External Structure and Topography
Anatomically, the organ forms the relief of the central part of the face, occupying a distinct nasal region — regio nasalis. In terms of spatial geometry, its shape is closest to a triangular pyramid. The entire outer surface of the structure is covered with skin.
In macroscopic structure, four key components are distinguished that smoothly transition into one another:
- Root of the nose (radix nasi) — the upper part of the structure.
- Dorsum of the nose (dorsum nasi) — the middle part forming the main facial profile.
- Apex of the nose (apex nasi) — the most anteriorly projecting free part of the pyramid.
- Alae of the nose (alae nasi) — the paired inferolateral parts.
The base for the formation of the dorsum is served by both bony elements (nasal bones) and a complex system of cartilages, which includes the lateral cartilages, septal cartilage, and alar cartilages.
Lateral Nasal Cartilage
The base of the lateral slopes is formed by the lateral nasal cartilage (cartilago nasi lateralis). This is a paired structure whose contours resemble an irregular triangle.
This structure plays a crucial biomechanical role: it directly participates in the formation of the dorsum and also partially covers the area of the nasal ala. Topographically, the lateral cartilage closely adheres to the nasal bone. Along the midline, it forms a firm connection with the corresponding cartilage of the opposite side and fuses with the nasal septal cartilage, creating a single supporting framework for the upper part of the organ.
Greater Alar Cartilage
The lower part of the cartilaginous skeleton is represented by the greater alar cartilage (cartilago alaris major). This is a paired anatomical element whose function is to form the entrance to the respiratory tract — it surrounds the nostrils anteriorly, laterally, and from the inner surface.
Structurally, the greater cartilage is divided into two crura:
- Medial crus (crus mediale) — the inner element. These paired crura serve as a natural barrier separating the right and left nostrils from each other. Right between them, the anteroinferior edge of the septal cartilage is tightly wedged.
- Lateral crus (crus laterale) — the outer element. It is significantly wider and longer than its medial counterpart. This specific anatomical structure acts as the main cartilaginous skeleton for the nasal ala.
Minor and Accessory Cartilages
Additionally, adjacent to the lateral crus of the greater cartilage are the minor alar cartilages (cartilagines alares minores). Topographically, they are located in the posterosuperior regions of the nasal ala, complementing the supporting contour.
In some cases, the anatomical picture may be expanded by the presence of accessory nasal cartilages — cartilagines nasi accessoriae.
It is important to note that absolutely all cartilages forming the skeleton are externally covered by a special membrane — the perichondrium (perichondrium). To ensure the structural integrity of the entire complex, the cartilages are securely fastened both to each other and to the adjacent bones of the facial skull by means of dense fibrous tissue.
Briefly: answers to topical questions
Which skull bones participate in forming the bony skeleton of the external nose?
The bony skeleton of the external nose is formed by the nasal bones, the frontal processes of the maxilla, and the nasal process of the frontal bone.
- Nasal bones (ossa nasalia) — paired bones forming the dorsum of the nose and determining its shape.
- Maxilla (maxilla) — its frontal processes form the lateral slopes (lateral boundaries) of the nose.
- Frontal bone (os frontale) — its nasal process articulates with the nasal bones, forming the upper boundary of the bony segment.
Which arteries provide the blood supply to the external nose?
The blood supply to the external nose is derived from branches of the facial, ophthalmic, and infraorbital arteries.
- Facial artery (a. facialis) — gives off branches to the external nose, including the angular artery (a. angularis).
- Ophthalmic artery (a. ophthalmica) — participates in the blood supply via the dorsal nasal artery (a. dorsalis nasi), which supplies the dorsum of the nose.
- Infraorbital artery (a. infraorbitalis) — forms anastomoses with branches of the facial artery.
An important anastomosis forms between the dorsal nasal artery and the angular artery, connecting the internal and external carotid artery systems.
Which nerves provide sensory innervation to the skin of the external nose?
Sensory innervation to the skin of the external nose is provided by branches of the ophthalmic and maxillary nerves (V1 and V2 branches of the trigeminal nerve).
- Infratrochlear nerve (n. infratrochlearis) — innervates the skin of the root of the nose.
- Anterior ethmoidal nerve (n. ethmoidalis anterior) — gives off external nasal branches (rr. nasales externi) that innervate the dorsum, alae, and tip of the nose.
- Infraorbital nerve (n. infraorbitalis) — gives off external nasal branches that provide sensory innervation to the skin of the lateral surface of the nose.
Into which lymph nodes does lymph drainage from the external nose occur?
Lymph drainage from the external nose occurs into the submandibular and superficial parotid lymph nodes.
- Submandibular lymph nodes (nodi lymphoidei submandibulares) — receive lymphatic vessels from the external nose and nostrils.
- Superficial parotid nodes (nodi parotidei superficiales) — receive lymph from the external nose as part of the anterior group of superficial lymphatic vessels.
Class and exam questions
To which division of the respiratory system does the external nose belong?
The external nose is the initial segment of the human respiratory system.
Which structures form the dorsum of the nose?
The dorsum of the nose is formed by the nasal bones, lateral nasal cartilages, septal cartilage, and alar cartilages.
What separates the nostrils from each other?
The nostrils are separated from each other by the medial crura of the greater alar cartilages, between which the anteroinferior edge of the septal cartilage is wedged.
Which part of the greater alar cartilage forms its main skeleton?
The main cartilaginous skeleton of the nasal ala is the lateral crus of the greater alar cartilage, as it is wider and longer than the medial crus.
What else to study on this topic
- Bony Structure: Nasal Bones and Their Articulations
- Anatomy of the Nasal Septal Cartilage
- Histological Structure of the Perichondrium and Fibrous Tissue
- Topographic Boundaries of the Nasal Region (regio nasalis)
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