Gross Anatomy L7

diaphragm

separates thoracic and abdominal cavities, musculotendinous, muscle of inspiration

crura

musculotendinous bands that anchor the diaphragm. R crus L1-L4 L crus L1-L3

median arcuate ligament

unites the crura in the middle

medial arcuate ligaments

fascia of psoas major, lumbar vertebral bodies L1 to L1 transverse processes

lateral arcuate ligaments

fascia of quadratus lumborum fascia

caval opening

allows passage of IVC, most anterior, passes through central tendon right of the midline at the level of the IV disc between T8 and T9

esophageal hiatus

through the R crus, allows passage of vagus nerve and esophagus to the left aortic hiatus at T10

aortic hiatus

posterior most opening between the crura of the diaphragm at T12, allows passage of aorta and thoracic duct

umbilicus

remnant of umbilical cord; centrally located but height is dictated by body composition (typically L3 or L4)

linea alba

vertical fibrous raphe in the midline of the anterior abdominal wall, splitting the rectus abdominis, where the aponeuroses of the lateral abdominal muscles interweave; attaches to xiphoid process and pubic symphysis

inguinal groove

demarcates the inguinal ligament, which separates the thigh from the anterolateral abdominal wall

anterior superior iliac spine (ASIS)

superior attachment of inguinal ligament

superior epigastric artery

enters the rectus sheath and supplies superior anterior abdominal wall; anastomoses with inferior epigastric artery

inferior epigastric artery

branch of external iliac artery, enters rectus sheath below the arcuate line and anastomoses with the superior epigastric artery

camper’s fascia

superficial layer of mostly adipose that is continuous with the thigh and perineum

scarpa’s fascia

deeper, membranous layer; superficial to the external oblique muscle; continues into the perineum but not the thigh

investing fascias

each lateral muscle (obliques and transversus abdominis) has a superficial and deep investing fascia attached to their inner and outer surfaces

rectus sheath

composed of the aponeuroses of the lateral abdominal muscles, encloses most of the rectus abdominis with anterior and posterior layers. anterior layer covers entire length of the muscle, initially composed of only the external oblique and anterior interior oblique aponeuroses, but below the arcuate line (below the umbilicus), contains all muscle aponeuroses. posterior layer extends to the arcuate line where it merges with the anterior layer; it is composed of the transversus abdominis aponeurosis and posterior internal oblique aponeurosis

inguinal ligament

thickening of the aponeurosis of external oblique muscle. attaches from ASIS to pubic tubercle. functions as an anatomical boundary between the abdomen and thigh

deep inguinal ring

on the deep surface of the anterior abdominal wall superior to the inguinal ligament, lateral to the inferior epigastric artery, and through the transversalis fascia

superficial inguinal ring

the external opening of the inguinal canal through the external oblique aponeurosis and just superior to the pubic tubercle, in both sexes contains the genitofemoral nerve and a portion of the ilio-inguinal nerve. females contain round ligament of the uterus, males contain the spermatic cord

gubernaculum

a cord of connective tissue that attaches from the developing gonads and passes through the anterior abdominal wall. extens into what will become scrotum/labia majora, guides the testis into the scrotum in males

processus vaginalis

outpocketing of the anterior abdominal wall that carries the muscular/fascial layers down into the developing scrotum; becomes the inguinal canal. creates two openings: through the transversalis fascia (deep inguinal ring) and the external oblique aponeurosis (superficial inguinal ring).

spermatic cord

suspends the testes in the scrotum, contains ductus deferens, testicular artery, pampiniform venous plexus

ductus deferens

transports sperm from epididymis to the ejaculatory ducts

pampiniform venous plexus

genital branch of genitofemoral nerve

scrotum

bi-layered sac that contains the testes, septum in midline separates each testis into it’s own compartment

inguinal hernia

occurs when a portion of the peritoneum passes through the abdominal wall into the groin

direct inguinal hernia

enters the inguinal canal through the posterior wall of the canal medial to the inferior epigastric artery

indirect inguinal hernia

occurs when the processus vaginalis remains open and the hernia passes through the deep inguinal ring lateral to the inferior epigastric vessels, may pass into scrotum or labia majus

lumbar plexus

ventral rami of L1-L4, with the plexus forming within the psoas major

iliohypogastric and ilioinguinal

T12-L1 and L1, motor: abdominal wall muscles, sensory: medial thigh and groin, exit psoas laterally, sometimes as a single trunk before dividing

genitofemoral

L1-L2, motor: cremaster muscle, sensory: anterior mons pubis/scrotum and upper anterior thigh, exits psoas anteriorly, splits into genital and femoral branches

lateral femoral cutaneous

L2-L3, motor: none, sensory: anterolateral thigh, exits psoas laterally

femoral

L2-L4, motor: iliacus, anterior compartment of thigh muscles, sensory: anterior thigh and medial leg, exit psoas laterally

obturator

L2-L4, motor: adductor compartment muscles, sensory: medial thigh, exits psoas medially

lumbosacral trunk

L4-L5, connection between lumbar and sacral plexuses, descends on the ala of the sacrum

subcostal nerve

ventral ramus of T12 spinal nerve, supplies abdominal wall muscles and cutaneous innervation of anterolateral abdomen, give off lumbar splanchnic nerves

lumbar splanchic nerves

nerves that medially that supply pelvic viscera with preganglionic sympathetic and visceral afferent fibers

abdominal aorta

rests on anterior surface of T12 to L4, branches into visceral unpaired, visceral paired, and parietal paired arteries

celiac trunk, superior and inferior mesenteric aa

visceral unpaired arteries to digestive tract

middle suprarenal, renal, gonadal aa

visceral paired arteries to kidney, suprarenal glands, and gonads

gonadal arteries

anterior branches that originate just below the renal arteries, pass inferolaterally on the surface of the psoas major, testicular arteries in males and ovarian arteries in females

subcostal, inferior phrenic, lumbar aa

parietal paired arteries to diaphragm and body wall

subcostal aa

lateral arteries that run beneath rib 12, in between internal oblique and transversus abdominis and supply abdominal wall

inferior phrenic aa

arise just below aortic hiatus of diaphragm, pass superior to supply inferior surface of diaphragm, origin of superior suprarenal arteries

lumbar artery

4 paired arteries that originate from the posterior aorta extend laterally across lumbar vertebral bodies, parallel the intercostal arteries and supply the posterior abdominal wall

median sacral artery

branches inferiorly off posterior aorta just above the bifurcation; runs on the anterior surface of sacrum/coccyx

inferior vena cava

runs on the right anterior surface of vertebral bodies, begins at L5 from union of common iliac veins and passes through the diaphragm at T8

left renal vein

unlike the right gonadal vein draining into the IVC directly, where does the left gonadal vein drain

cisterna chyli

saclike inferior end of the thoracic duct, forms to the right of the aorta at L1-L2