Rotatores Longi (Thoracis)
Back · Trunk
The rotatores longi are the longer of the two sets of rotatores, the deepest muscles of the transversospinales group, and are best developed in the thoracic region. Each arises from the transverse process of a thoracic vertebra and passes upward and medially to attach to the lamina and base of the spinous process of the vertebra two levels above. Spanning two segments, they rotate the thoracic spine toward the opposite side and, perhaps more importantly, stabilise adjacent vertebrae and provide proprioceptive feedback about spinal position. They are innervated by the posterior (dorsal) rami of the thoracic spinal nerves. Together with the shorter rotatores breves they form the deepest layer of the intrinsic back muscles.
Origin, Insertion, Action & Nerve
Origin
Transverse process of a thoracic vertebra
Insertion
Lamina and base of the spinous process of the vertebra two levels above
Action
Rotates the thoracic spine to the opposite side and stabilizes adjacent vertebrae
Nerve
Posterior (dorsal) rami of thoracic spinal nerves
Attachments explained
The Rotatores Longi (Thoracis) is defined first by where it attaches. Its origin is the more fixed anchor, usually the proximal or more stable end that stays put during contraction, while its insertion is the more mobile point that is pulled toward the origin when the muscle shortens.
Origin
Transverse process of a thoracic vertebra
Insertion
Lamina and base of the spinous process of the vertebra two levels above
Action & function
When the Rotatores Longi (Thoracis) contracts, it produces the following movement: Rotates the thoracic spine to the opposite side and stabilizes adjacent vertebrae.
As part of the Back group of the Trunk, it works alongside neighbouring muscles to generate smooth, coordinated movement and to stabilise the structures it acts on.
Nerve supply & clinical relevance
The Rotatores Longi (Thoracis) receives its nerve supply from the Posterior (dorsal) rami of thoracic spinal nerves.
Because a muscle can only contract when its nerve is intact, injury to the Posterior can weaken or paralyse the Rotatores Longi (Thoracis), impairing the movements it normally produces (rotates the thoracic spine to the opposite side and stabilizes adjacent vertebrae). This is why knowing the innervation is central to localising nerve lesions in clinical practice.
How to study the Rotatores Longi (Thoracis) (the OIANS method)
Remember that rotatores are the deepest and shortest of the transversospinales, and that the longi cross two vertebral levels rather than one. Their transverse-to-spinous course toward the vertebra two above explains their contralateral rotation, but their tiny cross-section means their real value is segmental stabilisation and position sense rather than powerful turning.
Keep the pair straight by counting segments: rotatores longi skip a vertebra and attach two levels up, while rotatores breves span a single level to the adjacent vertebra. Both are essentially confined to the thoracic region, where the rotatores are most distinct, so learning longi and breves side by side captures the whole set at once.
Frequently asked questions
Where is the Rotatores Longi (Thoracis) located?
The Rotatores Longi (Thoracis) is a muscle of the Back group, located in the Trunk.
What is the origin of the Rotatores Longi (Thoracis)?
Transverse process of a thoracic vertebra
What is the insertion of the Rotatores Longi (Thoracis)?
Lamina and base of the spinous process of the vertebra two levels above
What movements does the Rotatores Longi (Thoracis) produce?
Rotates the thoracic spine to the opposite side and stabilizes adjacent vertebrae
What nerve supplies the Rotatores Longi (Thoracis)?
Posterior (dorsal) rami of thoracic spinal nerves
Is the Rotatores Longi (Thoracis) free to study in OIANS?
The Rotatores Longi (Thoracis) is always free to browse. Its full origin, insertion, action and nerve details are open to everyone in the Muscle Directory. Quiz and Flashcard practice for the Trunk is part of the one-time Lifetime upgrade, though; only the Upper Limb decks are free to test yourself on.
Related muscles
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