVE SUPPLY
 Nerves are derived from the superior, middle
and inferior cervical sympathetic ganglia.
 Reach the thyroid gland through the cardiac
and laryngeal branches of the vagus
nerve, which runs along the arteries supplying
the gland.
 These postganglionic fibres are vasomotor and
indirectly affect the gland through its blood
supply.