1. Anatomy Review – Muscles
Presented by: Jon Chan

2. Muscles of the Neck
Sternocleidomastoid (SCM)
› O: sternal head – top of manubrium; clavicular
head – clavicle (medial 1/3)
› I: mastoid process & occipital bone
› A: unilaterally – lateral flexion of the head to
the same side, rotation of the head to the
opposite side; bilaterally – flexion of the head

4. Muscles of the Scapula
1.
2.
3.
4.
Serratus Anterior
Trapezius (Upper, Middle, Lower)
Levator Scapulae
Rhomboid (Major / Minor)

5. Muscles of the Scapula
• Serratus Anterior
› O: Anterolateral Superior Borders of ribs 1-8
› I: Medial border of scapula (Anterior Surface)
› A: protraction and upward rotation of scapula

7. Muscles of the Scapula
Trapezius (upper fibers)
› O: occipital protuberance, spinous process of C1 to C7, ligamentum nuchae
› I: Lateral 1/3 of the clavicle
› A: Scapula elevation and upward rotation
Trapezius (middle fibers)
› O: spinous process of T1 to T5
› I: spine of scapula, acromion process (medial border)
› A: scapula retraction
Trapezius (lower fibers)
› O: spinous process of T6 to T12
› I: medial portion of spine of scapula
› A: Scapula depression, retraction and upward rotation

8. Muscles of the Scapula
Levator Scapulae
› O: transverse process of C1 to C4
› I: medial superior angle of scapula
› A: scapulae elevation and downward rotation
Rhomboid Minor
› O: spinous process of C7 and T1
› I: medial border of scapula, superior to spine of scapula
› A: retraction and elevation of the scapula,
aids in downward rotation of the scapula
Rhomboid Major
› O: spinous process of T2 to T5
› I: medial border of scapula, inferior to spine of scapula
› A: scapula retraction, elevation, downward rotation

9. Muscles of the Shoulder
1.
2.
3.
4.
5.
Deltoid (anterior/middle/posterior)
Latissmus Dorsi
Teres Major
Pectoralis Major (Sternal / Clavicular heads)
Pectoralis Minor

10. Muscles of the Shoulder
Deltoid – Anterior
› O: Anterolateral 1/3 of clavicle
› I: deltoid tuberosity
› A: shoulder flexion, internal
rotation, and
horizontal adduction
Deltoid – Middle
› O: acromion process
› I: deltoid tuberosity
› A: Shoulder abduction
Deltoid – Posterior
› O: spine of scapula
› I: deltoid tuberosity
› A: Shoulder abduction,
extension, horizontal abduction and external rotation

11. Muscles of the Shoulder
Latissmus Dorsi
› O: Thoracolumbar fascia, iliac crest, 9-12 ribs, inferior
angle of scapula
› I: floor of biciptial groove of humerus
› A: shoulder extension, adduction and internal rotation
Teres Major
› O: inferior angle, inferior 1/3 lateral border of scapula
› I: medial lip of the bicipital groove of humerus
› A: shoulder extension, adduction and internal rotation

12. Teres Major

13. Muscles of the Shoulder
Pectoralis Major – Sternal portion
› O: sternum (anterior surface) and rib 1 - 7
› I: lateral lip of the bicipital groove of the humerus
› A: Shoulder adduction & internal rotation (both heads)
Sternocostal portion: shoulder Extension (from a flexed position)
Pectoralis Major – Clavicular portion
› O: medial ½ of clavicle (anterior surface)
› I: anterior, medial aspect of humerus, crest of greater tuberosity
› A: Shoulder adduction, internal rotation
Clavicular portion: shoulder flexion & horizontal adduction
Pectoralis Minor
› O: outer surface of ribs 3 -5 or 2-4 near costal cartilages
› I: coracoid process of scapula
› A: Scapula depression, downward rotation and anterior tilt

15. Muscles of the Rotator Cuff

16. Muscles of the Rotator Cuff
Supraspinatus
› O: supraspinous fossa
› I: greater tuberosity of humerus
› A: Shoulder abduction (esp 1st 30degree), stabilization of
the humeral head in the glenoid fossa
Infraspinatus
› O: infraspinous fossa
› I: greater tuberosity of humerus
› A: Shoulder External rotation, stabilization of the
humeral head in the glenoid fossa

17. Muscles of the Rotator Cuff
Teres Minor
› O: superior 2/3 of lateral border of scapula
› I: greater tuberosity of humerus
› A: Shoulder external rotation, stabilization of the humeral head in the
glenoid fossa
Subscapularis
› O: subscapular fossa
› I: lesser tuberosity of humerus
› A: medial rotation of the shoulder, stabilization of the humeral head
in the glenoid fossa
Note: the preceding four muscles are referred to as the rotator cuff

18. Muscles of the Arm
• Anterior Compartment
– Bicep Brachii
– Coracobrachialis
– Brachialis
– Brachioradialis

19. Biceps Brachii
Brachioradialis

20. Muscles of the Arm – Anterior
Compartment
Biceps Brachii
› Origin: Short head – coracoid process of scapula
› Long head – supraglenoid tubercle of scapula
› Insertion: both heads - radial tuberosity
› Action: Elbow flexion, Forearm supination, weak flexor
of shoulder
Coracobrachialis
› O: coracoid process
› I: medial aspect of middle humerus
› A: Shoulder flexion & adduction

21. Muscles of the Arm – Anterior
Compartment
Brachialis
› Origin: anterior surface of lower 1/2 humerus
› Insertion: coronoid process of ulna
› Action: Elbow flexion
Brachioradialis
› Origin: lateral supracondylar ridge of humerus
› Insertion: styloid process of radius
› Action: Elbow flexion, Forearm pronation and
supination

22. Muscles of the Arm
• Posterior Compartment
– Triceps
•
•
•
Long (visible)
Medial
Lateral (visible)

23. Muscles of the Arm – Posterior
Compartment
Triceps Brachii
› O: Long head – infraglenoid tubercle of scapula
Lateral head – posterior humerus above
radial groove
Medial Head – posterior humerus, below
radial groove
› I: olecranon process of ulna
› A: Elbow Extension

25. Muscles of the Thigh
• Anterior thigh
1. Sartorius
2. Quadriceps
•
Rectus Femoris, Vastus Medialis, Vastus Lateralis,
Vastus Intermedius

26. Muscles of the Thigh (anterior)
Sartorius
› O: ASIS
› I: superior aspect of medial tibia
› A: Hip flexion, external rotation,
abduction; knee flexion

27. Muscles of the Thigh (anterior)
Rectus Femoris
› O: AIIS, ilium above acetabulum
› I: tibial tuberosity via quadricep tendon to patella via
patellar ligament
› A: extension of the knee, hip flexion
Vastus Lateralis
› O: greater trochanter, linea aspera (lateral lip)
› I: tibial tuberosity via quadricep tendon to patella via
patellar ligament
› A: knee extension

28. Muscles of the Thigh (Anterior)
Vastus Intermedius
› O: anterior, lateral, surface of femur (superior aspect)
› I: tibial tuberosity via quadricep tendon to patella via patellar
ligament
› A: extension of the knee
Vastus Medialis
› O: intertrochanteric line, linea aspera (medial lip)
› I: tibial tuberosity via quadricep tendon to patella via patellar
ligament
› A: extension of the knee
Note: the preceding four muscles are referred to as the quadriceps

30. Muscles of the Thigh
• Medial Thigh
1.
2.
3.
4.
Adductor longus
Adductor Brevis
Adductor Magnus
Gracilis

31. Muscles of the Thigh (medial)
Adductor Longus
› O: body of pubis (anterior)
› I: middle to inferior 1/3 of linea aspera (medial lip)
› A: Hip adduction
Adductor Brevis
› O: body of pubis & inferior ramus of pubis
› I: pectineal line & superior aspect of linea aspera (medial lip)
› A: hip adduction
Adductor Magnus
› O: Adductor part: inferior ramus of pubis; Hamstring part: ischial tuberosity
› I: Adductor part: medial portion of femur, Hamstring part: adductor tubercle
› A: adduction and lateral rotation of the femur, extension of the hip

32. Muscles of the thigh (medial)
Gracilis
› O: body & inferior ramus of pubis
› I: superior part of the medial tibia (pes anserinus)
› A: Hip adduction and knee flexion and knee
internal rotation

34. Muscles of the Thigh
• Posterior Thigh
1. Biceps Femoris
2. Semi-tendinosus
3. Semi-membranosus

35. Muscles of thigh (posterior)
Biceps Femoris
› Origin: long head - ischial tuberosity, short head – lateral lip of linea aspera
› Insertion: lateral side of the head of fibula
› Action: knee flexion and external rotation of knee(if knee flexed), hip extension
Semitendinosus
› O: ischial tuberosity
› I: superior surface of medial tibia
› A: knee flexion, internal rotation of the knee (if knee is flexed); hip extension
Semimembranosus
› O: ischial tuberosity
› I: posterior aspect of the medial condyle of the tibia
› A: flexion and medial rotation of the knee; extension, adduction and medial rotation
of the hip
•
Note: the preceding three muscles are referred to as the hamstrings

37. Muscles of the Hip
• Superfiscal Layer
1.
2.
3.
4.
5.
Gluteus maximus
Gluteus medius
Gluteus minimus
Tensor fascia lata
Illiopsoas (psoas major / iliacus)

38. Muscles of the Hip
Gluteus Maximus
› O: ilium behind posterior gluteal line, sacrum, coccyx
› I: gluteal tuberosity and ITB
› A: hip extension and external rotation
Gluteus Medius
› O: ilium between posterior and anterior gluteal lines
› I: greater trochanter (lateral surface)
› A: Hip abduction & internal rotation, keep pelvis level
when LL on the same side bears weight

39. Muscles of the Hip
Gluteus Minimus
› O: ilium between anterior and inferior gluteal lines
› I: greater trochanter (anterior surface)
› A: hip flexion, abduction and internal rotation, keep
pelvis level when LL on the same side bears weight.
Tensor Fasciae Latae
› O: ASIS
› I: ITB
› A: Hip abduction and internal rotation

41. Muscles of the Hip
Psoas Major
› O: transverse process of all lumbar spine, sides of T12-L5 vertebrae
and discs.
› I: lesser trochanter of femur
› A: Hip flexion, maintains lordosis (posterior fibres)
Iliacus
› O: iliac fossa
› I: lesser trochanter of femur
› A: Hip flexion
Iliopsoas
the combination of psoas major and iliacus

43. Muscles of the Hip
• Deep Layer
– Piriformis
– Gemelli Superior
– Obturator Internus
– Gemelli Inferior
– Obturator Externus
– Quadratus femoris

44. Muscles of the Hip - deep
Piriformis
› O: sacrum (anterior surface)
› I: greater trochanter (medial surface)
› A: hip external rotation (with thigh extended), abduction and internal
rotation (with thigh flexed)
Obturator Externus
› O: outer surface of obturator foramen
› I: greater trochanter (medial surface)
› A: hip external rotation
Obturator Internus
› O: inner surface of obturator foramen
› I: greater trochanter (medial surface)
› A: hip external rotation

45. Muscles of the hip - deep
Gemellus Superior
› O: Ischial Spine
› I: greater trochanter (medial surface)
› A: Hip external rotation
Gemellus Inferior
› O: ischial tuberosity
› I: greater trochanter (medial surface)
› A: Hip external rotation
Quadratus Femoris
› O: lateral border of ischial tuberosity
› I: quadrate tubercle on intertrochanteric crest
› A: Hip external rotation
• Note: the preceding six muscles are referred to as the deep six lateral rotators of the
hip

47. Muscles of the Leg
• Anterior Compartment
1. Tibialis Anterior
2. Extensor Hallucis Longus
3. Extensor Digitorum

48. Muscles of the Leg (Anterior)
Tibialis anterior (TA)
› O: lateral condyle and superior lateral surface of tibia
› I: medial and inferior surfaces of medial cuneiform & base of 1 st metatarsal
› A: Ankle dorsiflexion and ankle inversion
Extensor digitorum longus (EDL)
› O: lateral condyle of tibia, superior medial surface of fibula
› I: dorsal surfaces of bases of the middle and distal phalanges 2nd – 5th toes
› A: extension of the lateral 4 toes, dorsiflexion of ankle and eversion of foot
Extensor hallucis longus (EHL)
› O: anterior surface of fibula (middle part)
› I: dorsal base of distal phalanx of the 1st toe
› A: extension of 1st toe; ankle dorsiflexion

50. Muscles of the Leg
• Lateral Compartment
1. Peroneous Longus
2. Peroneous Brevis

51. Muscles of the Leg (lateral)
Peroneus longus
› O: head of fibula and superior portion of lateral surface
of fibula
› I: base of 1st metatarsal & medial cuneiform
› A: Ankle eversion, weak ankle plantar flexor
Peroneus brevis
› O: distal portion of lateral surface of fibula
› I: tuberosity of 5th metatarsal
› A: Ankle eversion, weak ankle plantar flexor

53. Muscles of the Leg
• Posterior Compartment
– Superficial
1.Gastrocnemius
2.Soleus
– Deep
1.Tibialis Posterior (TP)
2.Flexor Digitorum Longus (FDL)
3.Flexor Hallucis Longus (FHL)

54. Muscles of the Leg (posterior)
Gastrocnemius
› O: lateral head - lateral condyle of femur; medial head - medial condyle of
femur
› I: calcaneus via Achilles tendon (common calcaneal tendon)
› A: ankle plantar flexion, Knee flexion
Soleus
› O: posterior surface of head and superior 1/3 of fibula; soleal line and
medial border of tibia
› I: calcaneus via Achilles tendon (common calcaneal tendon)
› A: ankle plantar flexion
Popliteus
› O: lateral condyle of femur (lateral surface)
› I: posterior surface of tibia, superior to soleal line
› A: Assist knee flexion, unlock knee joint (medially rotate tibia on unplanted
limb, laterally rotating femur on fixed tibia)

55. Gastronemius
Soleus

56. Muscles of the leg (Posterior)
Tibialis posterior
› O: posterior surface of tibia inferior to soleal line, posterior surface of fibula
› I: navicular, 3 cuneiforms and cuboid and 2nd, 3rd, 4th metatarsals
› A: ankle plantar flexion and inversion, supports medial arch of foot
Flexor digitorum longus (FDL)
› O: medial, posterior surface of tibia inferior to soleal line
› I: Bases of distal phalanges of the 2nd to 5th toes
› A: 2nd-5th toe flexion; ankle plantar flexion and inversion, supports medial arch of
foot
Flexor hallucis longus (FHL)
› O: distal posterior surface of fibula
› I: plantar surface of the base of distal phalanx of the hallux
› A: great toe flexion; assist ankle plantar flexion and inversion, supports medial arch
of foot

58. Muscles of the trunk
• Superfical (Core Strength)
1. Rectus Abdominal
2. External Oblique
3. Internal Oblique
• Deep (Core Stability)
1. Transverse Abdominis
2. Diaphragm
3. Pelvic Floor (Levator Ani)

59. Muscles of the trunk
Rectus Abdominis
› O: pubic crest and symphysis
› I: costal cartilages of rib 5 to 7
› A: bilaterally – forward flexion of the trunk; unilaterally –› lateral flexion of the trunk
to the same side
External Oblique
› O: rib 5 to 12
› I: broad abdominal aponeurosis to the linea alba, anterior iliac crest
› A: bilaterally – forward flexion of the trunk; unilaterally – lateral flexion of the trunk
to the same side and rotation of the trunk to the opposite side
Internal Oblique
› O: medial iliac crest and thoracolumbar fascia
› I: rib 10 to 12
› A: bilaterally – forward flexion of the trunk; unilaterally – lateral flexion and rotation
of the trunk to the same side

60. Muscles of the trunk
Transversus Abdominis
› O: iliac crest; thoracolumbar fascia, rib 6 to 12
› I: broad abdominal aponeurosis to the linea alba
› A: compression of abdominal viscera; stabilization of the lumbo-pelvic region
Diaphragm
› O: inner surface of the body wall: sternal portion – back of the xiphoid process;
costal portion – inner surfaces of lower six ribs; lumbar portion – anterior bodies
of lumbar vertebrae
› I: central tendon
› A: draws the central tendon downward increasing thoracic cavity volume during
inhalation
Pelvic Floor
› refers to a group of muscles of the inferior pelvis
› made up of the puborectalis, pubococcygeus, iliococcygeus (collectively the levator
ani) and ischiococcygeus
› extends from the body of the pubis to the coccyx and between the ischial spines
› functions to stabilize the joints of the pelvis including the sacroiliac joint

64. Muslces of the Spine
• Superficial
Erectus Spinae group
•
•
•
Semispinalis
Iliocoastalis
Lumborum
Quadratus Lumborum
• Deep
Multifidus

65. Erectus Spinae Group - Superfical
Semispinalis thoracis
› O: transverse process of T6 to T12
› I: spinous process of C6 to T4
› A: unilaterally – rotation of the spine to the opposite side; bilaterally – extension of
the spine
Semispinalis cervicis
› O: transverse process of T1 to T6
› I: spinous process of C2 to C5
› A: unilaterally – lateral flexion of the spine to the same side, rotation of the spine to
the opposite side; bilaterally – extension of the spine
Semispinalis capitis
› Origin: transverse process of C5 to T6
› Insertion: occipital bone
› Action: unilaterally – lateral flexion of the neck to the same side, rotation of the head
and neck to the opposite side; bilaterally – extension of the head and neck

66. Erectus Spinae Group - Superfical
Iliocostalis lumborum
› O: thoracolumbar fascia from the sacrum to spinous process of T11 to L5
› I: rib 6 to 12
› A: unilaterally – lateral flexion of the spine to the same side; bilaterally –
extension of the spine
Iliocostalis thoracis
› O: rib 6 to 12
› I: rib 1 to 6
› A: unilaterally – lateral flexion of the spine to the same side; bilaterally –
extension of the spine
Iliocostalis cervicis
› O: rib 3 to 6
› I: transverse process of C4 to C6
› A: unilaterally – lateral flexion of the spine to the same side; bilaterally –
extension of the spine

67. Erectus Spinae Group - Superfical
Longissimus thoracis
› O: thoracolumbar fascia on the lumbar spine
› I: transverse process of T1 to T12 and rib 6 to 12
› A: unilaterally – lateral flexion of the spine to the same side; bilaterally – extension
of the spine
Longissimus cervicis
› O: transverse process of T1 to T5
› I: transverse process of C2 to C6
› A: unilaterally – lateral flexion of the spine to the same side; bilaterally – extension
of the spine
Longissimus capitis
› O: transverse process of C4 to T5
› I: mastoid process
› A: unilaterally – lateral flexion and rotation of the head to the same side; bilaterally –
extension of the head and neck

69. Muscles of the Spine – Superficial
Quadratus lumborum (QL)
› O: posterior iliac crest
› I: 12th rib and transverse process of L1 to L4
› A: unilaterally - Spine
lateral flexion,
bilaterally – aids
Spine extension

70. Muscles of the Spine - Deep
Multifidus
› O: sacrum, transverse process of L1 to T12 and
the articular process of C4 to C7
› I: spinous process of all vertebrae except C1
spanning 2 to 3 intervertebral spaces
› A: stabilization of the spine; unilaterally –
rotation of the spine to the opposite side.
lateral flexion of the spine to the same side;
bilaterally – extension of the spine