Anatomy of the Thyroid Gland (and ovaries) Flashcards
what makes up the thyroid gland
2 lateral lobes (right and left) and an isthmus (a narrow connecting band)
what do the lobes of the thyroid attach to
lateral aspects of the thyroid and cricoid cartilages and to the trachea
where is the isthmus
lies anterior to the 2nd and 3rd cartilages of the trachea
what is a goitre
an enlarged gland
what happens to a lump in the thyroid when you swallow
will move superiorly and then inferior with the larynx
what is the adams apple
laryngeal prominence of the thyroid cartilage
where are the parathyroid glands
on the posterior surface of the thyroid gland’s lateral lobes
what glands make up the parathyroid glands
4 glands- superior and inferior on both sides
what is the pyramidal lobe
extension of the thyroid glandular tissue- can extend as far superiorly as the hyoid bone but most attach superiorly to the thyroid cartilage
where does the thyroid gland begin its development
as a midline epithelial proliferation at the tongue (foramen caecum in adults)
(at junction between anterior 2/3rds and posterior 1/3rd)
what is the migratory path of the thyroid gland
inferiorly whilst remaining attached to the tongue via the thyroglossal duct
when does the thyroid reach its final position
7th week of development
where can thyroglossal duct cysts or ectopic thyroid tissue be found
anywhere in thyroid or along migratory path
what is a platysma
a skeletal muscle in the superficial fascia
is a muscle of facial expression
what is the cranial nerve supply of the platysma muscles
cranial nerve VII
what does paravertebral deep fascia contain
postural neck muscles
cervical vertebrae
what does the investing fascia contain
encloses all other neck fascia
compartments enclose:
-trapezius
-sternocleidomastoid
where are the carotid sheaths and what do they contain
located anterolaterally either side of the thyroid gland contain: -vagus nerves -deep cervical lymph nodes -carotid arteries -internal jugular vein
where is the pretracheal fascia and what does it contain
located anteriorly contains: -oesophagus -trachea -thyroid gland -strap muscles -recurrent laryngeal nerve
what is the danger zone
area behind retopharyngeal space that extends down to the diaphragm- can allow infection to spread
what nerve supplies the SCM and trapezius
spinal accessory nerve
where does the trapezius attach inferiorly
spine of the scapula and the lateral end of the clavicle
what does the external jugular vein run within
the superficial fascia
what does the external jugular vein drain into
subclavian vein then into the brachiocephalic vein
what does the anterior jugular vein run within
superficial fascia
what does the anterior jugular vein drain into
external jugular vein
where does the sternal head of the SCM attach to
manubrium of the sternum
where does the clavicular head of the SCM attach to
medial end of the clavicle
where do both heads of the SCM attach to proximally
mastoid process of the temporal bone
what are the carotid sheath made of
deep fascia
where do the carotid sheath attach to
superiorly- base of the skull (around jugular foramen and the entrance to carotid canal)
inferiorly- mediastinal fascia
what is the blood supply of the thyroid and parathyroid glands
superior thyroid artery
from external carotid artery
from common carotid artery
inferior thyroid artery
from right subclavian artery
thyroid ima artery
from brachocephalic artery
what is the venous drainage of the thyroid and parathyroid glands
superior and middle thyroid vein- go into internal jugular veins
inferior thyroid veins- go into brachiocephalic veins
what is the lymphatic drainage of the thyroid and parathyroid glands
superior deep cervical lymph nodes
inferior deep cervical lymph nodes
on right- right lymphatic duct to right venous angle
on left- thoracic duct to the left venous angle
tracheal lymph nodes- comprised of pretracheal (front) and paratracheal (side) nodes
how does the vagus nerve travel in the neck
branches from the medulla oblongata
exit the skull via the jugular foramen
descend through in the carotid sheath
how does the vagus nerve travel in the thorax
descends through the chest:
right side- lateral to trachea
left- left side of aortic arch
both- posterior to the lung hilum and on the oesophagus
how does the vagus nerve travel in the abdomen
both vagus nerves pass through the diaphragm with the oesophagus
then divide into their terminal branches on the surface of the stomach
supply the abdominal organs with parasympathetic axons to the distal midgut
what is the paths of the recurrent laryngeal nerves
left- recurs under the arch of the aorta
right- recurs under the subclavian artery
where are the recurrent laryngeal nerves in the neck
between trachea and oesophagus
what are the strap muscles
infrahyoid muscles
- sternohyoid
- sternothyroid
- thyrohyoid
- omohyoid
what do the infrahyoid muscles do
position hyoid bone, swallowing, movement of the larynx, depressing the hyoid
what does the fascial sling of the omohyoid do
attaches the intermediate tendon of the omohyoid to the clavicle
what are the surgical approaches to the thyroid gland
- classical thyroidectomy
- endoscopy assisted thyroidectomy
- endoscopy trans-axillary approach
- endoscopy trans-breast approach
describe a classical thyroidectomy incision
a collar incision is made with natural skin crease/ within langers lines
incision superior to clavicles and jugular notch
incision is made through skin and platysema
what might be at risk in a thyroidectomy incision
anterior jugular veins right sternohyoid pretracheal fascia inferior thyroid veins vagus nerve right subclavian artery right recurrent laryngeal nerve
describe the process of a classical thyroidectomy
right carotid sheath structures retracted laterally
mobilise the thyroid lobes anteriorly to dissect the parathyroid glands and their blood supplies free from the posterior surface of the thyroid gland
thyroid isthmus sectioned and retracted laterally
what does the right recurrent laryngeal nerve supply
provides motor supply to most of the skeletal muscles that move the right vocal chord (intrinsic muscle of the larynx)
what does recurrent nerve injury result in
paralysis of the vocal chord
what does unilateral recurrent nerve injury result in
hoarseness or weakness of the voice and a weak cough
what does bilateral recurrent nerve injury cause
aphonia (inability to produce sound)
inability close the rima glottidis and prevent aspiration
inability to produce good cough (requires closure of rima glottidis)
what is the rima glottidis
opening between vocal chords
what nerve crosses the posterior triangle of the neck
accessory nerve
what do the ovaries secrete
oestrogen and progesterone
what is the blood supply to the ovaries
vascular anastomosis= ovarian artery (from aorta) + unterine atery (from internal iliac)
