Thyroid Gland anatomy
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Identify the organ in the picture?
Thyroid gland
Identify different parts?
Left lobe
Right lobes
Isthmus
Pyramidal lobeBlood Supply and Lymphatic Drainage
Arterial
• Superior thyroid artery (1st branch of external carotid)
• Inferior thyroid artery (from thyrocervical trunk from subclavian a. 1st part)
• Thyroidea ima (in 10% of population - from brachiocephalic artery or aorta)
Venous
• Superior and middle thyroid veins - into the IJV
• Inferior thyroid vein - into the brachiocephalic veins
Lymphatic drainage
• Pre-laryngeal
• Pre-tracheal
• Para-tracheal
• Upper and lower deep cervical
• Brachiocephalic lymph nodesWhat is the Nerve supply?
The 3 cervical ganglions (superior, middle and inferior) but mainly the middle.
Embryology of thyroid?
The thyroid gland develops from the foramen caecum (2/3 along the length of the tongue from the tip) - to pass forward and loop around and beneath (under) the hyoid bone.
What is thyroglossal cyst?
A fibrous cyst that forms from a persistent thyroglossal duct.
What is the Supply of RLN (Recurrent Laryngeal Nerve)?
Supplies all intrinsic laryngeal muscles except cricothyroid muscle.
Sensory innervation of the mucous membranes of the larynx below the vocal cords.What nerves could be damaged during thyroidectomy
Recurrent LN
External LN
Cervical sympathetic chainWhat is the clinical RLN injury
Unilateral RLN injury
Dysphagia
Diplophonia
Hoarseness
Bilateral RLN injury
Aphonia, inability to speak or cough.
Respiratory compromise
ELN injury
Abnormalities in pitch.Inability to sing with smooth change to each higher note (glissando or pitch glide)
Sympathetic chain
Horners syndrome -
Vagus nerve course in thorax & abdomen?
Thorax:
Left vagus nerveCrosses in front of the left subclavian artery. Enters the thorax between the left common carotid and subclavian arteries.
Descends on the left side of the aortic arch. Travels behind the phrenic nerve.
Courses behind the root of the left lung. Deviates medially and downwards to reach the esophagus and form the esophageal plexus with the right vagus nerve.Right vagus nerve
Crosses in front of the first part of the subclavian artery.
Travels behind the innominate vessels. Reaches the thorax on the right side of the trachea.
Inclines behind the hilum of the right lung. Courses medially towards the esophagus to form the esophageal plexus with the left vagus nerve.Abdomen:
The oesophageal plexus, formed by the union of the right and left vagus nerves, The vagus nerve enters the abdomen through the oesophageal hiatus at the level of the tenth thoracic vertebra (T10).
It divides into the anterior and posterior vagal trunks, which innervate the stomach, small intestine, liver, gallbladder, pancreas, and spleen.Nerves in oesophageal hiatus?
Ant & post vagal trunks.
What do they supply?
Stomach, duodenum, jejunum, ileum, cecum, ascending colon, medial 2/3 of transverse colon, spleen, pancreas, gall bladder
Muscle dissected to see thyroid?
Sternohyoid muscle
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