Thyroid Gland –absence of left lobe
This specimen shows absence of the left lobe of the thyroid gland.
The thyroid gland is a brownish-red and highly vascular endocrine gland, placed in the lower part of the neck. It is made up of the right lobe and the left lobe, connected with each other by the isthmus. The thyroid gland develops from the thyroglossal duct, which is seen in the floor of the developing pharynx. The duct descends in front of the neck along the midline. Finally, it diverges into two lobes connected by means of an isthmus. Several developmental anomalies of the thyroid gland are noted including abnormalities in its shape and lobes. One such anomaly is absence of one lobe, as seen in this specimen. The other structures that could be identified in this specimen are the thyroid cartilage, the cricoid cartilage and the trachea.
The thyroid cartilage is a shield-like, unpaired cartilage of the larynx. It is made up of two laminae, which unite to form the thyroid angle (Adam‚Äôs apple) in the midline of the neck.
The cricoid cartilage is a signet-ring shaped, unpaired cartilage of the larynx. It is narrow anteriorly and broad posteriorly. It forms a medial relation of the thyroid gland.
Larynx continues downwards as the trachea. Trachea is also known as the wind pipe. It transmits inhaled air to the lungs. It is made up of the C-shaped hyaline cartilaginous rings. These cartilaginous rings keep the lumen of the trachea open always.