Anatomy of the Lip

Anatomy of the Lip

The lip is a composite soft tissue structure of the skin, muscle and mucosa. This article details lip innervation, blood supply, muscles and function.

Summary Card


Neurovascular Supply
A composite soft tissue structure innervated by branches of the facial nerve and trigeminal nerve, and supplied by labial arteries.

Anatomical Landmarks
A specific set of landmarks includes the vermillion border, cupid's bow, philtrum, wet-dry mucosa, white roll, tubercle and commissure.

Aesthetic Subunits
The aesthetic subunits of the lip can be described as upper lateral, philtrum, lower lip, chin and cheek.

Muscles of the Lip
Act as depressors & elevators. Most insert into the modiolus and are innervated by buccal & mandibular branches of the facial nerve.

Flashcards
Evidence-based flashcards to improve your active recall. 



Lip Neurovascular Anatomy


Key Point

The lip is a composite soft tissue structure which receives motor innervation from branches of the facial nerve and sensation from trigeminal nerve branches.

The lip is a structure composed of skin, fat, muscle, and mucosa. The lip plays a vital role in oral competence, sensation, speech and cosmesis.

The neurovascular anatomy of the lip is detailed below

  • Motor: buccal and mandibular branches of facial nerve
  • Sensory: infraorbital (upper) & mental (lower) branches of trigeminal nerve.
  • Blood supply: superior and inferior labial branches of the facial artery
  • Lymph: ipsilateral submandibular nodes; the middle can drain to submental.

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Tip: the superior and inferior labial arteries are usually deep to the orbicularis at the level of the wet-dry mucosa.


Anatomical Lip Landmarks


Key Point

The lip has specific anatomical landmarks which should be respected during the reconstructive process. This includes the vermillion border, cupid's bow, philtrum, wet-dry mucosa, white roll, tubercle and commissure.


During the reconstruction of the lip in both elective and non-elective cases, it's important to identify key landmarks. This includes commissure, cupid's bow, tubercle and the red line (wet-dry vermillion line).

These anatomical landmarks of the lip can be visualised below.

A labelled diagram of a lip showing cupids bow, white roll, mucosa, vermillion border
Anatomical Landmarks of the Lap

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Tip: the philtrum is formed by decussation of orbicularis oris, the orbicularis ridge forms the white roll. 


Aesthetic Units of the Lip


Key Point

The aesthetic subunits of the lip can be described as upper lateral, philtrum, lower lip, chin and cheek.

The face has several areas of subunits to help with treatment algorithms and reconstructive options - the lip is no different. There are 5 aesthetic units directly relevant to the lip (six if you include the cheek).

These aesthetic subunits can be visualised in the diagram below.

Aesthetic Units of the Lip


Muscles of the Lip


Key Point

The muscles of the lip act as depressors and elevators. The majority of the muscles insert into the modiolus and are innervated by the buccal and mandibular branches of the facial nerve.


The muscles of the lip can be classified into elevators and depressors. Their primary innervation is through the buccal and mandibular branches. These muscles may be damaged during trauma, localised for botox or reconstructed in dynamic facial nerve surgeries.

A labelled drawing of the lip and it's muscles that have a role in depression and elevation
Muscles of the Lip

These muscles have specific origins and insertion points on the face. This clues the type of function (elevation or depression) and nerve innervation (buccal or mandibular branch).

These lip muscle origin and insertion points can be seen in the table below.

A table of lip muscles that shows their origin, insertion, action and nerve innervation
Table of Lip Muscles

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Tip: the modiolus is a site lateral to the commissure that is the site of multiple muscle insertions.


Flashcards

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They are continually updated for thePlasticsPro users.


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