Anatomical structures of the thorax Flashcards
Why is the horizontal plane between T4 and T5 important
Passes through the sternal angle
Separates the superior mediastinum from the inferior mediastinum
Marks where the arch of the aorta begins and ends
Passes through the site where the SVC enters the heart
Is the site where the trachea bifurcates into right and left main bronchi
Marks the superior limit of the pulmonary trunk
Where is thyroid glands located
Anterior neck
Between C5 and T1 vertebrae
Lies behind the sternohyoid and sternothyroid muscles, wrapping around the cricoid cartilage and superior tracheal rings
What are the two lobes of thyroid gland Connected by
Isthmus
What does the thyroid gland initially form during development
Floor of the primitive pharynx, near the base of the tongue
Two main arteries supplying the thyroid gland
Superior and inferior thyroid arteries
What is the artery that only 10% of the population have
Thyroid ima artery
Where does the thyroid ima artery branch from
Brachiocephalic trunk of the arch of aorta
What does the hydroid ima artery supply
Anterior surface and isthmus of thyroid gland
How is the venous drainage of the thyroid gland carried out
By the superior, middle and inferior thyroid veins
Superior and middle veins drain into the internal jugular veins, whereas the inferior drains into the brachiocephalic vein
What is the thymus gland involved in during adolescence
Development of immune system
what happens to the thymus gland after puberty
It decreases in size and slowly replaced with fat
Where is the thymus gland located
Within the thoracic superior mediastinum posterior to the manubrium of the sternum
Can extend superiorly into the neck and inferior into the anterior mediastinum
Describe the structure of thymus glsnd
Asymmetrical flat shape with a lobular structure
Lobules comprised of a series of follicles which have a medullary and cortical component
What is the cortical portion of thymus
Located peripherally within each follicle
Largely composed of lymphocytes, supported epithelial reticular cells
what is the medullary portion of thymus
Located centrally within each follicle
Contains fewer lymphocytes and an increased number of epithelial cells
Hassall’s corpuscles are also present
what are Hassall’s corpuscles
Concentric arrangements of epithelial reticular cells
Relations of thymus
Anteriorly: sternum
Posteriorly: pericardium, aortic arch, great vessels, left brachiocephalic vein, trachea
Laterally: pleura, pretracheal fascia
Sensory vagus nerve innervations
Innervates the skin of the external acoustic meat is and the internal surfaces of the laryngopharynx and larynx
Provides visceral sensation to the heart and abdominal viscera
Special sensory innervation of vagus nerve
Provides taste sensation to the epiglottis and root of the tongue
Motor innervations of vagus nerve
Provides motor innervation to majority of the muscles of the pharynx, soft palate and larynx
Parasympathetic innnervations of vagus nerve
Innervates smooth muscle of the trachea, bronchi and GI tract and regulates heart rhythm
where does the vagus nerve originate
Medulla of brainstem
Where does the vagus nerve exit the cranium from
Jugular foramen
With what other two cranial nerves does the vagus nerve exit the jugular foramen with
Glossopharyngeal (IX) Accessory nerves (XI)
