Anatomy of Deep Neck Spaces

Anatomy of Deep Neck Spaces

Today we'll explore the deep neck spaces.

The attachments and divisions of the cervical fascia create potential spaces in the neck. These are the deep neck spaces, which are clinically important as they can be pathways for serious infections. Understanding their boundaries and communications is crucial for diagnosis and management.

✨ Classification of Deep Neck Spaces

Deep neck spaces can be broadly classified by their location:

1. Spaces of the Face:

   • Buccal Space
   • Canine Space
   • Masticator Space (includes Submasseteric, Pterygomandibular, Superficial Temporal, Deep Temporal spaces)
   • Infratemporal Space (often considered part of deep temporal)
   • Parotid Space

2. Spaces of the Neck:

   • Along the Entire Length of the Neck:

     • Retropharyngeal Space
     • Danger Space
     • Prevertebral Space
     • Carotid Space

   • Suprahyoid Spaces:

     • Submental Space
     • Submandibular Space
     • Peritonsillar Space
     • Parapharyngeal (Lateral Pharyngeal) Space

   • Infrahyoid Spaces:

     • Anterior Visceral (Pretracheal) Space

📍 Spaces of the Face

1. Buccal Space (Buccinator Space)

• Location: Cheek, between the skin/platysma and the buccinator muscle.

• Boundaries:

  • Anteriorly: Angle of the mouth.
  • Posteriorly: Masseter muscle and Masticator space.
  • Superiorly: Zygomatic process of the maxilla.
  • Inferiorly: Depressor Anguli Oris muscle.
  • Medially: Buccinator muscle.
  • Laterally: Platysma, subcutaneous tissue, skin.

• Contents: Buccal pad of fat, Parotid (Stenson's) duct (pierces it), accessory parotid gland (~20%), facial/buccal arteries & veins, buccal branch of Facial nerve, buccal nerve (Mandibular division of CN V).

• Communications: Pterygomandibular, Infratemporal, Submasseteric, Parapharyngeal spaces (posteriorly); Canine space (superiorly).

2. Canine Space (Infraorbital Space)

• Location: Between Levator Anguli Oris (inferiorly) and Levator Labii Superioris (superiorly) muscles, in the region of the canine fossa.

• Boundaries:

  • Anteriorly: Orbicularis Oculi muscle.
  • Posteriorly: Buccinator muscle.
  • Superiorly: Levator Labii Superioris muscle.
  • Inferiorly: Caninus (Levator Anguli Oris) muscle.
  • Superficially/Laterally: Levator Labii Superioris.
  • Medially: Anterolateral surface of the Maxilla.

• Contents: Angular artery & vein, Infraorbital nerve.

• Communications: Buccal space (posteriorly), Submasseteric space.

3. Masticator Space

• Location: Paired suprahyoid space on each side of the face, enveloped by the splitting of the superficial layer of deep cervical fascia around the mandible.

• Boundaries:

  • Superiorly: Skull base.
  • Medially: Pharyngeal mucosa.
  • Laterally: Medial surface of mandibular ramus.
  • Posteromedially: Lateral pterygoid plate, superior constrictor, tensor/levator palatinae muscles.

• Subdivisions: This large space contains four smaller spaces:

  • Submasseteric Space (inferolateral)
  • Pterygomandibular Space (inferomedial)
  • Superficial Temporal Space (superolateral)
  • Deep Temporal Space (superomedial); its inferior part is the Infratemporal space.

• Contents: Muscles of mastication (Masseter, Temporalis, Lateral/Medial Pterygoids), Mandibular division of Trigeminal nerve (CN V3), Internal Maxillary artery, Inferior Alveolar nerve & vessels.

• Communications: Pterygopalatine fossa (via pterygomaxillary fissure).

a. Submasseteric Space

• Location: Over the angle of the jaw, between the lateral aspect of the mandible and the medial aspect of the Masseter muscle and its fascia. Deep to the Masseter, superficial to the mandible.

• Boundaries:

  • Anteriorly: Anterior margin of Masseter.
  • Posteriorly: Parotid gland.
  • Superiorly: Zygomatic arch.
  • Inferiorly: Inferior border of the Mandible.
  • Laterally: Masseter muscle.
  • Medially: Lateral surface of Mandibular ramus.

• Contents: Masseteric artery & vein.

• Communications: Buccal space (anteriorly), Pterygomandibular space (posteriorly), Parotid space (posteriorly), Superficial temporal space (superiorly).

b. Pterygomandibular Space (Pterygoid Space)

• Location: Between the Medial Pterygoid muscle (medially) and the medial surface of the mandibular ramus (laterally). Superficial to Medial Pterygoid, deep to Mandible.

• Boundaries:

  • Anteriorly: Posterior border of Buccal space.
  • Posteriorly: Parotid gland.
  • Superiorly: Lateral Pterygoid muscle.
  • Inferiorly: Inferior border of Mandible.
  • Medially: Medial Pterygoid muscle.
  • Laterally: Ascending ramus of Mandible.

• Contents: Mandibular division of Trigeminal nerve (CN V3), Inferior Alveolar artery & vein, Sphenomandibular ligament, Mylohyoid nerve & vessels.

• Communications: Buccal space (anteriorly), Lateral Pharyngeal (Parapharyngeal) space (medially), Peritonsillar space (medially), Submasseteric space (laterally), Parotid space (posteriorly), Deep temporal and temporal spaces (superiorly).

c. Superficial Temporal Space

• Location: Between the Temporalis fascia (laterally) and the Temporalis muscle (medially).

• Boundaries:

  • Laterally: Skin, Temporalis fascia.
  • Medially: Lateral border of Temporalis muscle.
  • Inferiorly: Superior surface of Lateral Pterygoid muscle.
  • Superiorly/Posteriorly: Attachment of Temporalis to cranium.
  • Anteriorly: Posterior wall of Maxillary sinus, Pterygomaxillary fissure.

• Contents: Temporal pad of fat, Temporal branch of Facial nerve.

• Communications: Buccal space, Deep temporal space.

d. Deep Temporal Space

• Location: Deep to the Temporalis muscle. Inferior part is the Infratemporal space.

• Boundaries:

  • Laterally: Medial surface of Temporalis muscle.
  • Medially: Lateral surface of Temporal bone.
  • Inferiorly: Superior surface of Lateral Pterygoid muscle.
  • Superiorly/Posteriorly: Attachment to cranium.
  • Anteriorly: Attachment of fascia to orbital process of zygoma.

• Contents: Pterygoid plexus, Internal Maxillary artery & vein, Mandibular division of Trigeminal nerve (CN V3), Skull base foramina.

• Communications: Buccal space, Superficial temporal space, Infratemporal space (inferiorly).

4. Infratemporal Space

• Location: Inferior portion/extension of the Deep Temporal space, posterior to the maxilla, between the lateral pterygoid plate (medially) and skull base (superiorly).

• Boundaries:

  • Superiorly: Greater wing of Sphenoid.
  • Inferiorly: Lateral Pterygoid muscle, Pterygomandibular space.
  • Anteriorly: Infratemporal surface of Maxilla, posterior surface of Zygomatic bone.
  • Medially: Lateral Pterygoid plate, part of Lateral Pterygoid muscle.
  • Posteriorly: Parotid gland.
  • Laterally: Temporalis muscle, Mandibular ramus.

• Contents: Branches of Maxillary artery, Pterygoid venous plexus, Mandibular division of Trigeminal nerve (CN V3).

• Communications: Pterygomandibular space (inferiorly), Buccal space (anteriorly), Cavernous sinus (via pterygoid plexus of veins).

5. Parotid Space

• Location: Around the Parotid gland, behind the mandibular ramus, enclosed by the splitting of the investing layer of the deep cervical fascia.

• Boundaries:

  • Superiorly: External Auditory Canal (EAC), apex of Mastoid process.
  • Inferiorly: Inferior mandibular margin.
  • Anteriorly: Masticator space.

• Contents: Parotid gland, intraparotid lymph nodes, Facial nerve (CN VII), External Carotid artery, Retromandibular vein.

• Communications: Parapharyngeal space (medially).

📍 Spaces Along the Entire Length of the Neck

These spaces extend from the skull base towards the thorax.

1. Retropharyngeal Space (Posterior Visceral Space)

• Location: Between the Buccopharyngeal fascia (posterior part of middle/visceral layer, anteriorly) and the Alar fascia (anterior layer of deep/prevertebral fascia, posteriorly). Behind the pharynx and cervical esophagus.

• Boundaries:

  • Superiorly: Base of skull.
  • Inferiorly: Bifurcation of trachea (Alar fascia fuses with buccopharyngeal fascia at T4/carina level).
  • Laterally: Carotid sheath and its contents.
  • Anteriorly: Buccopharyngeal fascia covering pharyngeal constrictors.
  • Posteriorly: Alar fascia.

• Divided into two lateral compartments (Spaces of Gillette) by a fibrous raphe. Acts as a bursa for pharyngeal expansion during deglutition.

• Contents: Retropharyngeal lymph nodes (of Rouvier), fat, loose areolar tissue, pharyngeal plexus (vessels/nerves).

• Communications: Parapharyngeal spaces (anterolaterally).

2. Danger Space

• Location: Between the Alar fascia (anteriorly) and the true Prevertebral fascia (posteriorly).

• Boundaries:

  • Superiorly: Base of skull.
  • Inferiorly: Extends down to the Posterior Mediastinum (up to T1 or even diaphragm).
  • Laterally: Fuses to the tips of the transverse processes.
  • Anteriorly: Alar fascia.
  • Posteriorly: True Prevertebral fascia.

• Contents: Loose areolar tissue.

• Clinical Importance: This space is called "Danger Space" because its loose tissue allows rapid down spread of infection (from retropharyngeal, parapharyngeal, or prevertebral spaces) directly into the Posterior Mediastinum. This poses a high risk of complications involving major vessels (vena cava, aortic arch), thoracic duct, trachea, and esophagus, potentially leading to death.

3. Prevertebral Space

• Location: Between the vertebral bodies (posteriorly) and the true Prevertebral fascia (anteriorly).

• Boundaries:

  • Anteriorly: True Prevertebral layer of deep cervical fascia.
  • Posteriorly: Vertebral bodies.
  • Superiorly: Base of skull.
  • Inferiorly: Coccyx.

• Contents: Paraspinal and prevertebral muscles, Scalene muscles, Vertebral artery & vein, Brachial Plexus, Phrenic nerve.

4. Carotid Space (Visceral Vascular Space)

• Location: Within the Carotid Sheath, which is formed by contributions from all three layers of the deep cervical fascia.

• Boundaries:

  • Superiorly: Base of skull.
  • Inferiorly: Arch of Aorta.

• Contents:

  • Common Carotid Artery (inferiorly) and Internal Carotid Artery (superiorly).
  • Internal Jugular Vein.
  • Vagus Nerve (CN X) (posterior to vessels).
  • Ansa Cervicalis (embedded in anterior wall of sheath).
  • In upper part: CN IX, XI, XII.
  • Deep Cervical Lymph Nodes (Levels II, III, IV).

📍 Suprahyoid Spaces

Located above the hyoid bone.

1. Submental Space

• Location: Potential space in the midline, under the chin, between the Mylohyoid muscle (superiorly) and Platysma (inferiorly).

• Boundaries:

  • Laterally: Anterior belly of Digastric muscle.
  • Anteriorly/Inferiorly: Superficial layer of deep cervical fascia.
  • Superiorly: Mylohyoid muscle.
  • Posteriorly: Hyoid bone.

• Contents: Submental lymph nodes, areolar connective tissue, Anterior Jugular veins.

• Communications: Submandibular spaces (posteriorly), Sublingual spaces (superiorly, via mylohyoid erosion).

2. Submandibular Space

• Location: Superiorly bounded by the floor of the mouth mucosa.

Divided by the Mylohyoid muscle into Sublingual Space (Above the mylohyoid)and Submaxillary Space (Below the mylohyoid).

• Boundaries:

  • Superiorly: Floor of mouth mucosa.
  • Laterally: Mandible.
  • Anteroinferiorly: Anterior belly of Digastric.
  • Posteroinferiorly: Posterior belly of Digastric.
  • Posteriorly: Hyoid bone.

• Contents:

  • Submandibular Gland (partially in both sublingual/submaxillary).
  • Branches of Facial and Lingual artery.
  • Submandibular lymph nodes.
  • Hypoglossal nerve (CN XII).
  • Nerve to Mylohyoid.
  • Lingual nerve.
  • (In Sublingual Space): Sublingual gland, Wharton's duct.

• Communications: Continuous around the posterior border of the Mylohyoid muscle. Communicates with: Submental space (anteriorly/medially), Sublingual space (posteriorly/superiorly), Parapharyngeal space (laterally).

3. Peritonsillar Space

• Location: Potential space between the fibrous capsule of the tonsil (medially) and the Superior Constrictor muscle (laterally).

• Boundaries:

  • Medially: Capsule of the Palatine Tonsil.
  • Laterally: Superior Constrictor muscle.
  • Anteriorly: Anterior pillar (Palatoglossal arch).
  • Posteriorly: Posterior pillar (Palatopharyngeal arch).

• Contents: Loose areolar tissue.

• Communications: Parapharyngeal (Lateral Pharyngeal) space.

4. Parapharyngeal Space (Lateral Pharyngeal Space or Pharyngomaxillary Space)

• Location: Inverted cone-shaped space lateral to the pharynx, extending from skull base to hyoid. Divided into two compartments by the Aponeurosis of Zuckerkandl and Testut (posterior thickening of buccopharyngeal fascia to styloid process/alar fascia):

  • Pre-styloid Compartment: Anterior to styloid process.
  • Post-styloid Compartment: Posterior to styloid process.

• Boundaries:

  • Superiorly: Skull base.
  • Inferiorly: Apex at Hyoid bone.
  • Posteriorly: Cervical vertebrae, Paravertebral muscles.
  • Anteriorly: Pterygomandibular raphe.
  • Laterally: Mandibular ramus, Parotid gland (deep lobe), Medial Pterygoid muscle.
  • Medially: Oropharynx, Nasopharynx.

• Contents:

  • Pre-styloid: Fat, connective tissue, Maxillary artery, Inferior Alveolar nerve, Lingual nerve, Auriculotemporal nerve, deep lobe of Parotid.
  • Post-styloid: Carotid sheath and its contents (Internal Carotid artery, Internal Jugular vein, Vagus nerve CN X), CN IX, XI, XII, Sympathetic chain, associated lymph nodes.

• Communications: Retropharyngeal space, Submandibular space, Parotid space, Carotid space, Visceral spaces.

📍 Infrahyoid Spaces

Located below the hyoid bone.

Anterior Visceral Space (Pretracheal Space)

• Location: Immediately anterior to the Trachea, extending from the Thyroid cartilage to the superior mediastinum.

• Boundaries:

  • Anteriorly: Middle layer of deep cervical fascia (enveloping thyroid/trachea).
  • Posteriorly: Deep layer of deep cervical fascia (prevertebral).
  • Superiorly: Thyroid cartilage.
  • Inferiorly: Superior mediastinum.

• Contents: Trachea, Thyroid gland, Parathyroid glands, Larynx, Cervical Esophagus, Recurrent Laryngeal Nerves, Cervical sympathetic chain.