thyroid, parathyroid and adrenal glands Flashcards
The adrenal gland is composed of two distinct tissues: the outer cortex and the inner medulla. The adrenal cortex tends to be fattier and thus has a more yellow hue. The adrenal medulla is more of a reddish-brown color. A thick capsule consisting of connective tissue surrounds the entire adrenal gland.
what are the layers of the adrenal cortex and what do they release
Zona glomerulosa – produces and secretes mineralocorticoids such as aldosterone.
Zona fasciculata – produces and secretes corticosteroids such as cortisol. It also secretes a small amount of androgens.
Zona reticularis – produces and secretes androgens such as dehydroepiandrosterone (DHES). It also secretes a small amount of corticosteroids.
where do the superior, middle and inferior adrenal arteries arise from respectively
Superior adrenal artery – arises from the inferior phrenic artery
Middle adrenal artery – arises from the abdominal aorta.
Inferior adrenal artery – arises from the renal arteries.
innervation of the Adrenal glands
The adrenal glands are innervated by the coeliac plexus and greater splanchnic nerves.
Sympathetic innervation to the adrenal medulla is via myelinated pre-synaptic fibres, mainly from the T10 to L1 spinal cord segments.
what does aldosterone do
Aldosterone acts in the body by binding to and activating a receptor in the cytoplasm of renal tubular cells. The activated receptor then stimulates the production of ion channels in the renal tubular cells. It thus increases sodium reabsorption into the blood and increases potassium excretion into the urine.
In the embryo, the thyroid gland begins development near the base of the tongue – in an area known as the …………….. It descends during development and reaches its destination in the anterior neck by ……..
The descent of the developing thyroid gland forms the ……………. – an epithelialised tract that connects the gland to its origin at the foramen cecum. It usually regresses by the 10th week of gestation, but can persist in some individuals. If it fails to regress, the duct can give rise to cysts or fistulae.
foramen cecum
week 7
thyroglossal duct
A thyroglossal cyst results from a build-up of secretions within the duct.
how does it present
It typically presents as a midline lump in the anterior neck which rises on tongue protrusion. If left untreated, this cyst can become infected, and form a cutaneous fistula – discharging out onto the skin of the anterior neck.
what arteries supply the thyroid
Superior thyroid artery – arises as the first branch of the external carotid artery. It lies in close proximity to the external branch of the superior laryngeal nerve (innervates the larynx).
Inferior thyroid artery – arises from the thyrocervical trunk (a branch of the subclavian artery). It lies in close proximity to the recurrent laryngeal nerve (innervates the larynx).
In a small proportion of people (around 10%) there is an additional artery present – the thyroid ima artery. It arises from the brachiocephalic trunk and supplies the anterior surface and isthmus of the thyroid gland.
Venous drainage is carried by the superior, middle, and inferior thyroid veins, which form a venous plexus around the thyroid gland.
The superior and middle veins drain into the internal jugular vein and the inferior empties into the brachiocephalic vein.
parathyroid gland supplied by what
inferior thyroid artery
venous via all three
thyroid gland vertebral level
C5-T1
hyoid bone
C4
only complete ring in body of cartilage
cricoid cartilage
post and ant triangles split by what
sternocleidomastoid
the thyroid gland start as a bud called the thyroglossal duct that pushes outwards from the pharyngeal floor and descend to become the thyroid gland at the foramen caecum ( post tongue) lower end becomes the gland top disappears
the thoracic duct should go if not cyst forms
what operation to remove the thyroglossal cyst
sistrunks operation
benign disease of the thyroid is more common if it expands what will get quashed
trachea and oesophagus
a retrosternal goitre will cause what on percussion
dull percussion note
where can thyroid cancer erode to
trachea, oespagus and carotid sheath ( worst as could rupture)
invade recurrent laryngeal nerve and invasion of cerival sympathetic chain causing horners syndrome ( decreased pupil size, a drooping eyelid and decreased sweating on the affected side of your face.)
invasion of the cervial sympathetic chain causes horners syndrome what are the symptoms of this
usually affects one side of the face miosis(small pupils) difference in pupil size ptosis - upper eyelid delayed dilation sunken eye anhidrosis on either side of the whole face
red flags for thyroid lumps
Red Flags for thyroid lumps: Rapid growth Cough/hoarse voice/stridor Multiple enlarged cervical lymph nodes Tethering of lump to surrounding structures
treatment for thyroid cancers
Treatment: Thyroidectomy Radioiodine therapy External beam radiotherapy (adjunct) Chemotherapy – only lymphoma
most common thyroid cancer
papillary
papillary cancer most common in
young women
follicular thyroid cancer spread to where
lugn and bone
5 types of cancer of thyroid
papillary follicular medullary anaplastic lymphoma
iodine deficiency can cause what
goitre
when performing a thyroidectomy what lines do you make an incision across
langers line - just above suprasternal notch
risk of thyroid surgery what are the complications
hypocalcemia
airway obstruction
recurrent laryngeal.n. injury
wound infection
symptoms of hypocalcaemia
tingling of lips face and fingertips
superior parathyroid glands come from where
4th pharyngeal pouch
the inferior parathyroid Gland comes from where
3rd pharyngeal pouch
2nd pharyngeal arch forms what
tonsil
1st pharyngeal arch forms what
Eustachian tube
