Anat Cell Biol.  2018 Dec;51(4):243-250. 10.5115/acb.2018.51.4.243.

Anatomical variations and developmental anomalies of the thyroid gland in Ethiopian population: a cadaveric study

• Dessie MA

• KMID: 2430191
• DOI: http://doi.org/10.5115/acb.2018.51.4.243

Abstract

Because of its embryonic origin, the thyroid gland is predisposed to multiple anatomical variations and developmental anomalies. These include the pyramidal lobe, the origin of levator glandular thyroidae, the absence of the isthmus, ectopic thyroid, accessory thyroid tissues, etc. These anatomical variations are clinically significant to surgeons, anatomists, and researchers. The present study was designed to report anatomical variations and developmental anomalies of the thyroid gland in Ethiopian population. The study was conducted on 40 cadavers used for routine dissection classes. The thyroid gland was exposed and observed for any variations and developmental anomalies. The length, width, and thickness of the lobes were measured using a vernier caliper. Differences in the incidence of pyramidal lobe and absence of the isthmus between sexes were tested using a Pearson chi-square test. The mean length, width, and thickness of the right lobe were 4.24 cm, 1.8 cm, and 1.6 cm, respectively, whereas it was 4.08 cm, 1.8 cm, and 1.6 cm, respectively for that of the left lobe. The pyramidal lobe was noted in 52.5% of the cadavers. The levator glandulae thyroidae were prevalent in 40% of the cadavers. The isthmus mainly overlies the 2nd to 4th tracheal rings and was absent in 7.5% of the cadavers. Accessory thyroid tissue and double pyramidal lobes were noted in 2.5% of the cadavers. Most of the variations of the thyroid gland were seen frequently in female but it was not statically significant. Different clinically important and rare variations of the thyroid gland were found.

Keyword

Thyroid gland; Isthmus; Pyramidal lobe; Levator glandulae thyroidae

MeSH Terms

Anatomists
Cadaver*
Female
Humans
Incidence
Surgeons
Thyroid Dysgenesis
Thyroid Gland*

Figure

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  Fig. 1 Pyramidal lobe originating from the central part of the isthmus and its apex attached to hyoid bone by levator glandulae thyroidae (LGT) in male cadaver. CCA, common carotid artery; IJV, internal jugular vein.

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  Fig. 2 Pyramidal lobe originating from the junction of the isthmus to the left lobe with levator glandulae thyroidae (LGT) attached to the hyoid bone.

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  Fig. 3 Pyramidal lobe at the junction of the isthmus to the right lobe with free apex.

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  Fig. 4 An accessory thyroid tissue overlying the isthmus along with right and left lobes. CCA, common carotid artery; IJV, internal jugular vein.

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  Fig. 5 The isthmus is absent; the pyramidal lobe originates from the left lobe and attached to the hyoid bone in a female cadaver. LGT, levator glandulae thyroidae.

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  Fig. 6 The right and left lobes of the thyroid gland with a narrow isthmus related to the 3rd tracheal ring.

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