Organs - Thyroid gland

Question 1

Anatomical location

Answer 1

Anterior neck.

Spans from C5-T1.

Consists of two lobes, connected by a central isthmus (butterfly shape).

Located within the visceral compartment of the neck. This compartment is bound by pretracheal fascia.

Question 2

Clinical relevance - thyroglossal cyst

Answer 2

Thyroid gland development begins in the base of the tongue - foramen cecum.

Reaches destination in the anterior neck by week 7.

Descent form the thyroglossal duct. Usually regresses by 10th week gestation but may persist. If it fails to regress, the duct can give rise to cysts and fistulae.

A buildup of secretions can build up within the duct, forming a cysts. This presents as a lump on the midline lump in the anterior neck, which rises with tongue protrusion.

If cyst infects - it forms a cutaneous fistula - this produces leaking discharge out onto the skin of the anterior neck.

Treated by complete excision - recurrence 2.5%.

Question 3

Anatomical relations?

Answer 3

Anteriorly - infrahyoid muscles (namely, the sternothyroid, sternohyoid and omohyoid)

Laterally - carotid sheath

Medially -

• Oesophagus, trachea, larynx and pharynx

Nerves - external and recurrent laryngeal

Question 4

Vasculature?

Answer 4

Arterial supply

1) Superior thyroid artery, arises from the ECA
2) Inferior thyroid artery, arises from teh thyrocervial trunk

Venous drainage

Superior, middle and inferior thyroid veins - forms a plexus

Question 5

Innervation?

Answer 5

Innervates by nerves derived from the sympathetic trunk.

However, these nerves do not determine secretion of thyroid hormone. The pituitary gland is responsible for this.

Question 6

Lymphatic drainage?

Answer 6

1) Paratracheal nodes
2) Deep cervical nodes

Question 7

Clinical relevance - recurrent laryngeal nerve

Answer 7

This nerve lies in close proximity to the thyroid - potential for damage during surgery.

They branch from the respective vagus nerve within the chest and hooks around the subclavian artery or the arch of the aorta.

It then runs back up the neck, running between the trachea and oesophagus in the tracheooesopheal groove. it passes under the thyroid to innervate the larynx.