Anatomy of the Thyroid Gland Flashcards
which cartilages of the trachea does the isthmus lie anterior to
2nd and 3rd
goitre
enlarged thyroid gland
how will a lump in the gland move during swallowing
superiorly then inferiorly
what is the prevalence of a pyramidal lobe
approx 50% of thyroid glands
pyramidal lobe
extends superiorly from isthmus - due to embryological development
most attach superiorly to thyroid cartilage. may extend as far as hyoid bone (superiorly)
isthmus may be complete or absent
most commonly originate from left lateral lobe
where are the parathyroid glands located
on the posterior surfaces of the thyroid glands lateral lobes
what is the junction between the anterior and posterior parts of the tongue called in adults
foramen caecum
describe the development of the thyroid gland
migrates inferiorly from the foramen caecum in the tongue to its final position in relation to the larynx/trachea - whilst still attached to the tongue by the thyroglossal duct
when does the gland reach its final position
in the 7th week of development
where can thyroglossal duct cysts or ectopic thyroid tissue be located in the migratory path
anywhere
platysma
superficial muscle that overlaps the sternocleidomastoid
located immediately deep to the skin within the superfical fascia of the neck
where are the platsymas
what muscle group does platysma belong to, an so what is its innervation
muscles of facial expression
CNVII (facial nerve)
which fascia encloses all other neck fascial compartments
investing (deep) fascia
investing (deep) fascia
deep to superficial fasica
encloses trapzius and sternocleidomastoid (CNXI)
carotid sheath position
deep to investing fascia
anterolaterally
what do the carotid sheaths contain
internal jugular veins
common and internal carotid arteries
CNX
deep cervical lymph nodes
prevertebral (deep ) fascia location
deep to investing fascia
posteriorly
what does the prevertebral fascia contain
cervical vertebrae
postural neck muscles
where is the pretracheal (deep) fascia
deep to investing fascia
anteriorly
what does the pretracheal fascia enclose
strap muscles
thyroid gland
trachea
oesophagus
recurrent laryngeal nerves
where is the retropharyngeal space
between the pretracheal and prevertebral fascia
how can infection spread in the neck
in the planes between the fasical tubes - the retropharyngeal space
what fascia is the sternocleiomastoid enclosed in
investing
along with trapezius
what are the attachments of the sternocleidomastoid
sternal head - manubrium of sternum
clavicular head - medial end of clavicle
where do both heads of the sternocleidomastoid attach superiorly
mastoid process of temporal bone
what are the attachments of the trapezius
originiates from occipital bone
inf: spine of scapula and lateral end of clavicle
describe the jugular vein drainage
anterior drains into external jugular vein
external drains into subclavian vein
what are the carotid sheaths made of
deep fascia
where do the carotid sheaths attach superiorly
base of the skull around the jugular foramen and entrance to the carotid canal
desribe the venous drainage of the thyroid and parathyroid glands
superior and middle thyroid veins drain into IJV
inferior thyroid vein drains into L braciocephalic vein (most of the time)
describe the arterial supply of the thyroid and parathyroid glands
describe the lypmhatic drainage of the thyroid and parathyroid glands
how is lymph returned to the right and left lymphatic ducts
right - via the right lymphatic duct to right venous angle
left - via thoracic duct to left venous angle
where does CNX orignate in the skull and exit the cranium
originates from medulla of brainstem
exits cranium through jugular foramen
describe CNX in the neck
descends through the neck in the carotid sheath
gives somatic branches to larynx: superior laryngeal nerve and right recurrent laryngeal nerve
describe CNX in the thorax
R CNX descends on the right lateral aspect of trachea, posterior to R lung root, and onto the oesophagus
L CNX descends on the left side of the arch of aorta, gives off the left recurrent laryngeal nerve, posterior to the left lung root and onto the oesophagus
describe CNX in the abdomen
both vagus nerves pass through diaphragm with the oesophagus (T10) an ddivide into their terminal branches on the surface of the stomach
supply the abdominal organs with parasympathetic axons to the distal midgut
describe the course of the recurrent laryngeal nerves
branches of CNX
left - recurs under arch of aorta
right - recurs under subclavian artery
what are teh strap muscles enclosed in
pretracheal (deep) fascia
along with thyroid gland, trachea and oesophagus
strap muscles
where are the strap muscles located
infra hyoid muscles - inferior to hyoid bone
what is the arterial supply of the strap muscles
sup and inf thyroid arteries
describe the attachment and course of omohyoid
inferior belly arises from scapula, runs superomedially under stenocleidomastoid muscle
attached to superior belly by an intermediate tendon that is anchored to the clavicle
describe a classic thyroidectomy incision
collar incision made within a natural skin crease or in the direction of Langer’s lines
incision just superior to clavicles and jugular notch
incision made through skin and platsyma
in thyroidectomy why is the incison made just superior to the clavicles and jugular notch
optimal aesthetics - scar hidden by clothing and reduced risk of keloid formation
what is the function of the right recurrent laryngeal nerve
somatic motor supply to most of the skeletal muscles that move the right vocal cord
what does recurrent nerve injury result in
paralysis of vocal cord
unilateral recurrent nerve injury
hoarseness or weakness of voice
and weak cough
bilateral recurrent nerve injury
aphonia (inability to produce sound) and inability to close rima glottidis to prevent aspiration or produce a good cough (requries closure of rima glottis)
