Coelom, Viscera, Cardiovascular & Lymphatic Systems – Vocabulary Review

Coelom (Ventral Body Cavity)

• Definition: The large anterior (ventral) body cavity housing thoracic and abdominopelvic viscera.

• Anatomical divider

  • Diaphragm – skeletal muscle sheet separating thoracic and abdominopelvic cavities.

• Major subdivisions & contents

  • Thoracic cavity

  • Pleural cavities (right & left) – lungs

  • Pericardial cavity – heart

  • Mediastinum – region between pleural sacs (contains heart, esophagus, trachea, great vessels, thymus, nerves)

  • Abdominopelvic cavity

  • Abdominal cavity – digestive organs, spleen, kidneys, etc.

  • Pelvic cavity – bladder, reproductive organs, distal large intestine

  • Peritoneal cavity (subset of abdominopelvic) – fluid-filled potential space surrounding intraperitoneal organs

Serous membranes (each = simple squamous epithelium + areolar CT)

• Pleural cavity

  • Visceral pleura – on lungs

  • Parietal pleura – on thoracic wall, diaphragm, mediastinum

• Pericardial cavity

  • Visceral pericardium (epicardium)

  • Parietal pericardium (serous layer deep to fibrous pericardium)

• Peritoneal cavity

  • Visceral peritoneum – on surface of intraperitoneal organs

  • Parietal peritoneum – lines abdominopelvic walls & inferior diaphragm

  • Peritoneal folds (double-layered serosa)

  • Mesenteries

    • Mesentery proper – suspends jejunum & ileum from posterior wall

    • Mesocolon – suspends transverse & sigmoid colons

  • Ligaments

    • Coronary ligament – liver ↔ diaphragm

    • Falciform ligament – liver ↔ anterior body wall

    • Ligamentum teres hepatis – remnant of umbilical vein in falciform free edge

  • Omenta

    • Greater omentum – stomach ↔ transverse colon

    • Lesser omentum – stomach ↔ liver

Diaphragm apertures

• Aortic hiatus – aorta

• Caval (vena caval) hiatus – inferior vena cava

• Esophageal hiatus – esophagus & vagus nerves (CN X)

Exit points from coelom

• Femoral triangle: femoral artery, femoral vein, lymphatics, femoral nerve ("A V L N" lateral➜medial in order)

• Inguinal canal: spermatic cord (males) / round ligament (females)

Retroperitoneal organs (posterior to parietal peritoneum)

• Duodenum (2nd–4th parts), pancreas, ascending & descending colons, adrenal glands, kidneys, ureters, urinary bladder, abdominal aorta, inferior vena cava

Intraperitoneal organs (suspended by mesentery, wrapped by visceral peritoneum)

• Jejunum, ileum, transverse colon, sigmoid colon, stomach, liver, gallbladder, spleen

Dissected nerves to identify

• Phrenic nerve – motor & sensory to diaphragm

• Vagus nerve (CN X) – parasympathetic to thorax & abdomen

• Recurrent laryngeal nerve – branch of vagus looping around aortic arch / right subclavian; motor to larynx

Additional lab emphases

• Spermatic cord components (vas deferens, testicular vessels, nerves, lymphatics) – studied fully in reproductive lab

• Venous valves – demonstrated on femoral vein

• Lymphatic system: recognize lymph nodes histologically; lymphatic vessels identified on charts only

• Formed elements of blood: erythrocytes, leukocytes (neutrophils, eosinophils, basophils, lymphocytes, monocytes), platelets

Cardiovascular System Overview

• Two fluid-transport systems

  • Cardiovascular – blood, vessels, heart

  • Lymphatic – lymph, lymphatic vessels, nodes, organs (covered separately)

Heart (Gross Anatomy)

• Pericardial sac (pericardium)

  • Fibrous pericardium – dense CT, anchors heart, prevents over-stretching

  • Parietal pericardium – serous membrane lining inner fibrous layer

• Heart wall layers

  • Epicardium = visceral pericardium (serous membrane)

  • Myocardium – cardiac muscle (thickest)

  • Endocardium – endothelium + areolar CT lining chambers & valves

• External landmarks

  • Apex – inferior pointed tip (left 5th ICS at mid-clavicular line)

  • Coronary (atrioventricular) sulcus – encircles heart between atria & ventricles

  • Interventricular sulci – anterior & posterior; mark septum & house coronary vessels

• Chambers / Structures

  • Atria

  • Right & left auricles (ear-like pouches)

  • Pectinate muscles (comb-like ridges) in right atrium & both auricles

  • Interatrial septum – contains fossa ovalis (remnant of fetal foramen ovale)

  • Atrioventricular (AV) valves

  • Right: tricuspid valve

  • Left: mitral (bicuspid) valve

  • Ventricles

  • Chordae tendineae – collagen cords connecting valve cusps to papillary muscles

  • Papillary muscles – prevent cusp prolapse

  • Trabeculae carneae – ridged muscular walls

  • Interventricular septum

  • Semilunar valves

  • Pulmonary semilunar – RV → pulmonary trunk

  • Aortic semilunar – LV → ascending aorta

• Coronary circulation

  • Right & left coronary arteries (from ascending aorta)

  • Anterior & posterior interventricular arteries

  • Cardiac veins → coronary sinus → right atrium

• Embryological remnants

  • Fossa ovalis – in interatrial septum (was foramen ovale)

  • Ligamentum arteriosum – aortic arch ↔ pulmonary trunk (was ductus arteriosus)

• Great vessels

  • Superior & inferior venae cavae (venous return)

  • Pulmonary trunk → right & left pulmonary arteries (deoxygenated blood to lungs)

  • Right & left superior pulmonary veins; right & left inferior pulmonary veins (oxygenated blood from lungs)

  • Ascending aorta → systemic circulation

Major Blood Vessels (Gross Anatomy)

(Indicate A = artery, V = vein; paired vessels are right & left unless noted)

• Leaving / entering heart

  • Pulmonary trunk (A) – deoxy blood to lungs

  • Pulmonary arteries (A)

  • Pulmonary veins (superior & inferior) (V) – oxy blood from lungs

  • Ascending/arch/thoracic/abdominal aorta (A) – systemic outflow

  • Superior & inferior vena cava (V) – systemic inflow

• Head, neck, upper limbs

  • Brachiocephalic artery (A) – R. head, neck, UL

  • Common carotid arteries (A) – head & neck

  • Internal carotid (A) – brain

  • External carotid (A) – face/scalp

  • Vertebral arteries (A) – brain (posterior circulation)

  • Subclavian arteries (A) – brain, neck, UL

  • Thyrocervical trunks (A) – thyroid & neck

  • Internal thoracic arteries (A) – anterior thoracic wall

  • Brachiocephalic veins (V), internal & external jugular veins (V), vertebral veins (V), subclavian veins (V)

• Thoracic wall

  • Azygos vein (V) – drains posterior thoracic wall

• Abdominal viscera

  • Celiac trunk (A)

  • Gastric artery (A) – stomach

  • Splenic artery (A) – spleen & pancreas

  • Common hepatic artery (A) – liver, gallbladder, stomach

  • Superior mesenteric artery (A) – small intestine, proximal large intestine, pancreas

  • Renal arteries (A) – kidneys

  • Suprarenal arteries (A) – adrenal glands

  • Inferior mesenteric artery (A) – distal large intestine

  • Hepatic portal vein (V) – gut → liver

  • Gastric, splenic, superior & inferior mesenteric veins (V)

  • Hepatic veins (V) – liver → IVC

  • Renal veins (V)

  • Suprarenal veins (V)

  • Ovarian/Testicular arteries (A) & veins (V)

• Pelvis & lower limb

  • Common iliac arteries & veins (A/V)

  • Internal iliac (A/V) – pelvis

  • External iliac (A/V) – lower limb

  • Femoral arteries & veins (A/V) – lower limb

  • Great saphenous vein (V) – superficial medial lower limb; possesses readily visible venous valves in dissection

(Note: order of vertebral, thyrocervical, and internal thoracic arteries from subclavian may vary; vertebral is usually most medial.)

Histology: Artery vs Vein vs Nerve (Cross-section)

• Arteries

  • Thick muscular wall (tunica media)

  • Round, relatively small lumen; may contain clumped RBCs (orange-red glass appearance)

  • Endothelium = simple squamous cells with bulging nuclei

• Veins

  • Thinner wall, large irregular or collapsed lumen

  • Endothelium similar to artery

  • May appear empty (clear) or full (opaque) depending on blood presence

• Nerves

  • No lumen; packed with numerous axons

  • Axons appear as dark dots each surrounded by white myelin sheath; grouped by CT into fascicles; whole nerve encased by CT (epineurium)

Blood & Formed Elements

• Erythrocytes – anucleate biconcave discs, O₂ transport

• Leukocytes

  • Neutrophils – multilobed nucleus, phagocytic

  • Eosinophils – bilobed nucleus, red granules, parasitic & allergic roles

  • Basophils – dark granules, histamine release

  • Lymphocytes – large nucleus, adaptive immunity (B & T cells)

  • Monocytes – kidney-shaped nucleus, become macrophages

• Thrombocytes (platelets) – fragments involved in clotting

Lymphatic System (brief, per lab scope)

• Lymph node histology: cortex with lymphoid follicles (germinal centers), medulla with medullary cords & sinuses

• Lymphatic vessels identified on instructional charts only (not dissected)

Laboratory & Practical Exam Reminders

• Identify phrenic, vagus, recurrent laryngeal nerves in cadaver

• Observe spermatic cord / round ligament before removal; full ID on reproductive exam

• Recognize formed blood elements on slides

• Distinguish arteries, veins, and nerves histologically

• For every named vessel on the list, know (1) whether it is an artery or vein and (2) the region it supplies or drains

• Indicate venous valves (e.g., on great saphenous or femoral vein) when present