muscles of the head neck and face Flashcards
sella turcica – location
- inside skull
- intersection of the greater + lesser wings of sphenoid
- saddle-shaped depression in the sphenoid bone
- “turk’s saddle”
sella turcica – function
- protects pituitary gland
- location for optic chiasm (where nerves from L + R eyes cross)
cribiform plate – location
- part of ethmoid bone
- located inside skull, directly above nasal passage
cribiform plate – function
- grooves on either side of the cribiform plate support the olfactory bulb and are perforated by foramina for the passage of the olfactory nerves
crista galli – location
- ridge of bone that projects upward from the middle line of the cribiform plate
- “rooster’s comb”
crista galli – function
- where olfactory cranial nerves extend to nose
cranial nerves vs spinal nerves
- cranial nerves come directly from brain
- spinal lnerves emerge from spinal cord
trachea – aka
“windpipe”
trachea – location
- center of anterior neck
- ribbed, cartilaginous tube roughly 1” diameter
- deep to thyroid gland
trachea – includes
superior to inferior:
- hyoid bone
- thyroid cartilage
- cricoid cartilage
- thyroid gland + isthmus
- tracheal rings
hyoid bone
- horseshoe-shaped bone that does not articulate with any other bone (“hyoid” = U-shaped)
- located parallel to base of mandible (jawline) and C-3 or C-4, superior to thyroid cartilage
- accessible + elevates upon swallowing
- attachment site for suprahyoid + infrahyoid myo
thyroid cartilage
- aka “Adam’s apple”
- located below chin, inferior to hyoid but superior to cricoid cartilage
cricoid cartilage
- the only complete ring of cartilage around the trachea (“cricoid” = ring shaped)
- is slightly larger than other trachael rings
- located just inferior to thyroid cartilage (Adam’s apple)
- attachment site for myo, cartilage + ligaments involved in opening/closing of airway + in speech production
thyroid gland
- two glands (L + R) that are connected by isthmus
- controls how quickly the body uses energy + makes proteins
- controls how sensitive the body is to other hormones
isthmus
- bridge connecting 2 lobes of the thyroid
- located inferior to cricoid cartilage
tracheal rings
- pliable but tough to maintain and open airway
- wraps 3/4 way around trachea (membrane closes at back)
sternocleidomastoid (SCM) – location
- located on lateral, anterior neck
- large belly w/ 2 heads (flate clavicular head + slender sternal head)
sternocleidomastoid (SCM) – origin
- top of manubrium (sternal head)
- medial 1/3 of clavical (clavicular head)
sternocleidomastoid (SCM) – insertion
mastoid proess of temporal bone
sternocleidomastoid (SCM) – action
- laterally flex head + neck to same side (unilaterally)
- rotate head + neck to opposite side (unilaterally)
- flex neck (bilaterally)
(shaking head no + nodding yes; cocking ear to listen)
sternocleidomastoid (SCM) – nerve
spinal accessory nerve (also nerve for trapezius) (aka cranial nerve XI)
(SCM + upper fibers of traps begin as one myo in embryo and split during development)
scalenes – location
- sandwiched b/w SCM + anterior flap of trapezius on the lateral, anterior neck
scalenes – names
- anterior scalene - lies partially tucked beneath SCM
- middle scalene - slightly larger, lies lateral to anterior scalene
- posterior scalene - deeper, smaller, b/w middle scalene + levator scapula
scalenes – origin
- anterior: TVP’s of C-3 to C-6
- middle: TVP’s of C-2 to C-7 (longer)
- posterior: TVP’s of C-6 and C-7 (shortest)
scalenes – insertion
- anterior + middle: 1st rib
- posterior: 2nd rib
scalenes – action
- laterally flex head + neck to same side (unilaterally)
- rotate head + neck to opposite side (unilaterally)
- flex head + neck (bilaterally – anterior scalenes only)
brachial plexus + relation to scalenes
- large branches of brachial plexus (group of nerves) pass thru small gap b/w anterior + middle scalenes, and run down arm (one of the branches, musculocutaneous nerve, goes thru coracobrachialis myo)
- compression or impingement of brachial plexus or one of its nerves can send a sharp, shooting sensation or numbness down arm
subclavian artery + relation to scalenes
- subclavian artery passes thru small gap b/w anterior + middle scalenes, and sends blood to arms
- passes b/w rib 1 + clavicle, so thoracic outlet syndrome could be harmful
masseter – location
- located on side of mandible
- consists of 2 overlapping bellies
masseter – function
- strongest myo in body relative to size
- primary chewing myo
- also used in speaking + swallowing
masseter – origin
zygomatic arch
masseter – insertion
angle + ramus of mandible
masseter – action
elevate mandible (at TMJ)
masseter – nerve
trigeminal nerve - mandibular branch (aka cranial nerve 5)
trigeminal nerve – 3 branches
- opthalmic branch
- maxillary branch
- mandibular branch
temporalis – location
- covers almost all of temporal bone (can palpate at temple area when teeth are clenched)
- fibers reach under zygomatic arch to connect at coronoid process
temporalis – origin
temporal fossa (almost all of temporal bone; some of parietal and frontal bone)
temporalis – insertion
- coronoid process of mandible
- anterior edge of ramus of mandible
temporalis – action
elevate mandible (at TMJ)
temporalis – nerve
trigeminal nerve - mandibular branch (aka cranial nerve 5)
suprahyoids – location
- located on underside of jaw, superior to hyoid bone
- stretch from edge of mandible to hyoid
- used for chewing, swallowing, speaking
suprahyoids – names
- geniohyoid (“genion” = chin)
- mylohyod (largest)
- stylohyoid (almost parallel to posterior belly of digastric)
suprahyoids – origin
- geniohyoid + mylohyoid: underside of mandible (though geniohyoid is smaller + just alongside midline of chin)
- stylohyoid: styloid process of temporal bone
suprahyoids – insertion
hyoid bone
suprahyoids – action
- elevate hyoid + tongue
- depress mandible (at TMJ)
digastric – location + uniqueness
- long myo composed of an anterior + posterior belly (“di” = two)
- anterior + poster bellies are separated by tendinous ring that’s attached to hyoid bone
- posterior belly penetrates thru stylohyoid
digastric – origin
mastoid process of temporal bone
digastric – insertion
inferior border of mandible (via tendinous ring)
digastric – action
- depress mandible
- elevate hyoid
infrahyoids – location
- located on anterior neck, superficial to trachea
- all 4 myo function as antagonists to suprahyoids
infrahyoids – names
- sternohyoid
- sternothyroid
- thyrohyoid
- omohyoid (“omos” = shoulder)
infrahyoids – origin
- sternohyoid + sternothyroid: top of manubrium
- thyrohyoid: thyroid cartilage
- omohyoid: scapula (“omos” = shoulder)
infrahyoids – insertion
- sternohyoid, thyrohyoid, omohyoid: hyoid bone
- sternothyroid: thyroid cartilage
infrahyoids – action
depress hyoid + thyroid cartilage
platysma – location
- thin, superficial sheath spanning anterior neck from mandible to chest
- integumentary myo that are embedded in superficial fascia + attach to skin + overlying myo (instead of connecting to bones)
- (in other mammals, a similar sheet of myo lies on the back)
platysma – origin
fascia covering superior part of pectoralis major
platysma – insertion
base of mandible
platysma – action
- tighten fascia of neck
- draw down corner of mouth (as in a frown or pout)
- creates infamous “Creature from the Black Lagoon” expression
platysma – nerve
cranial nerve VII (dysfunction leads to Bell’s Palsy)
occipitofrontalis – location
4 bellies (2 left and 2 right) that are attached by same tendon (galea aponeurosis, a broad sheath of connective tissue stretching across top of cranium)
occipitofrontalis – names
- frontalis
- occipitalis
occipitofrontalis – origin
galea aponeurosis (for both myos)
occipitofrontalis – insertion
- frontalis: skin superior to eyebrows
- occipitalis: superior nuchal line of occiput
occipitofrontalis – action
- raise eyebrows + wrinkle forehead (frontalis)
- anchor + retract galea posteriorly (occipitalis)
occipitofrontalis – nerve
cranial nerve VII (dysfunction leads to Bell’s Palsy)
medial and lateral pterygoids – location
- medial pterygoid located on interior side of mandible (shape + position mirror masseter myo)
- both myos can be accessed through the mouth
- both myos assist masseter + temporalis w/ movement of mandible
lateral pterygoids – significance
important bc attaches to TMJ (can massage this myo to relieve TMJ syndrome)
medial pterygoid – origin
- lateral pterygoid plate of sphenoid
- tuberosity of maxilla
medial pterygoid – insertion
medial surface of ramus of mandible
medial pterygoid – action
- laterally deviate mandible to opposite side (unilaterally)
- elevate + protract mandible (bilaterally)
medial pterygoid – nerve
trigeminal nerve (aka cranial nerve V)
lateral pterygoid – origin
- crest of greater wing of sphenoid bone (superior head)
- lateral pterygoid plate of sphenoid bone (inferior head)
lateral pterygoid – insertion
- articular disc + capsule of TMJ
- neck of mandible
lateral pterygoid – action
- laterally deviate mandible to opposite side (unilaterally)
- protract mandible (bilaterally)
lateral pterygoid – nerve
trigeminal nerve (aka cranial nerve V)
myo that elevate the mandible
- masseter
- temporalis
- medial pterygoid
myo that depress the mandible
- geniohyoid
- mylohyoid
- stylohyoid
- digastric (w/ hyoid fixed)
- platysma (assists)
myo that protract the mandible
- lateral pterygoid
- medial pterygoid
- masseter (assists)
myo that retract the mandible
- temporalis
- digastric
buccinator – location
bilateral myo located at center of cheek, on either side of corners of mouth
buccinator – action
- blowing, sucking
- visually can produce small dimple at cheek center
- puffing up cheeks will stretch buccinators
orbicularis oris – location
single, strong, sphincter myo that encircles mouth
orbicularis oris – action
- essential for speech + eating (closes mouth + shaping lips)
- indispensible to woodwind players
- can either narrow or protrude lips
common carotid artery – location
- ascends anterior, lateral neck
- lies deep to SCM + infrahyoid myo
common carotid artery – function
- primary supplier of blood to head + neck
- strong pulse can be felt medial to SCM at level of hyoid
facial nerve – location
- aka cranial nerve VII
- from tragus (ear), branches off + spreads across the face, scalp, neck
- often 2 or more branches of facial nerve cross superficially over zygomatic arch
facial nerve – function + dysfunction
- important to know its location due to proximity to other palpable structures on side of face
- lesion/injury of facial nerve can lead to Bell’s Palsy
vertebral artery – location
- branches off subclavian artery
- ascends neck thru transverse foramen of C-6 to C-1
- passes thru foramen magnum of occiput
vertebral artery – function
supplies blood to brain + spinal cord
parotid gland – location
- bilaterally located in front of earlobe, superficial to masseter myo
- has a soft, lumpy surface
- penetrated by facial nerve branches
parotid gland – function + dysfunction
- largest salivary gland
- parotitis (i.e. mumps) is when this gland is inflamed (and causes gerbil cheeks)
brachial plexus – location
- exits from TVP’s of C-5 to T-1
- squeezes between anterior + middle scalenes
- continues inferiorly + laterally underneath clavicle to axillary
brachial plexus – function
- large bundle of nerves that innervates shoulder + upper extremity
- compressing or impinging one of nerves in bundle can create a sharp, shooting sensation down arm
orbicularis oculi – location
- sphincter myo encircling eye
- thick outer fibers form “orbital “part of myo
- inner fibers form “palpebral” part of myo
brachial plexus – nerve roots
consists only of nerve roots C-5, C-5, C-7, C-8, and T-1
orbicularis oculi – function
- close eyelid
- squinting
- blinking
- “smiling” with eyes
- create crow’s fewer over time after chronic contraction
