Face

-The face forms the anterior aspect of the head.

Extent of the Face

• The face extends between the following anatomical landmarks:
  • Superiorly: It extends up to the hairline at its adolescent position.
  • Inferiorly: It reaches the chin and lower border of the mandible.
  • Laterally: It extends up to the auricles on either side.
• Note: The forehead is considered part of both the face and the scalp.

LAYERS OF FACE

• The face consists of two principal layers:
  • Skin
  • Superficial fascia containing the muscles of facial expression.
• Note: The deep fascia is generally absent in the face, except over the parotid gland, where it forms the parotid fascia, and over the buccinator muscle, where it forms the buccopharyngeal fascia.

Skin of the Face

– The skin of the face has the following characteristic features:

1. Rich vascularity: It receives an abundant blood supply from numerous arteries that form extensive anastomoses.
2. Numerous skin glands: It contains abundant sebaceous and sweat glands, particularly over the forehead, nose, and cheeks.
3. Laxity: The skin is loosely attached to the underlying tissues in several regions, particularly around the eyelids.
4. Firm attachment: The skin is tightly attached to the underlying cartilage and bone in certain regions, particularly over the nose and auricle.
5. Elasticity: The skin is highly elastic and accommodates movements produced during facial expression.
6. Mobility: The attachment of facial muscles to the skin allows movements responsible for different facial expressions.

Clinical Integration

1. Blushing and Blanching

• The rich vascular supply of the facial skin allows rapid changes in its colour. Blushing occurs due to dilation of cutaneous blood vessels, particularly during emotional stimulation. Blanching results from constriction of superficial blood vessels, as may occur during exposure to cold.

2. Facial Wounds

• Facial wounds may bleed profusely because of the abundant vascular supply. The rich blood supply also promotes rapid healing and reduces the risk of tissue necrosis. These characteristics are particularly useful in plastic and reconstructive surgery.

3. Acne (Pimples)

• Acne vulgaris commonly affects the face, particularly during adolescence and early adulthood. It develops due to blockage of hair follicles by keratin and sebum, often accompanied by inflammation. Increased sebaceous gland activity contributes to the development of acne.

4. Facial Edema

• The loose attachment of facial skin to the underlying tissues allows fluid to accumulate and spread easily. Edema is particularly noticeable around the eyelids because of the loose subcutaneous connective tissue. Periorbital puffiness may be an early manifestation of edema associated with certain renal diseases.

5. Boils (Furuncles)

• A furuncle is an acute bacterial infection involving a hair follicle and the surrounding tissue. Boils occurring over the nose and auricle are particularly painful because the skin is firmly attached to the underlying cartilage. Swelling and inflammation increase tissue tension, resulting in marked pain.

6. Gaping of Facial Wounds

• Many muscles of facial expression insert directly into the skin. When the skin is injured, contraction of these muscles may pull the wound margins apart. This produces gaping of facial wounds, particularly when the wound crosses the direction of natural skin tension lines.

Superficial fascia

– The superficial fascia of the face consists of loose connective tissue containing the following structures:

1. Muscles of facial expression
2. Blood vessels and nerves
3. Variable amounts of fat
4. Muscles of facial expression: These muscles are situated within the superficial fascia and are inserted into the skin. Their contraction produces different facial expressions.
5. Fat distribution: Subcutaneous fat is almost absent in the eyelids, whereas a well-developed buccal fat pad is present in the cheeks.
6. Suction pad of fat: The buccal fat pad is particularly prominent in infants and is also called the suction pad of fat. It supports the cheeks and prevents their collapse during suckling, thereby facilitating feeding.

MUSCLES OF FACIAL EXPRESSIONS

Peculiarities

·  The muscles of facial expression are located mainly in the subcutaneous tissue.

·  Most of these muscles insert into the skin, allowing movements that produce various facial expressions.

·  Morphologically, they represent remnants of the panniculus carnosus.

·  Embryologically, they develop from the second pharyngeal arch.

·  Nerve supply: All muscles of facial expression are supplied by the facial nerve (CN VII).

·  They contain small motor units that permit fine, precise movements.

·  Functions:

• They produce facial expressions associated with different emotions.
• They act as sphincters and dilators of facial openings, particularly the mouth, eyelids, and nostrils.

Groups of facial muscles

The muscles of facial expression are classified into six groups according to their location.

1. Muscles of the scalp

– Occipitofrontalis

2. Muscles around the orbital opening

• Corrugator supercilii
• Orbicularis oculi

3. Muscles around the nasal opening

• Procerus
• Compressor naris
• Dilator naris
• Depressor septi nasi

4. Muscles around the mouth

• Orbicularis oris
• Buccinator
• Levator labii superioris alaeque nasi
• Zygomaticus major
• Levator labii superioris
• Levator anguli oris
• Zygomaticus minor
• Depressor anguli oris
• Depressor labii inferioris
• Mentalis
• Risorius

5. Muscles around the auricle

• Auricularis anterior
• Auricularis posterior
• Auricularis superior

6. Muscle of the neck

– Platysma

Bell’s palsy

• Bell’s palsy is an acute lower motor neuron paralysis of the muscles of facial expression, usually affecting one side of the face.
• It results from dysfunction of the facial nerve (CN VII), commonly associated with inflammation and swelling of the nerve.
• The exact cause is often unknown, although reactivation of a latent viral infection may contribute.
• Injury to the facial nerve near or beyond the stylomastoid foramen can produce similar facial paralysis.

Supranuclear Facial Palsy

• The upper facial muscles receive bilateral corticobulbar innervation from both cerebral hemispheres.
• A unilateral lesion of the motor cortex or corticobulbar fibres above the facial motor nucleus produces supranuclear facial palsy.
• It predominantly affects the lower facial muscles on the side opposite the lesion.
• The upper facial muscles are relatively spared, allowing the patient to wrinkle the forehead and close the eyes.

Clinical significance: In lower motor neuron facial palsy, both the upper and lower facial muscles are affected on the same side. In supranuclear facial palsy, the lower face is predominantly affected, while forehead movements are usually preserved.

NERVE SUPPLY OF FACE

Motor Nerve Supply of Face

• The muscles of facial expression are supplied by the facial nerve (CN VII) because they develop from the second pharyngeal arch.
• The facial nerve supplies these muscles through five terminal branches:
  • Temporal branch
  • Zygomatic branch
  • Buccal branches
  • Marginal mandibular branch
  • Cervical branch

Muscles Supplied by the Branches of the Facial Nerve

1. Temporal branch: It supplies the frontalis, auricular muscles, upper part of orbicularis oculi, and corrugator supercilii.
2. Zygomatic branch: It mainly supplies the lower part of orbicularis oculi.
3. Buccal branches: They supply the muscles of the cheek and upper lip.
4. Marginal mandibular branch: It supplies the muscles of the lower lip.
5. Cervical branch: It supplies the platysma.

Sensory Nerve Supply of Face

• The skin of the face receives sensory innervation mainly from the trigeminal nerve (CN V).
• The skin over the angle of the mandible and adjacent parotid region is supplied by the great auricular nerve (C2–C3), a branch of the cervical plexus.
• The sensory distribution of the trigeminal nerve corresponds broadly to the embryological development of the face:
  • Upper one-third: It develops mainly from the frontonasal prominence and is supplied by the ophthalmic division (V1).
  • Middle one-third: It develops from the maxillary prominences and is supplied by the maxillary division (V2).
  • Lower one-third: It develops from the mandibular prominences and is supplied by the mandibular division (V3).

Cutaneous Nerves of the Face

The sensory nerves of the face are grouped according to their origin.

A. Ophthalmic division of the trigeminal nerve (V1)

1. Supratrochlear nerve
2. Supraorbital nerve
3. Lacrimal nerve
4. Infratrochlear nerve
5. External nasal nerve

B. Maxillary division of the trigeminal nerve (V2)

• Infraorbital nerve
• Zygomaticofacial nerve
• Zygomaticotemporal nerve

C. Mandibular division of the trigeminal nerve (V3)

• Auriculotemporal nerve
• Buccal nerve
• Mental nerve

D. Branches of the cervical plexus

1. Great auricular nerve (anterior division, C2–C3)
2. Transverse cervical nerve (C2–C3)
3. Lesser occipital nerve (C2)
4. Supraclavicular nerves (C3–C4)

A. Branches of the Ophthalmic Division (V1)

1. Supratrochlear Nerve

– It arises from the frontal nerve and supplies the medial part of the forehead and anterior scalp.

2. Supraorbital Nerve

• It emerges through the supraorbital notch or foramen and ascends over the forehead.
• It supplies the forehead, anterior scalp, upper eyelid, and frontal air sinus.

3. Lacrimal Nerve

– It supplies the lateral part of the upper eyelid and adjoining conjunctiva.

4. Infratrochlear Nerve

• It passes below the trochlea of the superior oblique muscle.
• It supplies the medial part of the upper eyelid, medial angle of the eye, and adjacent side of the nose.

5. External Nasal Nerve

• It is the terminal cutaneous branch of the anterior ethmoidal nerve.
• It emerges between the nasal bone and upper lateral nasal cartilage.
• It supplies the lower part of the dorsum and tip of the nose.

B. Branches of the Maxillary Division (V2)

6. Infraorbital Nerve

• It is the terminal continuation of the maxillary nerve and emerges through the infraorbital foramen.
• It divides into the following cutaneous branches:
  • Inferior palpebral branches: They supply the lower eyelid.
  • Superior labial branches: They supply the upper lip and adjoining cheek.
  • External nasal branches: They supply the side and ala of the nose.

7. Zygomaticofacial Nerve

• It arises from the zygomatic nerve, a branch of the maxillary nerve.
• It emerges through the zygomaticofacial foramen on the facial surface of the zygomatic bone.
• It supplies the skin over the prominence of the cheek.

8. Zygomaticotemporal Nerve

• It is a branch of the zygomatic nerve and passes through the zygomaticotemporal foramen.
• It supplies the skin over the anterior part of the temporal region.

C. Branches of the Mandibular Division (V3)

9. Auriculotemporal Nerve

• It passes behind the neck of the mandible and ascends with the superficial temporal vessels.
• Its auricular branches supply the anterior part of the auricle, external acoustic meatus, and adjoining tympanic membrane.
• Its temporal branches supply the skin over the temporal region.

10. Buccal Nerve

• It is a sensory branch of the anterior division of the mandibular nerve.
• It enters the cheek through the interval between the masseter and buccinator muscles.
• It supplies the skin of the cheek and mucous membrane covering the inner surface of the buccinator.

11. Mental Nerve

• It is a terminal branch of the inferior alveolar nerve, which arises from the mandibular nerve.
• It emerges through the mental foramen of the mandible.
• It supplies the skin of the chin and the skin and mucous membrane of the lower lip.

D. Branches of the Cervical Plexus

1. Great Auricular Nerve (C2–C3)

– Its anterior division supplies the skin over the angle of the mandible and parotid region.

2. Transverse Cervical Nerve (C2–C3)

– It supplies the skin over the anterior part of the neck, extending towards the lower border of the mandible.

3. Lesser Occipital Nerve (C2)

– It supplies the skin behind the auricle and over the lateral part of the occipital region.

4. Supraclavicular Nerves (C3–C4)

– They supply the skin over the lower part of the neck, clavicle, shoulder, and upper chest.

BLOOD SUPPLY AND LYMPHATIC DRAINAGE OF FACE

Arteries of the Face

– The face has a rich arterial supply derived mainly from the following arteries:

1. Facial artery
2. Transverse facial artery
3. Arteries accompanying the cutaneous nerves of the face

Facial artery

– The facial artery is the principal artery supplying the face.

Origin

– It arises from the external carotid artery in the neck, near the level of the greater horn of the hyoid bone.

Termination

• It ascends towards the medial angle of the eye, where its terminal part is called the angular artery.
• The angular artery anastomoses with the dorsal nasal branch of the ophthalmic artery.

Course

• The facial artery ascends through the neck and reaches the lower border of the mandible.
• It enters the face by winding around the lower border of the mandible at the anteroinferior border of the masseter muscle.
• At this point, it pierces the investing layer of the deep cervical fascia and is crossed superficially by the marginal mandibular branch of the facial nerve.
• The facial vein accompanies the artery, lying posterior to it.
• The artery follows a tortuous course upwards and forwards to reach a point approximately 1.25 cm lateral to the angle of the mouth.
• It then ascends along the side of the nose towards the medial angle of the eye, where it continues as the angular artery.
• During its course, the artery passes deep to the platysma, risorius, and zygomaticus major and minor muscles.

Branches

The facial artery gives the following branches in the face:

1. Inferior labial artery: It supplies the lower lip.
2. Superior labial artery: It supplies the upper lip and gives branches to the nasal septum and ala of the nose.
3. Lateral nasal artery: It supplies the ala and lateral part of the nose.
4. Muscular branches: They supply the adjacent muscles of facial expression.

Peculiarities of the Facial Artery

• Tortuous course: The winding course of the artery accommodates movements of the mandible, lips, and cheeks without excessive stretching of its wall.
• Extensive anastomoses: Its branches communicate with branches of the ophthalmic artery, establishing a connection between the external and internal carotid arterial systems.

Transverse Facial Artery

• The transverse facial artery usually arises from the superficial temporal artery within the parotid gland.
• It emerges from the anterior border of the gland and runs forwards across the face.
• It courses over the masseter muscle, usually between the zygomatic arch and parotid duct.
• It accompanies branches of the facial nerve, particularly the buccal branches.
• It supplies the parotid gland, masseter, and adjacent facial tissues.

<H4>Venous Drainage of Face

– The venous blood from the face is drained mainly through two veins:

1. Facial vein
2. Retromandibular vein

1. Facial Vein

• The facial vein is the principal vein draining the face.
• It lies posterior to the facial artery and follows a relatively straight course.

Formation

– The facial vein begins as the angular vein, formed by the union of the supratrochlear and supraorbital veins near the medial angle of the eye.

Course

• It descends obliquely downwards and backwards across the face.
• It passes posterior to the facial artery and continues towards the lower border of the mandible.
• It pierces the investing layer of the deep cervical fascia to enter the neck.

Termination

• It joins the anterior division of the retromandibular vein to form the common facial vein.
• The common facial vein terminates in the internal jugular vein.

Tributaries

• The facial vein receives tributaries that generally correspond to the branches of the facial artery.
• Its principal tributaries include the superior labial, inferior labial, lateral nasal, and deep facial veins.

2. Retromandibular Vein

Formation

– The retromandibular vein is formed by the union of the superficial temporal and maxillary veins within the parotid gland.

Course

• It descends through the parotid gland, posterior to the ramus of the mandible.
• Near the lower part of the gland, it divides into anterior and posterior divisions.

Termination

• Anterior division: It joins the facial vein to form the common facial vein, which drains into the internal jugular vein.
• Posterior division: It unites with the posterior auricular vein to form the external jugular vein, which drains into the subclavian vein.

Dangerous area of face

– The dangerous area of the face includes the lower part of the nose, upper lip, and adjoining parts of the cheeks.

Anatomical Basis

• The facial vein and its communicating veins are generally valveless, allowing blood to flow in either direction.
• The facial vein communicates with the cavernous sinus through two routes:
  • Ophthalmic route: Facial vein → Angular vein → Superior ophthalmic vein → Cavernous sinus.
  • Deep facial route: Facial vein → Deep facial vein → Pterygoid venous plexus → Emissary veins → Cavernous sinus.
• Facial muscle movements may influence venous flow and facilitate the spread of infection.

Clinical Significance

– Infection from this region may spread to the cavernous sinus, causing cavernous sinus thrombosis, a potentially life-threatening condition.

Lymphatic Drainage of Face

– The lymphatic drainage of the face is divided into three areas:

1. Upper Area

• It includes most of the forehead, temporal region, lateral halves of the eyelids, conjunctiva, cheeks, and parotid region.
• Lymph drains into the preauricular (superficial parotid) lymph nodes.

2. Middle Area

• It includes the central forehead, frontal sinus, medial halves of the eyelids, nose, maxillary sinus, upper lip, and lateral part of the lower jaw.
• Lymph drains into the submandibular lymph nodes.

3. Lower Area

• It includes the central part of the lower lip and chin.
• Lymph drains into the submental lymph nodes.