Study Guide #18 - Chapter 4: The Abdomen

These flashcards cover key concepts related to the posterior abdominal wall, kidneys, ureters, blood vessels, and nervous system components as studied in BIO475.

What is the Psoas Major muscle and its primary role?

The Psoas Major muscle is situated alongside the lumbar spine and is essential for flexing the hip as well as stabilizing the lower spine during movements.

What distinguishes the Psoas Minor muscle and why is it important?

The Psoas Minor muscle, while smaller than the Psoas Major, contributes to hip flexion and supports the stability of the lower spine.

What is the function of the Quadratus Lumborum muscle?

The Quadratus Lumborum muscle, located in the posterior abdominal wall, is important for bending the spine laterally and helping to stabilize the pelvis during various activities.

What role does the Iliacus muscle play in movement?

The Iliacus muscle works together with the Psoas Major to facilitate hip flexion and is crucial for actions such as walking and climbing.

What is the structure and function of the Diaphragm?

The Diaphragm is the main muscle involved in breathing, shaped like a dome, it separates the thoracic cavity from the abdominal cavity and contracts to allow air intake during inhalation.

Where is the posterior abdominal wall located?

The posterior abdominal wall is positioned at the back of the abdominal cavity, providing structural support and housing vital organs, blood vessels, and nerves essential for bodily functions.

What are the major components of the posterior abdominal wall?

The major components include:

a) Blood vessels and lymphatics: Such as the abdominal aorta and inferior vena cava, crucial for circulation and immune response.

b) Nervous system: Encompassing both autonomic and somatic nerves responsible for innervating the abdominal region and lower limbs.

c) Key organs: Including the kidneys and adrenal glands, which are important for filtration and hormone secretion.

Which structures traverse the diaphragm?

Key structures that pass through the diaphragm include:

• Aorta: Carries oxygenated blood from the heart to the lower body.

• Esophagus: Transports food and liquids from the throat to the stomach.

• Inferior Vena Cava: Returns deoxygenated blood from the lower body to the heart.

• Vagus Nerve: Provides nerve supply to thoracic and abdominal organs.

What are the primary functions of the kidneys?

a) Primary Function: The kidneys filter blood to eliminate waste products and excess substances, produce urine, and regulate electrolyte balance and blood pressure.

b) Location: They are retroperitoneally located on either side of the vertebral column, deep in the abdominal cavity, extending from the level of T12 to L3.

What critical points of contact do the kidneys have with surrounding structures?

The kidneys are in proximity to several vital structures, such as:

• Liver: Situated superiorly, influencing kidney functions.

• Duodenum and Pancreas: Located anteriorly, affecting digestive processes.

• Spleen: Positioned to the left, playing a role in blood filtration and immunity.

• Aorta and Inferior Vena Cava: Major blood vessels supplying and draining the kidneys.

What are the coverings of the kidneys, including fat and fascia features?

The kidneys are surrounded by renal fascia, which provides support, and perirenal fat that cushions and insulates them, protecting from trauma and helping maintain temperature.

What are the external characteristics of the kidneys?

The kidneys have a characteristic bean-like shape and are encased in a tough fibrous capsule. They feature:

• Renal Hila: Entry point for renal arteries and nerves as well as exit for renal veins and ureters.

• Renal Cortex: The outer region where initial blood filtration occurs.

What internal structures are found in the kidneys?

Key internal structures include:

a) Renal Cortex: Outer layer containing nephrons for blood filtering.

b) Renal Medulla: Inner section housing renal pyramids that concentrate urine.

c) Renal Pyramids: Triangular sections directing urine to renal calyces.

d) Renal Papilla: Tips of pyramids where urine exits into minor calyces.

e) Renal Sinus: Cavity housing renal pelvis and fat.

f) Minor and Major Calyx; Renal Pelvis: Collect urine from papillae and guide it to the ureters.

Which blood vessels supply the kidneys?

The kidneys receive blood via the renal arteries off the abdominal aorta and are drained by the renal veins that lead into the inferior vena cava.

What is the structure and function of the ureters?

Ureters are muscular tubes about 25-30 cm long that connect the kidneys to the bladder, using peristaltic movements to transport urine in a one-way direction.

What are three medical conditions related to the kidneys?

a) Urinary tract stones: Formed from minerals and salts, can cause pain, obstruction, and infection.

b) Urinary tract cancers: Malignant growths in parts of the urinary system, including kidneys and bladder, requiring timely diagnosis and treatment.

c) Kidney transplant: A surgical intervention where a healthy kidney from a donor is placed in a recipient with severe kidney dysfunction.

Describe the structure and function of the suprarenal glands (adrenal glands).

Small, triangular glands located on each kidney's upper pole, consisting of an outer cortex that produces hormones like cortisol and aldosterone, and an inner medulla that secretes adrenaline, crucial for metabolic regulation and stress response.

What are the blood supplies to the suprarenal glands?

The suprarenal glands are supplied by:

a) Superior suprarenal artery: Branches from the inferior phrenic artery.

b) Middle suprarenal artery: Branches from the abdominal aorta.

c) Inferior suprarenal artery: Branches from the renal artery.

What is the sympathetic innervation of the suprarenal glands?

The suprarenal glands receive sympathetic innervation from the thoracic splanchnic nerves, which stimulate adrenaline release during stressful circumstances, impacting heart and metabolic rates.

How does the abdominal aorta travel through the body?

The abdominal aorta descends along the spine, supplying blood to abdominal organs, and bifurcates into the common iliac arteries at the level of the fourth lumbar vertebra.

What are the branches of the abdominal aorta, ordered from superior to inferior?

The branches include:

1. Celiac trunk: Supplies the stomach, liver, and spleen.

2. Superior mesenteric artery: Supplies the small intestine and parts of the colon.

3. Renal arteries: Supply the kidneys.

4. Inferior mesenteric artery: Supplies the distal colon and rectum.

What pathway does the inferior vena cava follow?

The inferior vena cava begins at the junction of the common iliac veins, ascends through the abdomen, and drains deoxygenated blood back to the heart, culminating in the right atrium.

What tributaries flow into the inferior vena cava in ascending order?

Tributaries consist of:

1. Common iliac veins (left and right).

2. Lumbar veins draining the lower back.

3. Renal veins returning blood from each kidney.

4. Hepatic veins draining the liver.

Why do organs like the gastrointestinal tract not have veins emptying into the inferior vena cava?

Blood from these organs is directed through the hepatic portal vein to the liver for metabolic processing before it returns to the inferior vena cava.

What is deep vein thrombosis (DVT)? Name a treatment related to the inferior vena cava.

Deep vein thrombosis is the formation of blood clots in deep veins, typically in the legs. Treatment may involve placing a filter in the inferior vena cava to stop clots from traveling to the lungs (pulmonary embolism).

What major lymph node collections are found in the posterior abdominal wall?

Key lymph node collections include:

a) Lumbar lymph nodes: Critical for immune responses in the lower body.

b) Cysterna chyli: A lymphatic reservoir before draining into the thoracic duct.

What is the cysterna chyli?

The cysterna chyli is a lymphatic structure in the abdomen that collects lymph from the lower limbs, pelvis, and abdomen, channeling it into the thoracic duct.

What components make up the nervous system in the posterior abdomen?

The nervous system consists of:

a) Lumbar plexus: A nerve structure providing motor and sensory innervation to the lower limbs.

b) Thoracic splanchnic nerves: Autonomically supplying abdominal viscera.

c) Vagus nerve: Providing parasympathetic innervation to various abdominal organs.

How do postganglionic sympathetic neurons of the gastrointestinal tract operate?

Some postganglionic neurons arise in collateral ganglia (like the celiac ganglion), located near target organs, allowing direct influence on gastrointestinal functions.

Where are postganglionic neurons of the parasympathetic nervous system found?

Postganglionic neurons of the parasympathetic nervous system are located in or adjacent to the walls of target organs, enabling localized control over their functions.

How can issues in the large intestine cause pain in the anterior thigh?

Pain in the anterior thigh can stem from the large intestine due to shared nerve pathways, particularly through lumbar plexus connections and autonomic pathways.

What is the lumbar plexus and where is it situated?

The lumbar plexus is a network of nerves located in the lower back, originating from lumbar spinal segments (L1-L4), providing motor and sensory innervation to the lower limbs and parts of the pelvis.

What are the targets of the Iliohypogastric nerve?

The Iliohypogastric nerve provides sensory innervation to the skin of the lower abdomen and motor innervation to abdominal muscles.

What are the targets of the Ilioinguinal nerve?

The Ilioinguinal nerve provides sensory innervation to the groin and lower abdomen skin.

What are the targets of the Genitofemoral nerve?

The Genitofemoral nerve supplies sensory innervation to the anterior thigh and the external genitalia.

What are the targets of the Lateral cutaneous nerve of the thigh?

The Lateral cutaneous nerve of the thigh provides sensory innervation to the lateral thigh.

What are the targets of the Femoral nerve?

The Femoral nerve supplies motor innervation to the anterior thigh muscles and sensory innervation to the skin of the anterior thigh.

What are the targets of the Obturator nerve?

The Obturator nerve supplies motor innervation to the adductor muscles of the thigh.