Skeletal Muscles

Part 4: Appendicular Muscles

 Upper Limb Muscles
Deltoid
Origin:
• Lateral 1/3 of clavicle
• Acromion
• Spine of scapula
Insertion:
• Deltoid tuberosity of
humerus
Actions:
• Arm abduction
• Flexion of humerus
• Extension of humerus
• Medial and lateral rotation of humerus
Upper Limb Muscles – Rotator Cuff
Posterior View
Supraspinatus
Origin:
• Supraspinous fossa of
scapula

Insertion:
• Greater tubercle of
humerus

Action:
• Abduction of arm
• Stabilizes shoulder joint
Upper Limb Muscles – Rotator Cuff
Posterior View Infraspinatus

Origin:
• Infraspinous fossa

Insertion:
• Greater tubercle of
humerus

Action:
• Lateral rotation of arm
• Stabilizes shoulder joint
Scapula to Humerus – Rotator Cuff
Posterior View
Teres minor
Origin:
• Posterior scapula, lateral
border

Insertion:
• Greater tubercle of humerus

Action:
• Lateral rotation of arm
• Stabilizes shoulder joint
Upper Limb Muscles – Rotator Cuff
Anterior View
Subscapularis

Origin:
• Subscapular fossa

Insertion:
• Lesser tubercle of
humerus

Actions:
• Medial rotation of the
arm
• Stabilizes shoulder joint
 Upper Limb Muscles
Posterior View Teres major
Origin:
• Posterior surface of
scapula, inferior angle

Distal attachment:
• Medial lip of bicipital
groove

Actions:
• Medial rotation of arm
• Extension of arm
• Adduction of arm

Note: NOT a rotator cuff muscle!

Anterior Arm Muscles
Biceps brachii
Origin:
• Long head: Supraglenoid
tubercle of humerus
• Short head: Coracoid process of
scapula
Insertion:
• Radial tuberosity of radius

Actions:
• Forearm flexion
• Forearm supination **
• Flexion of the shoulder (minor)
Anterior Arm Muscles
Brachialis
Origin:
• Anterior distal humerus

Insertion:
• Coronoid process of ulna

Actions:
• Elbow (or forearm) flexion
Anterior/Posterior Arm Muscles
Brachioradialis
Origin:
• Lateral supracondylar ridge of
humerus

Insertion:
• Styloid process of radius

Action:
• Forearm flexion (in partial
supination)

“hand shake” muscle

Posterior Arm Muscles
Triceps brachii
Origin:
Long: infraglenoid tubercle of scapula
Medial: posterior surface of humerus
Lateral: posterior surface of humerus

Insertion:
• Olecranon process of ulna

Actions:
Extension of elbow (or forearm)
Adduction of shoulder (minor)
Stabilizes shoulder joint (minor)
 Forearm Muscles
• Anterior Compartment (mostly Flexors)
– Superficial group (4)
• Common flexor tendon on medial epicondyle of
humerus
– Intermediate group (1)
– Deep group (3)
• Do not cross elbow joint

• Posterior Compartment (mostly Extensors)

– Superficial group (4)
– Deep group (5)
Anterior Forearm Muscles – Superficial
All - Origin:
Medial epicondyle of the humerus
(common flexor origin)
Flexor Carpi Ulnaris also originates on the
Flexor carpi olecranon process of ulna and posterior border
Pronator ulnaris
teres of ulna
Flexor carpi Insertions:
radialis
Pronator teres lateral shaft of radius
Palmaris
Flexor carpi radialis base of 2nd and 3rd
longus metacarpal
Palmaris longus palmar aponeurosis
Flexor carpi ulnaris pisiform, base of 5th

metacarpal
Action: PT – pronates forearm; elbow flexion
FCR – flex and abduct wrist (or hand), elbow
flexion
PL – flex wrist; elbow flexion
Anterior Forearm Muscles - Intermediate
Flexor digitorum superficialis (FDS)

Humero-ulnar
Origin:
head • Medial epicondyle of humerus (CFO)
• Coronoid process of ulna
Flexor • Shaft of radius
digitorum
superficialis
Insertion:
• Middle phalanges of digits 2 – 5
Radial head
Actions:
Prox. interphalangeal joints: Flexion
Metacarpophalangeal joints: Flexion
Wrist: Flexion
Elbow: Flexion (weak)

“Bye-bye” muscle
Anterior Forearm Muscles - Deep
Origin:
Flexor digitorum profundus (FDP): Anterior and
medial ulna & interosseus membrane
Flexor pollicis longus (FPL): Anterior radius &
interosseus membrane
Pronator quadratus (PQ): Distal anterior ulna

Insertion:
FDP distal phalanges (digits 2 – 5)
FPL distal phalanx of thumb
PQ distal anterior radius

Actions:
FDP Flexion of distal IP joints; wrist flexion
FPL Flexion of distal thumb; wrist flexion
PQ Forearm pronation
 Insertions of FDS and FDP

http://www.ganfyd.org/images/3/34/Flexor_insertions.GIF
 Forearm Muscles
• Anterior Compartment (mostly Flexors)
– Superficial group (4)
• Common flexor tendon on medial epicondyle of
humerus
– Intermediate group (1)
– Deep group (3)
• Do not cross elbow joint

• Posterior Compartment (mostly Extensors)

– Superficial group (4)
– Deep group (5)
 Posterior Forearm Muscles - Superficial

Origin:
Lateral epicondyle of humerus (CEO)

Insertion:
ECRL: Base of second metacarpal
ECRB: Base of third metacarpal
ED: Distal phalanx of digits 2-5
ECU: Base of fifth metacarpal
 Posterior Forearm Muscles - Superficial

Actions:
• Extension of wrist (or hand)

• ECRL: Abducts wrist (or hand)

• ECRB: Abducts wrist (or hand)
• ED: Finger extension (digits 2-5)
• ECU: Adducts wrist (or hand)
 Posterior Forearm Muscles - Deep
Origin:
Supinator: CEO, proximal ulna

Abductor pollicis longus (APL),

Extensor pollicis longus (EPL) and
brevis (EPB): posterior surface of
radius & ulna, interosseous
membrane

Extensor Indicis (EI): posterior

surface of ulna, interosseous
membrane
 Posterior Forearm Muscles - Deep
Insertion
• Supinator: Proximal radius
• APL: First metacarpal, trapezium
• EPL: Distal phalanx of thumb
• EPB: Proximal phalanx of thumb
• EI: Distal phalanx of digit 2

Actions
Supinator: Forearm supination
APL: Abducts, extends thumb
EPL/EPB: Extend thumb
EI: Extend digit 2, extends wrist
Lower Limb Muscles – Hip and Thigh
Hip and Thigh Muscles:
Iliopsoas
Tensor fascia lata (TFL)
Sartorius
Adductor longus
Adductor magnus
Adductor brevis
Pectineus
Gracilis
Quadriceps (4)
Hamstrings (3) – posterior
Gluteals (3) - posterior
 Lower Limb Muscles – Hip & Thigh
Iliopsoas
Origin:
• Ilium
• Sacrum
• Vertebrae T12-L5

Insertion:
• Lesser trochanter of femur

Actions:
• Hip (thigh) flexion
• Trunk flexion at hip (taking a bow)
• Lateral flexion of vertebral column

http://www.lower-back-pain-answers.com/images/Iliopsoas.jpg
 Lower Limb Muscles – Hip and Thigh
Tensor fascia lata (TFL)
Origin:
• Iliac crest
• Anterior superior iliac spine

Insertion:
• Iliotibial tract (to knee)

Actions:
• Steadies leg and trunk
• Flexion of thigh (hip)
• Abduction of thigh (hip)
• Medial rotation of thigh (hip)
 Lower Limb Muscles – Hip and Thigh
Sartorius
Origin:
• Anterior superior iliac spine

Insertion:
• Medial tibial condyle

Actions:
• Flexion, abduction, lateral
rotation of thigh
• Knee flexion

*for crossing your legs

 Lower Limb Muscles – Hip and Thigh
Adductor Group
Adductor Magnus
Adductor Longus
Adductor Brevis
Pectineus
Gracilis
 Lower Limb Muscles – Hip and Thigh
Adductor Muscles
Origins:
• AM: Ischium & pubis, ischial
tuberosity
• AL: Pubis
• AB: Pubis
• Pectineus: Pubis
• Gracilis: Ischium and pubis
 Lower Limb Muscles – Hip and Thigh
Adductor Muscles
Insertions:
• AM, AL, AB, Pectineus: femur
• Gracilis: Medial tibia

Actions (All):
• Adduction of thigh
• Flexion of thigh
• Medial rotation of thigh
• AM: thigh extension (synergist to
hamstrings)
Lower Limb Muscles – Hip and Thigh
Quadriceps Femoris Group
Origins:
Rectus femoris (RF): AIIS,
Acetabulum
Vastus lateralis (VL): Greater
trochanter, proximal femur
Vastus medialis (VM): Proximal
femur
Vastus intermedius (VI): Proximal
femur
Lower Limb Muscles – Hip and Thigh
Quadriceps Femoris Group
Insertion:
• Patella & tibial tuberosity via
patellar ligament

Actions:
• Leg extension (ALL)
• RF: Flexion of thigh
 Lower Limb Muscles – Hip and Thigh
Gluteal Muscles
Origins:
Gluteus maximus: Ilium,
sacrum, coccyx
Gluteus medius
 Lower Limb Muscles – Hip and Thigh
Gluteal Muscles
Insertions:
Maximus: Gluteal tuberosity of
femur, IT band
Medius/Minimus: Greater trochanter
of femur

Actions:
Maximus: Extension, abduction,
lateral rotation of thigh
Medius/Minimus: Abduction and
medial rotation of thigh

*All important in stabilizing hips

during walking
 Lower Limb Muscles – Hip and Thigh
Hamstrings
• Biceps femoris (BF)
• Semitendinosus (ST)
• Semimembranosus (SM)

Origin:
• Ischial tuberosity
 Lower Limb Muscles – Hip and Thigh
Hamstrings
Insertion:
• BF: Head of fibula, lateral
condyle of tibia
• ST: Proximal tibia
• SM: Medial condyle of tibia

Actions:
• Thigh extension
• Knee flexion
 Leg Muscles - Posterior
Gastrocnemius
Origin:
• Medial and lateral
condyles of femur
Insertion:
• Calcaneus via Calcaneal
Tendon
Actions:
• Plantar flexion
• Knee flexion
 Leg Muscles - Posterior
Soleus
Origin:
• Proximal tibia
• Proximal fibula
• Interosseous membrane
Insertion:
• Calcaneus via Calcaneal Tendon
Action:
• Plantar flexion
 Leg Muscles - Anterior
Tibialis anterior (TA)
Extensor hallucis longus (EHL)
Extensor digitorum longus (EDL)

Origin:
TA: Lateral condyle of tibia, interosseus
membrane
EHL: Fibula, interosseous membrane
EDL: Lateral condyle of tibia, Proximal
fibula, interosseous membrane
 Leg Muscles - Anterior
Insertion:
TA: Medial cureiform, first metatarsal
EHL: Distal phalanx of great toe
EDL: Middle and distal phalanges of
digits 2-5

Actions:
Dorsiflexion (ALL)
TA: Inversion of foot
EHL: Extension of great toe
EDL: Extension of digits 2-5
Leg Muscles -
Anterior
Leg Muscles - Lateral
Fibularis Longus
Fibularis Brevis
Fibularis Tertius

Origin:
FL: Lateral fibula
FB: Distal fibula
FT: Distal fibula,
interosseous membrane
Leg Muscles - Lateral
Insertion:
FL: Medial cuneiform, first
metatarsal
FB: Fifth metatarsal (inferior
surface)
FT: Fifth metatarsal (superior
surface)

Action:
Eversion of foot (ALL)
FL/FB: Plantar flexion
FT: Dorsi flexion