ANATOMY OF THE PARATHYROID GLANDS

ANATOMY OF THE PARATHYROID GLANDS

The developmental embryology and surgical anatomy of the parathyroid glands are intimately linked, and knowledge of both is essential for successful surgical treatment of parathy roid disease. The parathyroid glands, of which there are four, develop from the third and fourth pharyngeal pouches between the Sir Richard Owen , 1804–1892, English comparative anatomist and palaeontologist. First director of the Natural History Museum, London, UK, and Hunterian Professor at the Royal College of Surgeons of England. Ivar Viktor Sandström , 1852–1889, medical student, Uppsala, Sweden. Marcel Eugene Gley , 1857–1930, French pathologist. William J MacCallum , 1874–1944, Professor of Pathology , Johns Hopkins Hospital, Baltimore, MD, USA. Felix Mandl , 1892–1957, Professor of Surgery , Vienna, Austria. fifth and 12th weeks of gestation. They are typically described as ‘Portland brick’ (yellow/brown) in colour and weigh approximately 30 /uni00A0 mg. Approximately 13% of the popula - tion have abnormal parathyroid tissue, with 5% having a true supernumerary gland. The blood supply of both the superior and inferior parathyroid glands arises from the inferior thy - - roidal artery . While the location of the individual glands may vary significantly , there appears to be a degree of symmetry between opposite sides that can be helpful during surgical dis - section. T he inferior parathyroid gland and the thymus arise from the third pharyngeal pouch. As a result of the longer normal embryological descent, there is correspondingly more varia - tion in their anatomical position. How ever, in more than 50% of cases they are located at the inferior pole of the thyroid - gland, on the anterior, lateral or posterior surface. The gland itself is freely mobile within a glob ule of fat adjacent to the lower pole ( Figure 56.1a ). The superior parathyroid glands arise from the dorsal por - tion of the fourth pharyngeal pouch. As a result of their more limited embryological descent they are more constant in posi - tion. In more than 80% of patients, the superior parathyroid g lands are located at the posterior aspect of the thyroid lobe in an area 2 /uni00A0 cm in diameter, centred 1 /uni00A0 cm around the junction of the inferior thyroid artery and the r ecurrent laryngeal nerve in strict proximity to the cricothyroid junction ( Figure 56.1b ). - The parathyroid glands are closely associated with, but con - tained within, a halo of fat that is freely mobile over the thyroid capsule.

The aetiology, presentation, investigation • and management of secondary and tertiary hyperparathyroidism The aetiology and management of parathyroid • carcinoma

Undescended (above ITA) Below intersection ITA and RLN Mediastinal (b) In carotid sheath 1% Paraoesophageal and below ITA Figure 56.1 Potential locations of the inferior (a) and superior (b)

ANATOMY OF THE PARATHYROID GLANDS

The developmental embryology and surgical anatomy of the parathyroid glands are intimately linked, and knowledge of both is essential for successful surgical treatment of parathy roid disease. The parathyroid glands, of which there are four, develop from the third and fourth pharyngeal pouches between the Sir Richard Owen , 1804–1892, English comparative anatomist and palaeontologist. First director of the Natural History Museum, London, UK, and Hunterian Professor at the Royal College of Surgeons of England. Ivar Viktor Sandström , 1852–1889, medical student, Uppsala, Sweden. Marcel Eugene Gley , 1857–1930, French pathologist. William J MacCallum , 1874–1944, Professor of Pathology , Johns Hopkins Hospital, Baltimore, MD, USA. Felix Mandl , 1892–1957, Professor of Surgery , Vienna, Austria. fifth and 12th weeks of gestation. They are typically described as ‘Portland brick’ (yellow/brown) in colour and weigh approximately 30 /uni00A0 mg. Approximately 13% of the popula - tion have abnormal parathyroid tissue, with 5% having a true supernumerary gland. The blood supply of both the superior and inferior parathyroid glands arises from the inferior thy - - roidal artery . While the location of the individual glands may vary significantly , there appears to be a degree of symmetry between opposite sides that can be helpful during surgical dis - section. T he inferior parathyroid gland and the thymus arise from the third pharyngeal pouch. As a result of the longer normal embryological descent, there is correspondingly more varia - tion in their anatomical position. How ever, in more than 50% of cases they are located at the inferior pole of the thyroid - gland, on the anterior, lateral or posterior surface. The gland itself is freely mobile within a glob ule of fat adjacent to the lower pole ( Figure 56.1a ). The superior parathyroid glands arise from the dorsal por - tion of the fourth pharyngeal pouch. As a result of their more limited embryological descent they are more constant in posi - tion. In more than 80% of patients, the superior parathyroid g lands are located at the posterior aspect of the thyroid lobe in an area 2 /uni00A0 cm in diameter, centred 1 /uni00A0 cm around the junction of the inferior thyroid artery and the r ecurrent laryngeal nerve in strict proximity to the cricothyroid junction ( Figure 56.1b ). - The parathyroid glands are closely associated with, but con - tained within, a halo of fat that is freely mobile over the thyroid capsule.

The aetiology, presentation, investigation • and management of secondary and tertiary hyperparathyroidism The aetiology and management of parathyroid • carcinoma

Undescended (above ITA) Below intersection ITA and RLN Mediastinal (b) In carotid sheath 1% Paraoesophageal and below ITA Figure 56.1 Potential locations of the inferior (a) and superior (b)