ANATOMY OF THYROID GLAND

By:

Waqas Nawaz11-arid-975DVM 2nd sem.

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.

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.

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.

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.

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")

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).

There are three main arteries supplying the thyroid gland:

1) Superior thyroid artery2) Inferior thyroid artery

Veins 1) Superior thyroid vein

2) Middle thyroid vein3) Inferior thyroid vein

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.

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