What are the layers of the face and neck?

From the Guidelines

The face and neck are composed of several layers, including the skin, subcutaneous tissue, fascia, muscle, and bone.

Layers of the Face and Neck

• Skin: The outermost layer, providing a barrier against external factors.
• Subcutaneous tissue: A layer of fat and connective tissue beneath the skin.
• Fascia: A layer of connective tissue surrounding muscles, bones, and other structures.
• Muscle: Multiple layers of muscles, including the platysma in the neck, which plays a crucial role in penetrating neck injuries 1.
• Bone: The underlying skeletal structure, including the mandible, maxilla, zygomatic bones, and cervical vertebrae. The facial nerve (CN VII) courses through the face and neck, and its anatomy is crucial in understanding facial trauma and cranial neuropathy 1.

Zones of the Neck

The neck is divided into three zones:

• Zone I: Extends from the clavicles and sternal notch to the cricoid cartilage.
• Zone II: Extends from the cricoid cartilage to the mandibular angle.
• Zone III: Extends from the mandibular angle to the skull base 1. These zones are important in evaluating penetrating neck injuries and determining the appropriate imaging and treatment approach. In evaluating facial trauma, a thorough understanding of the facial anatomy, including the facial buttresses, is essential 1. The facial buttresses are bony structures that provide support and stability to the face, and their disruption can lead to significant facial trauma. Imaging modalities, such as CT and MRI, play a crucial role in evaluating facial trauma and cranial neuropathy, and the choice of modality depends on the specific clinical scenario 1.

From the Research

Layers of the Face

• The face is arranged in five layers:
  • Layer 1: skin
  • Layer 2: subcutaneous fat including the retinacula cutis (composed of fibrous connective tissue)
  • Layer 3: superficial musculo-aponeurotic system (SMAS)
  • Layer 4: deep fat
  • Layer 5: periosteum or deep fascia 2
• The facial fat compartments are located in layers 2 and 4, each with unique characteristics and spatial relationships with the surrounding tissues 2

Layers of the Neck

• A fascia covering both sides of the platysma has been described, which can be considered as a surgical landmark in the neck 3
• The platysma muscle plays an increasingly important role in cervical surgery and constitutes the deep guarantee of the cervical corset 4

Superficial Musculoaponeurotic System (SMAS)

• The SMAS is a strictly superficial surgical anatomy structure derived from the primitive platysma muscle, and does not possess any bony insertion 4
• The SMAS is composed exclusively of platysma and risorius muscles, with no parotid aponeurosis 4
• The existence of a SMAS as a guiding structure for the surgeon in the other regions of the face and neck is controversial, with some studies suggesting it is not present in all facial regions 3

Fascial Spaces

• The face and neck have several fascial spaces, with varying terminology used by different authors 5
• A thorough knowledge of the nature of infective processes in the facial and cervical regions is essential, with anatomical relations forming the basis of diagnosis and therapy 5