Thyroid gland Session 6 Flashcards
where is the anterior triangle anatomically located
region located at the front of the neck
what r the borders of the anterior triangle
superior: inferior border of mandible
lateral: anterior border of sternocleidomastoid
medial: sagittal line down midline of neck
investing fascia vs visceral fasica
investing- covers roof of anterior triangle
visceral- covers floor of anterior triangle
Name the suprahyoid muscles
stylohyoid
digastric
mylohyoid
geniohyoid
name the infrahyoid muscles
omohyoid
sternohyoid
thyrohyoid
sternothyroid
where r the suprahyoid muscles located
superior to hyoid bone
where r the infrahyoid muscles located
inferior to the hyoid bone
what structures r found in the anterior triangle
common carotid bifurcation (internal and external)
internal jugular vein
CN 7, 9, 10, 11, 12
what is platsyma and its innervation
large flat superficial muscle muscle that lies anterior in the neck
CN 7
attachments of platysma
superior insertion onto inferior border of mandible
2 heads of origin from fascia of pectoralis major and deltoid
what r the attachments of sternocleidomastoid
attachment to sternum, clavicle and mastoid process of temporal bone
what innervates sternocleidomastoid
CN 11
what is the function of the infrahyoid muscles and what is the exception and why
depress hyoid
except sternothyroid- does not directly attach to hyoid bone unlike the other infrahyoid muscles
what r the attachments of sternohyoid
origin: manubrium of sternum, medial end of clavicle
insertion: inferior border ofhyoid bone
what are the attachments of omohyoid
origin: inferior belly from superior border of scapula near the suprascapular notch, superior belly from intermediate tendon
insertion: inferior belly intermediate tendon and superior body is body of hyoid bone
attachments of sternothyroid
origin: manubrium of sternum and costal cartilage of rib 1
insertion: thyroid cartilage
attachments of thryrohyoid
origin: thyroid cartilage
insertion: body of hyoid bone
what is the manubrium of sternum
superior part of sternum T3-4
what is ansa cervicalis
nerve loop from the cervical plexus
C1-C3
what innervates the infrahyoid muscles
omohyoid, sternohyoid and sternothyroid supplied by ansacervicalis
thyrohyoid innervated by CN 10
What is the carotid sheath
located posteriorly to sternocleidomastoid
part of deep cervical fascia of the neck
surrounds vital veins, arteies and nerves
what r the structures in the carotid sheath
carotid artery
internal jugular vein
common carotid (bifurcates into external/ internal)
vagus nerve
sympathetic plexus
part of recurrently laryngeal neve
on the surface: nerves of ansa cervicalis that supply the infra-hyoids
where is the thyroid gland located
in midline of anterior neck
in front of the trachea
describe the structure of the thyroid gland
left and right lobes on either side of the trachea
narrow isthmus attaches these lobes together which lies above the 2/3rd tracheal cartilages
what is the pyramidal lobe
small third lobe of thyroid found in some individuals
extends from isthmus to hyoid bone
more commonly comes out of left lobe
name the two poles of the thyroid gland and what lobes r they located on
upper pole and lower pole
on lateral lobes of thyroid gland
what is the relationship of the upper lobe with the oblique line of the thyroid cartilage and the attachment of the sternothyroid and thyrohyoid muscles
drainage of the venous drainage
superior, middle and inferior thyroid veins
superior: exits from upper pole and drains into internal jugular vein in carotid sheath
middle: exits from lateral side of gland and drains into internal jugular vein
inferior: drain into brachiocephalic vein
where r the parathyroid glands located
two small oval shaped glands on posterior of thyroid gland
where is the recurrent laryngeal nerve located and its path
in groove between trachea and oesophagus
travels upwards to the point it enters the larynx
what is the thoracic duct and its extent
main lymphatic vessel to systemic venous system
extends from T12 to root of neck
where can the vagus nerve be found in the anterior neck and its route
posterior to the carotid artery and internal jugular vein
vagus nerve travels up towards the chest anterior to the subclavian artery
at inferior border of artery, it branches to give the recurrent laryngeal branch
route of recurrent laryngeal nerve from its origin
branch of vagus= recurrent laryngeal
recurrent laryngeal passes under and behind subclavian artery
then ascends to the larynx in the groove between the oesophagus and the trachea
what does the thyroid gland produce
thyroxine
explain feedback of TRH and TSH
high blood thyroxine levels, inhibition of thyrotropin-releasing hormone and thyroid-stimulating hormone= thyroid epithelial cells decrease thyroxine production and vice versa
clinical relevance of location of thyroid
thyroid enlargement can suppress trachea (as it surrounds it on three sides) and compress the recurrent laryngeal nerve
