Levator glandulae thyroideae muscle
Citation, DOI & article data
The levator glandulae thyroideae muscle (a.k.a. musculus levator glandulae thyroideae or levator glandulae thyroideae of Soemmerring) is an anatomic variant, consisting of a band of fibrous/fibromuscular tissue, connecting the pyramidal lobe of the thyroid to the hyoid bone. When muscle fibers are present it is an accessory muscle.
It is most commonly found on the left side of the neck 1,2. A true midline structure is very rare 1. Although the pyramidal lobe is usually present, it is neither a constant, nor necessary, finding in those with this variant fibromuscular structure 1.
In the 1960s, in a large Japanese study of 210 cadavers with a levator glandulae thyroideae, Mori classified them into five main types 4:
- hyopyramidalis muscle
- hyoid bone to pyramidal lobe
- thyreopyramidalis muscle
- thyroid cartilage to pyramidal lobe
- thyreoglandularis muscle
- thyroid cartilage to the thyroid capsule
- hyoglandularis muscle
- hyoid bone to the thyroid capsule
- tracheoglandularis muscle
- proximal trachea to the isthmus of the thyroid
The levator glandulae thyroideae muscle originates from the inferior margin of the hyoid bone most frequently. Alternately, it may be rarely found to arise from the thyroid cartilage, or even the trachea 1,4.
When present, the levator glandulae thyroideae muscle most commonly inserts into the pyramidal lobe, much less commonly, the superior isthmus of the thyroid.
- small branch of the external laryngeal nerve
- few case reports have shown supply from twigs of the ansa cervicalis instead 1
- elevates the thyroid 5
History and etymology
The Prussian neuroanatomist, Samuel Thomas Soemmerring (1755-1830) described this thyroid variant in a report published in 1794. Although historically, Soemmerring is remembered most strongly for his cutting-edge work on the anatomy of the cranial nerves 3,5.
- 1. Chaudhary P, Singh Z, Khullar M, Arora K. Levator glandulae thyroideae, a fibromusculoglandular band with absence of pyramidal lobe and its innervation: a case report. (2013) Journal of clinical and diagnostic research : JCDR. 7 (7): 1421-4. doi:10.7860/JCDR/2013/6144.3186 - Pubmed
- 2. Chummy S. Sinnatamby. Last's Anatomy. (2018) ISBN: 9780702033940
- 3. Pearce JMS. Samuel Thomas Soemmerring (1755-1830): The Naming of Cranial Nerves. (2017) European neurology. 77 (5-6): 303-306. doi:10.1159/000475812 - Pubmed
- 4. MORI M. STATISTICS ON THE MUSCULATURE OF THE JAPANESE. (1964) Okajimas folia anatomica Japonica. 40: 195-300. doi:10.2535/ofaj1936.40.3_195 - Pubmed
- 5. Gregory JK, Guse DM. Unique variant of levator glandulae thyroideae muscle. (2007) Clinical anatomy (New York, N.Y.). 20 (8): 966-7. doi:10.1002/ca.20522 - Pubmed