Chapter 7- Muscular System Flashcards
origin & insertion
- skeletal muscles shorten and pull on bones they are attached to
- origin: done that doesn’t move when muscle contracts
- insertion: bone that moves when muscle contracts
fascicle arrangements (7)
- skeletal muscle fibres are arranged within a muscle in bundles called fascicles
- parallel
- fusiform
- circular
- triangular
- unipennate
- bipennate
- multipennate
muscle group actions
most muscles are arranged in opposing pairs at joints
- prime mover or agonist contracts to cause desired action
- anatgonist stretches and yields to prime mover
- synergists assist prime movers
- fixators stabilize the origin of prime mover
how muscles are named (7)
- direction of muscle fibers
- size
- shape
- action
- number of origins
- origins/insertion points
- location
axial muscles
- head and neck: facial expression, mastication, eyeball, neck
- muscles of trunk: breathing, spinal flexors, extensors and rotators
facial muscles
originate on skull and insert into overlying skin
occipitofrontalis (epicranius)
- frontal and occipital bellies joined by galea aponeurotica, a thin tough band of connective tissue
- raises eyebrows and wrinkles forehead
corrugated supercilii
- connects frontal bone to skin of eyebrows
- draws eyebrow inferiorly and medially
orbicularis oculii
- orbits eye
- orbital portion + palpebral portion
- serves to close the eye
levator palpebrae superioris
- originates on lesser wing of sphenoid, and inserts into upper eyelid
- responsible for elevating upper eyelid
nasalis
flares nostrils
lavator labii superioris
elevates upper lip
orbicularis oris
- orbits mouth
- closes lips, kissing/pucker of lips, used for speech
zygomaticus
- major and minor
- attaches to zygomatic bone
- draws angle to mouth up and laterally to smile or laugh
platysma
- origin: clavicular region
- insertion: mandible and cheek area
- draws outer part of lower lip down and back, depressing mandible
- gives tense neck appearance
masseter
mastication
- origin: zygomatic bone
- insertion: mandible
- elevates and retracts mandible
- powerful chewing muscle
temporalis
mastication
- origin: parietal bone
- insertion: mandible
- elevates and retreats mandible
- powerful chewing muscle
pterygoids
mastication
- lateral and medial
- allows mandible to be protracted, lowerd and move from side to side when chewing and talking
buccinator
- major lateral cheek muscle
- compresses cheek when blowing air
- sucking in and blowing out
extrinsic eye muscles
- superior rectus
- inferior rectus
- lateral rectus: abduction
- medial rectus: adduction
- superior oblique (@weird angle) goes through trochlea
- inferior oblique
sternocleidomastoid
- origin: sternum and clavicle
- insertion: temporal bone (mastoid process)
- bilateral contraction results in neck flexion
- unilateral contraction results in lateral flexion of the neck and rotates face in opposite direction
- prime mover of neck flexion
inhalation
1) rib cage expands
2) expansion of ribs moves sternum up and out
3) inhalation: diaphragm & external intercostals contracts (moves down)
exhalation
1) rib cage gets smaller and rib muscles relax
2) ribs and sternum depress
3) exhalation: diaphragm & internal intercostals relaxes (moves up)
external intercostals
-origin: inferior surface of superior ribs
-insertion: superior surface of inferior rib
pulls each rib up to increase ribcage volume
-each rib pulls the one beneath it
internal intercostals
- origin: superior surface of inferior rib
- insertion: inferior surface of superior rib
- pulls each rib down to decrease rib cage volume
- pulls rib above them down
serratus posterior superior
- elevates posterior ribs during inspiration
- works at same time of external intercostal
- origin: C7-T3 vertebrae
- insertion: ribs 2-5
serratus posterior inferior
- depresses posterior ribs during expiration
- works at same time as internal intercostal
- origin: T11-L2 vertebrae
- insertion: ribs 8-12
rectus abdominus
- 8 paired bodies
- fibres run vertically
- flexes the spine
- superficial
transverse abdominus
- fibres run deep horizontally
- increases abdominal pressure for coughing and puking
external obliques
- superficial
- rotate and flex spine
- 45 degree angle
internal obliques
- deeper
- rotate and flex spine
- 45 degree angle
erector spinae
- fibres run vertically
- 3 groupings:
1) illiocostalis
2) longissimus
3) spinalis - extends vertebral column
serratus anterior
- origin: ribs
- insertion: scapula
- pull scapula anteriorly and around rib cage
trapezius
-origin: occipital bone and cervical vertebrae
-insertion: clavicle and scapula
-fibres run in 3 directions:
1) superiorly: pull scapula up
2) middle: pull should blades back
3) inferior: pull scapula down
extend neck, elevate shoulder, adduct scapula, depress scapula
-thin, flat, superficial
pectoralis major
- origin: clavicle, sternum, ribs 1-6
- insertion: humerus
- flexes and adducts humerus
latissimus dorsi
- origin: T7-L5, ribs 9-12, ilium
- insertion: humerus
- powerful arm extender, adductor, medial rotator
- antagonist with pectorals major
deltoid
- covers lateral shoulder joint
- broad base and tapers to point
- fibres run in 3 directions: abduction(up &down, main job) flexion, extension
- origin: clavicle and scapula
- insertion: humerus
- flexes, abducts and extends arm
rotator cuff
4 muscles around glenohumeral joint:
- supraspinatus
- infraspinatus
- teres minor
- subscapularis
- origin: scapula
- insertion: humerus
- form a cuff around shoulder joint
- more stable on superior aspect
forearm flexors
cover most of humerus and cross anterior surface of elbow joint
bicep brachii
- superficial, 2 heads
- origin: scapula &humerus
- insertion: radius
- flexes forearm, helps with supination
brachialis
- deeper, smaller, more powerful
- origin: humerus
- insertion: ulna
- forearm flexor
forearm extensors
covers most of the humerus and crosses posterior surface of elbow joint
triceps brachii
- prime move of elbow extension
- 3 heads (medial, lateral, long)
- origin: scapula and humerus
- insertion: ulna
anconeus
- small
- synergist extensor
- origin: humerus
- insertion: ulna
brachioradialis
- synergist elbow flexor
- synergist pronator/supinator
- origin: humerus
- insertion: radius
pronator teres
- pronation
- origin: humerus and ulna
- insertion: radius
pronator quadrants
- pronation
- origin: ulna
- insertion: radius
supinator
- supination
- origin: humerus and ulna
- insertion:radius
muscles of hand
- flexors on anterior side
- extensors on posterior side
- muscles are named for their action and digit
palmar interossei
-adduct the fingers (together)
dorsal interossei
-abduct the fingers (apart)
gluteus maximus
- largest
- superficial
- thigh extension, abduction, and rotation
- origin: ilium
- insertion: femur
gluteus medius
- moderate size
- deeper
- thigh extension, abduction, and rotation
- origin: ilium
- insertion: femur
gluteus minimus
- smallest
- deepest
- thigh extension, abduction, and rotation
- origin: ilium
- insertion: femur
iliopsoas
- iliacus+ psoas major
- 2 muscles fused together
- powerful thigh flexor
iliacus
- part of iliopsoas
- thigh flexor
- origin: ilium
- insertion: femurs
psoas major
- part of iliopsoas
- thigh flexor
- origin: lumbar vertebrae
- insertion: femur
adductor muscles of medial thigh
- adductor longus
- adductor brevis
- gracialis
- all on medial aspect of thigh
- origin: pubis
- insertion: femur
quadriceps femoris
4 muscles:
- rectus femoris
- vastus lateralis
- vastus medialis
- vasts intermedius (underneact rectus femoris)
- merge into quadricep femoris tendon where patella forms’
- extends the leg (knee)
- origin: femur
- insertion: quadriceps tendon
sartorius
- flexes, abducts, laterally rotates thigh, flexes leg and medially rotates thigh
- “tailors muscle”
- longest muscle in body
- origin: ilium
- insertion: winds around medial aspect of knee and inserts on tibia
hamstring muscles
- semimembranosus
- semitendinosus
- biceps femoris (2 heads)
- extend hip and flex knee
- origin: ischial tuberosity
- insertion: tibia
tibialis anterior
- doriflexion
- origin: tibia
- insertion: tarsals
shinsplint syndrome
- overworking of tibias anterior
- running on hard surfaces
- tearing of tendonosus insertions into tibia
fibularis brevis
- eversion of foot
- origin: fibula
- insertion: 5th metatarsal
fibularis longus
- eversion of foot
- origin: fibula
- insertion: 1st metatarsal and tarsal
triceps surae
gastrocnemius + soles muscles of posterior leg
gastrocnemius
- medial and lateral heads
- plantar flexion (prime mover)
- thick and superficial
- origin: femur
- insertion: calcaneus via calcaneal tendon
soleus
- deep to gastrocnemius
- synergist to gastrocnemius
- plantar flexion
- origin: tibia and fibula
- insertion: calcaneus via calcaneal tendon
popliteus
- unlocks knee from full extension to being flexion
- flexes and medially rotates leg
- origin: femur and knee joint
- insertion: tibia
muscles of foot
- foot and toe flexor on plantar surface
- foot and toe extensors on dorsum
- muscles are named for action and what toe
dorsal interossei
abduct the toes (apart)
plantar interossei
adduct the toes (together)
