Muscles & Structures of the Abdominal Wall/Pelvis Flashcards
External oblique
Action
- Compresses and supports abdominal viscera
- flexes and rotates the trunk
External oblique
Innervation
Thoracoabdominal nn. T7–T11 and subcostal n.
External oblique
Blood supply
Superior and inferior epigastric a.a
Internal oblique
Innervation
Thoracoabdominal nn. T7–T11, subcostal n., and L1
Internal oblique
Blood supply
Superior and inferior epigastric a.a., deep circumflex iliac a.a.
Transversus abdominus
Action
- Compresses and supports abdominal viscera
- flexes and rotates the trunk
Transversus abdominus
Innervation
Thoracolumbar nn. T7-T11, subcostal n., and L1
Transversus abdominus
Blood supply
Deep circumflex iliac and inferior epigastric a.a.
Rectus abdominis
Origin
Xiphoid process, costal cartilages 5–7
Rectus abdominis
Insertion
Pubic symphysis, and pubic crest
Rectus abdominis
Action
Flexes trunk, assists in pelvic tilt, and compresses abdominal viscera
Rectus abdominis
Innervation
Thoracoabdominal nn. T7–T11 and subcostal n.
Rectus abdominis
Blood supply
Superior and inferior epigastric a.a.
Transverse mesocolon attachments
- Attaches transverse colon to the anterior surface of the duodenum and pancreas (along the posterior abdominal wall)
- Left end: phrenicocolic ligament, which attaches the left colic flexure to the diaphragm
Psoas major
Origin
Lumbar vertebrae (bodies, intervertebral discs, and transverse processes)
Psoas major
Insertion
Lesser trochanter of the femur
Psoas major
Action
Flexes the thigh and extends the vertebral column
Psoas major
Innervation
L1–L4 (anterior rami)
Psoas major
Blood supply
Lumbar branches of iliolumbar artery
Psoas minor
Origin
Lateral surface of T12 and L1
Psoas minor
Insertion
Iliopubic eminence and arcuate line of the ilium
Psoas minor
Action
Tilts pelvis posteriorly
Psoas minor
Innervation
L1–L2 (anterior rami)
Psoas minor
Blood supply
Lumbar branch of iliolumbar artery
Iliacus
Origin
Iliac fossa
Iliacus
Insertion
Lesser trochanter of the femur
Iliacus
Action
Flexes the thigh
Iliacus
Innervation
Femoral n.
Iliacus
Blood supply
Iliac branches of iliolumbar artery
Quadratus lumborum
Origin
12th rib and lumbar transverse processes
Quadratus lumborum
Insertion
Iliolumbar ligament and iliac crest
Quadratus lumborum
Action
Flexes vertebral column laterally and anchors the rib cage during respiration
Quadratus lumborum
Innervation
T12–L4 (anterior rami)
Quadratus lumborum
Blood supply
Iliolumbar artery
Superficial inguinal canal borders
Anterior: External oblique aponeurosis
Posterior: Conjoined tendon and transversus abdominus aponeurosis
Superior: Internal oblique and transverus abdominus aponeuroses
Inferior: Inguinal ligament and lacunar ligament
Lumbar plexus nerves (roots)
- Ilio-inguinal nerve (L1)
- Iliohypogastric nerve (L1)
- Lateral cutaneous nerve of thigh (L2, L3)
- Femoral nerve (L2-L4)
- Genitofemoral nerve (L1, L2)
- Obturator nerve (L2-L4)
- Lumbosacral trunk (L4, L5)
Ilioinguinal nerve course
From L1
- Enter the abdomen posterior to the medial arcuate ligaments
- Run between the transversus abdominis and internal oblique
Ilioinguinal nerve
area it supplies
Supply the skin of the suprapubic and inguinal regions.
Iliohypogastric nerve course
L1
- Runs above ilioinguinal n.
- Enter the abdomen posterior to the medial arcuate ligaments
- Run between the transversus abdominis and internal oblique
Iliohypogastric nerve (area it supplies)
Supply the skin of the suprapubic and inguinal regions
Lateral cutaneous nerve of the thigh nerve course
L2, L3
- Enters the thigh posterior to the inguinal ligament, just medial to the anterior superior iliac spine
Lateral cutaneous nerve of the thigh (area it supplies)
- Skin on the anterolateral surface of the thigh
Femoral nerve course
Emerges from the lateral border of the psoas
Femoral nerve (area it supplies)
Innervates the iliacus muscle and the extensor muscles of the knee
Genitofemoral nerve course
L1, L2
- Pierces the anterior surface of the psoas major muscle
Obturator nerve course
L2-L4
- Emerges from the medial border of the psoas
Obturator nerve (area it supplies)
Supplies adductor muscles of the thigh
Lumbosacral trunk course
Passes over the ala of the sacrum
Lumbosacral trunk (area it supplies)
Joins the sacral plexus
Internal iliac artery
Origin
Common iliac artery
Internal iliac artery
Course
- Passes medially over pelvic brim and descends into pelvic cavity
- Often forms anterior and posterior divisions
**BRANCHES ARE HIGHLY VARIABLE
Internal iliac artery
Distribution
Main blood supply to pelvic organs, gluteal muscles, and perineum
Anterior division of internal iliac artery
Course and Supply
- Course: Passes laterally along lateral wall of pelvis, dividing into visceral, obturator (and internal pudendal in males) arteries
- Supply: Pelvic viscera, perineum, and muscles of superior medial thigh
Anterior division of internal iliac artery
Typical branches
- Umbilical
- Obturator
- Inferior vesical (in males, comes of vaginal a. in females)
- Middle rectal
- Internal pudendal
- Uterine (in females)
- Vaginal (in females)
Posterior division of internal iliac artery
Course & Supply
- Course: Passes posteriorly and gives rise to parietal branches
- Pelvic wall and gluteal region
Posterior division of internal iliac artery
Typical branches
- Iliolumbar
- Lateral sacral (superior and inferior)
Umbilical artery
Origin
Anterior division of internal iliac artery
Umbilical artery
Course
Short pelvic course; gives off superior vesical arteries
- Afterwards, obliterates and becomes medial umbilical ligament
Umbilical artery
Distribution
Urinary bladder (females: superior aspect of urinary bladder) - In some males, supplies ductus deferens
Superior vesical artery
Origin
Patent part of umbilical artery
Superior vesical artery
Course
Usually multiple; pass to superior aspect of urinary bladder
Superior vesical artery
Distribution
Superior aspect of urinary bladder (and distal ureter in males)
Artery to ductus deferens
Origin
Superior or inferior vesical artery
Artery to ductus deferens
Course
Runs subperitoneally to ductus deferens
Artery to the ductus deferens
Distribution
Ductus deferens
- obviously in males only
Obturator artery
Origin
Anterior division of internal iliac artery
Obturator artery
Couse
Runs antero-inferiorly on lateral pelvic wall
- Through obturator foramen, often with obturator nerve
Obturator artery
Distribution
Pelvic muscles, nutrient artery to head of femur and medial compartment of thigh
(Also distributed to ilium in females)
Inferior vesical a.
Origin
Anterior division of internal iliac artery
- In males only
Inferior vesical a.
Course
Passes subperitoneally giving rise to prostatic artery
- occasionally gives rise the artery to the ductus deferens
Inferior vesical a.
Distribution
Inferior aspect of urinary bladder, pelvic ureter, seminal glands, and prostate
- In males only
Middle rectal artery
Origin
Anterior division of internal iliac artery
Middle rectal artery
Course
Descends in pelvis to rectum
descends to inferior part in females
Middle rectal artery
Distribution
- Inferior part of rectum (males and females)
- Seminal glands and prostate in males
Internal pudendal artery
Origin
Anterior division of internal iliac artery
Internal pudendal artery
Course
Exits pelvis through greater sciatic foramen and enters perineum via lesser sciatic foramen
Internal pudendal artery
Distribution
Main artery to perineum
- In males, includes muscles and skin of anal and urogenital triangles; erectile bodies
- In females, includes muscles of anal canal and perineum, skin and urogenital triangle and erectile bodies
Iliolumbar artery
Origin
Posterior division of internal iliac artery
Iliolumbar a.
Course
Ascends:
- Anterior to sacro-iliac joint
- Posterior to common iliac vessels and psoas major
Iliolumbar a.
Distribution
Iliacus, psoas major, quadratus lumborum muscles, and cauda equina in vertebral canal
Lateral sacral a. (superior and inferior)
Origin
Posterior division of internal iliac artery
Lateral sacral a. (superior and inferior)
Course
Run on anteromedial aspect of piriformis to send branches into pelvic sacral foramina
Lateral sacral a. (superior and inferior)
Distribution
Piriformis and erector spinae muscles, structures in sacral canal
Testicular (gonadal) a.
Origin
Abdominal aorta
Testicular (gonadal) a.
Course
Descends retroperitoneally; traverses inguinal canal and enters scrotum
Testicular (gonadal) a.
Distribution
Abdominal ureter, testis and epididymis
Ovarian artery (gonadal a.) Origin
Abdominal aorta
Ovarian artery (gonadal a.) Course
Crosses pelvic brim and descends in suspensory ligament to ovary
Ovarian artery (gonadal a.) Distribution
Abdominal and/or pelvic ureter, ovary, and ampullary end of uterine tube
Uterine artery
Origin
Anterior division of IIA
Uterine artery
Course
- Runs anteromedially between broad and cardinal ligs.
- Crosses ureter superiorly to lateral aspect of uterine cervix
Uterine artery
Distribution
Uterus, ligaments of uterus, medial parts of uterine tube and ovary, and superior vagina
Vaginal a.
Origin
Anterior division of IIA
Vaginal a.
Course
Divides into vaginal and inferior vesical branches
Vaginal a.
Distribution
Vaginal branch: lower vagina, vestibular bulb, and adjacent rectum
Inferior vesical branch: fundus of urinary bladder
External iliac artery branches
- Deep circumflex iliac artery
- Inferior epigastric artery (travels along lateral umbilical fold)
Superior gluteal artery
Origin, course
Origin: IIA
Course: often passes posteriorly between the anterior rami of L5 and S1
Inferior gluteal artery
Origin, course
Origin: IIA
Course: often passes posteriorly between the anterior rami of S2 and S3
Obturator internus
Origin
Pelvic surfaces of ilium and ischium, obturator membrane
Makes up lateral wall of pelvic diaphragm
Obturator internus
insertion
Greater trochanter of femur
Obturator internus
Innervation & Blood supply
Nerve to obturator internus (L5, S1, S2)
Internal pudendal and obturator arteries
Obturator internus
Action
Rotates hip joint laterally; assists in holding head of femur in acetabulum
Piriformis
Origin
Pelvic surface of S2-S4 segments, superior margin of greater sciatic notch, sacrotuberous ligament
(Makes up posterolateral wall of pelvic diaphragm)
Piriformis
Insertion
Greater trochanter of femur
Piriformis
Action
Rotates hip joint laterally; abducts hip joint; assists in holding head of femur in acetabulum
Piriformis
Innervation and Blood supply
Anterior rami of S1 and S2
Superior and inferior gluteal arteries,
internal pudendal artery
Levator ani (pubococcygeus, puborectalis, and iliococcygeus) Origin
Body of pubis, tendinous arch of obturator fascia, ischial spine
(Floor of pelvic diaphragm)
Levator ani
Insertion
Perineal body, coccyx, anococcygeal ligament, walls of prostate or vagina, rectum, and anal canal
Levator ani
Innervation
Nerve to levator ani (branches of S4), inferior anal (rectal) nerve, and coccygeal plexus
Levator ani
Action
Forms most of pelvic diaphragm that helps support pelvic viscera and resists increases in intra-abdominal pressure
Coccygeus (ischiococcygeus)
Origin
Ischial spine
Floor of pelvic diaphragm
Coccygeus (ischiococcygeus)
Insertion
Inferior end of sacrum and coccyx
Coccygeus (ischiococcygeus)
Action
Forms small part of pelvic diaphragm that supports pelvic viscera; flexes sacrococcygeal joints
Coccygeus (ischiococcygeus)
Innervation
Branches of S4 and S5 spinal nerves
Parts of the stomach
- Cardia (just under esophagus)
- Fundus (uppermost curve)
- Body
- Pyloric antrum (before narrowing, starts at angular notch)
- Pylorus (before pyloric sphincter)
Lesser curvature: Top curve of stomach
Greater curvature: Bottom curve of stomach