Anatomy of the Head and Neck

lecture 14

Abbas A. A. Shawka

Medical student

2nd stage

Subjects

Neck

- Anterior triangle 2

Thyroid• The thyroid gland is anterior in the

neck below and lateral to the thyroid cartilage

• It consists of :-

1. Two lateral lobes (which cover the anterolateral surfaces of the trachea, the cricoid cartilage and the lower part of the thyroid cartilage)

2. an isthmus that connects the lateral lobes and crosses the anterior surfaces of the second and third tracheal cartilages.

• Lying deep to the sternohyoid, sternothyroid, and omohyoid muscles, the thyroid gland is in the visceral compartment of the neck. This compartment also includes the pharynx, trachea, and esophagus and is surrounded by the pretracheallayers of fascia.

Development • The thyroid gland arises as a median

outgrowth from the floor of the pharynx near the base of the tongue.

• The foramen cecum of the tongue indicates the site of origin

• the thyroglossal duct marks the path of migration of the thyroid gland to its final adult location.

• The thyroglossal duct usually disappears early in development, but remnants may persist as a cyst or as a connection to the foramen cecum (i.e. , a fistula) .

Arterial supply of thyroid

• 1- superior thyroid artery

• Branch of ECA

• Traverse the thyrohyoid muscle

• After reaching superior pole of lateral lobe it will divided into :-

• Superior glandular branch

• Anastomoses with its twin across the isthmus

• Inferior glandular branch

• May anastomoses with the inferior thyroid artery

• When the inferior thyroid artery turns medially, it gives off an important branch (the ascending cervical artery) ,which continues to ascend on the anterior surface of the prevertebral muscles, supplying these muscles and sending branches to the spinal cord.

Arterial supply of thyroid 2. Inferior thyroid artery

• Arises from thyrocervical trunk ( 1st

part of subclavian a. )

• Reach the inferior pole of lateral lobe then divided into :-

• Inferior branch

• Anastomoses with posterior glandular branch of superior thyroid artery

• Ascending branch

• Supply the parathyroid glands

** thyroid ima artery MAY arises from brachiocephalic trunk or arotic arch asend in fron of trachea to supply the gland !!

Venous drainage of thyroid

1. superior thyroid vein ( drain into IJV )

• Drain area supplied by superior thyroid a.

•

2. Middle thyroid vein ( drain into IJV )

3. Inferior thyroid vein(drain into R.& L. brachiocephalic veins respectively)

• These two Drain the rest area of the thyroid

1

2

3

Recurrent laryngeal nerves • After branching from the vagus nerve

[X] and looping around the subclavian artery on the right and the arch of the aorta on the left, the recurrent laryngeal nerves ascend in a groove between the trachea and esophagus.

• They pass deep to the posteromedial surface of the lateral lobes of the thyroid gland

• Together with branches of the inferior thyroid arteries ,

• the recurrent laryngeal nerves are clearly related to, and may pass through ligaments, one on each side, that bind the thyroid gland to the trachea and to the cricoid cartilage of the larynx. These relationships need to be considered when surgically removing or manipulating the thyroid gland.

parathyroid gland • structures on the deep surface of the

lateral lobes of the thyroid gland. They are designated as the superior and inferior parathyroid glands .

• However,

• their position is quite variable and they may be anywhere from the carotid bifurcation superiorly to the mediastinum inferiorly.

• Derived from the third (the inferior parathyroid glands) and fourth (the superior parathyroid glands) pharyngeal pouches, these paired structures migrate to their final

• adult positions

• The arteries supplying the parathyroid glands are the inferior thyroid arteries, and venous and lymphatic drainage follows that described for the thyroid gland.

cervical part of sympathetic trunk• Most fibers to cervical ganglia is from

T1.

• Superior cervical ganglia

• Apposite to C1-C2 vertebrae

• Post ganglionic fibers of this ganglia distributed through C1,C2,C3,C4 spinal nerves !!

• Middle cervical ganglia

• Apposite to C6 vertebraPostganglionic fibers of this ganglia distributed through C5,C6 spinal nerves !!

• Inferior cervical ganglia

• Apposite to C7 vertebra

• Post ganglionic fibers of this ganglia distributed through C7,C8 spinal nerves !!

Neck lymph nodes

Superficial cervical nodes

Deep cervical nodes

- Posterior of scalp- Posterolateral of scalp

- Tonsils - Tonsillar region

- Tongue

Jugulodigastric LN

juguloomohyoid LN

Jugular trunk

Right

left

Right lymphatic duct

Thoracic duct