Practical 2 Muscles

Trapezius

origin: superior nuchal line, external occipital protuberance, ligamentum nuchae, spinous processes CVII to TXII and the related supraspinous ligaments

insertion: posterior border of lateral 1/3 of clavicle, acromion, superior edge of the crest of the spine of scapula

action: powerful elevator of the scapula; rotates the scapula during abduction of humerus above horizontal; middle fibers retract scapula; lower fibers depress scapula

motor innervation: accessory (CNXI)

Latissimus dorsi

origin: spinous processes of lower six thoracic vertebrae and related interspinous ligaments, via the thoracolumbar fascia to the spinous processes of the lumbar vertebrae, related interspinous ligaments and iliac crest, lower 3-4 ribs

insertion: floor of intertubercular sulcus

action: adduction, medial rotation, and extension of the arm at the glenohumeral joint

motor innervation: thoracodorsal nerve (C6, C7, C8)

Levator scapulae

origin: transverse processes of CI to CII vertebrae and posterior tubercles of transverse processes of CIII and CIV vertebrae

insertion: posterior surface of medial border of scapula from superior angle to root of spine of the scapula

action: elevates the scapula

motor innervation: branches directly from anterior rami of C3 and C4 spinal nerves and by branches (C5) from the dorsal scapular nerve

Anterior scalene

origin: anterior tubercles of the transverse processes of vertebrae CIII to CVI

insertion: scalene tubercle and upper surface of rib I

action: elevation of rib I

motor innervation: anterior rami of C4 to C7

Rhomboids (major and minor)

origin: spinous processes of TII-TV vertebrae and intervening supraspinous ligaments, lower end of ligamentum nuchae and spinous processes of CVII and TI vertebrae

insertion: posterior surface of medial border of scapula from the root of the spine of the scapula to the inferior angle, posterior surface of scapula at the root of the spine of the scapula

action: elevates and retracts the scapula

motor innervation: dorsal scapular nerve (C4, C5)

Deltoid

origin: inferior edge of the crest of the spine of the scapula, lateral margin of the acromion, anterior border of lateral 1/3 of clavicle

insertion: deltoid tuberosity of humerus

action: major abductor of arm, clavicular fibers assist in flexing the arm, posterior fibers assist in extending the arm

motor innervation: axillary nerve (C5, C6)

Pectoralis major

origin (clavicular and sternocostal head): anterior surface of medial 1/2 of clavicle, anterior surface of sternum, first seven costal cartilages, sternal end of sixth rib, aponeurosis of external oblique

insertion: lateral lip of intertubercular sulcus of humerus

action: flexion, adduction, and medial rotation of arm at glenohumeral joint, clavicular head - flexion of extended arm, sternocostal head - extension of flexed arm

motor innervation: medial and lateral pectoral nerves, clavicular head (C5, C6), sternocostal head (C6, C7, C8, T1)

Pectoralis minor

origin: anterior surfaces and superior borders of ribs III to V, and from deep fascia overlying the related intercostal spaces

insertion: coracoid process of scapula (medial border and upper surface)

action: pulls tip of shoulder down; protracts scapula

motor innervation: medial pectoral nerve (with a contribution from lateral pectoral nerve) [C5, C6, C7, C8, T1]

Serratus anterior

origin: lateral surfaces of upper 8-9 ribs and deep fascia overlying the related intercostal spaces

insertion: costal surface of medial border of scapula

action: protraction and rotation of the scapula, keeps medial border and inferior angle of scapula opposed to thoracic wall

motor innervation: long thoracic nerve (C5, C6, C7)

Supraspinatus

origin: medial 2/3 of the supraspinous fossa of the scapula and the deep fascia that covers the muscle

insertion: most superior facet on the greater tubercle of the humerus

action: rotator cuff muscle, participates in abduction of the glenohumeral joint, stabilization of glenohumeral joint

motor innervation: suprascapular nerve (C5, C6)

Infraspinatus

origin: medial 2/3 of the infraspinous fossa of the scapula and the deep fascia that covers the muscle

insertion: middle facet on posterior surface of the greater tubercle of the humerus

action: rotator cuff muscle, lateral rotation of arm at the glenohumeral joint, stabilization of glenohumeral joint

motor innervation: suprascapular nerve (C5, C6)

Teres minor

origin: upper 2/3 of a flattened strip of bone on the posterior surface of the scapula immediately adjacent to the lateral border of the scapula

insertion: inferior facet on the posterior surface of the greater tubercle of the humerus

action: rotator cuff muscle, lateral rotation of the arm at the glenohumeral joint, stabilization of glenohumeral joint

motor innervation: axillary nerve (C5, C6)

Subscapularis

origin: medial 2/3 of subscapular fossa

insertion: lesser tubercle of humerus

action: rotator cuff muscle, medial rotation of the arm at the glenohumeral joint

motor innervation: upper and lower subscapular nerves (C5, C6, C7)

Teres major

origin: elongate oval area on the posterior surface of the inferior angle of the scapula

insertion: medial lip of the intertubercular sulcus on the anterior surface of the humerus

action: medial rotation and extension of the arm at the glenohumeral joint

motor innervation: lower subscapular nerve (C5, C6, C7)

Biceps brachii

origin: long head - supraglenoid tubercle of scapula, short head - apex of coracoid process

insertion: radial tuberosity

action: powerful flexor of the forearm at the elbow joint and supinator of the forearm, accessory flexor of the arm at the glenohumeral joint

motor innervation: musculocutaneous nerve (C5, C6)

Coracobrachialis

origin: apex of coracoid process

insertion: linear roughening on mid-shaft of humerus on medial side

action: flexor of the arm at the glenohumeral joint, adducts arm

motor innervation: musculocutaneous nerve (C5, C6, C7)

Brachialis

origin: anterior aspect of humerus (medial and lateral surfaces) and adjacent intermuscular septae

insertion: tuberosity of the ulna

action: powerful flexor of the forearm at the elbow joint

motor innervation: musculocutaneous nerve (C5, C6), small contribution by the radial nerve (C7) to lateral part of muscle

Brachioradialis

origin: proximal part of lateral supraepicondylar ridge of humerus and adjacent intermuscular septum

insertion: lateral surface of distal end of radius

action: accessory flexor of elbow joint when forearm is mid-pronated

motor innervation: radial nerve (C5, C6) before division into superficial and deep branches

Triceps brachii

origin: long head - infraglenoid tubercle of scapula, medial head - posterior surface of humerus, lateral head - posterior surface of humerus

insertion: olecranon

action: extension of the forearm at the elbow joint, long head can also extend and adduct the arm at the shoulder joint

motor innervation: radial nerve (C6, C7, C8)

Pronator quadratus

origin: linear ridge on distal anterior surface of ulna

insertion: distal anterior surface of radius

action: pronation

motor innervation: median nerve (anterior interosseus nerve) [C7, C8]

Pronator teres

origin: humeral head - medial epicondyle and adjacent supraepicondylar ridge, ulnar head - medial side of coronoid process

insertion: roughening on lateral surface, mid-shaft of radius

action: pronation

motor innervation: median nerve (C6, C7)

Supinator

origin: superficial layer - lateral epicondyle of humerus, radial collateral and anular ligaments, deep layer - supinator crest of the ulna

insertion: lateral surface of radius superior to the anterior oblique line

action: supination

motor innervation: posterior interosseus nerve (C6, C7)

Iliacus

Origin: Posterior abdominal wall (iliac fossa)

Insertion: Lesser trochanter of femur

Action: Flexes the thigh at the hip joint

Innervation: Femoral nerve (L2, L3)

Psoas major

Origin: Posterior abdominal wall (lumbar transverse processes, intervertebral discs, and adjacent bodies from TXII to LV and tendinous arches between these points)

Insertion: Lesser trochanter of femur

Action: Flexes the thigh at the hip joint

Innervation: Anterior rami (L1, L2, L3)

Tensor fasciae latae

Origin: Lateral aspect of crest of ilium between anterior superior iliac spine and tubercle of the crest

Insertion: Iliotibial tract of fascia lata

Action: Stabilizes the knee in extension

Innervation: Superior gluteal nerve (L4, L5, S1)

Gluteus maximus

Origin: Fascia covering gluteus medius, external surface of ilium behind posterior gluteal line, fascia of erector spinae, dorsal surface of lower sacrum, lateral margin of coccyx, external surface of sacrotuberous ligament

Insertion: Posterior aspect of iliotibial tract of fascia lata and gluteal tuberosity of proximal femur

Action: Powerful extensor of flexed femur at hip joint; lateral stabilizer of hip joint and knee joint; laterally rotates and abducts thigh

Innervation: Inferior gluteal nerve (L5, S1, S2)

Gluteus medius

Origin: External surface of ilium between anterior and posterior gluteal line

Insertion: Elongate facet on the lateral surface of the greater trochanter

Action: Abducts femur at hip joint; holds pelvis secure over stance leg and prevents pelvic drop on the opposite swing side during walking; medially rotates thigh

Innervation: Superior gluteal nerve (L4, L5, S1)

Gluteus minimus

Origin: External surface of ilium between inferior and anterior gluteal lines

Insertion: Linear facet on the anterolateral aspect of the greater trochanter

Action: Abducts femur at hip joint; holds pelvis secure over stance leg and prevents pelvic drop on the opposite swing side during walking; medially rotates thigh

Innervation: Superior gluteal nerve (L4, L5, S1)

Piriformis

Origin: Anterior surface of sacrum between anterior sacral foramina

Insertion: Medial side of superior border of greater trochanter of femur

Action: Laterally rotates the extended femur at hip joint; abducts flexed femur at hip joint

Innervation: Branches from S1, S2

Quadratus femoris

Origin: Lateral aspect of the ischium just anterior to the ischial tuberosity

Insertion: Quadrate tubercle on the intertrochanteric crest of the proximal femur

Action: Laterally rotates femur at hip joint

Innervation: Nerve to quadratus femoris (L5, S1)

Obturator internus

Origin: Anterolateral wall of true pelvis; deep surface of obturator membrane and surrounding bone

Insertion: Medial side of greater trochanter of femur

Action: Laterally rotates the extended femur at hip joint; abducts flexed femur at hip joint

Innervation: Nerve to obturator internus (L5, S1)

Adductor longus

Origin: External surface of body of pubis (triangular depression inferior to pubic crest and lateral to pubic symphysis)

Insertion: Linea aspera on middle 1/3 of shaft of femur

Action: Adducts and medially rotates thigh at hip joint

Innervation: Obturator nerve (anterior division) (L2, L3, L4)

Adductor magnus

Origin: ischiopubic ramus, ischial tuberosity

Insertion: posterior surface of proximal femur, linea aspera, medial supracondylar line; adductor tubercle and supracondylar line

Action: Adducts and medially rotates thigh at hip joint

Innervation: Adductor part - obturator nerve (L2, L3, L4); Hamstring part - Sciatic nerve (tibial division) (L2, L3, L4)

Gracilis

Origin: A line on the external surfaces of the body of the pubis, the inferior pubic ramus, and the ramus of the ischium

Insertion: Medial surface of proximal shaft of tibia

Action: Adducts thigh at hip joint and flexes leg at knee joint

Innervation: Obturator nerve (L2, L3)

Pectineus

Origin: Pectineal line (pecten pubis) and adjacent bone of pelvis

Insertion: Oblique line extending from base of lesser trochanter to linea aspera on posterior surface of proximal femur

Action: Adducts and flexes thigh at hip joint

Innervation: Femoral nerve (L2, L3)

Rectus femoris

Origin: Straight head originates from the anterior inferior iliac spine; reflected head originates from the ilium just superior to the acetabulum

Insertion: Quadriceps femoris tendon

Action: Flexes the thigh at the hip joint and extends the leg at the knee joint

Innervation: Femoral nerve (L2, L3, L4)

Vastus lateralis

Origin: lateral part of intertrochanteric line, margin of greater trochanter, lateral margin of gluteal tuberosity, lateral lip of the linea aspera

Insertion: Quadriceps femoris tendon and lateral margin of patella

Action: Extends the leg at the knee joint

Innervation: Femoral nerve (L2, L3, L4)

Vastus medialis

Origin: Femur - medial part of intertrochanteric line, pectineal line, medial lip of the linea aspera, medial supracondylar line

Insertion: Quadriceps femoris tendon and medial border of patella

Action: Extends the leg at the knee joint

Innervation: Femoral nerve (L2, L3, L4)

Vastus intermedius

Origin: Femur - upper 2/3 of anterior and lateral surfaces

Insertion: Quadriceps femoris tendon and lateral margin of patella

Action: Extends the leg at the knee joint

Innervation: Femoral nerve (L2, L3, L4)

Sartorius

Origin: Anterior superior iliac spine

Insertion: Medial surface of tibia just inferomedial to tibial tuberosity

Action: Flexes the thigh at the hip joint and flexes the leg at the knee joint

Innervation: Femoral nerve (L2, L3)

Biceps femoris

Origin: Long head - inferomedial part of the upper area of the ischial tuberosity; short head - lateral lip of linea aspera

Insertion: Head of fibula

Action: Flexes leg at knee joint; extends and laterally rotates thigh at hip joint and laterally rotates leg at knee joint

Innervation: Sciatic nerve (L5, S1, S2)

Semitendinosus

Origin: Inferomedial part of the upper area of the ischial tuberosity

Insertion: Medial surface of proximal tibia

Action: Flexes leg at knee joint and extends thigh at hip joint; medially rotates thigh at hip joint and leg at knee joint

Innervation: Sciatic nerve (L5, S1, S2)

Semimembranosus

Origin: Superolateral impression on the ischial tuberosity

Insertion: Groove and adjacent bone on medial and posterior surface of medial tibial condyle

Action: Flexes leg at knee joint and extends thigh at hip joint; medially rotates thigh at hip joint and leg at knee joint

Innervation: Sciatic nerve (L5, S1, S2)

Popliteus

Origin: Lateral femoral condyle

Insertion: Posterior surface of proximal tibia

Action: Stabilizes knee joint (resists lateral rotation of tibia on femur), Unlocks knee joint (laterally rotates femur on fixed tibia)

Innervation: Tibial nerve (L4 to S1)

Tibialis anterior

Origin: Lateral surface of tibia and adjacent interosseus membrane

Insertion: Medial and inferior surfaces of medial cuneiform and adjacent surfaces on base of metatarsal I

Action: Dorsiflexion of foot at ankle joint; inversion of foot; dynamic support of medial arch of foot

Innervation: Deep fibular nerve (L4, L5)

Gastrocnemius

Origin: Medial head - posterior surface of distal femur just superior to medial condyle; lateral head - upper posterolateral surface of lateral femoral condyle

Insertion: Via calcaneal tendon, to posterior surface of calcaneus

Action: Plantarflexes foot and flexes knee

Innervation: Tibial nerve (S1, S2)

Soleus

Origin: Soleal line and medial border of tibia; posterior aspect of fibular head and adjacent surfaces of neck and proximal shaft; tendinous arch between tibial and fibular attachments

Insertion: Via calcaneal tendon to posterior surface of calcaneus

Action: Plantarflexes the foot

Innervation: Tibial nerve (S1, S2)

Fibularis longus

Origin: Upper lateral surface of fibula, head of fibula, and occasionally the lateral tibial condyle

Insertion: Undersurface of lateral sides of distal end of medial cuneiform and base of metatarsal I

Action: Eversion and plantarflexion of foot; supports mainly lateral and transverse arches of foot

Innervation: Superficial fibular nerve (L5, S1, S2)

Tibialis posterior

Origin: Posterior surfaces of interosseous membrane and adjacent regions of tibia and fibula

Insertion: Mainly to tuberosity navicular and adjacent region of medial cuneiform

Action: Inversion and plantarflexion of foot; support of medial arch of foot during walking

Innervation: Tibial nerve (L4, L5)

Flexor hallucis longus

Origin: Posterior surface of fibula and adjacent interosseus membrane

Insertion: Plantar surface of distal phalanx of great toe

Action: Flexes great toe; particularly active during the toe-off phase of walking when the body is propelled forward off the stance leg and the great toe is the last part of the foot to leave the ground

Innervation: Tibial nerve (S2, S3)

Flexor digitorum longus

Origin: Medial side of posterior surface of the tibia

Insertion: Plantar surfaces of bases of distal phalanges of the lateral four toes

Action: Flexes lateral four toes

Innervation: Tibial nerve (S2, S3)

Extensor digitorum longus

Origin: Proximal 1/2 of medial surface of fibula and related surface of lateral tibial condyle

Insertion: Via dorsal digital expansions into bases of distal and middle phalanges of lateral four toes

Action: Extension of lateral four toes and dorsiflexion of foot

Innervation: Deep fibular nerve (L5, S1)

External oblique

Origin: Muscular slips from the outer surfaces of the lower eight ribs (5-12)
Insertion: Lateral lip of iliac crest, aponeurosis ending in midline raphe (linea alba)
Action: Compress abdominal contents, both muscles flex trunk, each muscle bends trunk to same side, turning anterior part of abdomen to opposite side
Innervation: Anterior rami of lower six thoracic spinal nerves (T7 to T12)

Internal oblique

Origin: Iliac crest between origins of external and transversus, thoracolumbar fascia, lateral 2/3 of inguinal ligament
Insertion: Inferior border of lower 3 ribs (10-12), aponeurosis ending in linea alba, pubic crest and pectineal line
Action: Compress abdominal contents, both muscles flex trunk, each muscle bends trunk and turns anterior part of abdomen to same side
Innervation: Anterior rami of lower six thoracic spinal nerves (T7 to T12)

Transversus abdominis

Origin: Thoracolumbar fascia, medial lip of iliac crest, lateral 1/3 of inguinal ligament, costal cartilages of lower six ribs (7-12)
Insertion: Aponeurosis ending in linea alba, pubic crest and pectineal line
Action: Compress and support abdominal contents
Innervation: Anterior rami of lower six thoracic spinal nerves (T7 to T12) and L1

Rectus abdominis

Origin: Pubic crest, pubic tubercle, pubic symphysis
Insertion: Xiphoid process, costal cartilages of ribs 5-7
Action: Compress abdominal contents, flex vertebral column, tense abdominal wall
Innervation: Anterior rami of lower six thoracic spinal nerves (T7 to T12) and L1

Quadratus lumborum

Origin: Transverse processes of LV vertebra, iliolumbar ligament, and iliac crest
Insertion: Transverse processes of LI to LIV vertebrae and inferior border of rib XII
Action: Depress and stabilize rib XII and some lateral bending of the trunk
Innervation: Anterior rami of T12 and L1 to L4