Levator glandulae thyroideae muscle
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.
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Gross anatomy
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
Origin
The levator glandulae thyroideae 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.
Insertion
When present, the levator glandulae thyroideae most commonly inserts into the pyramidal lobe, much less commonly, the superior isthmus of the thyroid.
Innervation
- small branch of the external laryngeal nerve
- few case reports have shown supply from twigs of the ansa cervicalis instead 1
Action
- 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.
Related Radiopaedia articles
Anatomy: Head and neck
- skeleton of the head and neck
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cranial vault
- scalp (mnemonic)
- fontanelle
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sutures
- calvarial
- facial
- frontozygomatic suture
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- skull landmarks
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- skull base (foramina)
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facial bones
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cranial vault
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muscles of facial expression
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- levator labii superioris alaeque nasalis muscle
- levator labii superioris muscle
- zygomaticus major muscle
- zygomaticus minor muscle
- malaris muscle
- levator anguli oris muscle
- risorius muscle
- depressors, retractors and evertors of the lower lip
- depressor labii inferioris muscle
- depressor anguli oris muscle
- mentalis muscle
- compound sphincter
- orbicularis oris muscle
- incisivus superior muscle
- incisivus inferior muscle
- muscle of mastication:
- elevators, retractors and evertors of the upper lip
- muscles of the middle ear
- orbital muscles
- muscles of the soft palate
- pharyngeal muscles
- suprahyoid muscles
- infrahyoid muscles
- intrinsic muscles of the larynx
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deep spaces of the neck
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- retropharyngeal space
- suprasternal space (of Burns)
- visceral space
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common carotid artery
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common carotid artery
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arterial supply
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cranial nerves
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trigeminal nerve (CN V) (mnemonic)
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- ophthalmic division
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- abducens nerve (CN VI)
- facial nerve (CN VII)
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vestibulocochlear nerve (CN VIII)
- vestibular ganglion (Scarpa's ganglion)
- glossopharyngeal nerve (CN IX)
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vagus nerve (CN X)
- superior laryngeal nerve
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- (spinal) accessory nerve (CN XI)
- hypoglossal nerve (CN XII)
- parasympathetic ganglia of the head and neck
- greater occipital nerve
- third occipital nerve
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cervical plexus
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ansa cervicalis
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- contribution to the accessory nerve (CN XI)
- cutaneous branches
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- brachial plexus
- pharyngeal plexus
-
cranial nerves
- lymphatic drainage of the head and neck
- embryological development of the head and neck
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