The cheeks are described as the region below the eyes but above the jawline. The cheeks span between the nose and the ears. The cheeks are made up of many muscles, fat pads, glands, and tissues. This complex composition allows the checks to participate in eating, talking, and facial expression.
Structure of The Cheeks
Many structures help make up the cheeks. The superficial layer of the cheeks is skin. The skin on the face is similar to most skin in the human body. The skin is the first line of defense from the outside environment. As a part of the immune system, the cheeks contain hairs that help maintain homeostasis and glands that provide an antimicrobial defense.
Slightly deeper to the skin is the fat pads. The fat pads contribute to the contour and the fullness of the cheeks. The fat originates from different regions in the face, but all come together at the cheek. The fat that provides fullness to the superior part of the cheek comes from the infraorbital and lateral orbital fat pads. The fat that contributes fullness to the medial region of the cheek comes from the nasolabial fat pads. The area considered to be the middle cheek derives from middle and superficial medial fat pads. The lower border of the cheek contains superior jowl fat. The fat that makes up the lateral region of the cheek comes from the distal part of the lateral temporal fat pad.
The lateral region of the cheek also contains the parotid gland. The parotid gland also contributes to the fullness of the cheek. The parotid gland also secretes digestive enzymes into the oral cavity for digestion.
Deep to the fat pads are the muscles. There are many muscles in the cheek region. The masseter muscle is the largest in the cheek region. The masseter contributes to the lateral fullness of the cheek, but its primary function is mastication. The lower part of the orbicularis oculi muscle contributes to the superior part of the cheek. The levator labii superioris alaeque nasi muscle is on the lateral border of the nose, and it demarcates the medial contour of the cheek region. The muscle lateral to the levator labii superioris alaeque nasi muscle is the levator labii superioris, it is part of the medial cheek region. The zygomaticus minor muscle and the zygomaticus major muscle contributes to the middle cheek region. The zygomaticus major also has some attachment in the superior cheek region. Slightly lower to the zygomaticus muscles, the risorius muscle and the levator anguli oris lays. These two muscles attach to the angle of the mouth. Deep to all these muscles, lies the buccinator muscle. The buccinator muscle’s function is to hold food boluses in the mouth against the teeth during mastication.
The three bony structures that help form the cheek are the zygomatic bone, the maxilla bone, and the mandibular bone. The zygomatic bone and the maxilla bone makes up the superior bony region of the cheek. The maxilla bone also makes the medial bony region of the cheek. The mandibular bone makes the lower region and lateral bony regions of the cheek.
All of these structures work in sync to aid in digestion, talking, and facial expression. The cheek aids in enzymatic digestion by the secretion of the enzymes from the parotid gland. While in mechanical digestion, the cheek aids in maintaining the food in the mouth so that it can be chewed and swallowed. The majority of the muscles in the cheek region contribute to facial expression. The various facial expressions result from muscle contractions and changes in blood flow that manifest physically through the cheeks.
Blood Supply of The Cheeks
The main blood supply for the cheek is from the facial artery and the transverse facial artery. Both of these arteries are branches of the external carotid artery. The facial artery and the transverse facial artery will supply the majority of the cheek. The medial border of the cheek will receive blood from the angular artery. The angular artery is the facial artery’s terminal branch that ascends the tear trough (lateral contour of the nose). The superior border of the cheek also receives blood from the zygomatic-orbital artery. These arteries will go onto and form many anastomoses to provide collateral blood flow to the cheeks and its structures.[rx]
The lymph in the cheek regions drains into the preauricular or the submandibular lymph nodes. The medial and inferior regions of the cheek will drain towards the submandibular lymph nodes. The lateral and superior regions of the cheek will drain towards the preauricular lymph nodes. All the lymph from the right cheek will drain back into the right lymphatic duct while the left cheek will drain back into the thoracic duct.
Nerves
The cheek region receives innervation from the facial nerve and the trigeminal nerve. The facial nerve will ascend toward the face after exiting the stylomastoid foramen. The facial nerve will travel through the parotid gland. The facial nerve will split the parotid gland into two main lobes. As the facial nerve exits the parotid gland, it splits into five main branches: frontal, zygomatic, buccal, marginal mandibular, and cervical. The buccal branch will innervate the majority of the muscles in the cheek region except for the orbicularis oculi and the masseter muscle. Innervation of the orbicularis oculi muscle is from the zygomatic branch of the facial nerve. The facial nerve‘s innervation will coordinate the contraction of facial muscles. The different combinations of facial muscle contractions will produce various facial expressions. The trigeminal nerve will give sensory innervation to the entire face, including the cheeks. The trigeminal nerve also delivers motor innervation to the masseter muscle.[rx]
Muscles of The Cheeks
Muscles located in the cheek region:
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Orbicularis oculi muscle (lower border)
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Levator labii superioris muscle
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Levator labii superioris alaeque nasi muscle
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Risorius muscle
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Levator anguli oris muscle
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Zygomaticus major and minor muscles
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Buccinator muscle
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Masseter muscle
Most of the muscles in the cheek region will participate in facial expression except for the buccinator and the masseter muscle. The buccinator muscle is the muscle closes to the oral cavity. The buccinator muscle is the primary muscle that will participate in supporting the food bolus in the mouth during chewing and swallowing. The masseter muscle is the only muscle located in the cheek region and engages in mastication.
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