Muscles Of Thorax, Abdomen, And Pelvis

Front 1

Back 1

External Intercostals

Origin: Rib to rib oriented from superior to lateral, inferior to medial.
Action: Elevate Ribs (inhale)
Innervation: Intercostal Nerves

Front 2

Back 2

Internal/Innermost Intercostals

Origin: Rib to rib oriented from superior to medial, inferior to lateral.
Action: Depress Ribs (exhale)
Innervation: Intercostal Nerves

Front 3

Back 3

Transversus thoracis

Attach: posterior sternum to costal cartilage.
Action: Depress ribs.
Innervation: Intercostal nerves

Front 4

Back 4

Cremaster

Attach: medial edge of internal oblique to spermatic cord.
Action: Elevate testis
Innervation: genitofemoral nerve.

Front 5

Back 5

Diaphragm

Attach: from xiphoid process, inner surface of lower ribs, and costal cartilages, medial and lateral arcuate ligaments, & lumbar vertebrae via the crura, To the central tendon.
Action: inspiration (-) thoracic pressure by inferior displacement.
Innervation: phrenic nerve (C3-5)

Front 6

Back 6

External Oblique

Attach: from lower 8 ribs to iliac crest and rectus sheath
Action: flexion and rotation of the trunk, compression of the abdominal cavity.
Innervation: ventral rami T7-12

Front 7

Back 7

Transversus Abdominis

Attach: from lower six costal cartilages & thoracolumbar fascia to inguinal ligament, iliac crest, and rectus sheath.
Action: compression of thoracic cavity.
Innervation: lower thoracic and L1 ventral rami.

Front 8

Back 8

Quadratus Lumborum

Attach: from 12th rib to iliolumbar ligament and iliac crest.
Action: extension and lateral flexion of the trunk, and fixes 12th rib during respiration.
Innervation: Ventral rami T12-L3

Front 9

Back 9

Rectus Abdominus

Attach: from xiphoid process and adjacent castal cartilages to pubic crest and tubercle
Action: flexion of trunk and compression of abdominal cavity.
Innervation: lower thoracic ventral rami (thoracoabdominal nerves)

Front 10

Back 10

Internal Oblique

Attach: from thoracolumbar fascia to inguinal ligament, iliac crest, and rectus sheath.
Actions: flexion and rotation of trunk, compression of the abdominal cavity.
Innervation: lower thoracic and L1 ventral rami.

Front 11

Back 11

Obturator Internus

details to come

Front 12

Back 12

1. Iliacus
2. Psoas
3. Piriformis

Front 13

Back 13

Levator Ani

Attach: from pubic symphysis, obturator fascia, & ischial spine to midine raphe & anococcygeal ligament.
Action: support pelvic viscera, compress rectum and vagina.
Innervation: pudendal nerve & S4

Front 14

Back 14

Coccygeus

Attach: from ischial spine & sacrospinous ligament to coccyx.
Action: support & compress posterior pelvic floor.
Innervation: ventral rami S4-5

Front 15

Back 15

1. Levator Ani
2. Obturator Internus
3. Coccygeus
4. Piriformis
5. Sacrum
6. Ischial Spine
7. Obturator Canal
8. Pubic Tubercle
9. Pubic Crest
10. Pubic symphysis

Front 16

Back 16

Bulbospongiosus

attach: in male from median raphe & perineal body (central tendon) to surround bulb of penis; in female from the perineal body to surround vestibular bulb, vaginal orifice, & clitoris.
action: in male empties urethra, maintains erection & contracts during ejaculation; in female constricts vaginal orifice & contributes to erection of clitoris.
innervation: perineal branch of pudendal nerve

Front 17

Back 17

Ischiocavernosus

attach: from ischial tuberosity & ramus to aponeurosis surrounding crus of penis or clitoris.
action: compress crus during erection
innervation: perineal branch of pudendal nerve

Front 18

Back 18

sphincter ani externus

attach: from perineal body (central tendon) to anococcygeal raphe
action: close anal canal and fix perineal body.
innervation: perineal branch of pudendal nerve

Front 19

Back 19

sphincter urethrae

attach: surrounds urethra
action: compress urethra
nerve: perineal branch of pudendal nerve

Front 20

Back 20

Deep Transverse perineus

attach: from ischial tuberosity to perineal body (central tendon)
action: fixes perineal body
nerve: perineal branch of pudendal nerve

Front 21

Back 21

superficial transverse perineus

attach: from ischial tuberosity to perineal body (central tendon)
action: fixes perineal body
nerve: perineal branch of pudendal nerve

Front 22

Back 22

1. Bulbospongiosus .
2. Ischiocavernosus
3. Sphincter ani externus
4. Sphincter urethrae
5. Deep transverse perineus
6. Superficial transverse perineus