Thyroid Gland Flashcards
How does the thyroid gland begin to form during embryological development?
Proliferation on the medial surface of developing pharyngeal arches
Where is the site of development of the thyroid gland?
Between the tuberculum impar and copula
What is the site of origin of the thyroglossal duct?
A pit called the foramen cecum
Where is the thyroid gland located?
Anterior region of the neck
What are 4 medial relations of the thyroid gland?
- Larynx
- Trachea
- Pharynx
- Oesophagus
What lies in the groove between the oesophagus and the trachea|?
Recurrent laryngeal nerve
Where does the recurrent laryngeal nerve come from?
Branch of the vagus nerve
What are 4 anterolateral relations of the thyroid gland?
- Sternohyoid
- Superior belly omohyoid
- Sternothyroid
- Anterior boarder sternocleidomastoid
What are 3 posterior relations of the thyroid gland?
- Superior parathyroid gland
- Inferior parathyroid gland
- Anastomosis between superior and inferior thyroid artery
What is the visceral compartment which holds the thyroid gland?
Pretracheal fascia
Where does the thyroid gland extend from?
Oblique line of the thyroid to tracheal ring 4 or 5
What shape is the thyroid gland?
Butterfly shaped
What connects the two lobes of the thyroid?
Isthmus
What accessory lobe may be present in the thyroid?
Pyramidal lobe, which extends upward from isthmus anterior to thyroid cartilage
What are the 4 large arteries which supply the thyroid?
- Right inferior thyroid artery
- Left inferior thyroid artery
- Right superior thyroid artery
- Left superior thyroid artery
Where do the inferior thyroid arteries come from?
Thyrocervical trunk of subclavian artery
What part of the thyroid gland does the inferior thyroid arteries supply?
Posterior and inferior parts
Where do the superior thyroid arteries come from?
External carotid artery
What part of the thyroid gland does the superior thyroid arteries supply?
Upper pole
What is the accessory vessel which can be present and supply the thyroid gland?
Thyroid ima artery
Describe the path of the thyroid ima artery
Originates from aortic arch or brachiocephalic artery and enters the thyroid gland at inferior boarder of isthmus
Where does lymph from the thyroid gland mainly drain to?
Laterally into the deep cervical lymph nodes
Where does some of the lymph from the thyroid gland mainly drain to?
Paratracheal nodes
What are the 3 drains which provide venous drainage for the thyroid gland?
- Superior thyroid vein
- Middle thyroid vein
- Inferior thyroid veins
Where does the superior thyroid vein end?
Internal jugular vein
Where does the middle thyroid vein end?
Laterally into the internal jugular vein
Where are 2 ways the right inferior thyroid vein end?
- Right brachiocephalic vein
2. Anastomose with left inferior thyroid vein
What accompanies the superior thyroid artery as it descends to the upper pole of each lobe?
External laryngeal branch of superior laryngeal nerve
What accompanies the inferior thyroid artery as it ascends behind the gland?
Recurrent laryngeal nerve crosses either in front of behind this artery or may pass between its branches
What type of operation can damage the two main arteries supplying the thyroid gland?
Thyroidectomy
What two things does the external laryngeal nerve supply?
- Thyroid gland
2. Cricothyroid muscle
What is the function of the cricothyroid muscle?
Produce tension and elongation of the vocal folds resulting in higher pitch phonation
What 2 things can result from damage to the external laryngeal nerve?
- Inability to tense vocal folds
2. Hoarseness of voice
What is a tracheostomy?
Creation of an opening through the trachea
What are 3 functions of a tracheostomy?
- Exploration
- Removal of a foreign body
- Obtaining a biopsy specimen
What is a thyroidectomy used to treat?
Benign multinodular goitre
Where does the common carotid artery divide?
Upper boarder of thyroid cartilage
What is the carotid sinus?
Dilated area at the base of the internal carotid just superior to bifurcation of common carotid
What branch of the carotid artery gives no branches in the neck?
Internal carotid artery
What are 2 terminal branches of external carotid artery?
- Superficial temporal
2. Maxillary
What branch passed between the external and internal carotid artery?
Ascending pharyngeal
What are 3 branches from the anterior boarder of the external carotid artery?
- Superior thyroid
- Facial
- Lingual
What are 2 branches from the posterior boarder of the external carotid artery?
- Occipital
2. Posterior auricular
Where is the carotid sheath located?
Deep to sternocleidomastoid, extending from base of the skull to the first rib and sternum
What are 4 contents of the lower part of the carotid sheath?
- Common carotid artery
- Internal jugular vein
- Vagus nerve
- Deep cervical lymph nodes
Describe the relation of the common carotid artery to the internal jugular vein
Lies medial within the carotid sheath
Where is the vagus nerve situated in the carotid sheath?
Between common carotid artery and internal jugular vein
What 3 nerves are contained in the upper part of the carotid sheath?
- CN IX
- CN XI
- CN XII
Where is the ansa cervicalis found?
Embedded into the anterior wall of the carotid sheath
Where is a carotid artery pulse taken?
Deep to anterior boarder of sternocleidomastoid at the level of superior boarder of thyroid cartilage
What is the function of the carotid sinus?
Contains sensors which help regulate blood pressure
What is the purpose of carotid sinus massage?
Stimulates an area containing nerve areas to slow heart rate
What is the carotid body?
A small cluster of chemoreceptors
What is the function of the carotid body?
Detect changes in composition of blood flow
