THYROID&PARATHYROID_GLAND.pdf

Dr. NDAYISABA CORNEILLE
CEO of CHG
MBChB,DCM,BCSIT,CCNA
THE GROSS ANATOMY OF
THYROID & PARATHYROID
Supported BY
DR NDAYISABA CORNEILLE

OBJECTIVES
• By the end of the lecture, students should be able to:
• Describe briefly development of the thyroid & parathyroid
glands.
• Describe the shape, position, relations and structure of the
thyroid gland.
• Describe the shape, position, blood supply & lymphatic drainage
of the parathyroid glands.
• List the blood supply & lymphatic drainage of the thyroid gland.
• Describe the most common congenital anomalies of the thyroid
gland.
• List the nerves endanger with thyroidectomy operation.

VISCERA OF THE NECK
{ENDOCRINE}
INTRODUCTION
• Endocrine layer.
• Respiratory
layer.
• Alimentary
layer.

THE THYROID GLAND
• INTRODUCTION
• STRUCTURAL DESCRIPTION
• RELATIONS
• ARTERIAL SUPPLY
• VEINS
• LYMPHATICS
• INNERVATION
• HISTOLOGY
• CLINICAL CORRELATES

THYROID GLAND
INTRODUCTION
• The body's largest
endocrine gland
• Produces Thyroid hormone
and Calcitonin.
• Affects all areas of the
body except itself and the
spleen, testes, and uterus

STRUCTURAL DESCRIPTION
• Lies deep to the
sternothyroid and
sternohyoid muscles,
• Located at the level of
the C5 to T1 vertebrae
• Consists primarily of
right and left lobes
• Thin isthmus unites
the lobes, usually
anterior to the second
and third tracheal
rings

Structural description (con’t)
• Is surrounded by a thin
fibrous capsule
• Dense connective tissue
attaches the capsule to
the cricoid cartilage and
superior tracheal rings
• External to the capsule
is a loose sheath formed
by the visceral portion
of the pretracheal layer
of deep cervical fascia

RELATIONS OF THYROID GLAND
Anteriolateral, Posterior and Lateteral
relations

Anterolaterally:
1. Sternothyroid.
2. Sternohyoid.
3. Superior belly
of omohyoid
4. Sternomastoid.
RELATION
OF THE
THYROID
GLAND

Posteriorly:
Carotid sheath &
its contents.
Medially:
Larynx & pharynx,
Above.
 Trachea and
 Esophagus,
Below.
Recurrent
laryngeal nerve in
between.
 Cricothyroid
muscle & external
laryngeal nerve. DR NDAYISABA CORNEILLE

• It is rounded
and related to
the superior &
inferior
Parathyroid
glands.
• It is also related
to anastomosis
between
superior &
inferior thyroid
arteries.
Posterior border

 :
1-Superior thyroid artery:
It is a branch 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 that of
the opposite side.
2- Thyroidea ima artery:
If present, it arises from
aortic arch or from the
brachiocephalic artery.
It ascends in front of the
trachea to reach
the isthmus.
ARTERIAL SUPPLY

3-Inferior thyroid artery:
From thyrocervical trunk
of the 1st part of the
subclavian artery,
It ascends upwards to the
level of the cricoid
cartilage.
Then it curves medially
behind the carotid sheath.
Then it reaches to the
posterior aspect of the
gland.
The recurrent laryngeal
nerve crosses either in
front or behind this
artery.

Arterial Supply cont.

The blood supply and venous drainage
of the thyroid gland.

1-Superior thyroid vein internal jugular vein
2- Middle thyroid vein internal jugular vein
3- Inferior thyroid vein left brachiocephalic vein
Veins of Thyroid Gland
Lymph Of the
Thyroid Gland:
Deep cervical
& Paratracheal
lymph nodes.

LYMPHATIC DRAINAGE
• Lymphatic vessels of
the this gland run in
the interlobular
connective tissue,
usually near the
arteries.
• They communicate
with a capsular
network of lymphatic
vessels
• Some lymphatic
vessels may drain into
the brachiocephalic
lymph nodes or the
thoracic duct

INNERVATION
• They are derived
from the Superior,
Middle and Inferior
Cervical
sympathetic ganglia
• They reach the
gland through:
– The Cardiac plexus
– The superior
thyroid periarterial
plexus
– The inferior thyroid
periarterial plexus DR NDAYISABA CORNEILLE

Hormones of Thyroid gland
• Thyroid gland secretes three hormones:
1. Tetraiodothyronine or T4 (thyroxine)
2. Tri-iodothyronine or T3
3. Calcitonin.
• T4 is otherwise known as thyroxine and it
forms about 90% of the total secretion,
whereas T3 is only 9% to 10%.

PARATHYROID GLAND
INTRODUCTION & DESCRIPTION
• They are small flattened, oval glands
• Lie external to the thyroid capsule on
the medial half of the posterior
surface
• The SPThy glands and the IPThy
glands lies in relation to the point of
entry of the inferior thyroid arteries
• The superior parathyroid glands are
usually at the level of the inferior
border of the cricoid cartilage
• The inferior parathyroid glands has
varied position but usually near the
inferior pole

FUNCTIONS
• Produces Parathormone (PTH), controls the
metabolism of phosphorus and calcium in the
blood.
• The parathyroid glands target the skeleton,
kidneys, and intestine.

VESSELS OF THE PARATHYROID GLANDS
• Branches of Inferior thyroid arteries usually
supply the parathyroid glands
• From;
– the superior thyroid arteries
– the thyroid ima artery or
– the laryngeal, tracheal, and esophageal arteries
• Parathyroid veins drain into the thyroid plexus
of veins of the thyroid gland and trachea
• Lymphatic vessels into deep cervical lymph
nodes and paratracheal lymph nodes

INNERVATION
It is derived from thyroid
branches of the cervical
sympathetic ganglia
They are vasomotor rather
than secretomotor because
these glands are hormonally
regulated.

HISTOLOGY OF THYROID GLAND
• Histologically
composed of 20-30
million microscopic
spheroidal structures
called Thyroid follicles
• Made up of Two type
of cells
• Synthesis the Thyroid
hormones, thyroxine
& triiodothyronine, &
Calcitonin

THYROID FOLLICLES
• Lined by simple cuboidal
epithelium
• Central cavity containing
Colloid
• Colloid composed of
thyroglobulin
• Rich in rough
endoplasmic reticulum &
lysosome
• Generally round &
Centrally placed nucleus
• Synthesis the Thyroid
hormones, thyroxine &

PARAFOLLICULAR CELLS/ C - CELLS
• Lager than Thyroid
Follicular Cells
• Less stained in light
microscopy
• Less R.ER
• Long mitochondria
• Large Golgi complex
• Numerous small
granules
• Synthesis & secretion

HISTOLOGY OF PTHY GLAND
• The endocrine cells of the
parathyroid are arranged in cords
• The chief or principal cells & the
oxyphil cells are the cells PTHY
gland
• The chief cells are small polygonal
cells with a vesicular nucleus and a
pale-staining, slightly acidophilic
cytoplasm
• Oxyphil cells are larger polygonal
cells, and their cytoplasm contains
many acidophilic mitochondria with
abundant cristae.

functions
1) Stimulates osteoclastic activity in bones, thus
mobilizing bone calcium and increasing calcium
levels in blood.
2) Also stimulates absorption of dietary calcium from
small intestines and the reabsorption of calcium in
proximal convoluted tubules of the kidney(PCT).
3) Also strongly diminishes reabsorption of phosphate
in PCT.
• PTH secretion is controlled by calcium levels in
blood.

APPLIED ANATOMY
• Inadvertent Removal of the Parathyroid
Glands
• Pyramidal Lobe of the Thyroid Gland
• Thyroglossal Duct Cysts
• Ectopic Thyroid Gland
• Accessory Thyroid Glandular Tissue
• Enlargement of the Thyroid Gland
• Thyroidectomy
• Injury to the Recurrent Laryngeal Nerves

Inadvertent Removal of the
Parathyroid Glands
• The aberrant sites of these
glands are of concern when
searching for abnormal
parathyroid glands, as may
be necessary in treating
parathyroid adenoma
• Atrophy or inadvertent
surgical removal of all the
parathyroid glands results in
tetany, a severe neurologic
syndrome characterized by
muscle twitches and cramps.

Pyramidal Lobe of the Thyroid Gland
• Approximately 50% of
thyroid glands have a
pyramidal lobe.
• The pyramidal lobe and
the band develop from
remnants of the
epithelium and
connective tissue of
the thyroglossal duct.

Thyroglossal Duct Cysts

Ectopic Thyroid Gland
• Uncommonly, the thyroid
gland fails to descend from
its embryonic origin in the
tongue, resulting in a lingual
thyroid gland. Incomplete
descent results in the gland
being located high in the
neck, at or just inferior to the
hyoid.
• As a rule, an ectopic thyroid
gland in the median plane of
the neck is the only thyroid
tissue present.

Accessory Thyroid Glandular Tissue
• Portions of the
thyroglossal duct may
persist to form thyroid
tissue.
• Accessory thyroid
glandular tissue may
appear anywhere along
the embryonic course of
the thyroglossal duct(e.g.,
in the thymus inferior to
the thyroid gland or in the
thorax).

Enlargement of the Thyroid Gland
• Non-inflammatory
enlargement of the
thyroid gland, other
than the variable
enlargement that
may occur during
menstruation and
pregnancy, is called a
goiter. A goiter results
from a lack of iodine.

THYROIDECTOMY
• Excision of a malignant tumor of the thyroid
gland or other surgical procedure sometimes
necessitates removal of the gland
(thyroidectomy). In the surgical treatment of
hyperthyroidism, the posterior part of each
lobe of the enlarged thyroid is usually
preserved, a procedure called near-total
thyroidectomy.

Injury to the Recurrent Laryngeal
Nerves
• Hoarseness is the usual sign of unilateral
recurrent nerve injury; however, temporary
aphonia or disturbance of phonation (voice
production) and laryngeal spasm may occur.
These signs usually result from bruising the
recurrent laryngeal nerves during surgery or
from the pressure of accumulated blood and
serous exudate after the operation.

Anatomic complications of
thyroidectomy
1. Vascular injury
Thyroid arteries
2. Organ damage
the pleura (though rarely)
Tracheal perforation
Esophagus
Parathyroid glands

complications
3. Nerve injury
Vagus nerve
Recurrent laryngeal nerve
Superior laryngeal nerve
Cervical sympathetic chain

END
THANKS FOR LISTENING
By
MBChB,DCM,BCSIT,CCNA
Contact us:
amentalhealths@gmail.com/
ndayicoll@gmail.com
whatsaps :+256772497591
/+250788958241

THYROID&PARATHYROID_GLAND.pdf

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