Anatomy of the Thyroid Gland Flashcards
what are the anatomical relations of the thyroid gland?
larynx & trachea in the anterior neck
How many lobes does the thyroid have?
2 lateral lobes (right & left)
may have an Isthmus (a narrow connecting band)
Where do the lobes of the thyroid attach to?
lateral aspects of the thyroid & cricoid cartilages and to the trachea
Which tracheal cartilages does the isthmus lie anterior to?
2nd & 3rd cartilages of the trachea
What is the name given to an enlarged thyroid gland?
goitre
Where are the superior and inferior parathyroid glands found?
the posterior surface of the thyroid gland
What remnant of embryological development can be seen as part of the thyroid gland?
Pyramidal lobe
some not connected to the main thyroid gland1
Where can the pyramidal lobe attach to?
- Most attach superiorly to thyroid cartilage
* May extend as far superiorly as the hyoid bone
Where does thyroid development begin in the embryo?
at the junction between the anterior 2/3rds (horizontal) and posterior 1/3rd (vertical) of the tongue
When the thyroid migrates inferiorly during development, what does it remain attached to?
tongue via the thyroglossalduct
What is the name given to the superficial muscles found in the superficial fascia around the thyroid?
platysma
part of the muscles of facial expression
What nerve are the platysma muscles supplied by?
CN VII (the facial nerve)
What structures can be found in the pre-vertebral deep fascia?
Postural neck muscles
Cervical vertebrae
What 2 muscles are found in the investing fascia?
Trapezium
Sternocleidomastoid
What structures are contained in the carotid sheaths
- Vagus nerves
- Deep cervical lymph nodes
- Carotid arteries
- Internal jugular vein
What structures are located in the pre-tracheal fascia
- Oesophagus
- Trachea
- Thyroid gland
- Strap muscles
- Recurrent laryngeal nerves
What arteries are responsible for supplying the thyroid gland
Superior Thyroid Artery
Inferior Thyroid Artery
Thyroid Ima Artery (not seen in everyone)
Where does the superior thyroid artery branch from?
External carotid artery
Where does the inferior thyroid artery branch from?
R + L subclavian
What veins are responsible for draining the thyroid gland?
Superior Thyroid Vein
Middle Thyroid Vein
Inferior Thyroid Vein
Where do the superior and middle thyroid veins drain to?
Internal Jugular Vein
Where do the inferior thyroid veins drain to?
Brachiocephalic Vein
What lymph nodes surround the thyroid gland
Superior deep cervical lymph nodes
(Right) Inferior deep cervical lymph nodes
Pre-tracheal node
Para-tracheal node
What cranial nerve does the recurrent laryngeal nerve branch from?
CN X
Vagus Nerve
What structure does the Right Recurrent Laryngeal nerve loop underneath?
Right Subclavian Artery
What structure does the Left Recurrent Laryngeal nerve loop underneath?
Arch of the Aorta
Name the 4 strap muscles
Thyrohyoid
Sternohyoid
Omohyoid
Sternothyroid
How can the thyroid be surgically accessed?
- Classical thyroidectomy
- Endoscopically assisted thyroidectomy
- Endoscopic trans-axillary approach
- Endoscopic trans-breast approach
Where is the incision usually made in a classical thyroidectomy?
just superior to the clavicles & jugular notch
What does each recurrent laryngeal nerve supply?
somatic motor supply to most of the skeletal muscles that move each vocal cord
What does unilateral recurrent laryngeal nerve damage result in?
- hoarseness
- weakness of the voice
- a weak cough
What does bilateral recurrent laryngeal nerve injury result in?
- aphonia (inability to produce sound)
- inability to close the rima glottidis (opening between vocal cords)
=> cant prevent aspiration
=> cant produce good cough
