Anatomy Review – Muscles

Presented by: Jon Chan

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

Muscles of the Scapula

1. Serratus Anterior2. Trapezius (Upper, Middle, Lower)3. Levator Scapulae4. Rhomboid (Major / Minor)

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

Muscles of the ScapulaTrapezius (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

Muscles of the ScapulaLevator 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

Muscles of the Shoulder

1. Deltoid (anterior/middle/posterior)2. Latissmus Dorsi3. Teres Major4. Pectoralis Major (Sternal / Clavicular heads)5. Pectoralis Minor

Muscles of the ShoulderDeltoid – 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

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

Teres Major

Muscles of the ShoulderPectoralis 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 rotationClavicular 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

Muscles of the Rotator Cuff

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

Muscles of the Rotator CuffTeres 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

Muscles of the Arm

• Anterior Compartment– Bicep Brachii– Coracobrachialis– Brachialis– Brachioradialis

Brachioradialis

Biceps Brachii

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

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

Muscles of the Arm

• Posterior Compartment– Triceps

• Long (visible)• Medial • Lateral (visible)

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

Muscles of the Thigh

• Anterior thigh1. Sartorius2. Quadriceps

• Rectus Femoris, Vastus Medialis, Vastus Lateralis, Vastus Intermedius

Muscles of the Thigh (anterior)

Sartorius› O: ASIS› I: superior aspect of medial tibia› A: Hip flexion, external rotation, abduction; knee flexion

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

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

Muscles of the Thigh

• Medial Thigh1. Adductor longus2. Adductor Brevis3. Adductor Magnus4. Gracilis

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

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

Muscles of the Thigh

• Posterior Thigh1. Biceps Femoris2. Semi-tendinosus3. Semi-membranosus

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

Muscles of the Hip

• Superfiscal Layer1. Gluteus maximus2. Gluteus medius3. Gluteus minimus4. Tensor fascia lata5. Illiopsoas (psoas major / iliacus)

Muscles of the HipGluteus 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

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

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

Iliopsoasthe combination of psoas major and iliacus

Muscles of the Hip

• Deep Layer– Piriformis– Gemelli Superior– Obturator Internus– Gemelli Inferior– Obturator Externus– Quadratus femoris

Muscles of the Hip - deepPiriformis› 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

Muscles of the hip - deepGemellus 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

Muscles of the Leg

• Anterior Compartment1. Tibialis Anterior2. Extensor Hallucis Longus3. Extensor Digitorum

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 1st 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

Muscles of the Leg

• Lateral Compartment1. Peroneous Longus2. Peroneous Brevis

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

Muscles of the Leg

• Posterior Compartment– Superficial1.Gastrocnemius2.Soleus

– Deep1.Tibialis Posterior (TP)2.Flexor Digitorum Longus (FDL)3.Flexor Hallucis Longus (FHL)

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)

Gastronemius

Soleus

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

Muscles of the trunk

• Superfical (Core Strength)1. Rectus Abdominal2. External Oblique3. Internal Oblique

• Deep (Core Stability)1. Transverse Abdominis2. Diaphragm3. Pelvic Floor (Levator Ani)

Muscles of the trunkRectus 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

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

Muslces of the Spine

• SuperficialErectus Spinae group

• Semispinalis• Iliocoastalis• Lumborum

Quadratus Lumborum

• DeepMultifidus

Erectus Spinae Group - SuperficalSemispinalis 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

Erectus Spinae Group - SuperficalIliocostalis 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

Erectus Spinae Group - SuperficalLongissimus 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

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

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