Head and neck surface landmarks

Bony Landmarks - Skull & Spine Scaffolding

• Nasion & Glabella: Superior to nasal bridge; glabella is smooth area between eyebrows.
• Superciliary Arch: Bony ridge of the eyebrow.
• Zygomatic Arch: Palpable "cheekbone."
• Mastoid Process: Bony prominence posterior to earlobe.
• External Occipital Protuberance (Inion): Midline bump on posterior skull.
• Hyoid Bone: Mobile bone superior to larynx, level with C3 vertebra.
• Thyroid Cartilage: "Adam's Apple," superior border at C4.
• Cricoid Cartilage: Ring inferior to thyroid cartilage, at C6 level.
• Vertebral Prominens: Spinous process of C7, most prominent on neck flexion.

⭐ The cricoid cartilage at C6 is a critical landmark. It marks the junction of the larynx to the trachea and the pharynx to the esophagus. An emergency cricothyrotomy is performed by incising the membrane superior to it.

Soft Tissue Landmarks - Muscle & Cartilage

• Sternocleidomastoid (SCM): Key landmark dividing the neck into anterior and posterior triangles. Palpable from the mastoid process to the sternoclavicular joint.
• Trapezius: Forms the posterior border of the posterior triangle. Best palpated when shrugging the shoulders against resistance.
• Masseter: A primary muscle of mastication. Easily felt at the angle of the mandible when a patient clenches their teeth.
• Thyroid Cartilage: The laryngeal prominence ("Adam's Apple") is the most superior feature, typically aligning with the C4 vertebra.
• Cricoid Cartilage: A complete cartilaginous ring inferior to the thyroid cartilage, marking the C6 vertebral level.

⭐ The cricothyroid membrane, located in the space between the thyroid and cricoid cartilages, is the site for an emergency cricothyrotomy to establish an airway.

Triangles of the Neck - Danger Zones

The Sternocleidomastoid (SCM) muscle divides the neck into two major triangles, each containing vital neurovascular structures.

• Anterior Triangle: Medial to SCM.

  • Carotid: Contains the carotid sheath (common carotid a., internal jugular v., vagus n. [CN X]).
  • Submandibular: Houses the submandibular gland and facial artery/vein.
  • Submental: Contains lymph nodes.
  • Muscular: Infrahyoid muscles, thyroid, and parathyroid glands.

• Posterior Triangle: Lateral to SCM.

  • Occipital: Accessory nerve (CN XI) courses through here; vulnerable to injury.
  • Subclavian: Contains the subclavian artery/vein and brachial plexus trunks.

⭐ The Carotid Triangle is a critical surgical landmark. It provides access to the carotid sheath, essential for procedures like carotid endarterectomy. Palpation of the carotid pulse is performed here, just anterior to the SCM at the level of the cricoid cartilage.

Neurovascular Structures - Neck's Busy Highways

• Carotid Sheath: A fibrous connective tissue tube containing vital structures.

  • Contents: Common carotid artery (medial), internal jugular vein (lateral), vagus nerve (posterior).
  • 📌 Mnemonic: "I See 10 CCs in the IV" (I See = IJV, 10 = CN X, CC = Common Carotid, IV = IJV).

• Key Vessels & Nerves:

  • Internal Jugular Vein (IJV): Deep to the sternocleidomastoid (SCM) muscle.
  • External Jugular Vein (EJV): Superficial to the SCM, crosses it obliquely.
  • Subclavian Artery/Vein: Pass between the anterior/middle scalene muscles.

⭐ Exam Favourite: The phrenic nerve (C3, C4, C5) runs anterior to the anterior scalene muscle, while the brachial plexus and subclavian artery pass posterior to it.

• The vertebra prominens (C7) is the most prominent spinous process, a key palpable landmark.
• The hyoid bone is located at the C3 vertebral level, superior to the thyroid cartilage.
• The thyroid cartilage (Adam's apple) marks the C4-C5 vertebral level.
• The cricoid cartilage, at the C6 level, indicates the start of the trachea and esophagus.
• The carotid pulse is palpated anterior to the sternocleidomastoid muscle at the level of the thyroid cartilage.