Muscle Guide
Made by Emma Breukink (2026), Modified by Safia Haniya Yusuf (2027)
Pectoral/Axilla Region
Muscle
Origin
Insertion
Innervation
Action
trapezius
sup. nuchal
line, ext.
occipital
protuberance,
ligamentum
nuchae,
spinous
processes of
CV VII to TV
XII
lateral 1/3
clavicle,
acromion, spine
of scapula
CN XI (11)
Rotates, elevates,
retracts and
depresses scapula
latissimus dorsi
spinous
processes of
TV VI to LV V
and sacrum,
iliac crest and
ribs X to XII
intertubercular
groove (also
called
intertubercular
sulcus)
Thoracodorsal
n.
extends, adducts
and medially rotates
humerus l
levator scapulae
transverse
processes of
CV I-IV
superior angle
of
scapula
dorsal scapular
n.
elevates and rotates
scapula
rhomboid major (green)
and minor (red)
spinous
processes of
CV VII to TV
V
medial border
of
scapula
dorsal scapular
n.
retracts, elevates
and
rotates scapula
Deltoid
spine of
scapula,
acromion,
lateral
1/3 of clavicle
deltoid
tuberosity
axillary n.
abduct, flex and
extend arm,
medial and
lateral rotation
Supraspinatus (red)
supraspinous
fossa
superior facet
of
greater tubercle
greater
tubercle
suprascapular
n.
arm abduction
Infraspinatus (blue)
infraspinous
fossa
middle facet of
greater tubercle
suprascapular
n.
lateral rotation of
arm
teres major
lateral
scapular
border
superior to
inferior angle
medial lip of
intertubercular
sulcus (also
called crest of
the lesser
tubercle)
lower
subscapular n.
medial rotation and
adduction of arm,
extends a flexed
arm
teres minor (yellow)
lateral
scapular
border
superior to
teres major
inferior facet of
greater tubercle
axillary n.
lateral rotation of
arm
long head triceps
infraglenoid
tubercle of
scapula
olecranon
process via
common
tendon
radial n.
extends forearm
Subscapularis
subscapular
fossa
lesser tubercle
of humerus
upper and
lower
subscapular
nn.
medial rotation of
arm
pectoralis major
medial ½ of
clavicle,
anterior
Surface of
sternum
lateral lip of
intertubercular
sulcus (aka
crest of greater
tubercle)
medial and
lateral pectoral
nn.
flexion, adduction
and
medial rotation of
arm
pectoralis minor (yellow)
ribs 3-5
coracoid
process
medial pectoral
n.
pulls tip of
shoulder down
& protracts
scapula
Subclavius
first rib
inferior surface
of clavicle
n. to
subclavius
pulls tip of
shoulder down,
pulls clavicle
medially to
stabilize
sternoclavicular
joint
serratus anterior (green)
lateral surface
of
upper 8-9 ribs
costal surface
of
medial scapular
border
long thoracic n.
protraction,
rotation and
depression of
scapula
Shoulder & Upper Arm
Muscle
Origin
Insertion
Innervation
Action
Anterior compartment of arm (flexors)
Coracobrachialis (green)
coracoid process
medial
mid-shaft of
humerus
musculocuta
neous n.
arm flexor
biceps brachii (pink)
long head =
supraglenoid
tubercle of scapula
short head =
coracoid process
radial
tuberosity of
humerus
musculocuta
neous n.
forearm flexor &
supinator
Brachialis (blue)
anterior aspect of
distal humerus
tuberosity of
ulna
musculocuta
neous n.
forearm flexor
olecranon
radial n.
forearm extension,
long head can
extend & adduct arm
Posterior compartment of arm (extensors)
triceps brachii
long head =
supraglenoid
tubercle
medial head =
humeral shaft
inferior to radial
groove
lateral head =
humeral shaft
superior to radial
groove
Back (only responsible for name and function. All are innervated by posterior rami of spinal nerves)
Muscle
Innervation
Function
Posterior rami of the spinal
nerves.
Extend head/neck bilaterally
and rotate those structures
unilaterally.
Superficial
Splenius capitis
Intermediate (Erector Spinae column muscles)
Longissimus, Iliocostalis,
Spinalis
Posterior rami of the spinal
nerves.
extend the trunk and head/neck
when contracted bilaterally and
rotate the same structures when
contracted unilaterally
Posterior rami of the spinal
nerves.
Extend head/neck bilaterally
and rotate those structures
unilaterally. Roof of suboccipital
Δ
Deep
Semispinalis
Elbow & Forearm
Muscle
Origin
Insertion
Innervation
Action
Anterior compartment
Superficial muscle layer (from common flexor tendon → medial epicondyle)
pronator teres
humeral head =
common flexor
tendon ulnar head
= medial side of
coronoid process
lateral surface
of mid-shaft of
radius
median n.
forearm pronator &
weak flexor
flexor carpi radialis
(FCR)
common flexor
tendon
base of
metacarpals
2/3
median n.
hand flexor & abductor
(wrist)
palmaris longus
common flexor
tendon
palmar
aponeurosis
median n.
flexes hand @ wrist
flexor carpi ulnaris
(FCU)
humeral head
(common flexor
tendon) & ulnar
head (olecranon &
posterior ulna)
pisiform,
hamate, &
base of
metacarpal 5
ulnar n.
flexes & adducts hand
@ wrist
Intermediate muscle layer
flexor digitorum
superficialis (FDS)
(in red)
humero-ulnar head
(medial epicondyle
& coronoid
process) & radial
head (oblique line)
intermediate
phalanges 2-5
median n.
flexes int. phalanx, MP
joints, & wrist
flexor pollicis
longus (FPL)
anterior radius &
radial interosseous
membrane
base of distal
phalanx of
thumb
median nerve
(+ ant. interosseous n.)
flexes dist. phalanx of
thumb (& MP)
flexor digitorum
profundus (FDP)
anterior & medial
surface of ulna &
medial
interosseous
membrane
distal phalanx
of digits 2-5
median nerve
(lateral half) &
ulnar nerve
(medial half)
flexes dist. phalanx of
digits 2-5, MP joints, &
wrist
pronator quadratus
distal anterior
surface of ulna
distal anterior
surface of
radius
median nerve
(+ ant. interosseous n.)
pronation of forearm
Deep muscle layer
Posterior compartment
Superficial muscle layer
Brachioradialis
(red)
lateral
lateral distal
supracondylar ridge radius
radial n.
forearm flexor
Anconeus (orange
sliver)
lateral epicondyle
olecranon &
posterior ulna
radial n.
accessory forearm
exten.
extensor carpi
radialis longus
(ECRL)
lateral
base of
supracondylar ridge metacarpal 2
radial n.
extends & abducts
hand @ wrist
extensor carpi
radialis brevis
(ECRB)
common extensor
tendon
radial n. (deep)
extends & abducts
hand @ wrist
base of
metacarpals 2
&3
extensor carpi
ulnaris (ECU)
(purple)
common extensor
tendon & posterior
border of ulna
base of
metacarpal 5
radial n. (+
posterior interosseous n.)
extends & abducts
hand @ wrist
extensor digitorum
(yellow)
common extensor
tendon
extensor
hoods of digits
2-5
radial n. (+
posterior interosseous n.)
extends digits 2-5
extensor digiti
minimi (small
green sliver)
common extensor
tendon
extensor hood
of digit 5
radial n. (+
posterior interosseous n.)
extends digit 5
lateral epicondyle
(superficial) &
supinator crest of
ulna (deep)
lateral proximal radial n. (deep)
radius
Deep muscle layer
Supinator
forearm supination
extensor indicis
posterior surface of
ulna distal to EPL &
adjacent
interosseous
membrane
dorsal hood of
digit 2
radial n. (+
posterior interosseous n.)
extends digit 2
extensor pollicis
(purple)
posterior surface of
ulna distal to APL &
adjacent
interosseous
membrane
distal phalanx
of thumb
radial n. (+
posterior interosseous n.)
extends distal phalanx
of thumb (+ CMC &
MP joints)
extensor pollicis
brevis
posterior surface of
ulna distal to APL &
adjacent
interosseous
membrane
proximal
phalanx of
thumb
radial n. (+
posterior interosseous n.)
extends prox. thumb
phalanx @ MP joint (+
CMC joint)
abductor pollicis
longus (red)
proximal post.
surfaces of radius
& ulna + adjacent
inteross. mem.
lateral base of
MC 1
radial n. (+
posterior interosseous n.)
abducts thumb @
CMC joint
Wrist & Hand
Muscle
Origin
Insertion
Function
Thenar compartment (innervation by recurrent branch of median nerve)
abductor pollicis
brevis (blue)
flexor retinaculum,
scaphoid, trapezium
sesamoid bone,
proximal phalanx,
extensor hood(lat)
abduction at MP joint
flexor pollicis brevis
(red)
flexor retinaculum,
trapezium
sesamoid bone,
proximal phalanx,
extensor hood(lat)
flexion at MP joint
opponens pollicis
(green)
flexor retinaculum,
trapezium
palmar surface & lateral
margin of 1st
metacarpal
medial rotation during
opposition
Hypothenar compartment (innervation by deep ulnar nerve) palmaris brevis = superficial
palmaris brevis
palmar aponeurosis &
flexor retinaculum
skin of ulnar border of
palm
improves grip
abductor digiti
minimi (red)
pisiform, pisohamate
ligament
proximal phalanx of digit
5
abducts digit 5 @ MP
joint
flexor digiti minimi
(green)
flexor retinaculum &
hook of hamate
proximal phalanx of digit
5
flexes digit 5 @ MP joint
opponens digiti
minimi (blue)
flexor retinaculum &
hook of hamate
medial aspect of
metacarpal 5
lateral rotation during
opposition
Interosseus compartment
dorsal interossei
adjacent sides of
metacarpals
(bipennate)
extensor hoods & base
of proximal phalanges
2-5
ABducts digits 2-5,
extends IP
palmar interossei
medial or lateral sides
of metacarpals 2, 4, & 5
(unipennate)
extensor hoods & base
of proximal phalanges of
digits 2, 4, & 5
ADducts digits 2, 4, & 5;
extends IP joints
adductor pollicis
transverse head = MC 3
oblique head = capitate
& metacarpals 2 & 3
base of proximal
phalanx of digit 1 &
extensor hood
adduction of thumb, aids
in opposition
Anterior & Medial Thigh
Muscle
Origin
Insertion
Innervation
Action
Iliopsoas (green)
iliac fossa & TP
+ bodies of
T12-L5
lesser
trochanter of
the femur
ventral rami
L1-3 + femoral
n.
flexes the thigh
Sartorius (purple)
anterior superior
iliac spine
medial
surface of
proximal tibia
femoral n.
flexes and laterally
rotates thigh; flexes
& medially rotates
leg
tensor fasciae latae
(yellow)
anterior superior
iliac spine
iliotibial tract
superior
gluteal n.
abducts, medially
rotates, and flexes
thigh
Anterior thigh
Quadriceps
rectus femoris (has two
arrows)
anterior inferior
iliac spine
tibial
tuberosity
femoral n.
flexes thigh &
extends the leg
vastus medialis (medial to
rectus femoris)
medial lip of
linea aspera &
interochanteric
line
tibial
tuberosity
femoral n.
extends the leg
vastus lateralis (lateral to
rectus femoris)
lateral lip of linea tibial
aspera & greater tuberosity
trochanter
femoral n.
extends the leg
vastus intermedius (deep
to rectus femoris)
anterior & lateral
surfaces of
femur
tibial
tuberosity
femoral n.
extends the leg
body of pubis &
inferior pubic
ramus
superior part
of medial
surface of
tibia
obturator n.
adducts the thigh;
flexes & internally
rotates the leg
Medial thigh
Gracilis
Pectineus (orange)
superior pubic
ramus
pectineal line
of femur
femoral n.
adducts the thigh
adductor longus (yellow)
body of pubis
inferior to pubic
crest
middle third of
linea aspera
obturator n.
adducts the thigh
adductor brevis (green)
body of pubis &
inferior pubic
ramus
pectineal line
& proximal
linea aspera
obturator n.
adducts the thigh
adductor magnus (pink)
ischiopubic
ramus and
ischial tuberosity
gluteal
tuberosity,
linea aspera,
medial
supracondylar
line
(adductor);
adductor
tubercle of
femur
(hamstring
part)
obturator n.
(adductor);
tibial division
of sciatic
nerve
(hamstring)
adducts & extends
the thigh
obturator externus (purple)
external margins
of obturator
membrane
(medial)
trochanteric
obturator n.
fossa of femur
(lateral)
laterally rotates the
thigh
Gluteal Region & Posterior Thigh
Muscle
Origin
Insertion
Innervation
Action
gluteus maximus (red, cut)
ilium posterior to
posterior gluteal
line, dorsal
surface of sacrum
+ coccyx, &
sacrotuberous
ligament
iliotibial tract
& gluteal
tuberosity
inferior
gluteal n.
extends &
laterally
rotates the
thigh
gluteus medius (green, cut)
external surface of
ilium between
anterior &
posterior gluteal
lines & gluteal
fascia
lateral
surface of
greater
trochanter of
femur
superior
gluteal n.
abducts &
medially
rotates the
thigh
gluteus minimus (yellow)
lateral surface of
the ilium between
the anterior
gluteal & inferior
gluteal lines
anterior
surface of
greater
trochanter of
the femur
superior
gluteal n.
abducts &
medially
rotates the
thigh
tensor of fascia lata
anterior superior
iliac spine
iliotibial tract
superior
gluteal n.
abducts,
medially
rotates &
flexes the
thigh
Gluteal region
Piriformis (orange)
anterior surface of
the sacrum
greater
trochanter of
the femur
(lateral)
anterior rami
of S1 & S2
laterally
rotates the
thigh
obturator internus (purple)
internal margin of
obturator foramen
& inner surface of
obturator
membrane
greater
trochanter of
the femur
(lateral)
nerve to
obturator
internus
laterally
rotates the
thigh
superior gemellus (blue)
ischial spine
(medial)
greater
trochanter of
the femur
(lateral) &
obturator
internus
tendon
nerve to
obturator
internus
laterally
rotates the
thigh
inferior gemellus (red)
ischial tuberosity
(medial)
greater
trochanter of
the femur
(lateral) &
obturator
internus
tendon
nerve to
quadratus
femoris
laterally
rotates the
thigh
quadratus femoris (under inferior
gemellus)
ischial tuberosity
(medial)
quadrate
tubercle
(lateral)
nerve to
quadratus
femoris
laterally
rotates the
thigh
ischial tuberosity
(long head) &
lateral tip of linea
aspera (short
head)
head of
fibula
tibial division
of the sciatic
n. (long head)
& common
fibular
division of
sciatic n.
(short head)
extends the
thigh (long
head) &
flexes the leg
Posterior thigh
biceps femoris
Semitendinosus
ischial tuberosity
medial
surface of
the superior
part of tibia
tibial division
of sciatic n.
extends the
thigh &
flexes/
medially
rotates the
leg
semimembranosus
ischial tuberosity
extends the
thigh &
flexes/
medially
rotates the
leg
tibial division
of sciatic n.
extends the
thigh &
flexes/
medially
rotates the
leg
Leg & Foot Dorsum
Muscle
Origin
Insertion
Innervation
Action
gastrocnemius (yellow)
superior to lateral &
medial femoral
condyles
posterior
surface of
calcaneus vis
calcaneal
tendon
tibial n.
plantarflexes
the foot &
flexes the knee
Plantaris (purple)
lateral supracondylar
line of femur
posterior
surface of
calcaneus vis
calcaneal
tendon
tibial n.
plantarflexes
the foot &
flexes the knee
Posterior compartment
Superficial group
Soleus (green)
soleal line of the tibia
and head of the fibula
posterior
surface of
calcaneus vis
calcaneal
tendon
tibial n.
plantarflexes
the foot
Popliteus
lateral femoral
condyle
posterior
surface of tibia
superior to
soleal line
tibial n.
unlocks the
fully extended
leg, weakly
extends knee
tibialis posterior
tibia, fibula, &
interosseous
membrane
mainly to
navicular
tuberosity &
medial
cuneiform
tibial n.
inverts &
plantarflexes
the foot
flexor digitorum longus
medial part of
posterior surface of
tibia inferior to the
soleal line
bases of the
distal
phalanges of
the lateral 4
toes
tibial n.
flexes toes 2-5
and
plantarflexes
the foot
flexor hallucis longus
inferior two-thirds of
the fibula &
interosseous
membrane
base of the
distal phalanx
of the big toe
tibial n.
flexes the big
toe & plantar
flexes the foot
Deep group
Lateral compartment
fibularis longus (blue)
head & superior
two-thirds of lateral
surface of tibia
base of 1st
metatarsal &
medial
cuneiform
superficial
fibular n.
evert & plantar
flex the foot
fibularis brevis (yellow)
inferior two-thirds of
lateral surface of
fibula
tuberosity of
the 5th
metatarsal
bone
superficial
fibular n.
evert & plantar
flex the foot
deep fibular n. dorsiflexes &
inverts the foot
Anterior compartment & foot dorsum
Anterior leg
tibialis anterior (green)
lateral condyle &
superior lateral
surface of tibia
base of 1st
metatarsal &
medial
cuneiform
extensor hallucis longus
(purple)
middle part of anterior
surface of fibula &
interosseous membrane
dorsal aspect of deep fibular n.
base of distal
phalanx of big
toe
extends big
toe &
dorsiflexes the
foot
extensor digitorum
longus (red)
lateral condyle of tibia
& superior ¾ of
anterior surface of
interosseous mem
extensor
expansion of
distal
phalanges of
lateral 4 digits
deep fibular n. extends lateral
4 digits & dorsi
flexes the foot
fibularis tertius
inferior ⅓ of anterior
surface of fibula &
interosseous mem
dorsum of base
of 5th
metatarsal
deep fibular n. dorsiflexes &
everts foot
extensor digitorum brevis
(red)
calcaneus, floor of
tarsal sinus
extensor
expansions of
digits 2-5
deep fibular n. extends digits
extensor hallucis brevis
(yellow)
calcaneus, floor of
tarsal sinus
big toe
extensor
expansion
deep fibular n. extends big
toe
Foot dorsum
Sole of foot
Gluteal Region & Posterior Thigh
Muscle
Origin
Insertion
Innervation
Action
Flexor digitorum brevis
Calcaneal
tuberosity &
plantar
aponeurosis
Middle
phalanges of
lateral 4 toes
Medial
plantar n.
Flexes toes
2-5
Abductor hallucis
Medial process
of tuberosity &
plantar
aponeurosis
Medial side of
base of
proximal
phalanx of 1st
digit
Medial
plantar n.
Abducts &
flexes 1st
digit
Abductor digiti minimi
Medial & lateral
processes of
tuberosity of
calcaneus,
plantar
aponeurosis, &
inter- muscular
septa
Lateral side of
proximal
phalanx of 5th
digit
Lateral
plantar n.
Abducts &
flexes 5th
digit
Medial surface &
lateral margin of
plantar surface of
calcaneus
Posterolateral
margin of
tendon of
flexor
digitorum
longus
Lateral
plantar n.
Flexes lateral
4 digits
1st layer
2nd layer
Quadratus plantae
Lumbricals
Tendons of flexor
digitorum longus
Medial aspect
of extensor
expansion of
lateral 4 digits
Medial
plantar (1) &
lateral
plantar (2-4)
Flexes
proximal
phalanges &
extends
middle &
distal
phalanges of
digits 2-4
Flexor hallucis brevis
Lateral cuneiform
& cuboid (lateral
head) & tendon
of tibialis
posterior
(medial)
Both sides of
base of
proximal
phalanx of 1st
digit
Medial
plantar n.
Flexes
proximal
phalanx of
1st digit
Adductor hallucis
Bases of
metatarsals 2-4
(oblique head),
plantar ligaments
of MTP
(transverse
head)
Lateral side of
base of
proximal
phalanx of 1st
digit
Deep branch
of lateral
plantar n.
Adducts 1st
digit
Flexor digiti minimi
Base of 5th
metatarsal
Base of
proximal
phalanx of 5th
digit
Superficial
branch of
lateral
plantar n.
Flexes
proximal
phalanx of
5th digit
3rd layer
4th layer
Plantar interossei
Plantar surface
of metatarsals
3-5
Medial sides of
bases of
phalanges of
digits 3-5
Lateral
plantar n.
Adducts
digits 3-5 &
flexes MP
joints
Dorsal interossei
Adjacent sides of
metatarsals 1-5
Medial side of
proximal
phalanx of 2nd
digit (1st),
lateral sides of
proximal
phalanx of
digits 2-4
Lateral
plantar n.
Abducts
digits 2-4 &
flexes MTP
joints