Anatomy Topic 4 Case 9 Flashcards
Identify the general structure of the thyroid gland
- Two lateral lobes (covering anterolateral surfaces of trachea, cricoid and lower part of thyroid cartilage)
- Isthmus that connects the lateral lobes
The isthmus crosses which tracheal cartilages?
- Second and third
Which compartment of the neck is the thyroid gland located in?
- Visceral compartment of neck
- Deep to the infrahyoid muscles
Outline the histological origin of the thyroid gland
- Arises from median outgrowth from floor of pharynx
- Foramen cecum of the tongue is site of origin
- Thyroglossal duct marks the path of migration of thethyroid glandto its final adult location
The superior thyroid artery is a branch of which artery?
- First branch of external carotid artery
Outline the course of the superior thyroid artery
- Passes along lateral margin of thyrohyoid muscle
- Reaches superior part of lateral lobe on each side
- Where it divides into anterior and posterior glandular branches
The inferrio thyroid artery is a branch of which artery?
- Thyrocervical trunk
- Which arises from the subclavian artery
Outline the course of the inferior thyroid artery
- Ascends along medial edge of anterior scalenes
- Passes posteriorly to the carotid sheath
- Reaches the inferior pole of the lateral lobe of thethyroid gland
- Divides into inferior and ascending branches
What does the ascending branch of the inferior thyroid artery supply?
- Parathyroid glands
What is the thyroid ima artery?
- An inconsistent artery
- Which arises form brachiocephalic trunk or aortic arch
- Which ascends on anterior surface of trachea to supply thyroid gland
Outline the venous drainage of the thyroid
- Superior, middle and inferior thyroid veins
- Superior and middle thyroid veins drain into internal jugular vein
- Inferior thyroid veins drain into brachiocephalic veins
Outline the lymphatic drainage of the thyroid
- Paratracheal nodes beside trachea
- Deep cervical nodes inferior to omohyoid
Outline the course of the recurrent laryngeal nerve
- Branches from vagus nerve
- Loops around subclavian artery
- Ascend in a groove between trachea and oesophagus
- Enters larynx by passing deep to lower margin of inferior constrictor muscle
How many parathyroid glands are there?
- 4
- Superior and inferior pair
Where are the parathyroid glands located?
- Deep surface of lateral lobes of thyroid gland
Which pharyngeal pouches are the parathyroid glands derived from?
- Inferior: Third
- Superior: Fourth
Which triangle of the neck are the thyroid gland and parathyroid glands located?
- Muscular triangle
Identify the three histological layers of the adrenal cortex from superficial to deep
- Zona glomerulosa
- Zona fasciculata
- Zona reticularis
What does the zona glomerulosa secrete?
- Mineralocorticoids
- Principally aldosterone
What does the zona fasciculata secrete?
- Glucocorticoids
- Principally cortisol
What does the zona reticularis secrete?
- Sex hormones
Which is the thickest layer of the adrenal cortex?
- Zona fasciculata
Which layer of the adrenal cortex has cells arranged in clusters separated by trabeculae?
- Zone glomerulosa
Which layer of the adrenal cortex has cells arranged in branching cords and clusters?
- Zone reticularis
Which layer of the adrenal cortex has cells arranged in narrow columns and cords
- Zone fasciculata
Which layer of the adrenal cortex has a pale staining cytoplasm and why?
- Zona fasciculata
- Large numbers of lipid droplets are present
What does the adrenal medulla secrete?
- Catecholamines (adrenaline and noradrenaline)
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Why are secretory cells of the adrenal medulla sometimes called chromaffin cells?
- The secretory granules are oxidised to a brown colour
Secretion of catecholamines by the adrenal medulla is controlled by what?
- Preganglionic neurones of the sympathetic nervous system
What controls aldosterone secretion from the zona glomerulosa?
- Renin-angiotensin system
- Which in turn is controlled by the macula densa of the distal renal tubule
What controls cortisol secretion from the zona reticularis?
- Hypothalamus
- Via the anterior pituitary trophic hormone ACTH
- From stimuli including stress
