What is Bell's palsy ?

Bell’s palsy: 

• This is the lower motor neuron lesion of the facial nerve and resultant paralysis of the muscles that it supplies. 

• The course of the facial nerve: It starts from the seventh cranial nerve nucleus. 
• It is situated in the ventral part of the tegmentum of the pons, rounds VI nucleus along its course expands to form geniculate ganglion, it gives a branch to stapedius muscle, a branch supplying anterior 2/3rd of the tongue. 
• Emerging from stylomastoid foramen it enters the parotid gland and divides into:

– Temporal

– Zygomatic

– Mandibular

– Buccal

– Cervical branches.

 

MUSCLES THAT GET AFFECTED BY BELL'S PALSY:

• Occipitofrontalis-

ORIGIN-

• Occipital belly: from the superior nuchal line
• Frontalis-from the aponeurosis of epicranius.

INSERTION-

• Occipital belly inserts in the aponeurosis of epicranius.
• Frontalis inserts into the skin of the eyebrow

ACTION-wrinkling forehead (surprised face)

• Orbicularis oculi-

ORIGIN- from the front surface of the eye socket rim, which is also called the orbital margin.

INSERTION- inserts on to the lateral palpebral raphe

ACTION-closure of the eyelid (winking and forced squeezing)

• Corrugator-

ORIGIN-Corrugator: from the frontonasal suture and frontal bone and medial part of the superciliary arc

INSERTION-Corrugator: inserts on the medial half of skin of the eyebrow

ACTION-frowning forehead

• Procerus:

ORIGIN- nasal bone and lateral nasal cartilage

INSERTION- inserts on the skin at the roof of the nose

ACTION-Compress the nostrils and depress the cartilage of the nose

• Zygomaticus major and minor -

ORIGIN-

• Major: anterior surface of the zygomatic bone
• Minor: lateral aspect of the zygomatic bone

INSERTION-

• Major: modiolus, blends with the muscle of upper lip
• Minor: blends with the muscles of the upper lip (medial to zygomaticus major muscle)

ACTION-smiling

• Levator anguli oris-

ORIGIN-canine fossa of maxilla

INSERTION-modiolus

ACTION-elevates of the angle of mouth

 

• Levator labii superioris

ORIGIN-originates from medial infraorbital margin

INSERTION- blends with the skin and muscles of the upper lip

ACTION- elevation of the upper lip (showing upper teeth)

• Buccinator

ORIGIN- fibres arises from the alveolar process of maxilla and mandible, also from pterygomandibular raphe    

INSERTION- inserts in the angle of mouth radiating into the fibers of orbicularis oris

ACTION-blowing

• Orbicularis oris

ORIGIN- medial aspect of maxilla and mandible, modiolus at the angle of mouth

INSERTION-skin and mucous membrane of lips

ACTION-closing mouth, puckering the lips (making “O” with lips), kissing

• Risorius

ORIGIN- deep facia of the face and parotid

INSERTION-modiolus and skin at the angle of mouth

ACTION-draw back the mouth, assist other muscles in smiling or frowning

• Mentalis

ORIGIN-incisive fossa of mandible

INSERTION-lower part of the chin (mantolabial sulcus)

ACTION- protrusion of lower lips and elevation of the chin, help to pout

• Depressor anguli oris, depressor labii inferioris

ORIGIN- oblique line of mandible

INSERTION- insets to the skin and mucosa of lower lips

ACTION- frowning of mouth

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