abdomen/pelvis muscles

Question 1

cremaster

Answer 1

• attachments: medial edge of internal oblique > spermatic cord
• action: elevation of testis
• innervation: genitofemoral nerve L1-L2

Question 2

diaphragm

Answer 2

• attachments: xiphoid process, inner surface of lower ribs and costal cartilagess, medial and lateral arcuate ligaments, lumbar vertebrae via crura > central tendon
• action: inspiration (negative thoracic pressure by inferior displacement)
• innervation: phrenic nerve C3-C5

Question 3

external abdominal oblique

Answer 3

• attachments: lower 8 ribs > iliac crest, rectus sheath
• action: flexion and rotation of trunk, compresses abdominal caavity
• ventral rami T7-T12

Question 4

internal abdominal oblique

Answer 4

• attachments: thoracolumbar fascia > inguinal ligament, iliac crest, rectus sheath
• action: flexion and rotation of the trunk, compression of the abdominal cavity
• innervation: ventral rami T7-L1, iliohypogastric and ilioinguinal ventral rami

Question 5

quadratus lumborum

Answer 5

• attachments: 12th rib and transverse processes L1-L4 > iliolumbar ligament and iliac crest
• action: extension and lateral flexion of trunk, fixes 12th rib during respiration
• innervation: lumbar plexus ventral rami T12-L3

Question 6

rectus abdominis

Answer 6

• attachments: xiphoid process and adjacent costal cartilages of ribs 5-7 > pubic cest and tubercle (symphysis)
• action: flexion of trunk, compression of abdominal cavity
• innervation: lower thoracic ventral rami T5-T12

Question 7

transversus abdominis

Answer 7

• attachments: lower six costal cartilages and thoracolumbar fascia > inguinal ligament, iliac crest, rectus sheath
• action: compression of abdominal cavity
• innervation: lower thoracic T7-T12

Question 8

iliacus

Answer 8

• attachments: iliac fossa > less trochanter of femur
• action: flexion of thigh at hip joint
• innervation: femoral nerve

Question 9

psoas major

Answer 9

• attachments: transverse processes of T12-L4 > lesser trochanter of femur
• action: flexion of thigh at the hip joint
• innervation: ventral rami L1-L3

Question 10

piriformis

Answer 10

• attachments: sacrum > greater trochanter of femur
• action: lateral rotation of thigh at the hip joint
• innervation: nerve to piriformis

Question 11

obturator internus

Answer 11

• attachments: obturator membrane > greater trochanter of femur
• action: lateral rotation of thigh at hip joint
• innervation: nerve to obturator internus

Question 12

pelvic diaphragm/floor

Answer 12

coccygeus

levator ani (iliococcygeus, pubococcygeus, ruborectalis)

Question 13

coccygeus

Answer 13

• attachments: sacrospinous ligament > coccyx
• action: supports and compresses posterior pelvic floor
• innervation: ventral rami S4-S5

Question 14

levator ani

Answer 14

iliococcygeus, pubococcygeus, puborectalis

Question 15

iliococcygeus

Answer 15

• attachments: ischium and tendinous arch of obturator internus > coccyx and midline raphe
• action: support pelvic viscera
• innervation: levator ani nerve (S4), inferior rectal nerve (pudendal S3-S4), coccygeal plexus
  
  • same as pubococcygeus

Question 16

pubococcygeus

Answer 16

• attachments: pubis and tendinous arch of obturarot internus > coccyx and midline raphe and walls of prostate or vagina
• action: support pelvic viscera and compress vagina
• innervation levator ani nerve (S4), inferior rectal nerve (pudendal S3-S4), coccygeal plexus
  
  • same as iliococcygeus

Question 17

puborectalis

Answer 17

• attachments: pubis and wall of rectum
• action: maintain fecal continence
• innervation: levator ani nerve (S4)

Question 18

bulbospongiosus

Answer 18

• action:
  
  • male: empties urethra, maintains erection, contracts in ejaculation
  • female: constricts vaginal orifice and contributes to erection of clitoris
• innervation: perineal branch of pudendal nerve

Question 19

ischiocavernosus

Answer 19

• action: compresses crus during erection
• innervation: perineal branch of pudendal nerve

Question 20

external anal sphinccter

Answer 20

• action: closes anal canal and fixes perineal body
• innervation: inferior rectal branch of pudendal nerve

Question 21

superficial transverse perineal muscle

Answer 21

• attachments: inferior ramus of ischium and ischial tuberosity > inferior aspect of posterior border of perineal membrane to perineal body
• action: supports perineal body, supports pelvic viscera, resist increased intraabdominal pressure
• innervation: perineal branch of the pudendal nerve

Question 22

deep transverse perineal

Answer 22

• attachments: inferior ramus of ischium and ischial tuberosity > superior aspect of posterior border of perineal membrane > perineal body and external anal sphincter
• action: supports perineal body, supports pelvic viscera, resist increased intraabdominal pressure
• innervation: perineal branch of the pudendal nerve