The marginal mandibular branch of the facial nerve arises from the facial nerve (CN VII) in the parotid gland at the

parotid plexus The parotid plexus or plexus parotideus is the branch point of the facial nerve (extratemporal) after it leaves the stylomastoid foramen. This division takes place within the parotid gland The parotid gland is a major salivary gland in many a ...

. It passes anterior-ward deep to the

platysma The platysma muscle or platysma is a :wikt:superficial, 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 ...

and

depressor anguli oris The depressor anguli oris muscle (triangularis 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. Structure The depres ...

muscles. It provides motor innervation to muscles of the

lower lip 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. Mammal lips are soft, movable and serve to facilitate the ingestion of food (e.g. sucklin ...

and

chin The chin is the forward pointed part of the anterior mandible (List_of_human_anatomical_regions#Regions, mental region) below the lower lip. A fully developed human skull has a chin of between 0.7 cm and 1.1 cm. Evolution The presence of a we ...

: the

depressor labii inferioris muscle The depressor labii inferioris (or quadratus labii inferioris) is a facial muscle. It helps to lower the bottom lip. Structure The depressor labii inferioris muscle arises from the lateral surface of the mandible. This is below the mental for ...

depressor anguli oris muscle The depressor anguli oris muscle (triangularis 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. Structure The depres ...

, and

mentalis muscle 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" (as ...

. It communicates with the mental branch of the

inferior alveolar nerve The inferior alveolar nerve (IAN) (also the inferior dental nerve) is a sensory branch of the mandibular nerve (CN V3) (which is itself the third branch of the trigeminal nerve (CN V)). The nerve provides sensory innervation to the lower/mandibu ...

Clinical significance

Iatrogenic damage

The marginal mandibular nerve may be injured during surgery in the neck region, especially during excision of the submandibular salivary gland or during neck dissections due to lack of accurate knowledge of variations in the course, branches and relations. An injury to this nerve during a surgical procedure can distort the expression of the smile as well as other facial expressions. The marginal mandibular branch of the facial nerve is found superficial to the facial artery and (anterior) facial vein. Thus the facial artery can be used as an important landmark in locating the marginal mandibular nerve during surgical procedures.Batra APS, Mahajan A, Gupta K. Marginal mandibular branch of the facial nerve: An anatomical study. Indian Journal of Plastic Surgery : Official Publication of the Association of Plastic Surgeons of India. 2010;43(1):60-64. doi:10.4103/0970-0358.63968. Damage can cause paralysis of the three muscles it supplies, which can cause an asymmetrical smile due to lack of contraction of the

. This may be corrected with resection of the muscle, which tends to be successful.

Additional images

File:Lateral head anatomy detail.jpg, Lateral head anatomy detail File:Slide1BAB.JPG, Lateral head anatomy detail. Neonatal dissection.

References

External links

* - "Branches of Facial Nerve (CN VII)" * () * () * http://www.dartmouth.edu/~humananatomy/figures/chapter_47/47-5.HTM {{Authority control Facial nerve Nerves of the head and neck Neurology Nervous system Otorhinolaryngology