Intertransversarii Laterales Lumborum (Dorsal Parts) 1–5
Back · Trunk
The intertransversarii laterales lumborum are the lateral intertransverse muscles of the lumbar region, and they are described in two portions. The dorsal parts pass between the transverse (costal) processes of adjacent lumbar vertebrae, running from the transverse process of one vertebra to the transverse process of the vertebra above. Positioned to the side of the vertebral bodies, they laterally flex the lumbar spine to the acting side and, working across levels, help stabilise adjacent vertebrae during trunk movement. Consistent with their lateral position, they are innervated by the anterior (ventral) rami of the lumbar spinal nerves.
Origin, Insertion, Action & Nerve
Origin
Transverse process of a lumbar vertebra
Insertion
Transverse process of the adjacent vertebra above
Action
Laterally flexes the lumbar spine and stabilizes adjacent vertebrae
Nerve
Anterior (ventral) rami of lumbar spinal nerves
Attachments explained
The Intertransversarii Laterales Lumborum (Dorsal Parts) 1–5 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 lumbar vertebra
Insertion
Transverse process of the adjacent vertebra above
Action & function
When the Intertransversarii Laterales Lumborum (Dorsal Parts) 1–5 contracts, it produces the following movement: Laterally flexes the lumbar spine 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 Intertransversarii Laterales Lumborum (Dorsal Parts) 1–5 receives its nerve supply from the Anterior (ventral) rami of lumbar spinal nerves.
Because a muscle can only contract when its nerve is intact, injury to the Anterior can weaken or paralyse the Intertransversarii Laterales Lumborum (Dorsal Parts) 1–5, impairing the movements it normally produces (laterally flexes the lumbar spine and stabilizes adjacent vertebrae). This is why knowing the innervation is central to localising nerve lesions in clinical practice.
How to study the Intertransversarii Laterales Lumborum (Dorsal Parts) 1–5 (the OIANS method)
Separate the lumbar intertransversarii into a lateral group, which you are studying here, and a medial group. The lateral muscles connect the transverse processes, so anchoring the origin and insertion to those processes immediately explains the lateral flexion action. Remembering that the lateral group has both a dorsal and a ventral portion prepares you for the pair that follows.
Use innervation to cement the lateral versus medial split. The lateral lumbar intertransversarii, including these dorsal parts, are supplied by anterior (ventral) rami, whereas the medial set takes dorsal rami. Grouping the two lateral portions together under the ventral ramus rule keeps them distinct from their medial neighbour on the mammillary processes.
Frequently asked questions
Where is the Intertransversarii Laterales Lumborum (Dorsal Parts) 1–5 located?
The Intertransversarii Laterales Lumborum (Dorsal Parts) 1–5 is a muscle of the Back group, located in the Trunk.
What is the origin of the Intertransversarii Laterales Lumborum (Dorsal Parts) 1–5?
Transverse process of a lumbar vertebra
What is the insertion of the Intertransversarii Laterales Lumborum (Dorsal Parts) 1–5?
Transverse process of the adjacent vertebra above
What movements does the Intertransversarii Laterales Lumborum (Dorsal Parts) 1–5 produce?
Laterally flexes the lumbar spine and stabilizes adjacent vertebrae
What nerve supplies the Intertransversarii Laterales Lumborum (Dorsal Parts) 1–5?
Anterior (ventral) rami of lumbar spinal nerves
Is the Intertransversarii Laterales Lumborum (Dorsal Parts) 1–5 free to study in OIANS?
The Intertransversarii Laterales Lumborum (Dorsal Parts) 1–5 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
Study the Intertransversarii Laterales Lumborum (Dorsal Parts) 1–5
Test yourself on Trunk muscles with interactive quizzes and flashcards in the free OIANS app.
Quiz yourself → Flashcards Open the OIANS app
Browsing is always free. A one-time Lifetime unlock adds every region's quizzes, flashcards, progress tracking and explore tools.