Anatomy of the External Nose

Anatomy of the External Nose

This post is designed to help MBBS and ENT students understand the external nasal anatomy in a clear and structured manner.

🔹 Divisions of the Nose

The nose is divided into:

• External Nose – visible part of the nose

• Internal Nose – includes right and left nasal cavities, separated by the nasal septum

In this post, we'll focus on the external nose.

📐 Shape and Orientation

• Pyramidal in shape
• Root: Directed upwards
• Base: Directed downwards

🧱 Layers of the External Nose

1. Skin
2. Subcutaneous tissue (with 4 sublayers)
   • Superficial fatty layer
   • Fibromuscular layer (SMAS)
   • Deep fatty layer
   • Periosteum and perichondrium
3. Osteocartilaginous framework

1️⃣ Skin Layer

• Variable thickness depending on skin type and anatomical location

• Thin and loose over the dorsum and sides

• Thick and adherent over the tip and alar region, containing numerous sebaceous glands

Can you name a disease where we see hypertrophy of the sebaceous glands on the nose?

2️⃣ Subcutaneous Tissue Layer

a. Superficial Fatty Layer

• Lies directly beneath the dermis

b. Fibromuscular Layer (SMAS)

• Contains muscles of facial expression associated with nasal movements

• All these muscles are supplied by the facial nerve (CN VII).

What are the different muscles of the nose and what are their actions?

Which muscle is the ONLY dilator of the nose?

c. Deep Fatty Layer

• Contains neurovascular structures

What is the surgical importance of the deep fatty layer?

d. Periosteum and Perichondrium

• Covers underlying bone and cartilage

3️⃣ Osteocartilaginous Framework

Divided into:

🔸 Bony Part (Upper 1/3)

• Nasal bones(2) – fused in midline
• Nasal process of frontal bone
• Frontal process of maxilla

🔸 Cartilaginous Part (Lower 2/3)

1. Upper lateral cartilage

• Trapezoid shaped

• Forms the nasal valve (limen nasi) intranasally

1. Lower lateral cartilage (Alar cartilage)

• U-shaped

• Has lateral crus (forms ala) and medial crus (runs in columella)

1. Lesser alar (Sesamoid) cartilages

• Small cartilages above and lateral to alar cartilage

1. Septal cartilage

• Forms anterior support to nasal dorsum

What deformity do you see on loss of septal cartilage?

🩸 Arterial Supply of External Nose

🩸 Venous Drainage of External Nose

• Does not parallel arteries

• Drains into arteriovenous territories:

  • Frontomedian area → Facial vein
  • Orbitopalpebral area → Ophthalmic vein

What is the Danger Area of the Face? Why is it called so?

🧠 Nerve Supply of External Nose

🌿 Lymphatic Drainage of External Nose

• Submental nodes
• Submandibular nodes
• Facial nodes
• Occasionally, parotid region
• Drainage is often bilateral

📚 Key Exam Points

• Osteocartilaginous framework – common theory & viva question
• Danger area of the face – high clinical relevance