infrahyoid muscles and thyroid gland Flashcards
the thyroid gland begins where?
in floor of pharynx as an invagination at foramen cecum and then descends inferiorly alongside larynx
thyroid gland may be connected to foramen cecum by what?
thyroglossal duct
thyroid gland is divided into?
two lateral lobes connected by an isthmus
follicular cells are derived from?
endoderm
parafollicular cells are derived from?
ultimobranchial body (4-6 pouch)
where is the thyroid gland ?
between the 5th cervical and 1st thoracic vertebrae
arterial supply of thyroid
from superior and inferior thyroid arteries
superior thyroid artery
- the first branch to arise from the **external carotid artery
- glandular branches (lateral and anterior)
- thryoid ima artery (from brachiocephalic trunk)
**the inferior thyroid artery is from?
branch of thyrocervical trunk
venous drainage of thyroid
forms a plexus on surface of thyroid gland that drains into superior, middle, and inferior thyroid veins
what innervates the larynx?
superior laryngeal nerve and recurrent laryngeal nerve
two branches of vagus nerve
- superior laryngeal – internal laryngeal (sensory) and external laryngeal (motor)
- recurrent larygneal– right: behind the right subclavian artery; left: behind the aortic arch
the recurrent laryngeal nerve ascends between
trachea and esophagus
reccurent laryngeal nerve supplies
- motor innervation to laryngeal muscles (except cricothyroid)
- viscerosensory innervation to the laryngeal mucosa
what leads to ipsilateral palsy of vocal folds?
damage to recurrent laryngeal nerve (due to thyroidectomy)
- prevents abduction of vocal folds, causing hoarseness
- bilateral nerve loss causes asphyxiation