Embrology And Anatomy Of Parathyroid Glands – Overview

Parathyroid Gland

Small endocrine glands that are located in the anterior aspect of the neck.

Approximately 3x4x5 mm in size and typically weighs around 25 – 40 mg

Parathyroid gland produce parathyroid hormone which are responsible for calcium homeostasis

Development Of Parathyroid Glands

  • Begins at 5th week of gestation 
  • Developed from the 3rd and 4th pharyngeal pouches
  • From dorsal portion of third pharyngeal pouch – Inferior parathyroid gland
  • From dorsal portion of fourth pharyngeal pouch – Superior parathyroid gland

Anatomy Of Parathyroid Gland

  • Location – Posterior aspect of thyroid gland
  • High anatomical variation of its position can lead to injury during thyroid surgery 
  • Lies within the pretracheal fascia
  • Flat and oval in shape
  • Four parathyroid glands are present 
    • Superior parathyroid glands 
      • Situated approximately 1 cm superior to the entry of the inferior thyroid arteries into the thyroid gland
    • Inferior thyroid arteries 
      • Situated near the inferior poles of the thyroid gland
  •  Histologically – Two types of cells present 
    • Chief cells
      • Major cell type
      • Secrete parathyroid hormone
    • Oxyphil cells
      • Function is unknown
  • Blood supply
    • Arterial supply
      • Branches of inferior thyroid arteries (mainly) and superior thyroid artery 
      • There is a rich anatomosis between inferior and superior thyroid arteries 
    • Venous drainage
      • Thyroid plexus of veins
  • Nerve supply
    • By the thyroid branches of the cervical sympathetic ganglia
  • Relations 
    • Anteriorly – Thyroid gland
    • Posteriorly – Pretracheal fascia
    • Medially – Recurrent laryngeal nerve
    • Laterally – Common carotid artery 
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