Surface Landmarks of the Head and Neck

Skull & Scalp - Bony Beacons

Key palpable and radiological landmarks of the cranium:

• Nasion: Midpoint of frontonasal suture.
• Inion: External occipital protuberance's peak.
• Bregma: Coronal & sagittal sutures meet (anterior fontanelle site).
• Lambda: Lambdoid & sagittal sutures meet (posterior fontanelle site).
• Pterion: H-shaped sutural junction of frontal, parietal, temporal, and sphenoid (greater wing) bones.

  ⭐ Pterion: Weakest skull point; overlies anterior branch of middle meningeal artery. Fracture risks epidural hematoma.

• Asterion: Junction of parietomastoid, occipitomastoid, & lambdoid sutures.
• Vertex: Highest point of calvaria.
• Mastoid process: Temporal bone projection behind ear.
• Zygomatic arch: Cheekbone prominence; formed by temporal & zygomatic bones.

Facial Features - Surface Signs

• Supraorbital notch/foramen: Superior orbital margin; transmits supraorbital nerve & vessels.
• Infraorbital foramen: ~1cm below inferior orbital margin; transmits infraorbital nerve & vessels.

  ⭐ Clinical Pearl: Site for infraorbital nerve block, anesthetizing lower eyelid, side of nose, upper lip, and maxillary gingiva.

• Mental foramen: Mandible, below second premolar; transmits mental nerve & vessels.
• Canthi: Medial and lateral angles of the eye.
• Ala of nose: Fleshy lateral aspect of external nose.
• Philtrum: Midline groove from nasal septum to upper lip.
• Angle of mandible (Gonion): Junction of inferior border and posterior border of ramus.
• Parotid duct opening (Stensen's duct): Opposite upper second molar tooth, in buccal mucosa.

Neck Anatomy - Triangle Territory

The neck is divided by the Sternocleidomastoid (SCM) muscle. The Trapezius muscle forms the posterior border of the posterior triangle.

• Anterior Triangle:
  • Boundaries: SCM (posteriorly), mandible (superiorly), midline of neck (anteriorly).
  • Subdivisions:
    • Submental triangle
    • Submandibular (Digastric) triangle
    • Carotid triangle
    • Muscular triangle
• Posterior Triangle:
  • Boundaries: SCM (anteriorly), Trapezius (posteriorly), clavicle (inferiorly).
  • Subdivisions:
    • Occipital triangle
    • Supraclavicular (Subclavian/Omoclavicular) triangle

Key Palpable Landmarks (superior to inferior):

• Hyoid bone: Mobile, at C3 vertebra level.
• Thyroid cartilage: Prominent (Adam's apple), C4-C5 vertebrae level.
• Cricoid cartilage: Complete cartilaginous ring, C6 vertebra level.
• Suprasternal (Jugular) notch: Superior manubrium.

⭐ Cricoid cartilage (level C6): narrowest in pediatric airway; key landmark for adult emergency cricothyroidotomy.

Vascular & Neural - Palpable Pathways

• Arterial Pulses:
  • Carotid pulse: Ant. to SCM, hyoid (C3) level.
  • Superficial temporal pulse: Ant. to tragus, over temporal fascia.
  • Facial artery pulse: Mandible inf. border, masseter anteroinf. angle.
  • Subclavian artery pulse: Supraclavicular fossa, lat. to SCM clavicular head, on 1st rib.
• Venous Landmark:
  • External Jugular Vein (EJV): Crosses SCM obliquely; angle of mandible to mid-clavicle. Visible with ↑ intrathoracic pressure.
• Neural Landmarks:
  • Erb's point (Nerve point): Post. SCM border (upper ⅓ & lower ⅔ jnct., ~2.5 cm above clavicle). Cervical plexus branches emerge.
    • Nerves: Lesser occipital, Great auricular, Transverse cervical, Supraclavicular.
  • Great auricular nerve: Ascends SCM, parallel & post. to EJV.
  • Accessory nerve (CN XI): Line: mid-post. SCM border to mid-ant. trapezius border.

⭐ Erb's point: Key for cervical plexus block. Injury risks sensory loss (neck, shoulder) & potential phrenic nerve involvement.

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High‑Yield Points - ⚡ Biggest Takeaways

• Pterion: Weakest skull point; anterior middle meningeal artery deep.
• Hyoid bone: Mobile at C3 vertebral level, no bony articulations.
• Thyroid cartilage: Laryngeal prominence at C4-C5 vertebrae.
• Cricoid cartilage: Complete ring at C6; trachea begins, oesophagus posterior.
• Carotid bifurcation: Usually at C3-C4 or upper thyroid cartilage border.
• Nasion: Root of nose depression, junction of frontal & nasal bones.
• Mastoid process: Posterior to ear; relates to middle ear, facial nerve.