Thyroid Microcirculation
John H. Barker, Gary L. Anderson, Michael D. Menger in Clinically Applied Microcirculation Research, 2019
Each thyroid lobe is supplied by arterial blood from two primary sources.1,2 A superior thyroid artery, arising principally from the external carotid artery, supplies blood to the rostral area of the thyroid lobe. An inferior thyroid artery, deriving most often from the thyrocervical trunk, supplies blood to the caudal areas of the thyroid lobe. In addition to these bilateral arterial inputs to the thyroid, a thyroid ima artery may be located anterior to the trachea and, when present, provides blood to the inferior portion of the gland. This accessory artery appears to arise most often from the brachiocephalic artery, the right common carotid artery, or the aortic arch. Significant anastomoses among the arterial inputs to the thyroid gland occur, with the superior thyroid artery uniting with the contralateral artery in the isthmus area and with the inferior thyroid artery on the posterior and anterior surface of the thyroid gland. Anastomoses between thyroid arteries and the tracheal arterial supply (e.g., inferior laryngeal artery and tracheoesophageal artery) also exist.
Endoscopic and robotic thyroidectomy
Demetrius Pertsemlidis, William B. Inabnet III, Michel Gagner in Endocrine Surgery, 2017
In the thyroidectomy procedure, all of the dissections and ligations of vessels are performed using Harmonic curved shears. The upper pole of the thyroid is drawn downward and medially by the ProGrasp forceps, and the superior thyroid vessels are identified and divided individually. The lower pole is dissected from the adipose and cervical thymic tissue. The inferior thyroid artery is then divided close to the thyroid gland. After the thyroid gland is retracted medially, the perithyroidal fascia is divided and sharply dissected. The inferior thyroid artery is divided, the entire cervical course of the RLN is exposed, and the thyroid gland is dissected from the trachea. The contralateral thyroidectomy is performed using the same method applied for medial traction of the thyroid. The specimen is extracted through the axillary skin incision [30].
Head and Neck
Rui Diogo, Drew M. Noden, Christopher M. Smith, Julia Molnar, Julia C. Boughner, Claudia Barrocas, Joana Bruno in Understanding Human Anatomy and Pathology, 2018
The contents of the muscular triangle of the neck are the infrahyoid muscles, the thyroid gland, and the parathyroid glands. The boundaries of this triangle are: superolateral, the superior belly of the omohyoid muscle; inferolateral, the anterior border of the sternocleidomastoid muscle; and medial, the median plane of the neck. The infrahyoid muscles (Plate 3.19) were described in Section 3.4.4.1. The thyroid gland, located at vertebral levels CS T1, has a right thyroid lobe and a left thyroid lobe connected by the thyroid isthmus. Frequently, the thyroid gland has a pyramidal lobe extending superiorly from the isthmus. On the posterior side of the thyroid gland lie the small parathyroid glands: usually two on each side of the parotid gland. The superior thyroid artery and the inferior thyroid artery are branches of the external carotid artery and of the subclavian artery, respectively (Plate 3.22; described in detail in Section 3.3.2). The superior thyroid vein and middle thyroid vein are tributaries of the internal jugular vein. The inferior thyroid vein is a tributary of the brachiocephalic vein (Plate 3.23). Posteriorly, the recurrent laryngeal nerve ascends close to the thyroid gland in the groove between the trachea and the esophagus (described in detail in Section 3.3.1.10).
Ultrasound-guided thermal ablation for hyperparathyroidism: current status and prospects
Published in International Journal of Hyperthermia, 2022
Zhiguang Chen, Linggang Cheng, Wei Zhang, Wen He
The average dimensions of each gland are 5 mm × 3 mm × 1 mm (length × width × thickness), and each gland weighs approximately 60 mg [18,19]. The superior gland is relatively fixed and is located in the middle third of the posterior thyroid gland. The final position of the inferior gland changes considerably because of the relatively long descending process, with >50% located at the lower pole of the thyroid gland [20–22]. There are abundant vascular network anastomoses between the parathyroid gland and the pharynx, larynx, trachea, and esophagus. The blood supply to the parathyroid gland mainly comes from the inferior thyroid artery and, in a few cases, from the superior thyroid artery. The venous system of the parathyroid gland is accompanied by the corresponding artery, which flows into the internal jugular vein. Furthermore, the lymphatic drainage of the parathyroid gland is similar to that of the thyroid gland, leading to the deep neck and anterior trachea [23].
Anatomy and motor function of extra-laryngeal branching patterns of the recurrent laryngeal nerve; an electrophysiological study of 1001 nerves at risk
Published in Acta Chirurgica Belgica, 2023
A comprehensive anatomic and functional knowledge of the recurrent laryngeal nerve (RLN) has paramount importance in the safety of thyroid surgery. Many branches of the RLN have been established by anatomical studies under direct or microscopic observation [1,2]. Extra-laryngeal terminal branching (ETB) is a macroscopic variation that is visible along its cervical course of the RLN [3,4]. The thyroid surgeon must preserve both anatomic and functional integrity of all terminal branches if present. RLNs with terminal branches have division points along their cervical course at variable locations, creating different combinations. Therefore, in the case of bifid RLN, the location of division points should be established in order to identify and expose all neural branches. The RLN always intersects the inferior thyroid artery (ITA) along its course [5,6]. Branched RLNs are tabulated into subgroups of various types so that the crossing of the ITA and nerve branches should be identified separately [6]. Intraoperative nerve monitoring (IONM) is widely accepted method to assess the motor function of the RLN. In case of bifid nerve, electrophysiological activity of nerve branches may establish functional variations of the RLN. Thus, the importance of this study is both to expose all anatomic aspects of ETB pattern of the RLN, and to detect functional variations of nerve branches through IONM. This study aims to evaluate the variations in anatomy and electrophysiological activity of the cervical segment of the RLN in a prospective, consecutive surgery cohort.
Intra-operative vagal neuromonitoring predicts non-recurrent laryngeal nerves: technical notes and review of the recent literature
Published in Acta Chirurgica Belgica, 2021
S. Van Slycke, K. Van Den Heede, K. Magamadov, J.-P. Gillardin, H. Vermeersch, N. Brusselaers
A non-recurrent course of the laryngeal nerve is reported in few surgical cases and, as in the two presented cases, is found mostly on the right side (0.3–1.6% of all thyroid surgery cases) [3]. On the left side it is even more unique, thought to be found in less than 0.04%; and it has also been described in combination with a co-existing situs inversus and dextrocardia [1]. In our centre, we performed 590 thyroid surgery procedures from January 2010 to April 2013. We encountered three patients with a right non-recurrent laryngeal nerve (0.5%), of which two are presented here. Stedman was the first to report an anatomical variant of the inferior recurrent laryngeal nerve [4]. During autopsy he identified a branch of the vagal nerve which coursed directly to the laryngotracheal junction without turning around the subclavian artery. In that particular case the anatomical variant of the normal inferior laryngeal nerve was associated with an aberrant right subclavian artery and an extra-anatomical lusorian artery, which branched directly of the main aortic arch, distally of the left subclavian artery. This branch ran behind the esophagus to reach the right axillary area. After this first report, several other authors described this NRLN during autopsies [4,5]. Due to this anomaly, the nerve has been more frequently damaged during thyroid surgery, since it was often thought to be a branch of the inferior thyroid artery, leading to permanent hoarseness as iatrogenic consequence [6]. As seen in Figure 1, a type A NRLN can be mistaken for a branch of the inferior thyroid artery, a type B for a branch of the superior thyroid artery.
Related Knowledge Centers
- Carotid Sheath
- Longus Colli Muscle
- Sympathetic Trunk
- Thyrocervical Trunk
- Vertebral Artery
- Artery
- Thyroid
- Neck
- Cervical Ganglia
- Circulatory Anastomosis