Muscles Flashcards
Muscles nomenclature Muscles in action 1 and 2
How do muscles work?
Skeletal muscles work together or in opposition
Muscles only do what?
Muscles only pull
What happens to insertion and origin when muscles shorten?
As muscles shorten, the insertion generally moves toward the origin
How do muscles affect each other?
Whatever a muscle (or group of muscles) does, another muscle (or group) “undoes”
Origin
fixed or immovable point of attachment
Insertion
attachment to movable bone
Prime Movers (agonist)
provide the major force for producing a specific movement
Antagonists
oppose or reverse a particular move; they can be a prime mover (located opposite side of joint)
Synergists
Add force to a move
reduce undesirable or unnecessary movement
Fixators
synergists that immobilize a bone or muscle’s origin (fixing of scapula)
Fascicle
bundle of skeletal muscle fiber surrounded by perimysium
Parallel
Fascicles run parallel to the long axis of the muscle (sartorius)
fusiform
spindle-shaped muscles
biceps brachii
Pennate
short fascicles that attach obliquely to a central tendon running the length of the muscle
convergent
fascicles converge converge from a broad origin to a single tendon insertion
Circular
fascicles are arranged in concentric rings
Where do our muscles produce movement?
at joints
How do muscles act at joints?
Muscle only act at those joints that lie between it origin and insertion
First question to ask yourself about muscle mechanics?
What joint or joints the muscle crosses?
Assume subject is in anatomical position
Optimum Angle of Pull
Optimum is reached when two bones are just near a right angle
MAJOR SKEL MUSCLES: ANTERIOR VIEW
40 superficial muscles here are divided into 10 regional areas of the body
Maj skel mus: post view
27 superficial muscles divided into 7 regional areas of the body
Frontalis
covers forehead and dome of skull and raises eyebrows
Orbicularis oculi
sphincter muscle of eyelid
produces blinking and squinting
Zygomaticus
smiling muscle
Masseter
PM of jaw closure
Platysma
assists depressing mandible
Pulls lower lip back and down; tenses skin of neck
Temporalis
Closes Jaw
elevates and retracts mandible
holds mandible at rest position
sternocleidomastoid
bisects neck diagnolly
What is the origin of the sternocleidomastoid?
manubrium of sternum and medial 1/3 of clavicle
What is the insertion of the sternocleidomastoid?
mastoid process of temporal bone
What muscle is the prime mover action in the sternocleidomastoid?
head flexion and lateral flexion
sternohyoid
most medial muscle of neck, and Depression of hyoid bone
Trapezius
most superficial muscle of the posterior thorax; flat
What is the origin of the Trapezius muscle?
occipital bone
spinous process of C7 and all thoracic vertebrae
What is the insertion of Trapezius muscle?
lateral 1/3 of clavicle
acromion process
spine of scapula
What is action of upper fibers of traps ?
attach to clavicle aid suspending shoulder girdle
assists with elevate and upward rotation of scapula
Action of middle fibers of traps?
adduction of scapula, keeps scapulae from slipping laterally around the thorax when arms elevated
action of Lower fibers of traps?
stabilizes arm when trunk flexed example reach for high shelf
a shoulder shrug is an example of what fiber of the traps?
upper fibers
Bent-over or seated row is an example of what fiber of the traps?
middle fibers
Erector spinae are prime movers of what action and who are they?
back extension
Iliocostalis
longissimus
spinalis
Iliocostalis
most lateral
extends from pelvis to neck
Longissimus
intermediate
lumbar region to skull
Spinalis
medial most
lumbar to cervical
Quadratus lumborum origin
iliac crest and iliolumbar fascia
Quadratus lumborum insertion
transverse processes of upper 4 lumbar vertebrae
and 12th rib
what does quadratus lumborum maintain?
upright posture
lateral flexes lumbar spine
Quadratus lumborum is a what for respiration?
accessory breathing muscle inspiration
Ab muscle consist of what?
lateral and anterior abdominal wall
no bones
3 pairs=lateral wall
external and internal oblique, transervsus abdominis, and rectus abdominis
When are abs the best?
best when muscle is toned (feels tough when relaxed)
ab muscles functions?
support
protect
movement
(Iateral flexion ,rotation of trunk, anterior flexion of trunk)
Relax during inspiration
contracted aid in forced expiration
Valsalva maneuver
Defecation, childbirth, vomiting, coughing, burping and nose blowing
Rectus abodiminis
medial superficial muscle, vertical, lies on either side of the line alba, its the 6 pack
Rectus abdominis origin
pubic crest and adjacent ligament
Rectus abdominis insertion
xiphoid process, catrilages of ribs 5-7
external oblique origin
outer surface of lower 8 ribs
external oblique insertion
crest of pubic, linea alba iliac crest, and aponeurosis
internal oblique origin
anterior 2/3’s iliac crest, inguinal ligament, and fascia sheaths
internal oblique insertion
lower 3-4 ribs, pubic crest, linea alba
Transversus abdominis origin
costal cartilage of lower 6 ribs, inguinal ligament, lumbodorsal fascia
Transversus abdominis insertion
Linea alba, pubic crest
What are the 9 muscles crossing the shoulder joint?
Prime movers:
Latissimus dorsi
Pectoralis major
Deltoid
Rotator cuff: supraspinatus infraspinatus Teres minor subscapularis
Teres major
Coracobrachialis
what makes up the anterior thorax?
Pec major and minor
Pectoralis major origin
clavicle, sternum, 1-6 ribs, apneurosis of external oblique muscle
Pec major insertion
greater tubercle of humerous
Pec major action
PM of arm flexion, internal or medial rotation-rotate toward midline of body
Pec minor origin
anterior surfaces of ribs 3-5
Pec minor insertion
coracoid process of scapula
Pec minor action
draws scapula fwd and downward with ribs fixed; draws rib cage superior with scapula fixed
Serratus Anterior location
lies deep to the scapula, inferior to pectorals on lateral rib cage
Serratus Anterior description
serrated or sawtooth
Serratus Ant origin
series of muscle slips from ribs 1-8
serratus ant insertion
anterior surface of vertebral border of scapula
Serratus ant action
PM to protract and hold scapula against chest wall
rotates scapula: inferior angle moves laterally and upward, and play vital role in abduction and raising arm in horizontal plane
Latissimus Dorsi
broad flat triangular muscle of low back; play vital role in bringing arm down in a power stroke
Example latissimus dorsi use of power stroke
swimming(phelps)
rowing
hammering
Latissimus dorsi origin
lumbodorsal fascia, spines of t6-t12, spines of lumbar and sacral vertebrae, lower 3-4 rings, posterior iliac crest
Latissimus dorsi insertion
floor of bottom of intertubercular groove
Latissimus dorsi action
extends, adducts and rotates arm medially; draws shoulder downward and backward
deltoid forms
rounded shoulder muscle mass multipennate muscle
deltoid origin
1/3 clavicle
acromion process
spine of scapula
deltoid insertion
deltoid tuberosity of humerous
deltoid action
antagonist to pec major and latissimus dorsi
PM abduction of arm
anterior fibers flex and medially rotate humerus; posterior fibers extend and laterally rotate humerus
rotator cuff
muscles and tendons that stab shoulder
they keep head of humerus in the glenoid cavity
Supraspinatus origin
supraspinatus fossa
Supraspinatus insertion
superior most part of greater tubercle of humerus
supraspinatus action
abduction arm
stabilize shoulder jt
assists prevention of downward dislocation of humerus
Infraspinatus origin
lateral border of dorsal scapular surface
infraspinatus insertion
greater tubercle of humerus
infraspinatus action
lateral rotator of humorous; holds head of humerus in glenoid cavity
subscapularis origin
subscapularis fossa
subscapularis insertion
lesser tubercle of humerus
subscapularis action
medial rotation of humerus; helps hold humerus in glenoid cavity
Teres Major origin
Posterior/dorsal surface of inferior angle of scapula
Teres Major insertion
crest of lesser tubercle of humerus
Teres Maj action
extends medially rotates and adducts humerus; synergist to latissimus dorsi
Posterior Thorax location
at back and side of neck; deep to trapezius
Posterior Thorax origin
Transverse processes of C1-c4
Posterior Thorax insertion
vertebral border at the root of the spine
Posterior Thorax action
elevates and adducts scapula, similar to upper fibers of traps (synergists), when scapula fixed= flexes neck to same side