Med Muscular System



Muscular Anatomy Interact 3D



Eye Muscles



Neck Muscles



Shoulder Muscles



Name OriginInsertionActionNerve
Deltoidlateral 3rd of clavicle,
acromion & spine of
scapula
acromion & spine of
scapula
deltoid tuberosity of
humerus
• agonist of arm abduction with all fibers, antagonist of pectoralis major
& latissimus dorsi
• flexes & medially rotates humerus
with anterior fibers, synergist of
pectoralis major
• extends & laterally rotates arms with
posterior fibers
Axillary nerve
Supraspinatussupraspinous fossa of
scapula
superior part of
greater tubercle of
humerus
• stabilizes shoulder joint
• helps prevent downward dislocation
of humerus
Suprascapular
nerve
Infraspinatusinfraspinous fossa of
scapula
greater tubercle of
humerus, posterior to
supraspinatus
• helps to hold head of humerus in
glenoid cavity
• stabilizes the shoulder joint
• rotates humerus laterally
Suprascapular
nerve
Subscapularissubscapular fossa of
scapula
lesser tubercle of
humerus
• chief medial rotator of humerus, assisted by pectoralis major
• helps to hold head of humerus in
glenoid cavity, stablizes shoulder
Subcapular
nerve
Teres minorlateral border of dorsal scapular surfacegreater tubercle of
humerus, inferior to
infraspinatus
• helps to hold head of humerus in
glenoid cavity
• stabilizes the shoulder joint
• rotates humerus laterally
Axillary nerve
Teres majorposterior surface of scapula @ inferior angleintertubercular groove
of humerus, tendon
fused with tendon of
latissimus dorsi
• posteromedially extends, medially
rotates, & adducts arm
• synergist of latissimus dorsi
Lower scapular
nerve

Arm Muscles


NameOriginInsertionActionNerve
Coracobrachialiscoracoid process of
scapula
medial surface of
humerus shaft
• flexion & adduction of humerus
• synergist of pectoralis major
Musculocutaneous nerve
Biceps brachiilong head (65-1): tubercle above glenoid cavity and lip of glenoid
cavity of scapula
short head: (65-2): coracoid process of scapula
by common tendon to
radial tuberosity
• flexes elbow joint & supinates
forearm (usually at the same
time)
• weak flexor of arm @ shoulder
Musculocutaneous nerve
Brachialisfront of distal humeruscoronoid process of
ulna
• major forearm flexor, synergist
with biceps brachii
Musculocutaneous nerve
Brachioradialislateral supracondylar
ridge @ distal end of
humerus
base of styloid process of radius• synergist in forearm flexion, best
when forearm is partially flexed
• stabilizes the elbow during rapid
flexion & extension
Radial nerve
Triceps brachiilateral head: posterior shaft of humerus
long head:
infraglenoid tubercle
of scapula
medial head):
posterior humeral shaft
distal to radial groove
by common tendon
into olecranon process of ulna
• agonist of forearm extension
(medial head)
• antagonist of forearm flexors
• stablizes shoulder joint & assist in
arm adduction (long head tendon)
Radial nerve
Anconeuslateral epicondyle of
humerus
lateral aspect of olecranon process• abducts ulna during forearm
pronation
• synergist of triceps brachii in
elbow extension
Radial nerve

Forearm Rotators


NameOriginInsertionActionNerve
Pronator teresmedial epicondyle of humerus, coronoid process of ulnaby common tendon
into lateral radius,
midshaft
• pronates forearm
• weak flexor of elbow
Median nerve
Supinatorlateral epicondyle of humerus, radial collateral & annular ligaments,
supinator fossa & crest of ulna
lateral, anterior &
posterior surfaces of
proximal 1/3 of radius
• forcibly supinates forearm with
biceps brachii
• weakly supinates forearm working along
• antagonist of Pronator teres
Posterior interosseous nerve

Wrist Flexors


NameOriginInsertionActionNerve
Flexor carpi
radialis
medial epicondyle of
humerus
base of 2nd & 3rd
metacarpals (anterior)
• powerful flexor of wrist
• abducts the hand
• weak synergist of elbow flexion
Median nerve
Palmaris longusmedial epicondyle of
humerus
palmar aponeurosis,
skin & fascia of palm
• weak wrist flexor
• weak synergist of elbow flexion
• tenses skin of palm during hand
movements
Median nerve
Flexor carpi
ulnaris
medial epicondyle of
humerus, olecranon process & posterior surface of ulna
pisiform & hamate
bones & base of 5th
metacarpal (anterior)
• powerful flexor of writs
• adducts hand with extensor carpi ulnaris
• stabilized wrist during finger
extension
Ulnar nerve

Wrist Extensors


NameOriginInsertionActionNerve
Extensor carpi
radialis longus
lateral supracondylar
ridge of humerus
base of 2nd metacarpal (posterior)• extends wrist with extensor carpi ulnaris
• abducts write with flexor carpi radialis
Radial nerve
Extensor carpis
ulnaris
lateral epicondyle of
humerus & posterior
border of ulna
base of 5th meta• extends & adducts wristDeep branch of
radial nerve

Finger Muscles


NameOriginInsertionActionNerve
Flexor digitorum
superficialis
medial epicondyle of humerus, coronoid process of ulna, shaft of radiusby four tendons into
middle phalanges of
fingers 2-5
• flexes wrist & middle phalanges
of fingers 2-5
Median nerve
Extensor
digitorum
lateral epicondyle of humerusby four tendons into
extensor expansions
& distal phalanges of
fingers 2-5
• prime mover of finger extension
• extends wrist
• can abduct (flare) fingers
Posterior interosseous nerve, a branch of radial
nerve
Extensor digiti
minimi
lateral epicondyle of
humerus
extensor expansion of
5th digit
• extends 5th digitPosterior interosseous nerve,deep branch of
radial nerve
Extensor pollicis
longus
posterior surface of middle 3rd of ulnabase of distal phalanx
of thumb
• extends thumbPosterior interosseous nerve
Abductor pollicis
longus
posterior surface of radius & ulnabase of 1st metacarpal
& trapezium
• abducts & extends thumbPosterior interosseous nerve

Chest Muscles


NameOriginInsertionActionNerve
Pectoralis majorsternal end of clavicle, sternum, cartilage
of ribs 1-6, & aponeurosis of external
oblique muscle
by a short tendon into
intertubercular groove
of humerus
• agonist of arm flexion
• rotates arm medially
• adducts arm against resistance
• pulls rib cage upward with scapula
fixed
Lateral &
medial pectoral
nerves
Pectoralis minoranterior surface of
ribs 3-5 (or 2-4)
coracoid process of
scapula
• draws scapula forward & downward (ribs fixed)
• draws rib cage superiorly
(scapula fixed)
Both pectoral
nerves
Subclaviuscostal cartilage of
rib 1
groove on inferior
surface of clavicle
• stablizes & depresses
pectoral girdle
Nerve to subcla
vius
Serratus anterior
(boxer’s muscle)
by series of muscle
slips from ribs 1-9
anterior surface of
vertebral border of
scapula
• agonist to protract & hold
scapula against rib cage
• rotates scapula (infe
rior angle laterally &
upward)
• abduct & raise arm &
horizontal arm move
ments
Long thoracic
nerve

Abdominal Muscles


Above the Umbilicus

Gray399
Henry Vandyke Carter, Public domain, via Wikimedia Commons
Below the Umbilicus

Gray400
Henry Vandyke Carter, Public domain, via Wikimedia Commons

NameOriginInsertionAction Nerve
Rectus Abdominispubic crest & symphysisxyphoid process &
costal cartilages of
ribs 5-7
• flex & rotate lumbar region of vertebral column
• fix & depress ribs
• stabilize pelvis during
walking
• increase intra-abdominal
pressure
Intercostals
External obliqueouter surface of lower 8 ribslinea alba via aponeurosis• when together, synergist
to rectus abdominis, flex
vertebral column & com
press abdominal wall
• when alone, synergist to
muscles of back, rotate & lateral flexion of trunk
Intercostals
Internal obliquelumbar fascia, iliac
crest, & inguinal ligament
linea alba, pubic
crest, last 3 or 4 ribs,
& costal margin
• same as external obliqueIntercostals
Transverse abdominisinguinal ligament,
lumbar fascia, cartilages of last 6 ribs, iliac crest
linea alba, pubic crest• compresses abdominal
contents
Intercostals

Back Muscles


NameOriginInsertionActionNerve
Levator scapulaetransverse processes
of C1-C4
medial border of
scapula, superior to
spine
• elevates & adducts scapula (synergist to trapezius)
• tilts glenoid cavity down, flexes neck to same side (fixed scapula)
Cervical spinal
nerves & dorsal
scapular nerve
Trapeziusoccipital bone,
ligamentum nuchae,
spines of C7 – T12
spine & acromion of
scapula, lateral 3rd of
clavicle
• stabilizes, raises, retracts & rotates scapula
• adducts & retracts scapula (middle)
• elevates scapula or synergist to head extension(superior)
• depresses scapula & shoulder (inferior)
Accessory nerve
Rhomboid minorspinous processes of C7 & T1medial border of
scapula
• retract scapula (squaring shoulders), synergist with middle fibers of Trapezius
• rotate glenoid cavity downward (lowering arm against resistance)
• stabilize scapula
Dorsal scapular
nerve
Rhomboid majorspinous processes of
T2-T5
medial border of
scapula
• retract scapula (squaring shoulders), synergist with middle fibers of Trapezius
• rotate glenoid cavity downward (lowering arm against resistance)
• stabilize scapula
Dorsal scapular
nerve
Latissimus dorsivia lumbodorsal
fascia into spines of
T7-L5, lower 4 ribs &
iliac crest
floor of intertubercular groove of humerus• agonist of arm extension
• powerful arm adductor
• medially rotates arm & shoulder
• depresses scapula
• pulls body upward & forward with
arms fixed overhead
Thoracodorsal

Pelvic Muscles


Pelvic Floor Muscles Superior View


OpenStax, CC BY 4.0, via Wikimedia Commons
Pelvic Floor Muscles Inferior View


Openstax, CC BY 3.0, via Wikimedia Commons

NameOriginInsertionActionNerve
Coccygeusspine of ischiumsacrum & coccyx• supports pelvic viscera
• supports coccyx & pulls
it forward
S4 & S5
Levator aniinside pevis from pubis to ischial spineinner surface of coccyx• supports & maintains pelvic viscera
• resists downward thrusts
• forms sphincters at ano-rectal junction & vagina
• lifts anal canal during
defecation
S4 & inferior
rectal

Hip Muscles


Anterior Hip


Beth ohara, CC BY-SA 3.0, via Wikimedia Commons
Posterior Hip


Beth ohara~commonswiki, CC BY-SA 3.0, via Wikimedia Commons
Posterior Hip


Beth ohara~commonswiki, CC BY-SA 3.0, via Wikimedia Commons