Depressor Septi Nasi

Origin, Insertion, Action & Nerve

Attachments explained

The Depressor Septi Nasi 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.

Action & function

When the Depressor Septi Nasi contracts, it produces the following movement: Depresses the nasal septum and constricts the nostril.

As part of the Facial Expression 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 Depressor Septi Nasi receives its nerve supply from the Buccal branch of facial nerve (CN VII).

Because a muscle can only contract when its nerve is intact, injury to the Buccal branch of facial nerve can weaken or paralyse the Depressor Septi Nasi, impairing the movements it normally produces (depresses the nasal septum and constricts the nostril). This is why knowing the innervation is central to localising nerve lesions in clinical practice.

How to study the Depressor Septi Nasi (the OIANS method)

Fix the depressor septi nasi by remembering that its name describes its action precisely: it depresses the septum of the nose. Because it runs from the maxilla above the upper incisor up into the mobile septum, its pull draws the septum and nostril downward and inward. Feeling the nostrils narrow slightly when you exhale forcefully through the nose links the muscle to its function.

Keep its nerve consistent with the whole nasal group: as a facial muscle it is supplied by the facial nerve (CN VII) via the buccal branch. Study it as a partner to the alar part of nasalis, since the two together adjust the nostril; noting that some anatomists treat it as part of nasalis prevents confusion when it is listed either separately or as a subdivision.

Frequently asked questions

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