The Face – Anatomy, Nerve and Blood Supply, Functions

The Face – Anatomy, Nerve and Blood Supply, Functions

The Face is the most anterior region of the head is the face. The human face is a unique aspect of each individual. The face contains many structures that contribute to the display of emotions, feeding, seeing, smelling, and communicating. One of the most distinguishing qualities of the face is that it is used for personal identity from person to person. Identity is essential since the face is usually the first aspect of a human that is noticeable during encounters with other individuals.

Structure

The anatomy of the face can divide into three main regions: upper face, middle face, and lower face. The entire face is covered by skin superficially, while the deep anatomy contains muscles, fat pads, nerves, vessels, and bones.

Upper Face

The region that is considered the upper face starts from the hairline superiorly and ends just under the lower eyelid. The lateral borders of the upper face terminate around the temporal region. The upper face region contains the forehead, eyes, and temporal region.

Forehead

The forehead is the superior region of the upper face region. The superficial layer of the forehead is made up of skin. Deeper to the skin layer of the forehead is the fat pads. The central forehead fat pad is in the center of the forehead. Laterally to the central forehead pad is the middle forehead fat pad. The middle forehead fat pad is superior to the orbits. The fat pad that makes up the most lateral region of the upper face is the lateral temporal fat pad. The lateral temporal fat pad overlies the temporal regions and spans inferiorly to the angle of the mandible.

The muscular layer of the upper face is underneath the fat pads. The procerus muscle occipitofrontalis muscle, depressor supercilii muscle, and corrugator supercilii muscle form the majority of the forehead, while the temporal part contains the temporalis muscle. The procerus muscle is shaped like a pyramid and spans from the inferior part of the nasal bone to the middle part of the forehead. The procerus muscle is situated between the eyebrows and attaches to the frontalis muscle. The contraction of the procerus muscle allows for the elevation of the eyebrows. The occipitofrontalis muscle spans the majority of the forehead. The occipitofrontalis muscle originated from the galea aponeurosis superiorly and inserts and blends into the orbicularis oculi muscle. When the occipitofrontalis muscle contracts, it elevates the eyebrows and wrinkles the forehead. The depressor supercilii muscle originates from the medial orbital rim and inserts at the medial part of the bony orbit. The action of the depressor supercilii muscle is to depress the eyebrows. The corrugator supercilii muscle is a small muscle that originated from the supraorbital ridge and inserts on the skin of the forehead close to the eyebrows. The contraction of the corrugator supercilii muscle results in the wrinkling of the forehead. The temporalis muscle originates from the parietal and sphenoidal bone. The temporalis muscle inserts on the coronoid process and the retromolar fossa. The contraction of the temporalis muscle results in the elevation and retraction of the mandible.

The bony structure of the forehead is made up of the frontal bone predominantly, while the lateral region of the upper face that corresponds to the temporal part forms from the temporal and sphenoid bone.

Eyes

The eyes situate in the orbital sockets in the upper face region. The skin that is directly superior to the orbits is also the region where the eyebrows are found. Surrounding and covering the eyes are the eyelids. The eyelids divide into the upper and lower eyelids. At the edges of the eyelids are the eyelashes. The eyelids cover and provide eyes with protection. Deep to the skin over the eye region are the fat pads. The superior fat pad is superior to the orbit, but inferior to the eyebrows, while the inferior orbital fat pad is inferior to the orbit and it contributes to the fullness in the superior cheek region. Laterally to each orbit is a lateral orbital fat pad.

There is one muscle that encircles the orbit. The muscle that encircles the orbit is the orbicularis oculi muscle. The orbicularis oculi muscle originated from the frontal bone, lacrimal bone, and medial palpebral ligament. The orbicularis oculi muscle inserts into the lateral palpebral raphe. The function of the orbicularis oculi muscle is to close the eyelids. In contrast, the muscle that opens the eyelids is the levator palpebrae superioris muscle. The levator palpebrae superioris muscle is not on the face but rather is in the orbital socket.  Eye movement is under the control of six muscles. The six muscles that control the eyes are the superior rectus muscle, inferior rectus muscle, medial rectus muscle, lateral rectus muscle, superior oblique muscle, and the inferior oblique muscle.

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The bony structures that make the eye region are the frontal bone superiorly, nasal bone medially, maxilla inferomedially and the zygoma makes the inferior and the lateral part of the orbit.

Middle Face

The middle face region starts superior at the lower eyelid and spans inferior terminating just above the upper lip. The ears enclose the lateral borders of the central face. The central face region contains the nose, cheeks, and ears.

Nose

The nose is a midline structure that protrudes from the face. This protuberance is made from cartilage predominantly. But the base of the nose is made from the nasal bones. The nose is covered with skin superficially and has no underlying fat pads. The bony part of the nose has the nasalis muscle on top of it. The action of the nasalis muscle is to depress the tip of the nose, compression of the nasal bridge, and elevation of the nostrils. At the nasal septum, there is a muscle called the depressor alae nasi muscle. The depressor alae nasi muscle originates from the incisive fossa of the maxilla and inserts into the nasal septum. The action of the depressor alae nasi muscle is to depress the nasal septum and constriction of the nostrils.

Cheeks

The cheeks are lateral to the nose. The cheeks are covered with skin superficially, but deep to the skin, the cheeks contain a lot of fat pads. The most medial fat pad in the cheek region that demarcates the nose from the cheek is the nasolabial cheek fat pad. Just lateral to the middle cheek fat is the superficial medial cheek fat. The superficial medial cheek fat is directly inferior to the inferior orbital fat pad. More laterally, the middle cheek fat pad is lateral to the superficial cheek fat pad. The superficial cheek fat pad meets the inferior extension of the lateral temporal fat pad. The cheek region also contains a buccal fat pad that overlies the buccal muscle.

The muscular layer of the cheek contains many muscles. The cheek contains a muscle called the levator labii superioris alaeque nasi muscle. The levator labii superioris alaeque nasi muscle demarcates the medial part of the cheek and separates it from the nose. The levator labii superioris alaeque nasi muscle starts from the medial orbital wall, runs along the nostrils, and attaches to the upper lip. The action of the levator labii superioris alaeque nasi muscle is to elevate the upper lip and flares the nostrils. Just lateral to the levator labii superioris alaeque nasi muscle is the levator labii superioris muscle. The levator labii superioris labii muscle originates from the infraorbital margin and insets at the upper lip. The levator labii superioris muscle’s action is to elevate the upper lip. Slightly lateral to the levator labii superioris muscle is the zygomaticus minor and major muscles. The zygomaticus minor and major muscles originate from the zygomatic angle. The zygomaticus minor muscle inserts into the skin of the upper lip. The action of the zygomaticus minor muscle is to elevate the upper lip. As for the zygomaticus major muscle, it inserts into the modiolus of the mouth. The action of the zygomaticus major muscle is to draw the angle of the mouth superiorly and laterally. There is a small muscle lateral to the zygomaticus major muscle called the levator anguli oris muscle. The levator anguli oris muscle originates from the maxilla and inserts into the modiolus of the mouth. The action of the levator anguli oris muscle is to assist in smiling by elevation of the angle of the mouth. Underneath, the zygomaticus muscles lie the buccinator muscle. The buccinator muscle originates from the alveolar process of the maxilla and mandible, buccinator crest, and temporomandibular joint. The action of the buccinator muscle is to compress the food against the buccal mucosa during mastication. Laterally, to the buccinator and zygomaticus muscle is the masseter muscle. The masseter muscle originates from the zygomatic arch and the maxillary process on the zygomatic bone, and then it inserts at the ramus of the mandible. The action of the masseter muscle is to elevate and protrude the mandible during mastication. The masseter muscle and the region anterior the ear contains the parotid gland superficially. The parotid gland produces digestive enzymes and is the structure the facial nerve penetrates before it divides into five nerve branches.

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The bony structure that makes the cheek region is the maxilla bone.

Ears

The lateral structures that outline the middle face region are the ears. The ears are made from cartilage and function to funnel in sound. The ears have three muscles that act on it. The muscles that act on the ears are the auricular muscles (anterior, posterior, and superior). The auricular muscles originate from the galea aponeurosis and inserts onto the helix and pinna of the ear. The action of the auricular muscles is to wiggle the ears.

The bone structure that allows for the ears to protrude from is the temporal bone.

Lower Face

The lower face starts superiorly at the upper lip and ends inferiorly at the lower border of the chin. The lateral border of the lower face is made up of the angle of the mandible. The lower face region contains the lips, chin, and jaws.

Lips

In the lower face region, the lips are the most noticeable structures in the area. The lips divide into the upper and lower lips. The function of the lips is for the articulation of speech, eating, kissing, and sensory structures. The orbicularis oris muscle surrounds the lips. The orbicularis oris muscle is a sphincter muscle that originates from the mandible and maxilla then inserts onto the skin of the lips. The action of the orbicularis oris muscle is to alter the shapes of the lips for eating, speaking, kissing, and more. In the lower face region, the risorius muscle inserts into the modiolus at the angle of the mouth but originates from the parotid fascia. The action of the risorius muscle is to pull the angles of the mouth back. Most of the muscles in the lower face region will act predominantly on the lower lip. The medial region of the lower lip has two sets of paired muscles. These muscles are the mentalis and the depressor labii inferioris muscle. The mentalis muscle originates from the anterior mandible and inserts onto the chin. The action of the mentalis muscle is to protrude the lower lip, elevate, and wrinkle the skin of the jaw, while the depressor labii inferioris muscle originates from the mandible and inserts onto the lower lip. The action of the depressor labii inferioris muscle is to depress the lips. At the angles of the mouth, the depressor anguli oris muscle lies. The depressor anguli oris muscle originates from the tubercle of the mouth and inserts into the modiolus of the mouth. The action of the depressor anguli oris muscle is to depress the angle of the mouth.

The bony structures of the lips are made from the maxilla superiorly and the mandible inferiorly.

Chin and Jaw

The chin is also called mental protuberance. This structure appears on the midline of the mandible. The chin has a pre-mental fat pad that is close to the tip of the chin, while the jaw and jawline form from the lateral portions of the mandible. The jawline has the inferior jowl fat pad just lateral to the pre-mental fat pad. There is a small fat pad superior to the inferior jowl fat pad, and its called the superior jowl fat pad. The lower border of the chin and jawline have the platysma muscle. The platysma muscle is a superficial muscle that originates from the infraclavicular and supraclavicular regions then inserts onto the mandible, cheek, and mouth. The action of the platysma muscle is to depress the corners of the mouth and pull the neck skin superiorly. The platysma muscle also acts as a protective muscular layer for the vital structures such as the trachea, esophagus, carotid arteries, jugular veins, and nerves that are beneath the platysma muscle.

Blood Supply

The primary blood supply to the face derives from the external carotid artery and the branches of the external carotid artery. As the common carotid artery ascends cranially, it branches into the internal and external carotid arteries. The external carotid artery further branches into superior thyroid, lingual, facial, ascending pharyngeal, occipital, posterior auricular, maxillary, and superficial temporal arteries. The facial, superficial temporal, and maxillary arteries are the main vessels that will provide perfusion to the face. The superficial temporal artery travels toward the temporal and forehead region. The superficial temporal artery perfuses the structures mainly in the temporal and forehead territories. The facial artery is responsible for perfusing the majority of the face. The facial artery travels toward the nose and lips, while the maxillary artery provides some perfusion to the cheek region. The maxillary artery travels toward the deep structures and perfusing the deeper facial structures. As for the venous drainage, the face drains the majority of the venous blood via the facial vein. The facial vein eventually drains the blood back into the internal jugular vein.

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The lymphatic drainage of the face is dependent on the location of the face. The nasal region contains facial lymph nodes, while the region closer to the ears and angle of the mandible contains preauricular lymph nodes. The lymph in the face tends to drain to submental, submandibular, and cervical lymph nodes depending on which is closer. The right side of the face will eventually drain into the right lymphatic duct while the left side will drain into the thoracic duct. The right lymphatic duct and the thoracic duct then drain back into the central circulation.

Nerves

The face has two main nerve innervations. The nerves that innervate the face are cranial nerves. The facial nerve is responsible for the innervation of the muscles that participate in facial expression. The facial nerve penetrates through the parotid gland and then branches into five nerves: temporal, zygomatic, buccal, marginal mandibular, and posterior cervical nerve. The temporal branch of the facial nerve travels toward the temporal and forehead region. The zygomatic branch of the facial nerve travels along the zygoma and cheek region. The buccal branch of the facial nerve travels toward the buccal region. The marginal mandibular branch of the facial nerve travels toward the mandible. Lastly, the posterior cervical branch of the facial nerve travels toward the cervical region. These nerve branches provide motor innervation to the facial muscles that are near their corresponding paths/territories.

As for the sensory innervation of the face, the trigeminal nerve proves the sensory innervation to the face. The trigeminal nerve branches into three nerve branches. These branches are the ophthalmic, maxillary, and mandibular nerves. The ophthalmic nerve travels toward the forehead and provides sensory to the forehead and eye region. The maxillary nerve travels toward the maxilla bone and provides sensory innervation to the cheek and nose. The mandibular nerve travels with the mandible and provides sensory innervation to the jaw and lips. The trigeminal nerve also innervates the masseter muscle that contributes to the fullness of the cheeks. The eyes also receive additional innervation from the optic, oculomotor, trochlear, trigeminal, abducens, and facial nerves. The nose also receives special sensory innervation from the olfactory nerve. Lastly, the ears funnel in sound and convert it into audible sound via the vestibulocochlear nerve.

Muscles

These are the muscles located on the face.

  • Occipitofrontalis muscle
  • Temporalis muscle
  • Procerus muscle
  • Nasalis muscle
  • Depressor septi nasi muscle
  • Orbicularis oculi muscle
  • Corrugator supercilii muscle
  • Depressor supercilii muscle
  • Auricular muscles (anterior, superior and posterior)
  • Orbicularis oris muscle
  • Depressor anguli oris muscle
  • Risorius muscle
  • Zygomaticus major muscle
  • Zygomaticus minor muscle
  • Levator labii superioris muscle
  • Levator labii superioris alaeque nasi muscle
  • Depressor labii inferioris muscle
  • Levator anguli oris muscle
  • Buccinator muscle
  • Mentalis muscle
  • Platysma muscle
  • Masseter muscle

Most of these muscles receive innervation from the facial nerve and participate in facial expression except for the masseter muscle. The innervation of the masseter muscle is via the trigeminal nerve, and this muscle participates in mastication.

References

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