Download Thyroid gland

Thyroid gland
By
Dr. Adel Sahib Al-Mayaly
‫دعاء الصباح‬
Blood supply
• Thyroid is a vascular organ rich in blood
supply.
• Two main sources of arterial supply:• 1- External carotid artery;- sup. Thyroid
artery.
• 2- Subclavian artery;- inferior thyroid A.
• 3- Thyroideae ima A. ;- brachiocephalic art.
Blood supply
Superior Thyroid Artery
• the first branch from the anterior aspect of
the external carotid.
• It descends downward for a short distance it
pierces the pretracheal fascia & divides into
ant. & post. Branches.
• The external laryngeal n. lies behind the art, &
it leaves the art. just above the upper pole to
supply cricothyroid muscle
Inferior thyroid artery
• from the thyrocervical trunk.
• arches upwards and medially behind the carotid
sheath arches upwards and medially behind the
carotid sheath.
• It divides outside the pretracheal fascia into
• branches that pierce the fascia.
• The recurrent laryngeal nerve has a variable
relationship to the artery
•
Relation of RLN to IThA
Venous Drainage
• 1-Superior thyroid vein:• follows the superior thyroid artery and
enters drains to the internal jugular vein.
• 2- Middle thyroid vein:• Crosses anterior to the common carotid
artery to drain into the internal jugular
vein.
• The inferior thyroid vein:• Drain into brachiocephalic vein.
Parathyroid glands
Overview
• Parathyroid glands normally lie behind the
lobes of the thyroid gland.
• There are usually four glands two on each
side.
• Each weighs about 50 mg.
• They are brownish-yellow, which helps to
distinguish them from the deep red of the
thyroid gland.
•
Superior Gland
• It is the more constant in position.
• it is usually within the thyroid’s pretracheal
fascial capsule.
• At the middle of the back of the thyroid
lobe, level with the first tracheal ring and
above the inferior thyroid artery.
•
•
Inferior Gland
• is less constant in position.
• It is usually within the pretracheal fascial
sheath behind the lower pole but it may.
• be in the gland itself.
Blood Supply
• Both upper and lower parathyroid by an
anastomosis between the superior and
inferior arteries.
• Their minute veins join thyroid veins.
Lymph drainage
• As for lymph drainage of the thyroid
gland
Cervical plexus
Cervical plexus
• It is formed by the ventral primary divisions of
the first four cervical nerves.
• Each nerve, except the first, divides into the
superior branch and the inferior branch.
• C1 joins the upper branch of C2
• the adjacent upper and lower branches of C2
and C3 fuse
• Each nerve receives a gray ramus communicans
from the superior cervical ganglion.
Cervical plexus
• The loops lie on the surfaces of the levator
scapulae and the scalenus medius muscles
• It is covered by the upper part of SCM muscle.
• The plexus lies behind the prevertebral layer
• of deep cervical fascia.
• The plexus supplies the skin and the muscles
of the head, the neck, and the shoulders.
•
Branches
Cutaneous branches
• 1- The lesser occipital nerve (C2), which
supplies the back of the scalp and the auricle
• 2- The great auricular nerve (C2 and 3), which
supplies the skin over the angle of the mandible
• 3- The transverse cervical nerve (C2 and 3),
which supplies the skin over the front of the neck
• 4-The supraclavicular nerves (C3 and 4).
• The medial, and intermediate, and lateral
branches
• supply the skin over the shoulder region.
Muscular (Deep) branches
• 1- Communicating branch:- from C1 to
the hypoglossal nerve.
• It carries motor fibres to genniohyoid &
thyrohyoid muscles & to remaining infrahyoid
muscles.
• 2- Muscular branches:- from all roots to
prevertebral muscles.
Cervical plexus
• 3- proprioceptive branches:- from C2,3 to
SCM & C3,4 to trapezius m.
• 4- Descending cervicalis ( descending root
of ansa).
• 5- Phrenic nerve:- C3,4,5
• It runs vertically downward over scalenus
anterior m. behind subclavian v. to enter
mediastinum to supply diaphragm.