Facial Muscles & Nerves Flashcards
Why are facial muscles different from other muscles?
They have at least one attachment point to skin, soft tissues or other muscles rather than to bone.
The muscle surrounding the eye. Helps with winking and closing the eyes.
Orbicularis orbis
Happy muscle. Very superficial - found over the top of the buccinator muscle and inferior to the Zygomatic major. Very small muscle.
risorius
Pushes cheek against the teeth. Used during chewing to push food against the teeth.
buccinator
Elevates the upper lip. Lateral to the Levator labii superioris alaeque nasi.
Levator labii superioris
role: help elevate ?????
zygomatic minor
Happy muscle superior to the risorius.
zygomatic major. Pulls up the corners of the mouth for smiling.
Elevates the upper lip. Runs down the side of the nose.
levator labii superioris alaeque nasi
Depresses the lower lip
depressor labii inferioris
Lowers the cnr of the mouth - “sad muscle”
depressor anguli oris
Elevates and wrinkles the chin. Can also help to pull the lower lip outwards.
mentalis
A big sheet-like muscle that extends over the mandible and across the neck. Very superficial, lying directly under the skin. Helps to lower the mandible.
platysma
The nervous system has 2 major components. What are they?
CNS Central Nervous System (brain & spinal cord)
PNS Peripheral Nervous System (cranial nerves, spinal nerves)
PNS
Peripheral Nervous System
PNS is composed of what?
- Cranial Nerves
- Spinal Nerves
Individual neurons can only carry out one function. True or false?
True
Motor nerve fibres ONLY travel to muscles and glands. True or False?
True
What do autonomic nerves innervate?
- Cardiac Muscle
- Smooth muscle
- Glands
Nerves have 2 major roles. What are they?
- Motor signals to muscles and glands (motor nerve fibres)
- Carry information about the body’s environment from the tissues to the brain, ie temperature, pressure, pain.
Motor nerve fibres that ennervate only skeletal muscles. We have voluntary control over movements through these.
*Voluntary motor nerve fibres.
General Sensory Nerve fibres
Basic sensory information, ie temperature, pressure and pain, body position so that we can make adjustments to maintain homeostasis.
Special Sensory Nerve fibres
5 special senses: Vision, hearing, balance, taste and smell. Whole organs designed just for these senses.
Even though each neuron can only carry one type of information, one peripheral nerve is made up of hundreds on neurons all bundled together. What does this imply?
Each nerve can carry different types of information because it can be made up of a combination of motor, special sensory and general sensory.
How many pairs of cranial nerves are there?
12
How many individual cranial nerves are there?
24 - 12 pairs
How are cranial nerves numbered?
I - XII Anterior to Posterior, plus a name for each nerve.
Where are cranial nerves attached?
To the base of the brain.
How do the cranial nerves emerge through the skull?
via Foramina
2 important nerves innervate structures of the face. Which ones?
- CN V (Trigeminal Nerve)
- CN VII (Facial Nerve)
The Trigeminal Nerve carries which types of Neurons?
- General Sensory (whole FACE)
- Motor (TMJ muscles only)
Which nerve provides motor innervation for all of the muscles of facial expression?
CN VII (Facial Nerve)
All sensory information from the muscles and tissues of the face come in through which nerve?
CNV Trigeminal Nerve
Which nerve carries information from the happy muscles to let us know that we are smiling?
CNV Trigeminal Nerve
The Trigeminal ganglion gives rise to 3 branches, called…?
- Opthalmic Branch (V1)
- Maxillary Branch (V2)
- Mandibular Branch (V3)
This nerve carries sensory information from the forehead and nose.
CNV1 Opthalmic Nerve
This nerve carries sensory information from the cheekbones, temples, upper lip and sides of the nose.
CNV2 Maxillary Nerve
This nerve carries sensory information from the lower jaw, bottom lip and lateral cheeks and lateral temples.
CNV3 Mandibular Nerve
What would be the effect of damage to the Maxillary nerve (CNV2)
Loss of sensation to the upper lip, sides of the nose, upper cheeks and temples.
Where does CNVII emerge from the skull?
Stylomastoid Foramen
Which nerve emerges near the base of the ear and fans into 5 branches?
CNVII (motor)
The Facial Nerve
Which nerve emerges near the base of the ear and fans into 5 branches?
CNVII
The Facial Nerve
Name the 5 branches of the Facial Nerve.
1* The Temporal Branch 2* The Zygomatic Branches 3* The Buccal Branch 4* The Marginal Mandibular Branch 5* The Cervical Branch
The Temporal Branch of the Facial Nerve provides motor innervation to what structures?
The forehead, the temple region and part of the muscles surrounding the eye.
The Zygomatic Branch of the Facial Nerve provides motor innervation to what?
Supplies the muscles located in the cheekbone area including most of the elevators of the upper lip, including the zygomatic muscles and the two levator labii superioris muscles
What does the buccal branch of the facial nerve provide to to buccal muscle?
Motor innervation.
Which nerve runs along the lower jawline, innervating (motor) the lower lip muscles?
The Marginal Mandibular branch of the Facial Nerve
Which nerves runs under the mandible, deep to the platysma and provides movement to the platysma?
The Cervical Branch of the Facial Nerve
What happens if a motor nerve to the face is damaged?
- Muscle paralysis
2. Drooping of facial features in the area innervated by the damaged nerve.
Result of damage to the Marginal Mandibular branch?
Would not be able to depress the lower lip and corners of the mouth. Sagging of the corners of the mouth.
What is Facial Nerve Cross-Over?
Before the nerve emerges from the skull and branches, nerve fibre cross-over of some neurons occurs within the brain.
How many nerve fibres from each facial nerve stay on the same side of the body that they originate from?
1/2 nerve fibres stay on the side of nerve origin in the brain, and innervate motor function in the upper facial region: ie fibres from LHS of brain - 1/2 innervate motor function of upper LHS face.
How many nerve fibres from the facial nerve cross over? Where do they go?
1/2 of the Nerve fibres from the FACIAL NERVE cross over and contribute motor nerve fibres to BOTH upper and lower face. ie 1/2 of the fibres from the LHS of brain innervate motor for upper and lower RHS of face.
When the LHS facial nerve emerges 1/2 of the fibres come from the LHS of brain, and 1/2 from RHS of brain. Where do the LHS orignating fibres go?
Motor Innervation for upper LHS of face.
When the LHS facial nerve emerges 1/2 of the fibres come from the LHS of brain, and 1/2 from RHS of brain. Where do the RHS orignating fibres go?
They innervate motor function for muscles in the upper and lower LHS of the face.
Structures coming from the opposite side of the body:
Contralateral
Why do the upper facial muscles receive a bilateral facial nerve supply?
Because most come from the same side of the brain, but some are cross-overs from the opposite side of the brain.
Why do lower facial muscles receive a contralateral facial nerve supply?
Because Facial nerve fibres from the same side of the brain only travel to the upper face on that side. Therefore the lower face recieves innervation only from fibres that have crossed over from the other side of the brain before emerging and splitting into the 5 branches.
The upper part of the face has Facial Nerve fibres from both sides of the brain. True or false?
True.
The lower parts of the face have Facial Nerve fibres only from the opposite side of the brain, and none from the same side. True or false?
True
A trauma damages the Facial Nerve on the LHS at the point it begins in the brain, before cross-over. What are the results?
Paralysis to only the lower RHS quarter of the face. (The other 3 quarters also have innervation from the nerve originating on the RHS)
What effect if the Facial Nerve is damaged after it emerges from the stylomastoid foramen on the RHS, before it splits?
Paralysis to the entire RHS of the face, as in Facial Nerve Palsy.
What happens if the Zygomatic Branch of the facial nerve on the LHS is damaged?
Paralysis only to the muscles innervated by the Zygomatic branch on the LHS of the face.
What is the main artery that supplies the tissues of the face?
The Facial Artery.
Which artery does the Facial Artery branch from?
The External Carotid Artery
What creates a pulse point about a fingers breadth anterior to the angle of the mandible?
The Facial Artery.
Where does the facial artery terminate?
The medial corner of the eye.
Which blood vessel travels deep to the zygomatic major and levator labii superioris muscles?
The Facial Artery