test 2 Flashcards
Classification of muscle tissue
Skeletal - voluntary
Smooth - involuntary
Cardiac - Involuntary
what is the difference between voluntary and involuntary muscles
voluntary - we control it
involuntary - not consciously controlled, body controls it
Why do we study the muscles 3
Extra oral patient exams
Distinguish normal/abnormal
Understand source of muscle pain/loss of function
define origin and insertion
origin: Part of the muscle that does not move
insertion: attached to the more moveable structure
define belly
thicker, middle region of muscle between origin and insertion; located between 2 ends
define innervation
the supply of nerves to a specific body part; one to one relationship
what are the muscle groups
-Cervical muscles
-Muscles of facial expression
-Muscles of mastication
-Hyoid muscles (Suprahyoids and infrahyoids)
-Muscles of the tongue (Extrinsic and intrinsic muscles)
what are the clinical considerations for occlusal trauma 2
abfraction: loss of tooth structure at the cervical area (where tooth and gum meet)
attrition: gradual wear and loss of tooth structure due to the mechanical forces of chewing and grinding (tooth to tooth contact)
what are the cervical muscles
sternocleidomastoid and trapezius
sternocleidomastoid
origin
insertion
bellies
action
origin- clavicle and sternum
insertion- mastoid process of temporal and occipital bone
bellies- none
action- bends head to the side that contracts, flexes neck when both contract
trapezius
origin
insertion
bellies
action
origin - external surface of occipital bone; midline of cervical and thoracic regions
insertion - clavicle and scapula
bellies - none
action - lift clavicle and scapula when shoulders are shrugged
clinical considerations of cervical muscles 5
- muscle malfunction may cause head to move to one side or the other
- may not be able to raise chin during treatment
- may not be able to sit in ergonomically correct position
- usually from acute trauma such as vehicle/sport accidents or chronic stress via movement
- possibly related with headaches in lower skull region
describe muscles of facial expression
- paired
- all origins originate from surface of the skull bone (rarely the fascia)
- all insert on dermis of the skin
clinical considerations for muscles of facial expression
- Facial paralysis: damage to CNVII; inhibits muscle movement on the side of nerve damage; loss of voluntary muscle action; temporary or permanent; can occur with stroke, bell palsy, or parotid salivary gland cancer; twitching/spasms/weakness may resolve over time
- facial nerve within the parotid salivary gland can become anesthetized with an incorrectly administered inferior alveolar mandibular block leading to transient facial paralysis
epicranial muscle
origin
insertion
bellies
action
expression
origin - frontal belly originates at epicranial aponeurosis; occipital belly originates at occipital and temporal bones
insertion - frontal belly inserts at the eyebrow and root of the nose; occipital belly inserts at the epicranial aponeurosis
bellies - 2: frontal and occipital bellies separated by the epicranial aponeurosis
action - raise the eyebrows and scalp; the two bellies can act independently from eachother
expression - surprise
orbicularis oculi muscle
origin
insertion
bellies
action
expression
origin - orbital rim, frontal bone, and maxilla
insertion - lateral canthus
bellies - none
action - closes the eyelid, squints (crows feet)
expression - closing eye/ squint
orbicularis oris
origin
insertion
bellies
action/expression
origin - facial modiolus
insertion - labial commissure > diffusely in lip/nose; upper lip
bellies - none
action/expression - closing/pursing lips; pouting; grimacing; speech; press; tighten/thin; roll inward; thrust outward
buccinator
origin
insertion
bellies
action
origin - maxilla, mandible, pterygomandibular raphe
insertion - labial commissure (facial modiolus)
bellies - none
action/expression - compresses cheeks during chewing; pulls labial commissure laterally; shortens cheek vertically and horizontally; assists muscles of mastication
*pierced by parotid duct
risorius
origin
insertion
bellies
action
origin - fascia superficial to masseter muscle
insertion - labial commissure at facial modiolus
bellies - none
action/expression - stretches lips; widens mouth; stretches labial commissure laterally; grimace
*often underdeveloped, connected with platysma that stretches with it
levator labii superioris
origin
insertion
bellies
action
origin - maxilla
insertion - labial commissure of upper lip
bellies - none
action/expression - raises upper lip
levator labii superioris alaeque nasi
origin - maxilla
insertion - ala of nose; upper lip
bellies - none
action - raising upper lip and dilating/raises ala/nares with sneer/snarl
*Elvis muscle
zygomaticus major
origin - zygomatic bone
insertion - labial commissure
bellies - none
action/expression - smiling; elevates labial commissure laterally
*lateral to zygomaticus minor; genuine happiness is expressed when this muscles contracts WITH the orbicularis oculi
zygomaticus minor
origin - zygomatic bone
insertion - upper lip
bellies - none
action/expression - raising upper lip to assist in smile
*adjacent to insertion of levator labii superioris
levator anguli oris
origin - maxilla (canine fossa)
insertion - labial commissure
bellies
action/expression - assist in smiling, raises labial commissure
- deep to zygomaticus major and minor; connects with zygomaticus major, depressor anguli oris and orbicularis oris
depressor anguli oris
origin- inferior border of mandible
insertion - labial commissure
bellies - none
action/expression - frowning, lowers labial commissure
depressor labii inferioris
origin - inferior border of mandible
insertion - lower lip
bellies - none
action/expression - depresses lower lip; exposes canines
*deep to depressor anguli oris
mentalis
origin - mandible
insertion - chin
bellies
action/expression - raises chin, protrudes lower lip, “peach pit dimple”
*could dislodge a complete lower denture in an edentulous patient who lost alveolar process height
platysma
origin - clavicle; shoulder
insertion - mandible; muscles of mouth; facial modiolus
bellies
action/expression - raises neck skin; assist in grimace by pulling labial commissures down; horror/disgust
- creates platysma bands with age (turkey neck)
corrugator supercilii muscle
origin
insertion
bellies
action
expression
origin - supraorbital region of frontal bone
insertion - skin above the eyebrow
bellies - none
action - draws eyebrow inferiorly and medially
expression - anger/frowning
- chemodenervation to alleviate glabellar/frown lines (botox)
describe the muscles of mastication 6
- four paired muscles
- deep to muscles of facial expression
- all connect to the mandible at some point
- masseter, temporalis, medial and lateral pterygoid muscles
- may be involved w pathology associated with TMJ
- embryonic derivatives of first branchial/mandibular arch
masseter
origin
insertion
bellies
action
clinical consideration
origin - zygomatic arch
insertion - angle and ramus of mandible
bellies/heads - 2 heads, superficial and deep head
action - during bilateral contraction it elevates the mandible
masseteric hypertrophy
*most powerful and superficial muscle of mastication
what is masseteric hypertrophy 6
- enlargement of masseter muscle
- caused by clenching/grinding/bruxism/gum chewing
- asymptomatic, slightly firm when palpated
- usually bilateral, can be unilateral
- may be confused with dental infections and other diseases; however no symptoms of tenderness or pain are present
- may be associated with TMJ pathology
temporalis
origin
insertion
bellies
action
origin - temporal fossa
insertion - coronoid process of the mandible ramus
bellies - none
action - maintains mandible in rest position, allows freeway space, bilateral contraction of entire muscle raises mandible; bilateral contraction of posterior portion retracts/retrudes mandible
medial pterygoid
origin
insertion
bellies
action
origin - Deep head: medial side of lateral pterygoid plate and pterygoid fossa of sphenoid Superficial head: maxillary tuberosity and palatine bone
insertion - both onto medial surface of mandibular angle/ramus
bellies - 2 heads
action - bilateral contraction elevates mandible
*works with masseter
lateral pterygoid
origin
insertion
bellies
action
origin - superior head: infratemporal crest of greater wing of sphenoid bone. inferior head: lateral side of lateral pterygoid plate
insertion - anterior surface of neck of mandibular condyle
bellies - none
action - unilateral contraction shifts mandible to opposite side (lateral deviation); bilateral contraction protrudes* mandible forward and depresses* when opening
*fills in temporal fossa
what are the suprahyoid muscles
digastric
mylohyoid
stylohyoid
geniohyoid
what are the infrahyoid muscles
omohyoid
sternohyoid
sternothyroid
thyrohyoid
what is the action of the suprahyoids
- elevate the hyoid and larynx
- occurs during swallowing
- contraction of anterior suprahyoids depresses the mandible
what muscles are apart of the anterior group for suprahyoids
digastric (anterior belly)
mylohyoid
geniohyoid