[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Anatomy](https://durgical.com/en/anatomy/) › [Head and neck](https://durgical.com/en/anatomy/region/head-and-neck/) › Depressor anguli oris [Muscular system](https://durgical.com/en/anatomy/system/muscular-system/) · [Head and neck](https://durgical.com/en/anatomy/region/head-and-neck/) # Depressor anguli oris The depressor anguli oris is a triangular muscle from the jaw to the corner of the mouth; it pulls the corner down when frowning. [See in 3D →](https://durgical.app/?from=durgipedia&lang=en#region=head_neck&select=depressor_anguli_oris&side=r) Opens in the Durgical app, no sign-up needed. ## What it is A triangular muscle from the jaw to the mouth corner. ## What it does Pulls the mouth corner down (frown); weak on one side in facial palsy. ## Key points - Supplied by the marginal mandibular branch of the [facial nerve](https://durgical.com/en/anatomy/facial-nerve/) (with buccal branches): its loss gives a lopsided frown and lower lip - Congenital absence or underdevelopment causes asymmetric crying facies in newborns, sometimes with heart defects - Lies superficial to the depressor labii inferioris; the mental nerve emerges beneath the two ## Key facts **Origin** Oblique line of the mandible **Insertion** Angle of the mouth **Action** Pulls the mouth corner down **Nerve** Facial nerve (CN VII): marginal mandibular branch **Blood supply** [Facial artery](https://durgical.com/en/anatomy/facial-artery/) branches ## Relations **Superficial** [Skin](https://durgical.com/en/anatomy/skin/) and subcutaneous fat of the chin and lower cheek; the [platysma](https://durgical.com/en/anatomy/platysma/) blends into its lower fibres **Deep** [Depressor labii inferioris](https://durgical.com/en/anatomy/depressor-labii-inferioris/) and the [mental foramen](https://durgical.com/en/anatomy/mental-foramen/) with the mental nerve and vessels **Above** Modiolus at the angle of the mouth, where it meets the [orbicularis oris](https://durgical.com/en/anatomy/orbicularis-oris-muscle/), [risorius](https://durgical.com/en/anatomy/risorius-muscle/) and [zygomaticus major](https://durgical.com/en/anatomy/zygomaticus-major-muscle/) **Below** Oblique line of the [mandible](https://durgical.com/en/anatomy/mandible/), close to the platysma ## How to find it Asked to pull the corners of the mouth down hard (a sad face), a triangular band tightens from the jaw below the canine and premolars up to the mouth corner. ## Examination - Frowning or pulling the mouth corners down: the corner stays up on the weak side - In a crying newborn the lower lip pulls down on one side only; the forehead and eye closure stay normal, which separates it from facial nerve palsy ## On imaging Not usually imaged; its function is tested by asking the person to show the lower teeth. High-resolution ultrasound shows it as a triangle of muscle from the lower border of the mandible up to the corner of the mouth, and can guide botulinum toxin injection. In a newborn with asymmetric crying facies, an echocardiogram looks for associated heart defects; facial imaging is not needed. ## Clinical notes - Marginal mandibular branch injury in neck and jaw surgery leaves this muscle weak: the danger zone runs along the lower border of the mandible, where the branch crosses the facial artery and vein - Its pull deepens the «marionette» lines from the mouth corners in ageing faces - Asymmetric crying facies is linked in some children to cardiac anomalies, including the 22q11.2 deletion syndrome ## Development Second pharyngeal arch muscle; hypoplasia is present at birth and does not recover, unlike birth-trauma facial palsy. ## Test yourself Think of the answer, then tap the question to see it. ## Which facial nerve branch mainly supplies the depressor anguli oris, and what does its loss show? The marginal mandibular branch (with buccal branches); its loss gives a lopsided frown and lower lip. ## What is asymmetric crying facies in a newborn? Congenital absence or underdevelopment of the depressor anguli oris: the lower lip pulls down on one side when crying, sometimes with heart defects such as 22q11.2 deletion. ## How is asymmetric crying facies told apart from facial nerve palsy? The forehead and eye closure stay normal; only the depressor anguli oris is affected. [Add to my cards (3)](https://durgical.app/estudiar/?add=/en/anatomy/depressor-anguli-oris/) Educational information, not medical advice. For any symptom, see a health professional. ## Its names **Official Latin (TA2)** depressor anguli oris TA2 2076 **Official Spanish (DeCS)** Músculo depresor del ángulo de la boca **English (TA2)** Depressor anguli oris **Also called** depressor anguli oris muscle · triangularis muscle · musculus triangularis ## Related - [Facial nerve (VII)](https://durgical.com/en/anatomy/facial-nerve/) Sources: Terminologia Anatomica (TA2); [Anatomy, Head and Neck: Facial Muscles](https://www.ncbi.nlm.nih.gov/books/NBK493209/); [Anatomy, Head and Neck: Face](https://www.ncbi.nlm.nih.gov/books/NBK551530/). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/anatomy/depressor-anguli-oris/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/anatomy/depressor-anguli-oris/