Cheek

The cheek is the fleshy, soft, and prominent area on the side of the face, extending from the zygomatic bone (cheekbone) to the mandible (lower jaw). It consists of skin, subcutaneous tissue, muscles, fat, and blood vessels that provide structure, contour, and protection. The cheeks play a vital role in facial appearance, communication, and mastication (chewing) by housing essential muscles.

Location

The cheek is located on the lateral sides of the face, between the eyes and the jawline. Superiorly, it is bordered by the zygomatic arch (cheekbone), and inferiorly, it blends into the lower jaw. Medially, it connects to the nose and mouth, while laterally it reaches the ears.

Anatomy

The cheek is a complex anatomical structure located on the lateral aspect of the face, providing contour, structure, and housing important tissues. It is composed of bones, muscles, fat pads, blood vessels, nerves, skin, and connective tissue that work together to support mastication, expression, and appearance. Below is a detailed description of its anatomy:

Bony Framework

The structural foundation of the cheek is formed by the facial bones, primarily:

Zygomatic Bone (Cheekbone)

• A paired, prominent bone that forms the lateral prominence of the face.
• It articulates with:
• Maxilla (medially)
  • • Temporal bone (via the zygomatic arch)
    • Frontal bone (superiorly)
    • Sphenoid bone (posteriorly)

Maxilla

The upper jawbone contributes to the cheek by supporting the infraorbital region (below the eye).

Mandible

The lower jawbone defines the lower boundary of the cheek, connecting to the muscles and soft tissues of the area.

Zygomatic Arch

• Formed by the zygomatic bone and temporal bone, this arch creates the lateral contour of the cheek.
• These bones provide structure and anchor important muscles of mastication and facial expression.

Muscles of the Cheek

The muscles in the cheek can be categorized into muscles of facial expression and muscles of mastication:

Muscles of Facial Expression

These muscles move the overlying skin to create facial expressions. They are innervated by the facial nerve (cranial nerve VII): Buccinator:

• A deep, thin muscle of the cheek.
• Runs horizontally from the pterygomandibular raphe to the orbicularis oris.
• Forms the muscular foundation of the cheek.

Zygomaticus Major and Minor:

• Originate from the zygomatic bone and insert into the corner of the mouth.
• Important for smiling and lifting the cheeks upward.

Levator Anguli Oris: Elevates the corner of the mouth and blends with cheek muscles. Platysma: A superficial muscle extending from the neck to the cheeks, contributing to expressions like frowning.

Muscles of Mastication

These muscles are involved in chewing and are innervated by the mandibular branch of the trigeminal nerve (cranial nerve V3): Masseter:

• A strong, thick muscle that originates from the zygomatic arch and inserts on the ramus of the mandible.
• Provides strength to the lower cheek and jaw during chewing.^[6]

Temporalis: Although primarily located in the temporal region, its fibers extend downward toward the cheek to assist in closing the jaw.

Fat Pads of the Cheek

The cheeks contain important fat compartments that provide volume, contour, and protection: Buccal Fat Pad:

• A large, prominent fat pad located deep within the cheek, between the buccinator muscle and the masseter muscle.
• It contributes to the fullness of the cheek and acts as a cushion during chewing.

Superficial Fat Pads:

• Located just below the skin in the subcutaneous tissue, providing volume and contour to the cheeks.
• The distribution of fat pads gives the cheeks their characteristic fullness and shape.

Skin and Subcutaneous Tissue

The skin of the cheek is:

• Thick and highly vascular, with sebaceous glands, sweat glands, and hair follicles.
• Overlying the subcutaneous tissue, which contains fat, connective tissue, blood vessels, and nerves.^[3]

The subcutaneous tissue allows mobility of the skin over the underlying muscles.

Nerve Supply of the Cheek

The cheek receives its innervation from both sensory and motor nerves:

 Sensory Innervation

Provided by the trigeminal nerve (cranial nerve V):

• Infraorbital Nerve (branch of maxillary nerve, V2):
  • Supplies sensation to the upper cheek and infraorbital region.
• Buccal Nerve (branch of mandibular nerve, V3):
  • Provides sensation to the skin of the cheek and mucosa of the inner cheek.

Motor Innervation

The muscles of facial expression are innervated by branches of the facial nerve (cranial nerve VII), including:

• Buccal Branch: Supplies the buccinator muscle and other facial muscles of the cheek.^[1]

Blood Supply of the Cheek

The cheeks have a rich blood supply, primarily derived from the external carotid artery:

• Facial Artery: Provides the main blood supply to the cheek through branches like the buccal artery and superior labial artery.
• Transverse Facial Artery: A branch of the superficial temporal artery that supplies the lateral cheek.
• Infraorbital Artery: A branch of the maxillary artery that supplies the infraorbital region.
• Venous Drainage: Venous blood from the cheeks drains into the facial vein, which connects to the internal jugular vein.

Lymphatic Drainage of the Cheek

The lymphatics of the cheek drain into regional lymph nodes, including:

• Submandibular Lymph Nodes: Drain the upper and lower cheek.
• Preauricular Lymph Nodes: Drain the lateral cheek near the ears.
• Parotid Lymph Nodes: Associated with the parotid gland, draining part of the lateral face.

Oral Mucosa

The inner lining of the cheek consists of oral mucosa, which is soft and moist to facilitate functions such as chewing and speaking. The mucosa is continuous with the gums and lips and includes:

• Buccal Mucosa: Lines the inner cheek, supported by the buccinator muscle.
• Parotid Duct (Stensen’s Duct):
  • Opens into the buccal mucosa near the upper second molar tooth.
  • It drains saliva from the parotid gland into the oral cavity.^[8]

Function

The cheek serves multiple critical functions related to mastication (chewing), facial expressions, speech, and protection of vital structures. Composed of muscles, bones, fat pads, nerves, and skin, the cheeks play an important role in facial aesthetics, oral function, and sensory perception. Below is a detailed explanation of the functions of the cheek:

Mastication (Chewing)

The cheeks are essential for the process of chewing and preparing food for digestion:

• The buccinator muscle, which forms the main muscular structure of the cheek, compresses the cheek against the teeth.
• This action prevents food from falling into the oral vestibule (the space between the teeth and lips) and helps position food for chewing.
• The cheeks also work with the tongue to guide food between the molars for grinding.

Coordination:

• The buccinator and masseter muscles work together to maintain food movement during chewing.^[7]
• Without proper cheek function, food would not be efficiently broken down in the oral cavity.

Speech and Articulation

The cheeks contribute to speech production and sound modulation:

• By controlling the position and pressure of the lips and oral cavity, the cheeks help produce certain speech sounds.
• The buccinator muscle, in particular, adjusts the oral cavity size to articulate words by controlling airflow and movements of the lips.

Examples:

• Sounds like "p," "b," and "m" require precise cheek and lip movements.
• Cheeks stabilize the position of the oral tissues, which ensures smooth sound production.

Facial Expression

The cheeks play a key role in non-verbal communication by facilitating a wide range of facial expressions:

• The muscles of facial expression (e.g., zygomaticus major, zygomaticus minor, and buccinator) enable movements of the cheeks, contributing to expressions like:
  • Smiling (lifting the cheeks upward).
  • Frowning (lowering the cheeks and corners of the mouth).
  • Puffing or compressing the cheeks to convey surprise, anger, or emphasis.

Facial expressions are critical for social interaction, emotional communication, and non-verbal cues.

Aesthetic and Structural Support

The cheeks provide contour and shape to the face, contributing to overall facial aesthetics:

• The zygomatic bones (cheekbones) form the lateral prominence of the face.
• The buccal fat pads give fullness and volume to the cheeks, which is important for facial symmetry and youthfulness.
• Loss of fat or muscle tone in the cheeks (e.g., aging) can lead to a sunken appearance, altering facial aesthetics.

The cheeks also support the overlying skin and soft tissues, maintaining facial integrity and preventing sagging.

Protection of Oral and Facial Structures

The cheeks act as a protective layer for underlying vital structures:

• Buccal fat pads and muscles cushion the teeth, jaw, and bones during impact or trauma.^[5]
• The skin of the cheeks protects against external injuries, microorganisms, and environmental factors.
• The cheeks shield the parotid duct (Stensen’s duct), which drains saliva into the mouth near the upper molars.

Assistance in Respiration

The cheeks assist in respiratory functions when breathing through the mouth:

• The cheeks maintain the shape and stability of the oral cavity, ensuring unobstructed airflow into the pharynx and lungs.
• By keeping the oral cavity open and in proper position, the cheeks facilitate mouth breathing when nasal passages are blocked.

Suction and Swallowing

The cheeks contribute to suction and swallowing, especially in infants and during specific activities:

• In infants, the buccinator muscle and buccal fat pads help create a seal during breastfeeding, allowing for efficient suction.
• During swallowing, the cheeks maintain food in the oral cavity and guide it toward the pharynx.

The cheeks play a role in adults when creating suction for activities such as drinking from a straw.

Sensory Perception

The skin and mucosa of the cheeks are highly sensitive to touch, temperature, and pain, which helps in sensory feedback:

• Mechanoreceptors detect sensations like pressure or touch (e.g., food against the cheek).
• Thermoreceptors detect temperature changes (e.g., hot or cold food).
• Nociceptors detect pain caused by trauma, irritation, or oral injuries.

This sensory input is transmitted to the brain via the trigeminal nerve (cranial nerve V).

Thermoregulation

The cheeks play a minor role in regulating body temperature through the skin:

• The cheeks contain sweat glands that release sweat to cool the body during overheating.
• The rich vascular network (facial artery and veins) in the cheeks allows for heat dissipation by dilating or constricting blood vessels.

Reservoir for Saliva

The inner lining of the cheek (buccal mucosa) acts as a reservoir for saliva:

• The parotid duct opens into the cheek near the upper second molar, delivering saliva to moisten food during chewing.^[3]
• Saliva softens food, aids digestion, and prevents the oral cavity from drying out.

Clinical Significance

The cheek plays a vital role in facial structure, mastication, and expression, making it clinically significant for various injuries and medical conditions:

Facial Trauma

• Fractures of the zygomatic bone (cheekbone) or maxilla are common in blunt trauma (e.g., accidents, sports injuries).
• Zygomaticomaxillary complex fractures can cause facial asymmetry, difficulty chewing, and eye movement issues.

Soft Tissue Injuries

Lacerations, bruising, or burns to the cheeks may affect aesthetics and underlying muscles (e.g., buccinator).

Buccal Fat Pad Disorders

• Buccal fat pad atrophy leads to sunken cheeks (aging or malnutrition).
• Excessive fat may require surgical reduction for cosmetic reasons.

Parotid Duct Obstruction

The parotid duct opens into the cheek; obstruction (stones or infection) can cause parotitis and swelling.

Infections

Conditions like cellulitis, abscesses, or dental infections can spread to the cheeks, causing pain and swelling.^[2]

Neurological Disorders

• Injury to the facial nerve (CN VII) can cause facial paralysis, affecting cheek movement.
• Trigeminal neuralgia involves severe pain along the cheek due to trigeminal nerve irritation.