Anatomical boundaries of the region
The superficial lateral facial region (regio facialis lateralis superficialis) has clearly defined borders that serve as primary surgical landmarks when planning surgical approaches.
- Superiorly: the boundary is formed by bony structures—the zygomatic arch and the inferior orbital margin.
- Inferiorly: the region is strictly bounded by the inferior border of the mandible.
- Anteriorly: the dividing line runs along natural skin folds, including the nasolabial and nasofacial sulci, and descends to the angle of the mouth.
- Posteriorly: the boundary corresponds to the posterior border of the mandibular ramus.
Division into topographic segments
For the convenience of clinical examination and surgical precision, this extensive anatomical zone is traditionally subdivided into three narrower regions. Each of them has specific boundaries and contents:
- Buccal region (regio buccalis): occupies the space located anterior to the masseter muscle.
- Parotidomasseteric region (regio parotideomasseterica): its area completely corresponds to the location of the masseter muscle and the parotid gland of the same name.
- Deep facial region (regio facialis profunda): a topographically complex compartment located deep medial to the mandibular ramus.
External landmarks and palpation of bony structures
To orient oneself correctly within the lateral facial region, the physician utilizes a number of bony structures that are easily identified by palpation through the skin. Precise palpation avoids damage to vital structures.
- Zygomatic bone and zygomatic arch (arcus zygomaticus): these structures are easily palpated just below the lateral angles of the patient's eyes.
- Infraorbital margin: its relief is uneven. Externally, it is defined as a sharp margin, but medially it becomes noticeably smoothed, forming a smooth transition into the nasal dorsum.
- Canine fossa (fossa canina): palpated inferior to the infraorbital margin. It should be noted that it is mainly defined in lean individuals. Inferiorly, this fossa smoothly transitions into the alveolar process.
- Condylar process: an element of the temporomandibular joint (TMJ). It can be palpated anterior to the tragus of the ear by asking the patient to move the jaw.
- Coronoid process: is also accessible for palpation. It is identified below the zygomatic arch, but can only be felt when the mouth is open.
- Mandible: its shape is not constant and directly depends on the patient's age and dentition. In the center of the mandible, the mental protuberance (protuberantia mentalis) stands out, and on either side of it are the mental tubercles (tuberculi mentales).
Palpation of soft tissues and salivary glands
In addition to the bony framework, muscular and glandular formations are examined in the lateral facial region. Their condition is assessed according to the following criteria:
- Masseter muscle: it is well contoured and palpated on the outer surface of the mandibular ramus. To make its contours as clear as possible, the patient is asked to clench their teeth tightly.
- Buccal fat pad (fat pad of Bichat): visualized or felt on palpation as a depression or small elevation located anterior to the masseter muscle.
- Parotid salivary gland: healthy gland tissue itself is normally not palpable. However, the clinician can easily find its duct. It is defined as a dense longitudinal cord that runs parallel to the zygomatic arch, located 1–2 centimeters below it.
Briefly: answers to topical questions
What is the layered structure of the buccal region?
The buccal region features a full set of soft tissue layers, including the skin externally, subcutaneous adipose tissue, and mimetic muscles. The muscular layer is formed by the buccinator muscle and the buccal fat pad. Externally, the buccinator muscle is covered by the buccopharyngeal fascia, and internally it is lined by the mucous membrane.
What anatomical structures pass through the substance of the parotid gland?
Nerves, vessels, and lymph nodes pass through the thickness of the parotid gland. The nerves include the facial nerve, forming a plexus, and the auriculotemporal nerve. Vascular structures are represented by the external carotid artery along with its terminal branches and the retromandibular vein. Deep lymph nodes are located within the gland substance, while superficial ones lie on the fascia.
What does the content of the deep facial region include?
The deep facial region contains the pterygoid venous plexus, the maxillary artery, and branches of the mandibular nerve. The region is located medial to the mandibular ramus and directly borders the deep part of the parotid gland.
Which branches are given off by the facial nerve as it forms the greater pes anserinus?
Forming the parotid plexus within the gland, the facial nerve divides into branches that innervate the facial expression muscles. These include the temporal, zygomatic, and buccal branches, as well as the marginal mandibular branch and the cervical branch.
Which arteries and veins provide blood supply and venous drainage in the buccal region?
The facial artery and facial vein are described in the buccal region. In its initial section, the facial artery runs in the subcutaneous tissue of the buccal region and, unlike the vein, is highly tortuous. It anastomoses with the transverse facial artery, buccal and supraorbital arteries, as well as branches of the ophthalmic artery. The projection of the facial artery and vein runs from the intersection of the anterior border of the masseter muscle with the inferior border of the mandible to the medial angle of the eye; at the level of the nasal ala along this line, the anastomosis of the facial vein with the pterygoid venous plexus is identified.
For quick memorization of the boundaries, imagine a square frame on the cheek: superiorly — zygomatic arch, inferiorly — mandibular border, anteriorly — nasolabial fold, posteriorly — mandibular ramus.
Class and exam questions
Is it possible to palpate the parotid salivary gland itself normally?
No, healthy parotid salivary gland tissue is not palpable. However, one can feel its excretory duct as a dense cord running parallel to and just below the zygomatic arch.
How to properly locate the coronoid process of the mandible during an examination?
The coronoid process is palpated just below the zygomatic arch. The main condition for its successful identification is that the patient must open their mouth during palpation.
What determines the anatomical shape of the mandible?
The shape of the mandible is individual. It primarily depends on the patient's age and the degree of dentition preservation.
What else to study on this topic
- Projections of neurovascular structures of the face onto the skin
- Detailed topography of the deep facial region (regio facialis profunda)
- Syntopy and course of the parotid duct
- Anatomical features and functions of the buccal fat pad (fat pad of Bichat)
- Topography of temporomandibular joint elements during jaw movements
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