--- title: "Philtrum | Anatomy and Physiology I" description: "Philtrum is the vertical groove between the nose and upper lip, a surface landmark in Anatomy and Physiology I linked to facial structure and expression." canonical: "https://fiveable.me/anatomy-physiology/key-terms/philtrum" type: "key-term" subject: "Anatomy and Physiology I" unit: "Unit 22" --- # Philtrum | Anatomy and Physiology I ## Definition The philtrum is the vertical groove between the nose and the upper lip. In Anatomy and Physiology I, it is a visible facial landmark used to describe external nose and lip anatomy. ## What It Is The philtrum is the shallow vertical groove in the middle of the upper lip, running from the base of the nose down to the vermilion border of the lip. In Anatomy and Physiology I, you treat it as an external facial landmark, not as a deep internal structure. It is part of the visible anatomy of the mouth and nose region, so it comes up when you identify surface features of the face. A useful way to think about the philtrum is as the midline space between the two sides of the upper lip. The groove is formed by the way tissues of the upper lip and surrounding facial structures develop and fuse during embryonic development. That is why it is normally centered and symmetrical, though the depth and shape can vary from person to person. The philtrum sits right below the nose, so it is often described alongside the external nose, upper lip, and nearby facial landmarks. It does not conduct air, move food, or exchange gases. Instead, it is mostly a descriptive anatomical feature that helps you locate and describe the face accurately in lab work, models, diagrams, and physical exam language. Even though the philtrum is a small surface feature, it matters because anatomy is built from precise location language. If you are labeling a face diagram or identifying structures on a specimen, you need to know the difference between the philtrum, the upper lip itself, and the surrounding nasal structures. That is especially true in A&P, where one small landmark can anchor a whole region of the body. You may also hear the philtrum mentioned in clinical descriptions of facial appearance. In a basic A&P setting, though, the main job is simple: recognize the groove, know where it is, and use it to orient yourself in the facial anatomy of the respiratory and oral regions. ## Why It Matters The philtrum matters because it gives you a clear surface landmark for the face, and A&P depends on accurate location language. When you study the respiratory tract, the upper airway begins with the nose and continues through the nasal cavity, so being able to identify nearby facial structures helps you stay oriented in diagrams and dissections. It also helps separate structures that are easy to blur together on a labeled image. The external nose, upper lip, and philtrum sit close together, but they are not the same thing. If a quiz asks you to identify the groove between the nose and upper lip, you need the exact term instead of a general description. In a face model or cadaver image, the philtrum can also help you find the midline. That matters when you are describing symmetry, alignment, or the relative position of other structures. A small landmark like this can make your answers sound more precise and more confident. The concept also supports embryology connections later in the course, because facial features develop from tissues that fuse in predictable patterns. Even if your current lesson is focused on respiratory anatomy, the philtrum gives you a quick example of how surface anatomy reflects deeper developmental anatomy. ## Connections ### Upper Lip The philtrum is the groove above the upper lip, so you need to distinguish the landmark from the lip tissue itself. When you label a face diagram, the upper lip is the broader soft tissue region, while the philtrum is the midline depression just above it. Mixing them up can throw off your orientation on facial anatomy questions. ### [External Nose](/anatomy-physiology/key-terms/external-nose) The philtrum sits directly below the external nose, which makes the two structures part of the same surface region. In Anatomy and Physiology I, that proximity matters when you describe the anterior face or trace the path from the nose down to the mouth. It is a useful anchor point for identifying midline facial landmarks. ### [Nasal Septum](/anatomy-physiology/key-terms/nasal-septum) Both the philtrum and the nasal septum line up with the body’s midline, but they are in different regions and have different structures. The nasal septum divides the nasal cavity internally, while the philtrum is an external groove on the upper lip. This comparison helps you separate internal airway anatomy from visible facial anatomy. ### Respiratory Tract The philtrum is not part of the respiratory tract, but it sits right next to the entrance to the upper airway. That makes it a helpful landmark when you are studying the nose and nasal cavity, since the external face is the starting point for the respiratory system’s conducting structures. It is a location cue, not an airway structure. ## On the AP Exam A quiz or lab practical might ask you to identify the philtrum on a facial model, a diagram, or a photo of the anterior face. The task is usually straightforward: point to the vertical groove between the nose and upper lip, then use that landmark to describe nearby structures like the external nose or upper lip. If the question is image-based, watch for wording that describes a midline depression rather than a full lip structure. If the prompt asks about the respiratory system, the philtrum may show up as part of the visible surface anatomy around the upper airway, not as a structure that moves air. On short-answer questions, the best response is brief and exact, with a location phrase that shows you know where it sits on the face. ## Key Takeaways - The philtrum is the vertical groove between the nose and upper lip. - In Anatomy and Physiology I, it is treated as a surface landmark of the face, not an internal organ or airway passage. - Its position helps you orient yourself on diagrams of the external nose, upper lip, and nearby respiratory structures. - The philtrum is useful in lab ID questions because it gives you a precise way to describe the midline of the upper face. - Knowing the philtrum helps you separate the surface anatomy of the face from the deeper structures of the respiratory tract. ## FAQs ### What is the philtrum in Anatomy and Physiology I? The philtrum is the vertical groove between the nose and the upper lip. In A&P, it is a surface landmark used to describe the central area of the face. It is not part of the respiratory tract itself. ### Where is the philtrum located? It is located on the midline of the face, running from the base of the nose to the top border of the upper lip. If you picture the area right under the nose, the philtrum is the shallow groove in the center. That makes it easy to find on diagrams and models. ### Is the philtrum part of the upper lip? Not exactly. The upper lip is the broader soft tissue region, while the philtrum is the groove just above it. They are neighboring surface features, so it is easy to mix them up on images. ### Why does the philtrum matter in respiratory system anatomy? It does not move air, but it helps you orient yourself around the upper airway. Because it sits right below the external nose, it is a useful landmark when identifying the nose, upper lip, and other structures around the entrance to the respiratory tract. ## Related Study Guides - [22.1 Organs and Structures of the Respiratory System ](/anatomy-physiology/unit-22/1-organs-structures-respiratory-system/study-guide/kin1cjWgv47M9lbF) ## About This Document Canonical Fiveable pages are available as Markdown at the same path plus `.md`. - [llms.txt](https://fiveable.me/llms.txt): index of Fiveable's sections and URL patterns - [llms-full.txt](https://fiveable.me/llms-full.txt): complete subject and unit listing - [MCP server](https://fiveable.me/mcp): call Fiveable as tools instead of fetching pages (`https://fiveable.me/api/mcp`) - [MCP server for AP teachers](https://fiveable.me/mcp/teachers): a teacher's classes, assignments and AP-rubric grading (`https://fiveable.me/api/mcp/teacher`) ## Structured Data ```json {"@context":"https://schema.org","@graph":[{"@type":"LearningResource","@id":"https://fiveable.me/anatomy-physiology/key-terms/philtrum#resource","name":"Philtrum | Anatomy and Physiology I","url":"https://fiveable.me/anatomy-physiology/key-terms/philtrum","learningResourceType":"Concept explainer","educationalLevel":"AP® / High School","about":{"@id":"https://fiveable.me/anatomy-physiology/key-terms/philtrum#term"},"audience":{"@type":"EducationalAudience","educationalRole":"student"},"dateModified":"2026-07-03T02:20:41.765Z","isPartOf":{"@type":"Collection","name":"Anatomy and Physiology I Key Terms","url":"https://fiveable.me/anatomy-physiology/key-terms"},"author":{"@type":"Organization","@id":"https://fiveable.me/editorial#content-team","name":"Fiveable Content Team","url":"https://fiveable.me/editorial","parentOrganization":{"@id":"https://fiveable.me/#organization"},"member":[{"@type":"Person","name":"Amanda DoAmaral","sameAs":["https://www.linkedin.com/in/adoamaral"]},{"@type":"Person","name":"Becky Bahr","sameAs":["https://www.linkedin.com/in/becky-bahr-b52743132"]}]},"publisher":{"@type":"Organization","name":"Fiveable","url":"https://fiveable.me"}},{"@type":"DefinedTerm","@id":"https://fiveable.me/anatomy-physiology/key-terms/philtrum#term","name":"philtrum","description":"The philtrum is the vertical groove between the nose and the upper lip. 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