Anatomy of Face in a Nutshell

Anatomy of Face

Skin of the face:

• Anchored to deep tissue only at the dorsum of nose and the chin
• It is very pliable elsewhere due to lack of deep fascia
• Thus, edema of the face is very common and is not limited.
  • Bleeding in arm is limited by deep fascia of the arm
  • Bleeding in the face will spread through wide area due to lack of limits of deep fascia
• It is very vascular: has strong anastomosis between vessels of the face, thus wounds will repair nicely.

Sensory Innervation of the face: all from CN V (trigeminal)

• CN V1- Opthalmic nerve
  • Supraorbital nerve

1. 1. • comes through supraorbital foramen
      • Goes superiorly onto forehead

• • Supratrochlear nerve- Goes superiorly to forehead (more medially)
  • Infratrochlear- originates near medial supraorbital margin and travels inferiorly
  • External Nasal- supplies dorsum of the nose
  • Lacrimal- on lateral side of supraorbital margin, travels superiorly / inferiorly to supply both aspects of the lateral side of the eye brow / temple region
  • Thus, have 5 terminal branches of CN V1 that supply forehead, eyebrow, dorsum of nose
• CN V2- Maxillary nerve
  • Infraorbital

1. 1. • Comes through infraorbital foramen
      • Travels inferiorly to supply cueek

• • Zygomatico temporal- travels superiorly to supply temple
  • Zygomatico facial- travels inferiorly to supply cheek
• CN V3- Mandibular nerve
  • Auriculotemporal- originates more inferiorly on cheek, but travels far superiorly to supply temple / lateral face
  • Buccal- travels inferiorly, supplies lower lateral cheek
  • Mental

1. 1. • Comes through the Mental Foramen
      • Numerous branches supply chin and lower lip

• Trigeminal does supply ear as well (no details)

Blood supply to the face:

• Facial artery: chief artery to the face (medial aspect esp.)
  • Starts within common carotidà external carotidà Facial artery
  • Is very serpentine in its path- allows flexibility to account for dynamic nature of face / neck
  • Winds through the submandibular gland
  • Courses from chin across cheek and up to the medial angle of the eye
  • Ends as the angular artery- changed name as approached the medial aspect of the eye.
  • Key Branches:

1. 1. • Submental branch – to submental triangle
      • Superior labial- upper lip

• • • Inferior labial – lower lip

• • • Other branches supply the facial muscles

• Superficial temporal artery: from the external carotid
  • Supplies the lateral aspect of the face
  • Branch- Transverse facial artery which travels medially across face toward nose
• Veins:
  • Supraorbital / supratrochlear match those same named arteries in the forehead
  • Facial vein is much straighter than facial artery, receives analogous tributaries. Is the primary drainage of the face.
  • Retromandibular (runs with external carotid) meets the facial vein to form the common facial vein→joins with internal jugular (may vary)
  • At the medial corner of the eye, angular vein has options

• • • May drain inferiorly on mentioned pathway via facial vein
    • May be a part of the ophthalmic drainage system of the eye
      1. May enter the opthalmic vein
      2. Flows into the cavernous sinus: a dural sinus inside the skull
         1. superficial tissue is thus draining into skull
         2. creates a danger area on the face:
            1. Triangular area: includes upper lip, skin beneath eye, lateral nose, medial cheek
            2. these tissues may drain into dural sinuses
            3. microbe infection on this skin may travel to the brain (meningitis etc.)

1. 1. • May flow into pterygoid plexus as well

Muscles of face (facial expression)

• Attached to the skin of the face (there is no deep fascia)
• All lie in the subcutaneous tissue of the face
• Most do not have bony attachment (some do) in the face
  • Is a cosmetic issue
  • Were they bound to bone, we could tighten them surgically
• All are supplied by CN VII (Facial Nerve)
• All muscles were derived from the mesenchyme of the 2^nd pharyngeal arch.
• Most of these muscles act as dilators / sphincters of orbit, nares, or mouth and are thus concentrated in the medial aspect of the face.
• Platysma:
  • Located in superficial fascia of the neck
  • Acts by tensing the skin of the lower jaw
• Frontooccipitalis:
  • Made up of 2 parts: Frontal belly / Occipital belly
  • No bony attachment
  • Frontal belly (known as Frontalis) raises the eyebrows, wrinkles skin of  forehead
• Orbicularis Oculi
  • Acts as a sphincter around the eye
  • May extend down onto the cheek
  • Portion is in the upper eyelid
  • Action is to close the eye
• Orbicularis Oris
  • Around the  mouth
  • Action is to purse lips
• Acting on the lips:
  • Levator labii superioris- elevates upper lip
  • Depressor labii inferioris- draws the lower lip down
  • Depressor anguli oris- at corner of mouth, draws it inferiorly / laterally
  • Levator anguli oris- extends from corner of mouth laterally / superiorly
  • Zygomaticus major / minor- at corner of the mouth, smiling
  • Levator labii superioris alaque nasi – draws up upper lip / flares nostrils
  • Buccinator- keeps food between teeth, used to play instruments

Facial nerve: CN VII

• Many motor components:
  • Supplies the muscles of facial expression
  • Supply posterior belly of digastric
  • Supply stylohyoid
  • All derived from mesenchyme of 2^nd pharyngeal arch
• Taste component: anterior 2/3 of the tongue
• Parasympathetic component:
  • Lacrimal gland (tears)
  • Mucus glands of the nasal cavity / oral cavity
  • Submandibular / sublingual salivary glands.
• Sensory component: to the skin of the area around the ear
• Pathway:
  • Facial nerve comes off brainstem→ enters skull (petrous portion of temporal bone) via internal auditory meatus
  • In the temporal bone: takes a right angle turn and heads down through bony canal (Facial canal) and exits temporal bone through Stylomastoid Foramen.

• • • Motor component of facial nerve exits through foramen
      1. Facial muscles
      2. Stylohyoid
      3. Posterior belly of digastric
    • Portion heads toward parotid gland (does not innervate it, just passes into it)
      1. While in parotid gland, it forms a network
      2. 5 terminal branches emerge from the parotid gland in a network type way (not neat and linear). (Two Zebras Bit My Cookie) (no memorize targets)
         1. T: Temporal- supplies fontalis
         2. Z: Zygomatic- orbicularis oculi
         3. B: Buccal- those that elevate upper lip
         4. M: Mandibular- depress lower lip
         5. C: Cervical- supplies platysma

• Clinical: Bell’s Palsy
  • Temporary paralysis of muscles of facial expression
  • Sometimes due to impact on motor branch of facial nerve
  • Wake up in the morning with a flaccid face (may mistake for a stroke)
  • Is quite common
  • Main cause is a middle ear infection- inflammation due to close proximity of middle ear to Facial Canal in which nerve travels.
  • Recovery varies, usually treat with steroids.
  • May need to patch the eye shut to prevent it from drying out ( cannot close on its own)
• Parotid Gland:
  • Parotid duct emerges and carries saliva into oral cavity
  • 5 branches emerge to their respective destinations in the face
  • External carotid deep / Superficial temporal (continuous)
  • Retromandibular vein / superficial temporal vein (continuous)
  • Auriculotemporal nerve

1. 1. • Branch of the third division of CN V
      • Supplies skin over the parotid and up into the temple

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