Muscles of facial expression

Muscles of face bring about different types of facial expressions, hence the name muscles of facial expression, the actions of many of them are implied by their names.

CHARACTERISTICS:

  1. Lie in superficial fascia and inserted into the skin.
  2. Morphological, they represent subcutaneous muscle of lower animals, called panniculus carnosus.
  3. Embryologically, develop from mesoderm of 2nd pharyngeal arch, hence supplied by facial nerve
  4. Functionally, perform all important functions of non-verbal communication in addition to closing and opening of orifices.

MUSCLES AROUND THE ORIFICE OF EYE

🔹️Orbicularis oculi

Consists of three parts:

  1. Orbital part: arises from medial palpebral ligament, frontal process of maxilla and adjoining part of frontal bone. Fibres form complete elliptical loops around the eyes.

It closes the eye tightly during intense sunlight and also for winking.

2. Palpebral part: arises from medial palpebral ligament and sweeps laterally over the upper and lower eyelids to be inserted into lateral palpebral ligament.

It closes the eyelids gently as in sleep or in blinking.

3. Lacrimal part: arises from posterior lacrimal crest and lacrimal fascia and passes laterally in front of tarsal plates of both eyelids to be inserted into lateral palpebral range.

It dilates the lacrimal sac , thus helping in the drainage of lacrimal fluid.

🔹️Corrugator supervision

It arises from medial end of superciliary arch, passes laterally and upwards to be inserted into the skin of eyebrow.

It drags the eyebrow medially and downwards producing vertical wrinkles on the the forehead.

🔹️Frontalis

It elevates the eyebrows and produces transverse wrinkles on the forehead.

🔹️Levator palpebra superioris

It elevates the upper eyelid.

MUSCLES AROUND NASAL CAVITY

🔹️Procerus

Arises from nasal bone, passes upwards to be inserted into the skin of lower part of the forehead.

It produces transverse wrinkles across the bridge of the nose.

🔹️Nasalis

Consists of 2 parts:

  1. Compressor naris: arises from maxilla close to nasal notch, passes upwards and medially to form aponeurosis across the bridge of the nose.

It compresses the nasal aperture.

2. Dilator naris: arises from maxilla for the margin of nasal notch and inserted into the lateral part Ala of nose.

Dilates the anterior nasal apertures.

🔹️DEPRESSOR SEPTI

It arises incisive fossa of the maxilla and is inserted into the lower mobile part of the nasal septum.

It fixes the nasal septum to allow dilation of anterior nasal aperture by dilator naris.

MUSCLES AROUND MOUTH

🔹️Orbicularis Oris

It has extrinsic and intrinsic portions. The major extrinsic portion is composed of interlacing fibres of the muscles which converge around the mouth for their insertion into the lips. The fibres of buccinator converge towards modulus and form chiasma.

The intrinsic portion consists of fibres running obliquely between the skin and mucous membranes of lips, incisive slips, which pass laterally into lips and interlace with fibres of peripheral part of orbicularis oris.

🔹️Nine muscles which converge around the mouth

  1. Levator labii superioris alaeque nasii: arises from frontal process of maxilla, inserted into Ala of nose. Elevates upper lip and dilates the nostrils.
  2. Levator labii superioris: arises from maxilla just above infraorbital frames and inserted into upper lip. Elevates upper lip.
  3. Levator anguli oris: arises from maxilla below infraorbital foramen, inserted into angle of mouth. Raises the angle of mouth.
  4. Zygomaticus minor: arises from zygomatic bone, inserted into upper lip. Elevates upper lip.
  5. Zygomaticus major: arises from zygomatic bone, inserted into angle of mouth. Draws angle of mouth upward and laterally.
  6. Depressor labii inferioris: arises from anterior oblique line of mandible, inserted into lower lip. Draws lower lip downward and laterally.
  7. Depressor anguli oris: arises from posterior part of oblique line of mandible, inserted into angle of mouth.
  8. Risorius: arises from parotid fascia, inserted into angle of mouth. Retracts angle of mouth gently.
  9. Buccinator: arises from outer surface of alveolar process of maxilla, pterygomandibular raphe, outer surface of alveolar process of mandible. It flattens the cheek and helps in blowing the cheek.

Muscle of chin: Mentalis

Arises from incisive fossa of mandible, inserted into lower lip.

It puckers the chin and protrudes the lower lip.

REFERENCE:

Vishram Singh: Textbook of Anatomy

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