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Skeletal Muscles
General terms & skeletal muscles survey
269
Anatomy
Undergraduate 4
11/05/2013

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Term
Origin
Definition
Attachment of a muscle that remains relatively fixed during muscular contraction
Term
Insertion
Definition
Movable attachment of a muscle
Term
agonist
Definition
Muscle that bears the major responsibility for effecting a particular movement; a prime mover
Term
antagonist
Definition
(1) Muscle that reverses, or opposes, the action of another muscle. (2) Hormone that opposes the action of another hormone
Term
prime mover
Definition
Muscle that bears the major responsibility for effecting a particular movement; an agonist
Term
synergist
Definition
(1) muscle that aids the action of a prime mover by effecting the same movement or by stabilizing joints across which the prime mover acts, preventing undesirable movements. (2) Hormone that amplifies the effect of another hormone at a target cell
Term
anatomical position
Definition
standing straight forward, legs apart, palms facing forward
Term
abduction
Definition
to move away from the midline of the body
Term
adduction
Definition
to move toward the midline of the body
Term
flexion
Definition
Movement that decreases the angle of the joint; example: bending the knee from a straight to an angled position
Term
extension
Definition
Movement that increases the angle of a joint; ex: straightening a flexed knee
Term
rotation
Definition
The turning of a bone around its own long axis
Term
circumduction
Definition
Movement of a body part so that is outlines a cone in space
Term
pronation
Definition
Inward rotation of the forearm causing the radius to cross diagonally over the ulna -- palms face posteriorly
Term
supination
Definition
the outward rotation of the forearm causing palms to face anteriorly
Term
inversion
Definition
to turn inwards; inversion of the foot
Term
eversion
Definition
to turn outwards; eversion of the foot
Term
dorsiflexion
Definition
movement that brings the top of the foot towards the lower leg
Term
plantar flexion
Definition
extension of the ankle, pointing the toes
Term
8 muscles of facial expression
Definition
1)epicranius
2) Orbicularis oculi
3) Orbicularis Oris
4) zygomaticus
5) risorius
6) triangularis
7) platysma
8) buccinator
Term
epicranius (general description)
Definition
=frontalis (frontal belly) + occipitalis (occipital belly)
-Bipartite muscle consisting of the frontal and occipital bellies connected by the epicranial aponeurosis.
-The alternate actions of these two muscles pull scalp forward and backward

EYEBROW RAISER; SKEPTICAL MUSCLE
Term
Frontal belly (of the epicranius)
Definition
*Covers forehead and dome of skull; no bony attachment
*origin: epicranial aponeurosis
*insertion: skin of eyebrows and root of nose
*action= with aponeurosis fixed, it raises the eyebrows
and wrinkles forehead skin horizontally
Term
occipital belly (of the epicranius)
Definition
*Overlies posterior occiput; by pulling on the epicranial aponeurosis, fixes origin of frontal belly
*origin: occipital and frontal lobes
*insertion: epicranial aponeurosis
*action: fixes aponeurosis and pulls scalp posteriorly
Term
orbicularis oculi
Definition
WINK MUSCLE
*thin, flat sphincter muscle of eyelid; surrounds rim of the orbit
*origin: frontal and maxillary bones and ligaments around orbit
*insertion: tissue of eyelid
*action: closes eye; produces blinking and squinting; draws eyebrows inferiorly
Term
orbicularis oris
Definition
PUCKER MUSCLE
*origin: arises indirectly from maxilla and mandible
*Insertion: encircles mouth; inserts into muscle and skin at angles of mouth
*action: closes lip; purses and protrudes lips; kissing and whistling muscle
Term
zygomaticus
Definition
SMILING MUSCLE
*muscle pair extending diagonally from cheekbone to corner of mouth
origin: zygomatic bone
insertion: skin and muscle at corner of mouth
action: raises lateral corners of mouth upward
Term
risorius
Definition
LAUGHING MUSCLE
*slender muscle inferior and lateral to zygomaticus
origin: lateral fascia associated with masseter muscle
insertion: skin at angle of mouth
action: draws corner of lip laterally; tenses lips
Term
What is a synergist to the zygomaticus?
Definition
Risorius muscle
Term
Triangularis (aka depressor anguli oris)
Definition
FROWNING MUSCLE
origin: body of mandible below incisors
insertion: skin and muscle at angle of mouth below insertion of zygomaticus
action: draws corner of mouth down and laterally
Term
platysma
Definition
NECK MUSCLE
origin: fascia of chest (over pectoral muscles and deltoid)
insertion: lower margin of mandible, and skin and muscle a corner of mouth
action: tenses skin of neck; helps depress mandible; pulls lower lip back and down, producing downward sag of mouth
Term
buccinator
Definition
CHEEK MUSCLE
*deep to masseter; principal muscle of the cheek
origin: molar region of maxilla and mandible
insertion: orbicularis oris
action: compresses cheek; draws corner of mouth laterally; helps hold food between teeth during chewing
Term
2 muscles of mastication (chewing)
Definition
masseter & temporalis
Term
Masseter
Definition
origin: zygomatic arch and zygomatic bone
insertion: angle and ramus of mandible
action: prime mover of jaw closure; elevates mandible
Term
temporalis
Definition
*fan shaped muscle that covers parts of the temporal, frontal and parietal bones
origin: temporal fossa
insertion: coronoid process of mandible via a tendon that passes deep to zygomatic arch
action: closes jaw; elevates and retracts mandible; maintains position of the mandible at rest; deep anterior part may help protract mandible
Term
3 muscles that move the head
Definition
1. sternocleidomastoid
2. splenius capitis
3. semispinalis capitis
Term
3 attachment sites of the sternocleidomastoid muscle
Definition
sternum (breast bone), mastoid process, and clavicle
Term
sternocleidomastoid
Definition
*two headed muscle located deep to platysma on anterolateral surface of the neck; key muscular landmark in neck
origin: manubrium of sternum and medial portion of clavicle
insertion: mastoid process of temporal bone and superior nuchal line of occipital bone
action: flexes and laterally rotates the head; each muscle rotates head toward shoulder on opposite side and tilts or laterally flexes head to its own side
Term
splenius capitis
Definition
-capitis portion is known as the bandage muscle because it covers and holds down deeper neck muscles
origin: ligamentum nuchae, spinous processes of vertebrae C7-T6
insertion: mastoid process of temporal bone and occipital bone
action: extends or hyperextends head; when splenius muscles on one side are activated, head rotates and bends laterally toward same side
Term
semispinalis capitis
Definition
*composite muscle forming part of deep layer of intrinsic back muscles; extends from thoracic region to head
origin: transverse processes of C7-T12
insertion: occipital bone
action: extends vertebral column and head and rotates them to opposite side; acts synergistically with sternocleidomastoid muscles of opposite sides
Term
Synergist muscle of the sternocleidomastoid muscle
Definition
semispinalis capitis
Term
5 muscles that move the pectoral girdle
Definition
1) trapezius
2) rhomboideus major
3) levator scapulae
4) serratus anterior
5) pectoralis minor
Term
Trapezius
Definition
*most superficial muscle of posterior thorax; flat and triangular in shape
origin: occipital bone, ligamentum nuchae, and spinous processes of C7, and all thoracic vertebrae
insertion: continuous insertion along acromion and spine of scapula and lateral third of clavicle
action: stabilizes, raises, retracts, and rotates scapula
Term
rhomboideus major
Definition
*shaped like a rhombus or diamond; lies deep to the trapezius and inferior to levator scapulae; minor is the more superior muscle
origin: spinous processes of C7 and T1 (minor) and spinous processes of T2-T5 (major)
insertion: medial border of scapula
action: stabilizes scapula; when the muscles act together they adduct the scapula, and then rotates the scapula so the glenoid cavity is downward
ex: paddling a canoe
Term
levator scapulae
Definition
*located at back and side of neck; deep to trapezius; thick strap-like muscle
origin: transverse processes of C1-C4
insertion: medial border of scapula, superior to spine
action: elevates/adducts scapula; tilts glenoid cavity downward when scapula is fixed and flexes neck to the same side
Term
serratus anterior
Definition
*boundary looks like a serrated knife
*fan shaped muscle; lies deep to scapula; deep and inferior to pectoral muscles on lateral rib cage; forms medial wall of axilla
origin: by a series of muscle slips from ribs 1-8 (or 9)
insertion: entire anterior surface of vertebral border of scapula
action: rotates scapula so its inferior angle moves laterally and upward; prime mover to protract and hold scapula against chest wall
Term
which muscle is called the boxer muscle and why?
Definition
serratus anterior--> because it abducts and raises arm and in horizontal arm movements (pushing, punching)
Term
pectoralis minor
Definition
*directly beneath and obscured by pectoralis major
origin: anterior surfaces of ribs 3-5 or 2-4
insertion: coracoid process of scapula
action: with ribs fixed, draws scapula forward and downward; with scapula fixed, it draws ribcage superiorly
Term
What do the muscles of the pectoral girdle do?
Definition
-closely associated with the muscles of the upper arm
-connect the scapula to nearby bones, which moves the scapula (shoulder blade) up, down, forward, and backward
Term
2 muscles that flex the upper arms
Definition
1. coracobrachialis
2. pectoralis major
Term
coracobrachialis
Definition
origin= coracoid process of the scapula
insertion= medial surface of the humerus shaft
action: flexes and adducts humerus
Term
what is a synergist of the pectoralis major?
Definition
coracobrachialis
Term
pectoralis major
Definition
origin: sternal end of clavicle, sternum, cartilage of ribs 1-6 and aponeurosis of external oblique muscle
insertion: fibers converge to insert by a short tendon into intertubercular sulcus and greater tubercle of humerus
action: prime mover of arm flexion; rotates arm medially; adducts arm
-used in throwing, pushing, climbing and forced inspiration
Term
what is the prime mover of arm flexion?
Definition
pectoralis major
Term
2 muscles that extend the upper arms
Definition
1. teres major
2. latissimus dorsi
-agonists
Term
teres major
Definition
origin: posterior surface of scapula at inferior angle
insertion: crest of lesser tubercle on anterior humerus; insertion tendon fused with that of latissimus dorsi
action: extends, medially rotates, and adducts humerus
Term
what is a synergist of the teres major?
Definition
latissimus dorsi
Term
latissimus dorsi
Definition
origin: indirect attachment of via lumbodorsal fascia into spines of lower six thoracic vertebrae, lumbar vertebrae, lower 3-4 ribs, and iliac crest; also from scapula's inferior angle
insertion: spirals around teres major to insert in floor of intertubercular sulcus of humerus
action: prime mover of arm extension; powerful arm adductor; medially rotates arm at shoulder
Term
which muscle plays an important role in a power stroke?
Definition
latissimus dorsi
Term
2 muscles that abduct the upper arm
Definition
1. supraspinatus
2. deltoid
Term
supraspinatus
Definition
*deep to trapezius; a rotator cuff muscle
origin: supraspinous fossa of scapula
insertion: superior part of greater tubercle of humerus
action: initiates abduction; stabilizes shoulder joint
Term
deltoid
Definition
origin: embraces insertion of the trapezius; lateral third of clavicle; acromion and spine of scapula
insertion: deltoid tuberosity of humerus
action: prime mover of arm abduction when all its fibers contract simultaneously
Term
which muscle is a common site for intramuscular injection?
Definition
deltoid
Term
which muscle is an antagonist of the pectoralis major and latissimus dorsi?
Definition
deltoid
Term
3 muscles that rotate the upper arm
Definition
1. subscapularis
2. infraspinatus
3. teres minor
Term
subscapularis
Definition
origin: subscapular fossa of scapula
insertion: lesser tubercle of humerus
action: chief medial rotator of humerus; stabilizes shoulder joint; helps hold head of humerus in glenoid cavity
Term
infraspinatus
Definition
origin: infraspinous fossa of scapula
insertion: greater tubercle of humerus posterior to insertion of supraspinatus
action: rotates humerus laterally
Term
teres minor
Definition
origin: lateral border of dorsal scapular surface
insertion: greater tubercle of humerus inferior to infraspinatus insertion
action: rotates humerus laterally; same as infraspinatus
Term
4 rotator cuff muscles
Definition
1. subscapularis
2. supraspinatus
3. infraspinatus
4. teres minor
Term
3 muscles that flex the forearm
Definition
1. biceps brachii
2. brachialis
3. brachioradialis
Term
biceps brachii
Definition
-two headed muscle
origin=short head: coracoid process; long head: supraglenoid tuberosity and lip of glenoid cavity.
insertion=common tendon intro radial tuberosity
action: flexes elbow joint and supinates forearm; weak flexor of arm at shoulder
Term
where does the long head of the biceps brachii run?
Definition
runs within the capsule and into the intertubercular sulcus of humerus
Term
brachialis
Definition
deep to biceps brachii on distal humerus
origin: front of distal humerus; embraces insertion of deltoid muscle
insertion: coronoid process of ulna and capsule of elbow joint
action: a major forearm flexor; lefts ulna as biceps lifts the radius
Term
brachioradialis
Definition
origin: lateral supracondylar ridge at distal end of humerus
insertion: base of radial styloid process
action: synergist in flexing forearm; stabilizes elbow during rapid flexion and extension
Term
muscle that extends the forearm
Definition
triceps brachii
Term
triceps brachii
Definition
-three headed origin
origin: long head-infraglenoid tubercle of scapula. lateral head- posterior shaft of humerus. medial head- posterior humeral shaft distal to radial groove
insertion: common tendon into olecrannon of ulna
action: powerful forearm extensor: prime mover
Term
what is the antagoinst of forearm flexors?
Definition
triceps brachii
Term
3 muscles that rotate the forearm
Definition
1. supinator
2. pronator tres
3. pronator quadratus
Term
supinator
Definition
origin: lateral epicondyle of humerus; proximal ulna
insertion: proximal end of radius
action: assists biceps brachii to forcibly supinate forearm
Term
what's an antagonist of the pronator muscles?
Definition
supinator
Term
pronator tres
Definition
-two headed muscles
origin: medial epicondyle of humerus; coronoid process of ulna
insertion: by common tendon into lateral radius, midshaft
action: pronates forearm; weak flexor of elbow
Term
pronator quadratus
Definition
origin: distal portion of anterior ulnar shaft
insertion: distal surface of anterior radius
action: prime mover of forearm pronation;
Term
what is the deepest muscle of the distal forearm?
Definition
pronator quadratus
Term
what is the only muscle that solely arises from the ulna and solely inserts into the radius?
Definition
pronator quadratus
Term
what is the prime mover of forearm pronation?
Definition
pronator quadratus
Term
4 muscles that flex the wrist, hand, and fingers
Definition
1. flexor carpi radialis
2. flexor carpi ulnaris
3. palmaris longus
4. flexor digitorum profundus

*all originate on the medial epicondyle and course along the anterior side of the arm
Term
flexor carpi radialis
Definition
origin: medial epicondyle of humerus
insertion: base of second and third metacarpals
action: powerful flexor of wrist; abducts hand-weak synergist of elbow flexion
Term
flexor carpi ulnaris
Definition
most medial muscle of the group
origin: medial epicondyle of humerus
insertion: base of fifth metacarpal
action: powerful flexor of the wrist; adducts hand; stabilizes wrist during finger extension
Term
palmaris longus
Definition
origin: medial epicondyle of the humerus
insertion: palmar aponeurosis (fascia of palm)
action: tenses skin and fascia of palm during hand movements; weak wrist flexor; weak synergist for elbow flexion
Term
flexor digitorum profundus
Definition
origin: coronoid process, anteromedial surface of ulna, and interosseous membrane
insertion: by four tendons into distal phalanges of fingers 2-5
action: flexes disal interphalangeal joints
Term
4 muscles that extend the wrist, hand, and fingers
Definition
1. extensor carpi radialis longus
2. extensor carpi radialis brevis
3. extensor carpi ulnaris
4. extensor digitorum

*all originate on the lateral epicondyle and course along the posterior side of the arm
Term
extensor carpis radialis longus
Definition
origin: lateral supracondylar ridge of humerus
insertion: base of second metacarpal
action: extends wrist and abducts wrist
Term
extensor carpis radialis brevis
Definition
origin: lateral epicondyle of humerus
insertion: base of third metacarpal
action: extends and abducts wrist
Term
extensor carpi ulnaris
Definition
origin: lateral epicondyle of humerus and posterior border of ulna
insertion: base of fifth metacarpal
action: extends wrist and adducts wrist

*most media of superficial posterior muscle
Term
which two muscles adduct the wrist?
Definition
extensor carpi ulnaris
flexor carpi ulnaris
Term
which two muscles abduct the wrist?
Definition
extensor carpi radialis longus
flexor carpi radialis
Term
extensor digitorum
Definition
origin: lateral epicondyle of humerus
insertion: by four tendons into extensor expansions and distal phalanges of fingers 2-5
action: prime mover of finger extension; can abduct fingers
Term
what do the bellies (fleshy portions) of these muscles do?
Definition
-closer to the elbow than to the wrist.
-therefore wrist is a bundle of tendons that insert into the bones of the wrist and hand. The tendons are bound down by retinaculum
Term
4 muscles of the abdominal wall in order from most superficial to deepest
Definition
1. rectus abdominis
2. external oblique
3. internal oblique
4. transversus abdominis

-broad, flat muscles separated by layers of fascia
Term
where do the abdominal muscles connect?
Definition
-they connect anteriorly at the linea alba
Term
What do contractions of the abdominal wall muscles cause?
Definition
increased intra-abdominal pressure that is important in coughing, urination, defecation, giving birth, and forceful exhalation
Term
rectus abdominus
Definition
medial abdominal muscle
origin: pubic crest and symphysis
insertion: xiphoid process and costal cartilages of ribs 5-7
action: flex and rotates lumbar region of vertebral column; fix and depresses ribs, stabilizes pelvis during walking, increases intra-abdominal pressure; used in sit ups and crunches
Term
external oblique
Definition
largets and most superifical of the 3 lateral muscles
origin: by fleshy strips from outer surfaces of lower eight ribs
insertion: linea alba via a broad aponeurosi; some into pubic crest and tubercle and iliac crest
action: when pair contracts simultaneously it flexes vertebral column and compresses abdominal wall; individually it aids muscles of back in rotating and flexing laterally; used in oblique curls
Term
internal oblique
Definition
origin: lumbar fascia, iliac crest and inguinal ligament
insertion: linea alba, pubic crest, last 3 or 4 ribs and costal margin
action: acting simultaneously: flex vertebral column and compress abdominal wall-individually: rotates trunk and flexes back laterally
Term
transversus abdominus
Definition
deepest
origin: inguinal ligament, lumbar fascia, cartilages of last 6 ribs; iliac crest
insertion: linea alba, pubic crest
action: compresses abdominal contents
Term
2 anterior muscles that flex the thigh (iliopsoas muscles)
Definition
psoas major
iliacus
Term
psoas major
Definition
more medial muscle of the pair
origin: by fleshy slips from transverse processes, bodies, and discs of lumbar vertebrae and T12
insertion: lesser trochanter of femus via iliopsoas tendon
action: flexing thigh, or for flexing trunk on thigh, also flexes vertebral column laterally; important postural muscle
Term
iliacus
Definition
large, fan shaped, lateral muscle
origin: iliac fossa and crest, ala of sacrum
insertion: lesser trochanter of femur via iliopsoas tendon
action: prime mover for flexing thigh, or for flexing trunk on thigh as during a bow
Term
4 posterior muscles that move the thigh
Definition
1. gluteus maximus
2. gluteus medius
3. gluteus minimus
4. tensor fascia latae (only one that flexes the thigh)
Term
gluteus maximus
Definition
-largest and most superficial gluteus muscle
-important site for intramuscular injection
origin: dorsal ilium, sacrum and coccyx
insertion: gluteal tuberosity of femur; iliotibial tract
action: major extensor of thigh; laterally rotates and abducts thigh
Term
gluteus medius
Definition
-important site for intramuscular injections (better than maximus)
origin: between anterior and posterior gluteal lines on lateral surface of ilium
insertion: by short tendon into lateral aspect of greater trochanter of femur
action: abducts and medially rotates thigh; steadies pelvis
Term
which muscles are important in walking?
Definition
gluteus medius and glueteus minimus
Term
gluteus minimus
Definition
origin: between anterior and inferior gluteal lines on external surface of ilium
insertion: anterior border of greater trochanter of femur
action: abducts and medially rotates thigh
Term
3 muscles that adduct the thigh
Definition
adductor longus
adductor magnus
gracilis
Term
adductor longus
Definition
-most anterior
origin: pubis near pubic symphysis
insertion: linea aspera
action: adducts, flexes and medially rotates thigh
Term
adductor magnus
Definition
triangular muscle with a broad insertion
origin: ischial and pubic rami and ischial tuberosity
insertion: linea aspera and adductor tubercle of femur
action: anterior part-adducts and medially rotates and flexes thigh. posterior part-synergist to hamstrings to extend thigh
Term
gracilis
Definition
long, thin, superficial muscle of medial thigh
origin: inferior ramus and body of pubis and adjacent ischial ramus
insertion: medial surface of tibia just inferior to its medial condyle
action: adducts thigh, flexes and medially rotates leg
Term
which thigh adductor, is also part hamstring in action?
Definition
adductor magnus
Term
Muscles that move the thigh in general
Definition
=origins on the pelvic girdle bones and insertions on the femur
Term
what do the anterior thigh muscles do
Definition
flexes the thigh
Term
what do the posterior thigh muscles do
Definition
extend, abducts and rotates the thigh
Term
what do the medial thigh muscles do
Definition
adduct the thigh
Term
4 muscles that are part of the "hamstring" group- they flex the knee-one is not a true hamstring muscle
Definition
biceps femoris
semitendinosus
semimembranosus
sartorius (not a true hamstring muscle)
Term
which muscle is not a true hamstring muscle?
Definition
sartorius
Term
what is the longest muscle in the body?
Definition
Sartorius-comes down the anterior thigh
Term
Sartorius
Definition
origin: anterior superior iliac spine
insertion: winds around medial aspect of knee and inserts into medial aspect of proximal tibia
action: flexes, abducts, and laterally rotates thigh-carries out movements at the hip and knee joints
Term
biceps femoris
Definition
most lateral muscle of the group; arises from two heads
origin: ischial tuberosity (long head); linea aspera, lateral supracondylar line, and distal femur (short head)
action: extends thigh and flexes knee; laterally rotates leg
Term
semitendinosus
Definition
origin: ischial tuberosity
insertion: medial aspect of upper tibial shaft
action: extends thigh and flexes knee; medially rotates leg
Term
semimembranosus
Definition
origin: ischial tuberosity
insertion: medial condyle of tibial
action: extends thigh and flexes knee; medially rotates leg
Term
which two muscles medially rotate the leg?
Definition
semitendinosus and semimembranosus
Term
4 muscles that make up the quadriceps group and extend the knee
Definition
rectus femoris
vastus lateralis
vastus medialis
vastus intermedius
Term
quadriceps femoris general
Definition
-forms the front and sides of the thigh
-common insertion point: quadriceps tendon
-powerful knee extensor
Term
rectus femoris
Definition
origin: anterior inferior iliac spine and superior margin of acetabelum
insertion: patella and tibial tuberosity via patellar ligament
action: extends knee and flexes thigh at hip
Term
vastus lateralis
Definition
origin: greater trochanter, intertochanteric line, linea aspera
insertion: patella and tibial tuberosity via patellar ligament
action: extends and stabilizes knee
Term
vastus medialis
Definition
origin: linea aspera, intertrochanteric and medial supracondylar lines
insertion: patella and tibial tuberosity via patellar ligament
action: extends knee
Term
vastus intermedius
Definition
origin: anterior and lateral surfaces of proximal femur shaft
insertion: patella and tibial tuberosity via patellar ligament
action: extends knee
Term
Muscles that move the lower leg-general
Definition
origins: femur and pelvic girdle bones
insertions: tibia and fibula
3/4 hamstring muscles (sartorius, semimembranosus, and semitendinosus) insert on the medial side of the tibia, biceps femoris inserts on the lateral side of the knee into the fibula
Term
what is the area often referred to as the "goose foot"?
Definition
region of insertion of the sartorius, semimembranosus and semitendinosus
Term
3 dorsiflexors that move the ankle, foot, and toes
Definition
1. tibialis anterior
2. peroneus (fibularis) tertius
3. extensor digitorum longus

-all located on the anterior side
Term
tibialis anterior
Definition
origin: lateral condyle and upper 2/3 of tibial shaft; interosseous membrane
insertion: by tendon into the inferior surface of medial cuneiform and first metatarsal bone
action: prime mover of dorsiflexion; inverts foot
Term
fibularis (peroneus) tertius
Definition
origin: distal anterior surface of fibula and interosseous membrane
insertion: tendon inserts on dorsum of fifth metatarsal
action: dorsiflexes and everts foot
Term
extensor digitorum longus
Definition
origin: lateral condyle of tibia; proximal 3/4 of fibula; interosseous membrane
insertion: middle and distal phalanges of toes 2-5 via extensor expansion
action: prime mover of toe extension; dorsiflexes foot
Term
5 muscles that plantar flex the ankle, foot and toes
Definition
1. gastrocnemius
2.soleus
3. flexor digitorum longus
4. tibialis posterior
5. fibularis (peroneus) longus
Term
Gastrocnemius
Definition
origin: by two heads from medial and lateral condyles of femur
insertion: posterior calcaneous via calcaneal tendon
action: plantar flexes foot when knee is extended

-posterior compartment
Term
soleus
Definition
origin: extensive origin from superior tibia, fibula, and interosseous membrane
insertion: posterior calcaneous via calcaneal tendon
action: plantar flexes foot; important muscle for walking, running and dancing

-posterior compartment
Term
what is the largest tendon in the body?
Definition
achilles/ calcaneal tendon
Term
which muscles shape the posterior calf and inserts via the achilles heal?
Definition
Triceps surae: gastrocnemius & soleus
Term
flexor digitorum longus
Definition
origin: posterior tibia
insertion: tendon runs behind medial malleolus and inserts into distal phalanges of toes 2-5
action: plantar flexes and inverts foot; flexes toes
-posterior compartment
Term
tibialis posterior
Definition
origin: superior tibia and fibula and interosseous membrane
insertion: tendon passes behind medial malleolus and under arch of foot; inserts into several tarsals and metatarsals II-IV
-posterior side
Term
fibularis (peroneus) longus
Definition
origin: head and upper portion of lateral fibula
insertion: by long tendon that curves under foot to first metatarsal and medial cuneiform
action: plantar flexes and everts foot
-lateral side
Term
Muscles that move the ankle, foot and toes-general
Definition
origins: femur, tibia, and fibula
insertions: various bones of the ankle and foot
-ankle contains retinaculum and tendon sheaths
Term
3 functions of skeletal muscles
Definition
1. movement
2. preventing movement (ex. posture)
3. Heat production (helps keep body temp.)
Term
What is muscle tone?
Definition
a low grade state of continuous contraction that is important to keep posture
Term
How are skeletal muscles classified?
Definition
based on:
-anatomic location
-cooperative function
Term
What is skeletal muscle?
Definition
most muscles are attached to the skeleton
Term
How do skeletal muscles move?
Definition
they only know how to actively shorten (brings insertion closer to the origin)
Term
Which end is more movable?
Definition
insertion
Term
Which end is usually closer to the trunk?
Definition
origin
Term
what is a tendon?
Definition
a band of dense, regular fibrous connective tissue that attaches muscle to bone
Term
what is a ligament?
Definition
a band of dense regular fibrous connective tissue that attaches bone to bone
Term
antagonist muscles
Definition
pair of muscles with opposite action
Term
agonist muscle
Definition
group of muscles all doing the same function
Term
prime mover
Definition
strongest muscle of an agonist group
Term
synergist
Definition
nonprime mover; works with the prime mover to do the action
Term
aponeurosis
Definition
a broad sheet of fibrous connective tissue
Term
tendon sheath
Definition
elongated bursae filled with synovial fluid that helps minimize friction
Term
retinaculum
Definition
band of dense, fibrous connective tissue that binds down 1 or more tendons in a pulley-like fashion
Term
endomysium
Definition
connective tissue that surrounds individual skeletal muscle cells
Term
perimysium
Definition
connective tissue that surrounds bundles of cells called fassicles
Term
epimysium
Definition
connective tissue that surrounds the entire skeletal muscle
Term
fascia
Definition
connective tissue that surrounds groups of skeletal muscles
Term
3 functions of connective tissue wrappings
Definition
1. avenue for blood vessels
2. avenue for nerves
3. helps transmit the force of contraction to the skeleton
Term
isometric contraction
Definition
contraction where the length between the 2 cells and elastic element remain the same
Term
isotonic contraction
Definition
contraction where the length does change byt the force ("tension") doesn't change
Term
Muscle stretch reflexes
Definition
-all skeletal muscles have these and these help remain posture
-need neurons/nerves to have reflexes
Term
Why does skeletal muscle have nerves?
Definition
so the brain knows what you're doing and for muscle stretch reflexes
Term
propiroception
Definition
sensory neurons from skeletal muscles telling your brain what you are doing
Term
kinesthesia
Definition
the awareness of body movement
Term
Muscle cells
Definition
giant, multinucleated cells
Term
sarcolemma
Definition
muscle cell membrane
Term
sarcoplasm
Definition
muscle cell cytoplasm
Term
sarcoplasmic reticulum
Definition
muscle cell endoplasmic reticulum
-actively stores up calcium ions
-periodically releases calcium ions back into the cytoplasm when an action potential comes by, which triggers a muscle contraction
Term
T(transverse) tubules
Definition
any of the small tubules which run transversely through a striated muscle fiber and through which electrical impulses are transmitted from the sarcoplasm to the fiber's interior
Term
myofibril
Definition
bundle of myofilaments (ex. action and myosin)
Term
what do action potentials do?
Definition
trigger a muscle contraction via the sliding filament mechanism
Term
what is the muscular system based on?
Definition
all different types of levers
Term
3 different classes of levers
Definition
1. 1st class: fulcrum in the middle
2. 2nd class: load is in the middle
3. 3rd class: effort is in the middle
Term
What happens when there is paralysis of the facial nerve (cranial nerve 7)?
Definition
paralyzes your ability to do facial expressions
Term
Bell's palsy
Definition
paralysis of the facial muscles
Term
What happens to muscle tone when you sleep?
Definition
you lose it
Term
what happens when the sternocleidomastoid contracts to one side?
Definition
-you have lateral flexion to the same side and rotation to the opposite side
Term
What happens when the splenius capitus contracts on one side?
Definition
it laterally extends and rotates to the same side
Term
What happens when the semispinalis capitus contracts to one side?
Definition
lateral flexion to the same side but rotation to the opposite side
Term
what are the accessory muscles of inhalation?
Definition
pectoralis major and minor
sternocleidomastoid
upper trapezius
latissimus dorsi
and a few others
Term
1st step for the cross bridge cycle
Definition
1. cross bridge formation. Energized myosin head attaches to an actin myofilament, forming a cross bridge
Term
2nd step for the cross bridge cycle
Definition
2. The power/working stroke. ADP and Pi are released and the myosin head pivots and bends, changing to its bent low-energy state. As a result it pulls the actin filament toward the m line
Term
3rd step for the cross bridge cycle
Definition
3. Cross bridge detachment. After ATP attaches to myosin, the link between the myosin and actin weakens, and the myosin head detaches. (Cross bridge breaks)
Term
4th step for the cross bridge cycle
Definition
4. Cocking of the myosin head. As ATP is hydrolyzed to ADP to Pi, the myosin head returns to its prestroke high-energy, or "cocked" position
Term
How many ATPs are lost with the each turn of the cross bridge cycle?
Definition
1 ATP
Term
What happens to the cross bridge cycle when there is no more ATP present?
Definition
then all the myosins will be stuck to actin so muscles cannot be separated
Term
Rigor Mortis
Definition
Rigid muscles- when the myosin is stuck to action so the muscles can't be separated
Term
What does that Na/K ATPase pump do?
Definition
creates concentration gradients and electrical gradients by pumping 3 Na ions out for every 2 K ions that enter the cell
Term
What does the Ca ATP pump do?
Definition
pumps more calcium outside than inside the cell
Term
What is the electrical current inside the cell?
Definition
inside is more negative, outside is more positive
Term
What happens at -90?
Definition
It is the negative resting cell membrane potential
Term
What happens at -70?
Definition
The threshold potential for the sodium gate-sodium gate opens here
Term
What happens from -70 to 0?
Definition
depolarization because sodium is rushing into the cell
Term
What happens at 0?
Definition
the cell is not polarized at all
-cell membrane potential
Term
What happens at +10?
Definition
Na+ gate slams closed and K+ gate opens, which causes K+ to rush out so the inside of the cell becomes more and more negative again
Term
what is a motor unit?
Definition
consists of one motor neuron and all the muscle fibers it innervates, or supplies.
Term
what is a muscle twitch?
Definition
a motor units response to a single action potential of its motor neuron
Term
7 steps in excitation contraction coupling
Definition
1. Action potential is spreading down the neurons. You have to consciously think about the contraction at the upper and lower motor neuron action potential, which triggers events at the skeletal muscle cell
2. Action potential reaches end of axon, triggering the opening of voltage regulated Calcium gates
3. Calcium influx into the neuron triggers release of Ach by exocytosis
4. Ach binding to receptor opens the neighboring Na/K chemically regulated gate==> net depolarization
5. Depolarization in the neuromuscular junction triggers the neighboring cell membrane to undergo an AP, which spreads over cell surface and through T-tubules
6. AP in T-tubules triggers release of Ca ions from sarcoplasmic reticulum into cytoplasm
7. Ca ions bind to troponin, pulling tropomysin out of the way, allowing myosin globular head to attach to action (sliding filament contraction)
Term
4 steps required to stop the contraction
Definition
1. active transport Ca ions back into the sarcoplasmic reticulum via a sacroplasmic reticulum calcium ATPase pump
2. Stop thinking about contraction (stops upper and lower motor neuron action potentials)
3. Remove the Ach from the neuromuscular junction
4. Na/K ATPase pumps must continue to actively transport Na and K ions to establish the negative resting cell membrane potential
Term
What enzyme splits and deactivates Ach?
Definition
acetylcholinerterase enzyme
Term
What is Botulism?
Definition
food poisoning due to exposure to botulinum toxin (produced by clostridium botulinum)
Term
How does botulism affect the body?
Definition
Prevents the release of Ach from lower motorneurons so they cannot contract
Term
Non-depolarizing agents used for muscle relaxants in surgery
Definition
tubocurarine and pancuronium
-both bind to and block nicotinic cholinecgic receptors
Term
Depolarizing agents used for muscle relaxants in surgery
Definition
succinyl choline
-binds to and over stimulates nicotinic ACh receptors--> causes excessive depolarization and rapid muscle fatigue and paralysis
Term
What is myasthenia gravis?
Definition
autoimmune disease in which you make antibodies to your own ACh receptors, can destroy them or at least block Ach from binding to them
Term
Treatment for myasthenia gravis
Definition
anticholinesterase drugs which block the destruction of ACh
Term
What do organophosphates do?
Definition
block AchE so your muscle can't relax
Term
2 factors that affect the strength of muscle contraction
Definition
1. muscle design
2. # of available cross bridges
Term
What percentage of ATP is consumed to run the sodium/potassium pumps for muscles?
Definition
40%
Term
How do skeletal muscle cells respond to nerve signals?
Definition
cells exhibit a threshold stimulus and an all or none reaction (either they contract or they do not, no inbetween)
Term
What is a threshold stimulus?
Definition
minimum stimulus needed to trigger a contraction
Term
What do entire motor units have?
Definition
1. A threshold stimulus (smaller motor units have a lower threshold stimulus)
2. an all or non response
Term
How do skeletal muscles as a whole respond to nerve signals?
Definition
You can have different amounts of contraction; individual muscle contractions get fused together to make a sustained contraction
Term
what is multiple motor unit recruitment?
Definition
it's when more and more muscle cells are reaching their thresholds
Term
What is temporal summation?
Definition
a sustained contraction (all of the action potentials together)
Term
What is a tetanic contraction?
Definition
maximum contraction
Term
What is tetanus?
Definition
illness due to exposure to the tetanus toxin, which is produced by clostridium tetani
-tetanus causes excessive spasms of the skeletal muscles
Term
What does the tetanus toxin?
Definition
blocks the release of inhibitory (-) neurotransmitter from upper motor neurons, so the lower motor neuron is getting over active
Term
What causes lockjaw?
Definition
tetanus in the maxillary area
Term
What is skeletal muscle hypertrophy?
Definition
increase in size of skeletal muscle cells and entire muscles
Term
Changes that occur inside the cells during skeletal muscle hypertrophy?
Definition
Increased production of action/myosin and other microfilaments and increased amount of sarcoplasmic reticulum and increased number of mitochondria
Term
What is skeletal muscle atrophy?
Definition
decrease in size of skeletal muscle cells and entire muscles
Term
What are changes that occur inside the cells during skeletal muscle atrophy?
Definition
decreased action/myosin/myofilaments
-decreased sarcoplasmic reticulum and mitochondria
Term
What is disuse atrophy?
Definition
muscles not being stimulated
ex: due to extended bed rest or limb immobilzation
Term
What is denervation atrophy?
Definition
due to damage to upper and lower motor neuron that stimulates the muscle
ex: due to spinal cord injury or disease (as in ALS or poliomyelitis)
Term
What are the 3 types of skeletal muscle fibers?
Definition
1. Type I fibers (SO)
2. Type IIb fibers (FG)
3. Type IIa fibers (FO)
Term
What are type I fibers?
Definition
-"red fibers"
-slow oxidative fibers
-specialized for longer periods of aerobic cell respiration
-used in muscles dealing with posture
Term
Why are type I fibers called red fibers?
Definition
they have a rich blood supply, rich supply of myoglobin, which binds to and stores O2 and cells are loaded with mitochondria (mitochondria is loaded with iron)
Term
What are type I fibers called slow?
Definition
refers to the fact that these are slow twitch fibers, meaning they take a bit longer to reach maximum contraction
-have slower acting myosin globular head ATPase enzymes
Term
What are type IIb fibers?
Definition
-"white fibers"
-FG=fast glycolytic fibers
-specialized for shorter bursts of more intense exercise and anaerobic exercise
-have high levels of glycolytic enzymes, bigger diameter, and loaded with granules of glycogen, fewer mitochondria, less myoglobin
used when doing a 100 meter dash
Term
What are type IIb fibers called fast glycolytic fibers?
Definition
because they are fast twitch fibers meaning they have fast acting myosin globular head ATPase enzymes
Term
What are type IIa fibers?
Definition
fast oxidative
hybrid of the other 2
-fast twitch, fast oxidative (prefers aerobic cell respiration)
-pinkish color
used when running marathon
Term
Which type of fiber has the most creatine phosphate?
Definition
FG, type IIb
Term
Where does ATP come from skeletal muscles at rest?
Definition
from aerobic cell respiration of glucose and fatty acids from blood
Term
Where does ATP come from during moderate exercise?
Definition
-need a quicker source of ATP
-glycogenolysis in the cell: glucose is shuttled through aerobic cell respiration
with continued moderate exercise.. ATP comes mostly from aerobic cell respiration of fatty acids from blood
Term
Where does ATP come from during a sprint?
Definition
ATP usage is high (& cell respiration isn't fast enough to provide all ATP)
-free ATP is used up quickly so cells start retrieving ATP from creatine phosphate inside the cells
Term
How does the creatine kinase work?
Definition
It breaks off the phosphate from the creatine phosphate and creates ATP from ADP during exercise
-at rest, ATP enters creatine and a phosphate is cut off to make ADP and creatine phosphate
Term
Where does ATP come from during continued, intense exercise?
Definition
-decreased blood flow, which decreases delivery of O2 and nutrients so the cell shifts over to anaerobic cell respiration, which buys a little more time, so ATP levels decrease and lactic acid levels increase leading to muscular fatigue
Term
Effects of muscular fatigue with decreased pH?
Definition
decreased pH which can denature enzymes ex. glycolytic enzymes, which leads to a decrease of calcium ions binding to troponin
Term
Effects of muscular fatigue with increased phosphate concentration?
Definition
decreases calcium ions being released from the sacroplasmic reticulum hence triggering less contractions
-increased phosphate also decreased release of phosphate attached to myosin globular head
Term
Effects of muscular fatigue with decreased ATP
Definition
-decreased contraction (less sliding filament activation)
-decreased activity of Na/K ATPase pump so they can't maintain the normal steep gradients for Na and K across the cell membrane, thus hampering the normal action potential on skeletal muscles
-harder to actively transport calcium ions back into the sarcoplasmic reticulum which leads to muscle cramping
-no ATP to bind and unlock cross bridge so it can lead to muscle cramping
Term
First way to pay back the O2 debt
Definition
Muscles relax so it reeestablishes blood flow
-glucose/fatty acids and O2 binding to myoglobin both leads to increased cell respiration and increased ATP, which replenishes the creatine phosphate stores
Term
What does increased ATP do when paying back the O2 debt?
Definition
-powers the Na/K ATPase pump
-SR Ca ATPase pump
-sliding filament mechanism
Term
2nd way to pay back the 02 debt
Definition
Muscles relax, which reestablishes blood flow which causes lactic acid to enter the blood stream which returns muscle pH back to normal
Term
How long does it take for 1 action potential to take place?
Definition
3 miliseconds
Term
what is the diameter of a muscle cell?
Definition
100 micrometers
Term
What are the only 2 types of cells that can hold glycogen?
Definition
skeletal muscle cells and liver cells
Term
Cori cycle
Definition
1. lactic acid leaves the muscle and enters the cori cycle
2. lactic acid enters the liver, becomes pyruvate, and then becomes glucose and then becomes glycogen (remains in liver)
3. some glucose leaves the liver and enters the cori cycle to enter the muscle cell
Term
gluconeogenesis
Definition
(in liver) metabolic pathway that converts pyruvate back to glucose =
Term
thick filaments of a muscle
Definition
contains myosin and extend the entire length of the A band. They are connected at the middle of the sarcomere at the M line
Term
thin filaments of a muscle
Definition
contain actin and extend across the I band and partway into the A band
Term
myosin
Definition
consists of 2 heavy and 4 light polypeptide chains, and has a rodlike tail attached by a flexible hinger to two globular heads
Term
actin
Definition
has globular action, which bear the active sites to which the myosin heads attach during contraction
Term
tropomyosin
Definition
spirals about the actin and core and helps stiffen and stabilize it
-in relax muscle fibers, they block myosin-binding sites on actin so that myosin heads on the thick filaments cannot bind to the thin filaments
Term
troponin
Definition
globular 3-polypeptide complex, they inhibit subunit that binds to actin, binds tropomyosin and helps binds to actin, and binds calcium ions
Term
sliding filament mechanism
Definition
states that during contraction, the thin filaments slide past the thick ones so that the actin and myosin filaments overlap to a greater degree
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