Triangles of the Neck

Posterior Triangle

• Boundaries:
  • Posterior border of Sternocleidomastoid
  • Anterior border of Trapezius
  • Clavicle
• Roof:
  • Investing Layer of the Deep Cervical Fascia
• Floor:
  • Prevertebral Fascia lying on (from above downwards):
    • Splenius
    • Levator Scapulae
    • Scalenus Medius
  • Scalenus Anterior and the 1st digitation of Serratus Anterior may contribute to the floor
• Apex lies high up at the back of the skull on the Superior Nuchal Line
• Contents:
  • Nerves
    • [[Spinal Accessory Nerve
    • Cervical Plexus (Branches)
      • Lesser Occipital Nerve
      • Greater Auricular Nerve
      • Transverse Cervical Nerve
      • Supraclavicular Nerve
    • Deep to the Prevertebral fascia
      • Brachial Plexus (Three Trunks)
  • Arteries
    • Subclavian Artery (3rd part)
    • Transverse Cervical
    • Suprascapular artery
    • Occipital Artery
  • Lymph Nodes
    • Lie between the roof and floor
    • 2-3 Occipital Nodes in the subcutaneous tissue at the apex
    • Several Supraclavicular Nodes above the clavicle (Really are outlying members of the lower group of Deep Cervical Nodes)
  • Muscles
    • Omohyoid Muscle (Inferior Belly)
    • Anterior, middle and posterior scalene
    • Levator scapulae
  • Vein
    • External Jugular Vein

Anterior Triangle

• Boundaries:
  • Anterior border of Sternocleidomastoid
  • Lower border of the Mandible
  • The midline
• Subdivided into Carotid Triangle, Digastric Triangle, Submental Triangle, and Muscular Triangle

Carotid Triangle

• Boundaries:
  • Sternocleidomastoid
  • Posterior Belly of Digastric Muscle
  • Superior Belly of Omohyoid
• Contents:
  • Artery
    • Bifurcation of Common Carotid Artery into internal and external
    • Branches of External Carotid Artery (except Posterior Auricular)
  • Veins
    • Internal jugular vein
    • Lingual Vein
    • Facial Vein
    • Superior Thyroid Veins
  • Nerves:
    • Hypoglossal Nerve
    • Vagus Nerve
    • Internal and External Laryngeal Nerves
    • Superior Root of the Ansa Cervicalis
    • Spinal accessory nerve
    • Sympathetic trunk
  • Lymph Nodes

Submandibular Triangle

• Boundaries:
  • Mandible
  • Anterior and Posterior Bellies of Digastric
• Contents:
  • Submandibular Gland
  • Submandibular Lymph Nodes
  • Facial artery and vein
  • Submental Vessels
  • Mylohyoid Vessels
  • Hypoglossal Nerve
  • Mylohyoid Nerve

Submental Triangle

• Boundaries:
  • Anterior Bellies of Digastric
  • Body of Hyoid (Triangle crosses midline)
• Contents:
  • Anterior Jugular Veins
  • Lymph Nodes

Muscular Triangle

• Boundaries:
  • Sternocleidomastoid
  • Superior Belly of Omohyoid
  • Midline from Hyoid to Jugular Notch
• Contents:
  • Parts of Larynx
  • Trachea
  • Pharynx
  • Oesophagus
  • Thyroid and Parathyroid Glands
    • Their Vessels
    • Their Nerves
  • Lymph Nodes