Anterior triangle

Dr Yuranga Weerakkody ◉ and Dr Arjna Kanagarajah et al.

The anterior triangle forms the anterior compartment of the neck and is separated from the posterior triangle by the sternocleidomastoid muscle. The triangles of the neck are surgically focused, first described from early dissection-based anatomical studies which predated cross-sectional anatomical description based on imaging (see deep spaces of the neck)..

Gross anatomy

The anterior triangle is an inverted triangle with its base above and the apex pointing downwards at the manubrium of the sternum. It can be further subdivided into smaller triangles by the crossing of digastric and omohyoid muscles.

Contents

The anterior triangle is subdivided into 3 paired triangles and a single midline triangle:

Paired triangles:

Single midline triangle:

submental triangle

Boundaries

anterior: median line of the neck
posterior: anterior margin of sternocleidomastoid
base: inferior border of the mandible

Related pathology

Determining the nature or origin of masses in the anterior triangle is difficult clinically. Radiological investigations are paramount in defining the origin and the extent of these masses. Head and neck tumors often metastasize to lymph nodes in the neck. A significant proportion of patients with head and neck malignancy have lymph node metastasis in the neck on presentation. Therefore understanding the anatomical position of lymph nodes in the neck help to stage the disease and aids in the planning of surgical management.

References

Anatomy: Head and neck

Anatomy: Head and neck

skeleton of the head and neck
- cranial vault
  - scalp (mnemonic)
    - galea aponeurotica
  - sutures
    - calvarial
    - facial
      - frontozygomatic suture
      - frontomaxillary suture
      - frontolacrimal suture
      - frontonasal suture
      - temporozygomatic suture
      - zygomaticomaxillary suture
      - parietotemporal suture (parietomastoid suture)
      - occipitotemporal suture (occipitomastoid suture)
      - sphenofrontal suture
      - sphenozygomatic suture
      - spheno-occipital suture (not a true suture)
      - lacrimomaxillary suture
      - nasomaxillary suture
      - internasal suture
    - basal/internal
  - skull landmarks
    - nasion
    - glabella
    - bregma
    - vertex
    - lambda
    - inion
    - pterion
    - asterion
    - basion
    - opisthion
    - obelion
  - frontal bone
    - supratrochlear foramen
    - supraorbital foramen
  - temporal bone
  - parietal bone
    - parietal foramen
  - occipital bone
    - clivus
      - inferior median clival canal
        foveola pharyngica recess
    - occipital condyle
- skull base (foramina)
- facial bones
  - midline single bones
  - paired bilateral bones
- cervical spine
- hyoid bone
- laryngeal cartilages
muscles of the head and neck
- muscles of the tongue (mnemonic)
  - extrinsic muscles of the tongue
  - intrinsic muscles of the tongue
- muscles of mastication
- muscles of facial expression
  - occipitalis muscle
  - circumorbital and palpebral muscles
  - nasal muscles
  - buccolabial muscles
    - elevators, retractors and evertors of the upper lip
      - levator labii superioris alaeque nasalis muscle
      - levator labii superioris muscle
      - zygomaticus major muscle
      - zygomaticus minor muscle
      - malaris muscle
      - levator anguli oris muscle
      - risorius muscle
    - depressors, retractors and evertors of the lower lip
      - depressor labii inferioris muscle
      - depressor anguli oris muscle
      - mentalis muscle
    - compound sphincter
      - orbicularis oris muscle
      - incisivus superior muscle
      - incisivus inferior muscle
    - muscle of mastication:
      - buccinator muscle
- muscles of the middle ear
  - stapedius muscle
  - tensor tympani muscle
- orbital muscles
  - extraocular muscles
  - levator palpebrae superioris muscle
    - superior tarsal muscle
- muscles of the soft palate
- pharyngeal muscles
- suprahyoid muscles
- infrahyoid muscles
- intrinsic muscles of the larynx
- muscles of the neck
- accessory muscles of the neck
  - levator glandulae thyroideae muscle
deep cervical fascia
deep spaces of the neck
surgical triangles of the neck
- anterior triangle
- posterior triangle
  - occipital triangle
  - supraclavicular triangle
orbit
ear
paranasal sinuses
nose
oral cavity
pharynx
larynx
viscera of the neck
blood supply of the head and neck
- arterial supply
  - common carotid artery
- venous drainage
innervation of the head and neck
- cranial nerves
  - olfactory nerve (CN I)
  - optic nerve (CN II)
  - oculomotor nerve (CN III)
  - trochlear nerve (CN IV)
  - trigeminal nerve (CN V) (mnemonic)
    - trigeminal ganglion
    - ophthalmic division
      - tentorial nerve
      - frontal nerve
        
        supra-orbital nerve
        
        supratrochlear nerve
      - lacrimal nerve
      - nasociliary nerve
        
        small communicating branch to the ciliary ganglion
        
        short ciliary nerves
        
        long ciliary nerves
        
        infratrochlear nerve
        
        posterior ethmoidal nerve
        
        anterior ethmoidal nerve
    - maxillary division
    - mandibular division
  - abducens nerve (CN VI)
  - facial nerve (CN VII)
    - chorda tympani
    - nerve to stapedius
  - vestibulocochlear nerve (CN VIII)
  - glossopharyngeal nerve (CN IX)
    - Jacobson nerve
  - vagus nerve (CN X)
    - superior laryngeal nerve
      - external laryngeal nerve
      - internal laryngeal nerve
    - recurrent laryngeal nerve (inferior laryngeal nerve)
  - (spinal) accessory nerve (CN XI)
  - hypoglossal nerve (CN XII)
- parasympathetic ganglia of the head and neck
- greater occipital nerve
- cervical plexus
  - muscular branches
    - longus capitis
    - longus colli
    - scalenes
    - geniohyoid
    - thyrohyoid
    - ansa cervicalis
      - omohyoid (superior and inferior bellies separately)
      - sternothyroid
      - sternohyoid
    - phrenic nerve
      - accessory phrenic nerve
    - contribution to the accessory nerve (CN XI)
  - cutaneous branches
- brachial plexus
- pharyngeal plexus
lymphatic drainage of the head and neck

Article information

rID: 54108

System: Head & Neck

Section: Anatomy

Synonyms or Alternate Spellings:

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