Biol 2325: Abdomen (part 1: muscles, abdominal body wall vessels, and nerves)

What is the abdomen?

The area from below the diaphragm to

the pelvic inlet

rectus abdominis

tendonous intersections

Function of tendonous intersections

Allows the use of specific segments of the rectus abdominis instead of having one huge muscle

Linea alba

midline tendinous seam joining the abdominal muscles

What is the most anterior abdominal muscle?

rectus abdominis muscle

Function of the rectus abdominis

Pulls the ribs down for forced breathing (exhalation), helps compress the abdominal cavity

What part of the musculature pattern is the rectus abdominis?

Ventral musculature

External oblique muscle

What are the two laminae of the external oblique

Superficial lamina and the deep lamina

External oblique muscle- superficial lamina

aponeurosis of external oblique

(The pink on the image)

What is the fiber orientation of the external oblique?

Medially and inferiorly ("ex" to "sex")

Inguinal ligament

Thickened part of the bottom of the external oblique aponeurosis

Function of the external oblique

Contralateral rotation, compresses the abdominal cavity, flex the trunk (when using both sides of the muscle)

External oblique deep lamina

What musculature layer is the external oblique muscle superficial lamina?

Lateral supracostal or lateral outermost muscle layer

What musculature layer (of the muscle pattern) is the external oblique deep lamina?

Lateral external musculature layer

Internal oblique muscle

What is the fiber orientation of the internal oblique muscles?

Superiormedially, meaning they run upwards and inwards

Internal oblique muscle aponeurosis

Does the internal oblique muscle aponeurosis cover the ribs?

No

how does the internal oblique Aponeurosis change in relation to the rectus abdominis?

Part of the internal oblique aponeurosis runs infront of the rectus abdominis while part runs behind

Function or the internal oblique muscles

Ipsilateral rotation and flexion of the trunk

What muscle pattern layer is the internal oblique muscle?

Lateral middle muscle layer

transversus abdominis muscle

Anteriolateral muscle of the internal muscle layer

is the transversus abdominis anterior or posterior to the rectus abdominis?

Posterior

What is fiber orientation of the transversus abdominis?

Horizontally, or "transversely"

Function of the transversus abdominis muscle

Increase interabdominal pressure

What muscle layer (of the muscle pattern) is the transversus abdominis?

Lateral internal muscle layer

Quadratus Lumborum Muscle

Structure of the quadratus lumborum

Muscle that attaches to the transverse processes of the lumbar vertebrae

Function of the quadratus lumborum muscle

Stabilize the lumbar curvature of the spine and ipsilaterally flex the trunk

What muscle layer is the quadratus lumborum in respect to the muscle pattern?

Lateral internal muscle layer

What two abdominal muscles are in the lateral internal layer of the abdomen?

Transversus abdominis and quadratus lumborum muscles

Psoas major muscle

Structure of the psoas major muscle

"S" shaped muscle that attaches to the transverse processes and front of the vertebral bodies of the lumbar spine

Function of the psoas major

Stabalize the lordotic curve (along with the quadratus lumborum), also ipsilaterally flexes the abdomen and flex the hip

Main function of the psoas major

flexion at hip

What mucle layer is the psoas major?

Subvertebral

Psoas minor muscle

Is the psoas minor in front or behind the psoas major?

In front

Function of psoas minor

flexion of lumbar vertebral column

What muscle layer is the psoas minor?

Subvertebral

Functional significance of abdominal body wall

Protect internal organs while allowing more dynamics that bone would. Its a "dynamic retaining wall"

What are the aponeurosis of the internal oblique, external oblique, and transversus abdominis doing ABOVE the belly button?

They wrap the rectus abdominis. the aponeurosis of the transversus abdominis running behind the rectus abdominis with the other two running in front

What happens to the internal/external oblique and transversus abdominis aponeurosis below the belly button?

All the aponeurosis are in front of the rectus abdominis

inferior phrenic arteries

supply the inferior surface of diaphragm

What do inferior phrenic arteries branch from?

Directly off the aorta

lumbar arteries

small, paired blood vessels that originate from the abdominal aorta and supply the POSTERIOR abdominal wall. They are similar to the intercostal arteries in the abdomen.

Are the inferior phrenic arteries and lumbar arteries posterior or anterior body wall supply arteries?

Posterior

superior epigastric artery

branch of internal thoracic artery that supplies the upper anterior abdominal wall

What muscle is supplied by the superior epigastric artery?

Rectus abdominis

What forms a collateral circuit with the superior epigastric artery

Inferior epigastric artery

inferior epigastric artery

A lower anterior supply artery.

From which artery does the inferior epigastric artery branch?

The external iliac artery.

In which direction does the inferior epigastric artery travel?

Superiorly into the abdominal body wall.

Lumbar veins

Inferior phrenic veins

drain the inferior surface of the diaphragm into the inferior vena cava

Ascending lumbar veins

Branches off the common iliac vein that receive blood from the lumbar veins

Where do the right ascending lumbar veins go?

The azygos vein

Where do the left ascending lumbar veins go?

The hemiazygos vein

Why do we have more veins than arteries?

There is more volume of blood coming back to the heart than leaving it. Act as a blood reservoir

Are the lumbar and inferior phrenic arteries posterior or anterior supply vessels?

Posterior supply vessels

Superior epigastric veins

Upper anterior drainage veins into the internal thoracic veins

Inferior epigastric vein

LOWER anterior drainage veins into the external iliac veins

When does the right ascending lumbar vein become named the azygos vein?

When it exits the top of the diaphragm

What is the abdominal wall from T7-T11 innervated by?

Intercostal nerves

What is the abdominal wall at level T12 innervated by?

Thoracis spinal nerve T12 called "subcostal nerve" because its below the last rib

What are the three lumbar spinal nerves?

Iliohypogastric nerve, ilioinguinal nerve, genitofemoral nerve

iliohypogastric nerve

Lumbar spinal nerve L1 superficial to quadratus lumborum

Where is the iliohypogastric nerve relative to the ilioinguinal nerve?

It is superior to the ilioinguinal nerve

Does the Iliohypogastric nerve have a lateral cutaneous branch?

Yes

function of iliohypogastric nerve

provides sensation to the skin of the lower abdomen and gluteal region

Ilioinguinal nerve

branch of the L1 spinal nerve

Does the inguinal nerve have lateral cutaneous branches?

No

Does the ilioinguinal nerve have an anterior cutaneous branch?

Yes

function of ilioinguinal nerve

innervates lower abdominal muscles, skin over superior/medial thigh and portions of external genitalia

genitofemoral nerve

Lumbar spinal nerve L2

Function on the genitofemoral nerve

provides sensation to the skin of the upper anterior thigh, the scrotum (in males), and the mons pubis (in females)