Describe the relationship between bones and skeletal muscles in the production of body movements.
skeletal muscle is attached to bone at origin and
... [Show More] insertion. skeletal muscle contracts and pulls on bone. bones serve as levers. joint act as a fulcrum. load is the weight of the object.
Describe how the prime mover, antagonist, synergist and fixator in a muscle group work together to produce movements.
Opposing pairs of muscle group, often on opposite side of the body, balance out movement. The agonist and antagonist change roles depending on the movement. If they contract equally then there is stability and no movement. The agonist will initiate a contraction and the antagonist will yield and stretch to that effect. Fixaor stabilze the origin. Synergists support the needs of the prime mover by stabilizing intermediate joints. .
describe the characteristics used in the naming of skeletal muscles.
combination of word roots of distinctive features.
- direction of muscle fascicles (rectus are parallel to midline; transverse are perpendicular to midline; oblique are diagonal to midline)
-size (major/ minor or short/long)
-shape (deltoid =triangular; trapezius = trapezoid)
-action (flexor - decrease joint angle; extensor - increase joint angle)
- number of origins (biceps = two origins)
list the names, locations and actions of principal skeletal muscles.
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list the origins and insertions of several specific skeletal muscles.
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origin
attachment of muscle's tendon onto the stationary bone. usually proximal.
insertion
attachment of the muscles tendon to the moveable bone. usual distal.
belly (body)
fleshy part of the tendons between the tendons
lever system and leverage (fulcrum, effort, load/resistance)
levers - bones (rigid structure that moves around a fixed point (fulcrum) and i acted on by two opposing forces: load and effort
fulcrum - joint
load/resistance - weight of object + bone holding it
effort - of the muscle that needs to contact
prime mover or agonist
within opposing pairs of skeletal muscles, this one leads the contraction to cause an action
antagonist
within opposing pair of skeletal muscles, this one yields and stretches to the force of the prime mover (agonist)
synergist
("work together") prevent unwanted movement at intermediate joints or aid the movement of the prime mover, these muscles contract and stabilize the intermediate joints. e.g., allow fingers to flex but wrists don't have to.
fixator
Stabilize the origin of the prime mover, so then the prime movers can act more efficiently. (steady the proximal end of the limb while movement occurs distally.
occipitofrontalis: frontal belly and occipital belly
Location: Frontal belly superior to the frontal bone. Posterior part called occipital belly superficial to the occipital bone.
Action: Anterior frontal belly draws scalp anteriorly (e.g., wrinkles forehead in surprise). Occipital belly draws scalp posteriorly.
orbicularis oris
(circular mouth) Location: around mouth opening
Action: closes and protrudes lips when kissing; compresses lips against teeth; shapes lips during speech.
zygomaticus major
Location: attaches from zygomatic bone to corner of mouth
Action: moves mouth superiorly and laterally
buccinator
Location: major muscle formation in the cheek
Action: compresses the cheek during blowing action e.g. playing trumpet, whistling, sucking, helps chew
orbicularis oculi
(orb=circular; oculi=eye)
Location: cicular path around eye
Action: closes the eyes
*masseter
(chewer)
Origin: maxilla and zygomatic arch
Insertion: Angle and ramus of mandible
Location:
Action: Elevates mandible when closing mouth
*temporalis
(time/temples)
Origin: Temporal bone
Insertion: Coronoid process and ramus of mandible
Action: Elevates and retract mandible
Location: Large fan of muscles above the temporal lobe
*sternocleidomastoid
(streno=breastbone; cleido=clavicle; mastoid=mastoid process of temporal bone)
Origin: sternal head; manubrium of sternum; clavicular head; medial third of clavicle.
Insertion: Mastoid process of temporal bone and lateral half of superior superior muchal line
Location: the big strong muscle that can be felt at the side of the neck
Action: flex cervical portion of vertebral column; extend head on atlanto-occipital joint; laterally flex and rotate neck; extension of head
*rectus abdominis
(rectus=fascicles parallel to midline)
Origin: pubic crest and pubic symphysis
Insertion: cartilage of ribs 5-7 and xiphoid process
Action: Flexes vertebral column, especially lumbar. Compresses abdomen for forces exhalation and to help with child birth and going to the bathroom.
external oblique
Location: Superficial lateral abdomen. fascicles extend inferiorly and medially. Action: acting together bilaterally to compress abdomen and flex vertebral column; acts unilaterally to flex, rotate vertebral column.
internal oblique
Location: deeper than external oblique. Action: both act together to compress abdomen and flex vertebral column; acts singly to flex and rotate v. column. esp. lumbar.
transversus abdominis
(fascicles are perpendicular to the midline) Location: deeper than the internal oblique Action: compresses abdomen
diaphragm
Location: separates thoractic and abdominal cavity. Action: powers breathing - during inhalation the dome shape contracts and flattens, which increases space in the thoracic cavity. relaxation of the thoracic cause it to move superiorly and decrease vertical dimension of thor. cav. which result in exhalation.
external intercostal
Location: superficial layer in the spaces between ribs. Action: Elevate thoracic cavity and increases anteroposterior dimension in inhalation; in exhalation this space decreases.
internal intercostal
Location: deep to the external intercostal; fascicles move inferiorly laterally. . Action: contraction draw adjacent ribs together to decreases dimension of thoracic cavity.
*trapezius
Location: superficial/ upper back. It extends from the skull and vertebral column to the pectoral girdle (large, flat, triangular). Acion: rotates and stabilizes scapula; can help extend head. Origin: Superior nuchal line of occipital bone, ligamentum nuchae, and spines of C7-T12. Insertion: clavicle and acromion and spine of scapula.
*levator scapulae
(elevates scapula) Origin: Transverse processes of C1-C4. Insertion: Superior vertebral border of scapula. Location: area between cervix of neck and medial edge of scapula. Action: Elevates scapula and rotates in downward.
rhomboid major
Location: deep to the trapezius; from the spine T2-T5 to the medial edge /vertebral border of the scapula inferior to the spine. Action: Elevates and abducts scapula, rotates it downward. stabilizes.
*pectoralis major
Origin: clavicle (clavicular head), sternum, costal cartilages of second to sixth rib and sometimes first to seventh ribs (sternocostal head). Insertion: Greater tubercle and lateral lip of intertubercular sulcus of humerus. Action: adducts and medially rotate arm at shoulder joint; clavicular head flexes arm and sternocostal head extends flexed arm to side of trunk. Location: extend from sternum clavicle are collects with muscles in the upper humerus, below the deltoid.
latissimus dorsi
(widest + on the back) Location: Beneath T7 extends all the way down the spine and up the sides. forms most of the posterior wall of the axilla. Action: Extend, adducts, and medially rotate arm at shoulder joint. draw arm inferiorly and posteriorly.
*deltoid
Origin: acromial extremity of clavicle, acromion of scapula, and spine of scapula. Insertion: deltoid tuberosity of humerus. Action: abduct arm at shoulder joint; medially and laterally rotate arm at shoulder.
subscapularis
Origin: subscapular fossa of scapula. Insertion: Lesser tubercle of humerus. Action: Medially rotates arm at shoulder joint. Location: subscapular fossa - anterior side of scapula.
*supraspinatus
Origin: Supraspinous fossa of scapula. Insertion: greater tubercle of humerus. Action: Assists deltoid muscle in abducting arm at shoulder joint. Location: above/ superior to the infraspinatus.
infraspinatus
(infra=below) Location: below suprapinatus on the scapula. Action: Laterally rotates arm at shoulder joint.
teres major
Location: inferior to the teres minor - scapula to humerus. Action: extends arm at shoulder joint and assists in adduction and medial rotation of arm and shoulder joint.
teres minor
Location: Inferior/ below the infraspinatus; scapula to humerus. Action: laterally rotates and extends arm.
*biceps brachii
Origin: Long head originates from tubercle above glenoid cavity of scapula (supraglenoid tubercle). Short head originates from coracoid process of scapula. Insertion: Radial tuberosity of radius and bicipital aponeurosis. Action: Flexes forearm at elbow joint; supinates forearm at radioulnar joints, and flexes arm at shoulder joint.
brachialis
Location: anterior surface of humerus to the ulna. Action: Flexes forearm at elbow joint.
brachioradialis
Location: humerus to radius. Action: Flexe forearm at elbow joint; supinates (turns palms anteriorly)and pronates (turns palms postreiorly) forearm at radioulnar joint
*triceps brachii
Origin: Long head originate from infraglenoid tubercle, a projection inferior to the glenoid cavity of scapula. Insertion: olecranon of ulna. Action: extends forearm at elbow. Action: extends forearm at elbow joint and extends arm at shoulder joint.
pronator teres
(forearm pronator - turn palms posteriorly0 Origin: Medial epicondyle of humerus and coronoid process of ulna. Insertion: midlateral surface of radius. Action: pronates forearm at radioulnar joints and weakly flexes forearm at elbow joint.
supinator
(turns palms anteriorly) humerus near elbow to to radius. Action: supinates forearm at radioulnar joint.
*flexor carpi radialis
(flexor = decrease angle at joint; carpi=wrist; radi=radius) Origin: medial epicondyle of humerus. Location: second and third metacarpals. Action: flexes and abducts hand (radial deviation) at wrist joint
palmaris longus
(palm + long) Location: humerus to the fascia in the centre of the palm. Action: weakly flexes hand at wrist joint.
*flexor carpi ulnaris
(flexes + wrist + ulna) Origin: medial epicondyle of humerus and superior posterior border of ulna. Insertion: Pisiform, hamate, and base of fifth metacarpal. Action: Flexes and abducts hand (ulnar deviation) at wrist joint.
*flexor digitorum superficialis
(flex + fingers/toe + close to the surface) Origin: medial epicondyle of humerus, coronoid process of ulna, and ridge along lateral margin of anterior surface of radius. Insertion: middle phalanx of each finger. Action: flexes middle phalanx of each finger at proximal interphalangeal joint; proximal phalanx of each finger at meta carpophalangeal joint, and hand at wrist joint.
extensor carpi radialis longus
(increases angle at joint) origin: lateral supracondylear ridge of humerus. Insertion: second metacarpal. Action: extends and abducts hand at wrist joint (ulnar deviation).
*extensor digitorum
(extension of digits) Origin: lateral epicondyle of humerus. Insertion: distal and middle phalanges of each finger. Action: Extends distal and middle phalanges of each finger at interphalangeal joints, proximal phalanx of each finger at metacarpophalangeal, and hand at wrist joint.
*extensor carpi ulnaris
Origin: lateral epicondyle of humerus and poterior border of ulna. Insertion: fifth metacarpal. Action: Extends and adducts hand at wrist joint (ulnar deviation).
erector spinae
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*psoas major
(psoa=muscle of the loin; major=larger) Location: lateral to the Iliacus. Origin: transverse processes and bodies of lumbar vertebrae. Insertion: with iliacas into lesser trochanter of femur. Action: psoas major and iliacus muscles acting together flex thigh at hip joint, rotate thigh laterally, and flex trunk on hip as in sitting up from supine position.
Iliacus
(Iliac = illium) Location: lliac and sacrum alongside the psoas major into lesser trochanter of femur. Action: works with psoas to flex thigh at hip; flex trunk when sitting up from supine; rotates thigh laterally.
*gluteus maximus
(glute=rump of but; maximus= largest) Location: superficial to the other smaller muscles in that region. Origin: lliac crest , sacrum, coccyx, and aponeurosis of sacrospinalis. Insertion: IIiotibial tract of fascia lata and superior lateral part of linea aspera (gluteal tuberosity) under greater trochanter of femur. Action: extend thigh at hip joint and laterally rotates thigh.
gluteus medius
(medius= middle) Location: llium to femur. Action: abducts thigh at hip joint and medially rotates thigh.
adductor longus
(moves parts closer to midline + long). Location: pubic area to femur. Action: Adducts and flexes thigh at hip joint and rotates thigh.
adductor magnus
(magnus=large) Location: pubic and ishium area to femur. Action: thigh at hip joint and rotates thigh; anterior part flexes thigh at hip joint, and posterior part extends thigh at hip joint.
quadriceps femoris (commonly called the "quads")
(quadricep=four heads; femoris=femur) largest muscle in the body. comprised of rectus femoris, vastus lateralis vastus medialis, vastus intermedius. Location: anterior surface and sides of the thighs. Action: extends leg at knee joint
*rectus femoris
(rectus=fascicle parallel to midline) Location: anterior aspect of the thigh. Origin: anterior inferior iliac spine. Insertion: patella via quadriceps tendon and then tibial tuberosity via patellar ligament. Action: All four heads extend leg at knee joint. Rectus femoris acts alone to flex thigh at hip joint.
vastus lateralis
Location: on the lateral aspect of the thigh. Action: works as a part of quads to extend leg at knee.
vastus medialis
Location:medial aspect of the thigh. Action: works as a part of quads to extend leg at knee.
vastus intermedius
Location: deep to the rectus femoris between the vastus lateralis and vastus medialis.
sartorius
(tailor's muscle - cross legged position) Location: across the thigh of the hip bone ilium to the medial side of the tibia. Action: flexes leg at knee joint; weakly flexes, abducts, and laterally rotates thigh at hip joint. [Show Less]