ANATOMY - thyroid and parathyroid Flashcards
how many lobes are there in the thyroid
names
2 - right and left
what connects the 2 lobes of the thyroid
isthmus
name 2 anatomical variations in the thyroid gland
no/incomplete isthmus
pyramidal lobe - superior to rest of gland
embryologically where does the thyroid gland originate
foramen caecum
what is the path of the thyroid gland in embryology
thyroglossal duct
embryological abnormalities of thyroid (4)
failure of descent (lingual thyroid)
excessive descent (retrosternal thyroid)
thyroglossal duct cysts
ectopic thyroid tissue
where would you find a thyroglossal duct cyst
midline
where would you find ectopic thyroid tissue
anywhere along path of thyroid migration
how does the thyroid move on swallowing
superiorly then inferiorly
how do you feel for the thyroid gland
just below adams apple
spinal level of isthmus
C5-T1
in which layer is the platysma muscles
superficial fascia/subcut tissue
in which layer is the sternocleidomastoid and trapezius muscle in
investing deep fascia
what are the 2 layers of the neck that completely encircle the neck
superficial fascia
investing deep fascia
what are the attachments of the sternocleidomastoid muscle (3)
sternum
clavicle
mastoid process of temporal
what does the prevertebral deep fascia surround
postural neck muscles that surround the spine
where are the carotid sheaths in respect to the thyroid gland
anterolateral
contents of carotid sheath (4)
be specific
common carotid artery (just internal at C4)
internal jugular vein
vagus nerve
deep cervical lymph nodes
contents of pretracheal deep fascia (5)
strap muscles thyroid gland trachea oesophagus 2 recurrent laryngeal nerves
what do the strap muscles do
pull hyoid bone down
what are the 4 strap muscles
sternohyoid
omohyoid
thyrohyoid
sternothyroid
where does the sternohyoid (strap muscle) go
from hyoid bone to sternum
where does the omohyoid (strap muscle) go
from shoulder (omo) to hyoid bone
where does thyrohyoid (strap muscle) go
from thyroid to hyoid bone
where does the sternothyroid (strap muscle) go
from manubrium of sternum to thyroid
which of the strap muscles has 2 bellies (superior and inferior)
omohyoid
which strap muscle has an ‘intermediate tendon’ attached to the clavicle, that changes the course of the muscle (bc of superior and inferior bellies)
omohyoid
what are the muscles in the superficial fascia of the neck called
platysma muscles (right and left)
which arteries supply the superior thyroid
superior thyroid arteries
which arteries supply the inferior thyroid
inferior thyroid arteries
which artery supplies the isthmus of the thyroid (anatomical variation)
thyroid ima artery
where does the superior thyroid arteries come from
external carotid arteries (left and right)
where does the inferior thyroid arteries come from
subclavian arteries
on which side does the subclavian artery come directly from the arch of the aorta
left
where does the thyroid ima artery come from (if it exists)
right common carotid
what is the general blood supply/drainage to each side of the thyroid
2 inputs - superior and inferior
3 outputs - superior, middle and inferior
what drains the superior thyroid gland
superior thyroid vein
what drains most of the inferior thyroid
middle thyroid vein
what drains a little of the inferior thyroid
inferior thyroid vein
where does the superior thyroid vein drain
internal jugular vein
where does the middle thyroid vein drain
internal jugular vein
where does the L inferior thyroid vein drain
L brachiocephalic vein
where does the R inferior thyroid vein drain
L brachiocephalic (or R brachiocephalic or angle between the 2 brachiocephalics)
where does the superior thyroid drain its lymph
superior deep cervical lymph nodes
where does the inferior thyroid drain its lymph
inferior deep cervical lymph nodes
paratracheal lymph nodes
pretracheal lymph node
where does lymph in the deep cervical lymph nodes drain
right lymphatic duct or thoracic duct (on the left) then into the right/left venous angle
which nerve palsy may present with hoarse voice
vagus CN X
what is most likely to be damage in a thyroidectomy
recurrent laryngeal branches of the vagus CN X
in which layer of neck fascia does the vagus nerve travel in
carotid sheath
next to which artery does the vagus nerve travel
common carotid artery
what are the first branches of the vagus nerve
superior laryngeal branches
what do the superior laryngeal branches of the vagus nerve supply
cricothyroid muscles and mucosa above the vocal cords
which nerve are the superior laryngeal branches part of
vagus nerve CN X
what happens to the superior laryngeal nerves after they branch off the vagus
split into internal and external superior laryngeal nerves
what is supplied by the inferior laryngeal nerve
all laryngeal muscles apart from cricothyroid muscles
where does the inferior laryngeal nerve come from
recurrent laryngeal nerve
at what level does the recurrent laryngeal nerve change into the inferior thyroid nerve
cricothyroid joint
what supplies the mucosa of the throat above the vocal cords
internal superior laryngeal nerve (branch of vagus)
the internal one bc muscosa is inside = internal
what supplies the mucosa of the throat below the vocal cords
inferior laryngeal nerve (from the recurrent laryngeal nerve)
what nerve supplies most of the laryngeal muscles
inferior laryngeal nerve (form the recurrent laryngeal nerve)
what nerve supplies the cricothyroid muscles (diff from the rest of the laryngeal muscles)
external superior laryngeal nerve
the external one bc muscle is on the outside = external
what is the anastomoses between the internal laryngeal nerve and the inferior laryngeal nerve called
galens anastomoses
where does the right vagus go after it travels down the right trachea then right oesophagus
posterior oesophagus (laRP = right, posterior)
where does the right recurrent laryngeal branch of the vagus nerve go under (loop round)
right subclavian artery (in neck)
where does the left recurrent laryngeal branch of the vagus nerve go under (loop round)
ligamentum arteriosum (remnant of ductus arteriosum)
where does the left vagus go after it travels down the left trachea and oesophagus
anterior oesophagus (LArp = left, anterior)
which groove do the recurrent vagus nerves travel in
tracheoesophageal groove
how does recurrent vagus nerve injury present
why
hoarseness
they supply the vocal cords
what does the anterior jugular vein drain
face
where does the anterior jugular vein drain into
external jugular vein
what are langers lines
how were they found many years ago
the lines of skin tension
found on a cadaver
where do you cut in a thyroidectomy
superior to clavicle and jugular notch
what is berrys ligament
anchors the posterior thyroid gland in place
why is berrys ligament significant in thyroidectomy
need to cut through it to mobilise thyroid
what structure is close to berrys ligament and hence likely to be damaged in thyroidectomy
recurrent laryngeal branch of vagus
how many parathyroid glands are there
4
what are the names of the parathyroid glands
left superior
left inferior
right superior
right inferior
where are the parathyroid glands location
behind thyroid gland (1 parathyroid gland behind each thyroid gland lobe)
