Rectus Capitis Lateralis
Neck · Head & Neck
The rectus capitis lateralis is a short, flat prevertebral muscle lying lateral to the atlanto-occipital joint. It arises from the upper surface of the transverse process of the atlas and ascends to insert on the inferior surface of the jugular process of the occipital bone. Positioned to the side of the joint rather than in front of it, its action is lateral flexion of the head at the atlanto-occipital joint, tilting the head toward the same side. It is supplied by the anterior rami of C1 and C2 and is regarded as a homologue of the posterior intertransverse muscles of the neck.
Origin, Insertion, Action & Nerve
Origin
Upper surface of the transverse process of the atlas (C1)
Insertion
Inferior surface of the jugular process of the occipital bone
Action
Laterally flexes the head at the atlanto-occipital joint
Nerve
Anterior rami of C1–C2
Attachments explained
The Rectus Capitis Lateralis 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
Upper surface of the transverse process of the atlas (C1)
Insertion
Inferior surface of the jugular process of the occipital bone
Action & function
When the Rectus Capitis Lateralis contracts, it produces the following movement: Laterally flexes the head at the atlanto-occipital joint.
As part of the Neck group of the Head & Neck, it works alongside neighbouring muscles to generate smooth, coordinated movement and to stabilise the structures it acts on.
Nerve supply & clinical relevance
The Rectus Capitis Lateralis receives its nerve supply from the Anterior rami of C1–C2. This nerve carries fibres from spinal segment(s) C1, C2.
Because a muscle can only contract when its nerve is intact, injury to the Anterior rami of C1–C2 or to its spinal roots (C1, C2) can weaken or paralyse the Rectus Capitis Lateralis, impairing the movements it normally produces (laterally flexes the head at the atlanto-occipital joint). This is why knowing the innervation is central to localising nerve lesions in clinical practice.
How to study the Rectus Capitis Lateralis (the OIANS method)
Read the name literally: rectus capitis lateralis is a straight head muscle placed laterally, so it side-bends the head. Trace it from the transverse process of the atlas up to the jugular process of the occipital bone, and its lateral position beside the atlanto-occipital joint explains why it produces lateral flexion rather than the pure flexion of its anterior neighbour.
Pair it in memory with the rectus capitis anterior: both are small C1 to C2 supplied muscles crossing the atlanto-occipital joint, but the anterior one flexes and the lateral one side-bends. Recalling that it is considered a homologue of the intertransverse muscles helps explain both its short transverse course and its side-bending role.
Frequently asked questions
Where is the Rectus Capitis Lateralis located?
The Rectus Capitis Lateralis is a muscle of the Neck group, located in the Head & Neck.
What is the origin of the Rectus Capitis Lateralis?
Upper surface of the transverse process of the atlas (C1)
What is the insertion of the Rectus Capitis Lateralis?
Inferior surface of the jugular process of the occipital bone
What movements does the Rectus Capitis Lateralis produce?
Laterally flexes the head at the atlanto-occipital joint
What nerve supplies the Rectus Capitis Lateralis?
Anterior rami of C1–C2
Is the Rectus Capitis Lateralis free to study in OIANS?
The Rectus Capitis Lateralis 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 Head & Neck is part of the one-time Lifetime upgrade, though; only the Upper Limb decks are free to test yourself on.
Related muscles
Study the Rectus Capitis Lateralis
Test yourself on Head & Neck 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.