What is the Nasolabial Region?
The nasolabial region is the anatomical area of the face that encompasses the nasolabial fold (the crease running from the side of the nose to the corner of the mouth), along with the surrounding structures including the upper lip, lateral nose, and adjacent cheek tissues 1, 2.
Anatomical Components
The nasolabial region consists of multiple tissue layers working together:
Surface Anatomy
- The nasolabial fold itself: A visible crease or groove that extends from the lateral aspect of the nose (alar base) downward toward the oral commissure (corner of the mouth)
- Upper lip structures: Including the cutaneous portion and the philtrum
- Lateral nasal structures: The alar base and adjacent nasal sidewall
- Medial cheek soft tissues: The fat and muscle compartments adjacent to the fold 3
Deep Tissue Architecture
The nasolabial region has a complex three-dimensional structure 2:
Subcutaneous fat distribution: The medial side of the nasolabial groove contains approximately 1.3 mm of subcutaneous fat, while the lateral side has approximately 4.5 mm—this asymmetric fat distribution contributes to the fold's appearance 2
Muscular attachments: Muscle fibers attach directly to the dermis on the medial aspect of the nasolabial groove, with fewer attachments laterally. The muscles of facial expression, particularly those involved in smiling (levator labii superioris, zygomaticus major and minor, levator anguli oris), create and define the fold through their dynamic action 4
Fascial-fatty layer: A distinct fascial-fatty layer exists in the superficial subdermal space, extending from the upper lip across the nasolabial fold to the cheek mass. This layer is a primary ptotic element responsible for facial aging changes 5
SMAS (Superficial Musculoaponeurotic System): Present in the upper lip as the superficial portion of the orbicularis oris muscle, extending into the region 5
Clinical Significance
Anatomical Variations
The nasolabial fold demonstrates considerable person-to-person variation and can be classified into three main morphological types: convex, concave, and straight 4. The fold's shape and depth result from the interaction between the skin-fat envelope and underlying facial muscles—essentially a "conflict" between soft tissues and dynamic muscular forces 4.
Age-Related Changes
The nasolabial region undergoes predictable changes with aging 1:
- Nasal root width increases with age
- Morphological and anatomical nasal widths increase, though at a lower rate in senior populations
- The fascial-fatty layer and cheek skin become ptotic, deepening the nasolabial fold 5
Surgical Relevance
Understanding the nasolabial region is critical for 6:
- Facial trauma assessment: The region is evaluated when assessing midface injuries, maxillary fractures, and zygomaticomaxillary complex fractures 7
- Rhinoplasty planning: The nasolabial region must be considered when correcting nasal deviations and asymmetries, as the alar base position directly affects facial balance 6
- Aesthetic procedures: The region is a primary target for facial rejuvenation procedures, as the nasolabial fold deepens with aging and tissue ptosis 5
Functional Considerations
The nasolabial region plays a role in facial expression and communication. The muscles in this area are responsible for smiling and other emotional expressions. In facial palsy, the nasolabial fold disappears due to loss of muscular function 4.