Depressor labii inferioris muscle

Last updated
Depressor labii
Depressor labii inferioris.png
Muscles of the head, face, and neck.
Details
Origin Oblique line of the mandible, between the symphysis and the mental foramen
Insertion Integument of the lower lip, orbicularis oris fibers, its fellow of the opposite side
Nerve Marginal mandibular branch of the facial nerve
Actions Depression of the lower lip
Antagonist Orbicularis oris muscle
Identifiers
Latin musculus depressor labii inferioris
TA98 A04.1.03.033
TA2 2083
FMA 46816
Anatomical terms of muscle

The depressor labii inferioris (or quadratus labii inferioris) is a facial muscle. It helps to lower the bottom lip.

Contents

Structure

The depressor labii inferioris muscle arises from the lateral surface of the mandible. [1] This is below the mental foramen, and the origin may be around 3 cm wide. [1] It inserts on the skin of the lower lip, blending in with the orbicularis oris muscle around 2 cm wide. [1] At its origin, depressor labii is continuous with the fibers of the platysma muscle. Some yellow fat is intermingled with the fibers.

Nerve supply

The depressor labii inferioris muscle is supplied by the marginal mandibular branch of the facial nerve. [1] [2]

Function

The depressor labii inferioris muscle helps to depress and everts the lower lip. [1] It is the most important of the muscles of the lower lip for this function. [1] It is an antagonist of the orbicularis oris muscle. [1] It is needed to expose the mandibular (lower) teeth during smiling. [1]

Clinical significance

Resection

The depressor labii inferioris muscle may be resected (cut and removed) using surgery to correct an asymmetry of the lower lip when smiling. [1] This asymmetry can be caused by paralysis of the marginal mandibular branch of the facial nerve on one side, so the healthy side may be cut to create symmetry. [1] Local anaesthesia may be used, such as by blocking the mental nerve. [1] This operation tends to be successful. [1]

History

The depressor labii inferioris muscle has also (mainly historically) been called the quadratus labii inferioris muscle. [1]

See also

Additional images

Related Research Articles

<span class="mw-page-title-main">Facial nerve</span> Cranial nerve VII, for the face and tasting

The facial nerve, also known as the seventh cranial nerve, cranial nerve VII, or simply CN VII, is a cranial nerve that emerges from the pons of the brainstem, controls the muscles of facial expression, and functions in the conveyance of taste sensations from the anterior two-thirds of the tongue. The nerve typically travels from the pons through the facial canal in the temporal bone and exits the skull at the stylomastoid foramen. It arises from the brainstem from an area posterior to the cranial nerve VI and anterior to cranial nerve VIII.

<span class="mw-page-title-main">Buccinator muscle</span> Muscle

The buccinator is a thin quadrilateral muscle occupying the interval between the maxilla and the mandible at the side of the face. It forms the anterior part of the cheek or the lateral wall of the oral cavity.

<span class="mw-page-title-main">Orbicularis oris muscle</span> Kissing muscles

In human anatomy, the orbicularis oris muscle is a complex of muscles in the lips that encircles the mouth. It is not a true sphincter, as was once thought, as it is actually composed of four independent quadrants that interlace and give only an appearance of circularity.

<span class="mw-page-title-main">Lip</span> Visible body parts at the mouth

The lips are a horizontal pair of soft appendages attached to the jaws and are the most visible part of the mouth of many animals, including humans. Vertebrate lips are soft, movable and serve to facilitate the ingestion of food and the articulation of sound and speech. Human lips are also a somatosensory organ, and can be an erogenous zone when used in kissing and other acts of intimacy.

<span class="mw-page-title-main">Platysma muscle</span> Human neck muscle

The platysma muscle is a superficial muscle of the human neck that overlaps the sternocleidomastoid. It covers the anterior surface of the neck superficially. When it contracts, it produces a slight wrinkling of the neck, and a "bowstring" effect on either side of the neck.

<span class="mw-page-title-main">Zygomaticus major muscle</span> Facial muscle that raises the corner of the mouth and moves it posteriorly during smiling

The zygomaticus major muscle is a muscle of the face. It arises from either zygomatic arch (cheekbone); it inserts at the corner of the mouth. It is innervated by branches of the facial nerve.

<span class="mw-page-title-main">Levator labii superioris</span> Muscle of the face

The levator labii superioris is a muscle of the human body used in facial expression. It is a broad sheet, the origin of which extends from the side of the nose to the zygomatic bone.

<span class="mw-page-title-main">Mentalis</span> Muscle that raises the central portion of the lower lip

The mentalis muscle is a paired central muscle of the lower lip, situated at the tip of the chin. It originates from the mentum of the mandible, and inserts into the soft tissue of the chin. It is sometimes referred to as the "pouting muscle" due to it raising the lower lip and causing chin wrinkles.

<span class="mw-page-title-main">Depressor anguli oris muscle</span> Facial muscle that depresses the corner of the mouth during frowning

The depressor anguli oris muscle is a facial muscle. It originates from the mandible and inserts into the angle of the mouth. It is associated with frowning, as it depresses the corner of the mouth.

<span class="mw-page-title-main">Facial artery</span> Blood vessel supplying blood to the superficial face

The facial artery is a branch of the external carotid artery that supplies structures of the superficial face.

<span class="mw-page-title-main">Modiolus (face)</span> Chiasma of facial muscles

In facial anatomy, the modiolus is a dense, compact, mobile, fibromuscular tissue mass of facial muscles formed by the interlacing of a number of muscles just lateral to the angle of the mouth opposite the second upper premolar tooth.

<span class="mw-page-title-main">Mental foramen</span> Opening on the anterior aspect of the mandible through which the mental nerve and vessels exit

The mental foramen is one of two foramina (openings) located on the anterior surface of the mandible. It is part of the mandibular canal. It transmits the terminal branches of the inferior alveolar nerve and the mental vessels.

<span class="mw-page-title-main">Mental nerve</span> Sensory nerve of the face

The mental nerve is a sensory nerve of the face. It is a branch of the posterior trunk of the inferior alveolar nerve, itself a branch of the mandibular nerve (CN V3), itself a branch of the trigeminal nerve (CN V). It provides sensation to the front of the chin and the lower lip, as well as the gums of the anterior mandibular (lower) teeth. It can be blocked with local anaesthesia for procedures on the chin, lower lip, and mucous membrane of the inner cheek. Problems with the nerve cause chin numbness.

<span class="mw-page-title-main">Marginal mandibular branch of the facial nerve</span>

The marginal mandibular branch of the facial nerve arises from the facial nerve in the parotid gland at the parotid plexus. It passes anterior-ward deep to the platysma and depressor anguli oris muscles. It provides motor innervation to muscles of the lower lip and chin: the depressor labii inferioris muscle, depressor anguli oris muscle, and mentalis muscle. It communicates with the mental branch of the inferior alveolar nerve.

<span class="mw-page-title-main">Buccal branches of the facial nerve</span>

The buccal branches of the facial nerve, are of larger size than the rest of the branches, pass horizontally forward to be distributed below the orbit and around the mouth.

<span class="mw-page-title-main">Submental artery</span> Branch of the facial artery

The submental artery is the largest branch of the facial artery in the neck. It first runs forward under the mouth, then turns upward upon reaching the chin.

<span class="mw-page-title-main">Facial muscles</span> Muscles of the face

The facial muscles are a group of striated skeletal muscles supplied by the facial nerve that, among other things, control facial expression. These muscles are also called mimetic muscles. They are only found in mammals, although they derive from neural crest cells found in all vertebrates. They are the only muscles that attach to the dermis.

Lip reconstruction may be required after trauma or surgical excision. The lips are considered the beginning of the oral cavity and are the most common site of oral cancer. Any reconstruction of the lips must include both functional and cosmetic considerations. The lips are necessary for speech, facial expression, and eating. Because of their prominent location on the face, even small abnormalities can be apparent.

Jaw reduction or mandible angle reduction is a type of surgery to narrow the lower one-third of the face—particularly the contribution from the mandible and its muscular attachments. There are several techniques for treatment—including surgical and non-surgical methods. A square lower jaw can be considered a masculine trait, especially in Asian countries. As a result, whereas square lower jaws are often considered a positive trait in men, a wide mandible can be perceived as discordant or masculine on women, or sometimes in certain men, particularly when there is asymmetry.

<span class="mw-page-title-main">Mandible</span> Lower jaw bone

In jawed vertebrates, the mandible, lower jaw, or jawbone is a bone that makes up the lower – and typically more mobile – component of the mouth.

References

PD-icon.svgThis article incorporates text in the public domain from page 383 of the 20th edition of Gray's Anatomy (1918)

  1. 1 2 3 4 5 6 7 8 9 10 11 12 13 Hussain, G; Manktelow, R.T; Tomat, L.R (September 2004). "Depressor labii inferioris resection: an effective treatment for marginal mandibular nerve paralysis". British Journal of Plastic Surgery . 57 (6): 502–510. doi:10.1016/j.bjps.2004.04.003. ISSN   0007-1226 via ScienceDirect.
  2. Tapiwa Mabvuure, Nigel; Pinto-Lopes, Rui; Bolton, Lauren; Tzafetta, Kallirroi (August 2021). "Lower lip depressor reanimation using anterior belly of digastric muscle transfer improves psychological wellbeing in facial palsy patients". British Journal of Oral and Maxillofacial Surgery. doi:10.1016/j.bjoms.2021.07.025. ISSN   0266-4356.