THYROID, PARATHYROID AND SUPRARENAL GLANDS

Dr Rania Gabr

By the end of the lecture, the student should be able to:

Describe the shape, position, relations and structure of the thyroid gland.

List the blood supply & lymphatic drainage of the thyroid gland.

Describe the shape, position, blood supply & lymphatic drainage of the parathyroid glands.

Describe the shape, position, blood supply & lymphatic drainage of the adenal glands.

OBJECTIVES

Deep cervical fascia of the neck

It is divided into 3 layers:

1- Investing layer.

2- Pretracheal layer.

3- Prevertebral layer. 3

Consists of right & left lobes.

The 2 lobes are connected to each other by a narrow isthmus, which overlies the 2nd 3rd & 4th tracheal rings.

It is surrounded by a sheath derived from the pretracheal layer of cervical fascia.

Thyroid gland

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Each lobe is pear shaped, with its apex directed upward as for as the oblique line of the thyroid cartilage its base lies at the 4th or 5th tracheal ring.

The isthmus extends across the midline in front of the 2nd 3rd & 4th tracheal rings.

Anterior

Posterior

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Inside the pretracheal facial capsule, there is another capsule. So, it s surrounded by 2 membranes.

A small pyramidal lobe is often present which projects from the upper border of the isthmus usually to left of middle line.

Pyramidal lobe is connected to hyoid bone by a fibrous or muscular band called levator glandulae thyroideae.

This represents the fibrosed & obliterated thyroglossal duct.

Levator glandul

ae thyroid

eae

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Anterolaterally: (4 S).

1. Sternothyroid.

2. Sternohyoid.

3. Superior belly of omohyoid

4. Sternomastoid.

RELATIONs OF THE

THYROID

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:

1-Superior thyroid artery:From the external carotid artery It descends to the upper pole of the

lobe, with the external laryngeal nerve.

It runs along the upper border of the isthmus to anastomosis with its fellow.

2- Thyroidea ima artery:If present, it arises from aortic arch

or from brachiocephalic artery.It ascends in front of the trachea to

reach the isthmus.

ARTERIAL SUPPLY

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3-Inferior thyroid artery

From the thyrocervical trunk of 1st part of subclavian artery, ascends behind the gland to the level of cricoid cartilage.

It curves medially behind the carotid sheath.

Then it reaches the posterior aspect of the gland & descends downwards.

The recurrent laryngeal nerve crosses either in front or behind it.

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1-Superior thyroid vein internal jugular vein 2- Middle thyroid vein internal jugular vein3- Inferior thyroid veinunite left brachiocephalic

vein

Veins of Thyroid Gland

Lymph Of the Thyroid Gland:Deep cervical & paratracheal

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Nerves:

Sympathetic fibers from superior, middle, and inferior cervical ganglia reach the gland through the

1- laryngeal and 2- cardiac branches of the vagus

nerve

4 small ovoid bodies, about 6 mm. long.

They lie within the fascial capsule of the gland, (between the 2 membranes).

2 superior parathyroid has a constant position at the middle of posterior border of the gland.

2 inferior parathyroid usually at the level of the inferior pole.

They sometimes lie within the thyroid tissue or sometimes outside the fascial capsule.

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PARATHYROID GLAND

• Arterial supply• They are supplied mainly by the

inferior thyroid artery

• Venous Drainage• Blood is drained mainly by inferior

thyroid vein

• Lympahatic drainage• Lymph is drained to deep cervical and

paratracheal lymph nodes

• Nerve Supply• They are supplied by sympathetic

fibers

SUPRARENAL GLANDS The two suprarenal glands

are yellowish retroperitoneal organs that lie on the upper poles of the kidneys , just above the level of T12

They are surrounded by renal fascia (but are separated from the kidneys by the perirenal fat).

Each gland has an outer cortex and an inner medulla.

• The right gland is pyramidal in shape and caps the upper pole of the right kidney.

• Relations: • Anterior:

right lobe of the liver and inferior vena cava.

• Posterior: diaphragm.

• The left gland is crescentic in shape and extends along the medial border of the left kidney from the upper pole to the hilus.

• Relations: • Anterior:

pancreas, lesser sac, and stomach

• Posterior: diaphragm.

Arteries: Each gland receives branches from three main arteries:

1- Superior suprarenal a. from Inferior phrenic

2- Middle suprarenal art. From the Aorta

3- Inferior suprarenal art. From Renal artery.

• Veins: • A single vein

emerges from the hilum of each gland

• The right adrenal vein drains into the Inferior vena cava

• The left adrenal vein drains into the Lt Renal vein on the left. • Nerve Supply:

Preganglionic sympathetic fibers derived from the splanchnic nerves. Most of the nerves end in the medulla of the gland.

• Lymph Drainage: The lymph drains into the lateral aortic nodes.

Thank You