Intertransversarii Laterales Lumborum (Ventral Parts) 1–5
Back · Trunk
The ventral parts of the intertransversarii laterales lumborum are the anterior portion of the lateral lumbar intertransverse muscles. Like their dorsal companions, they span between the transverse (costal) processes of adjacent lumbar vertebrae, running from the transverse process of one vertebra to that of the vertebra above but lying more anteriorly. Their lateral placement relative to the vertebral bodies produces lateral flexion of the lumbar spine to the same side, and collectively they contribute to segmental stabilisation of the trunk. They are supplied 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 (Ventral 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 (Ventral 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 (Ventral 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 (Ventral 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 (Ventral Parts) 1–5 (the OIANS method)
Study the ventral parts as the front half of the lateral lumbar intertransverse muscles, paired with the dorsal parts you have already learned. Since both portions bridge the same transverse processes, the action of lateral flexion is identical; only the depth of the slip differs. Picturing the ventral parts lying closer to the front of the transverse processes helps you keep the two halves clear.
Reinforce the shared innervation rule for the lateral lumbar group: both dorsal and ventral parts take anterior (ventral) rami. Because the exiting lumbar ventral rami pass in front of these muscles, their supply is a natural consequence of position, and this is the reliable point of contrast against the medial lumbar intertransversarii that take dorsal rami.
Frequently asked questions
Where is the Intertransversarii Laterales Lumborum (Ventral Parts) 1–5 located?
The Intertransversarii Laterales Lumborum (Ventral Parts) 1–5 is a muscle of the Back group, located in the Trunk.
What is the origin of the Intertransversarii Laterales Lumborum (Ventral Parts) 1–5?
Transverse process of a lumbar vertebra
What is the insertion of the Intertransversarii Laterales Lumborum (Ventral Parts) 1–5?
Transverse process of the adjacent vertebra above
What movements does the Intertransversarii Laterales Lumborum (Ventral Parts) 1–5 produce?
Laterally flexes the lumbar spine and stabilizes adjacent vertebrae
What nerve supplies the Intertransversarii Laterales Lumborum (Ventral Parts) 1–5?
Anterior (ventral) rami of lumbar spinal nerves
Is the Intertransversarii Laterales Lumborum (Ventral Parts) 1–5 free to study in OIANS?
The Intertransversarii Laterales Lumborum (Ventral 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
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