Head and neck

• The surface anatomy of the neck can be used to distinguish two areas - the anterior and posterior triangle
• Borders of the anterior triangle of the neck:

  • medially - midline of the neck
  • Superiorly - inferior border of the mandible
  • Laterally - anterior border of the sternocleidomastoid muscle
• The anterior triangle of the neck contains 4 subdivisions:

  • Carotid triangle
  • Submental triangle
  • Submandibular triangle
  • Muscular triangle
• The carotid triangle of the anterior neck contents:

  • Common carotid artery - bifurcates within the carotid triangle
  • Internal jugular vein
  • Hypoglossal and vagus nerves
• The muscular triangle of the anterior neck actually has 4 boundaries. It is more inferior than the other subdivisions. It contains:

  • Infrahyoid muscles
  • Pharynx
  • Thyroid
  • Parathyroid glands
• Borders of the posterior triangle of the neck:

  • Posterior border of the sternocleidomastoid
  • Anterior border of the trapezius muscle
  • Middle 1/3 of the clavicle
• Contents of the posterior triangle of the neck:

  • Anterior, middle and posterior scalene muscle
  • External jugular vein
  • Accessory nerve
  • Cervical plexus - forming the phrenic nerve
  • Trunks of the brachial plexus
• The carotid artery bifurcates at C4 - the level of the thyroid notch
• C7 - vertebrae prominens - landmark of palpating and counting vertebrae in the neck
• There are 7 vertebrae in the neck - two are given unique names:

  • C1 = atlas
  • C2 = axis
• Atlas (C1) and axis (C2):

  • Axis has an odontoid process that protrudes into the atlas
  • Atlas has a transverse ligament that stabilises the odontoid process
  • The axis has a superior articular facets which articulate with the inferior articular facets of the atlas - forms the two lateral atlanto-axial joints
• Characteristic features of the cervical vertebrae:

  • Triangular vertebral foramen
  • Bifid spinous process
  • Transverse foramina - give passage to the vertebral artery, vein and sympathetic nerves
• Atlanto-axial joint = rotation of head
• Ligaments of the spine:

  • Anterior and posterior longitudinal ligaments - covers the vertebral bodies and intervertebral discs
  • Ligamentum flavum - connects the laminae of adjacent vertebrae
  • Interspinous ligament - connects the spinous processes of adjacent vertebrae
• LeFort fractures = transverse fractures of the midface

  Zygomatic = cheek bone
• Cranial nerves that supply the extraocular muscles pass through the inferior and superior orbital fissures - orbital fracture can cause diplopia
• ·       Layers of fascia can limit the spread of infection, however infections that reach that potential spaces between the neck and fascia have a well defined spread

  ·       Retropharyngeal infection/abscess can spread to the superior mediastinum
• Fascial compartments of the neck:

  • Investing layer - most superficial layer that surrounds all structures in the neck
  • Pretracheal fascia
  • Prevertebral layer
  • Carotid sheaths - common carotid, internal jugular vein, vagus nerve and cervical lymph nodes
• The paranasal sinuses are large air sacs that give tone to our voice - drain into the nasal cavity

  Maxillary sinus more likely to get infected as it drains thick mucus against gravity into the nasal cavity
• The "little area" / kiesselbach plexus is the most common area of bleeding that causes epistaxis