Written Examination Part IV. (36 pts) - Essay: Lower Limb and Thorax (August 31, 2006)

Note: This is an answer guide. An outline of topics to discuss. It is not "the answer."

Heart - Structure and Function of Valves - August 31, 2006

Discuss the structure and function (including blood flow to the coronary vessels) of the semilunar valves and the atrioventricular valves (12 pts)

The valves of the heart direct blood flow in one direction

  • Between the atria and the ventricles are the atrioventricular valves
  • Between the ventricles and arterial trunks are the semilunar valves
  • Healthy valves permit little to no back flow
  • Integrated with the skeleton of the heart
  • Located in the ventricles (atrioventricular valves) and at the base of the arterial trunks (semilunar valves)
  • The atrioventricular valves and the semilunar valves are closed by pressure (they are not closed by muscular contraction applied to the cusps)
  • IVC to rt atria to tricuspid to rt ventricle to pulmonary valve to pulmonary artery to lungs to pulmonary veins to left atria to biscupid (mitral) valve to left ventricle to aortic valve to systemic circulation to coronary arteries during diastole
  • Atrioventricular valves close (lub) during systole whereas the semilunar valves close (dub) during diastole

Atrioventricular valve - Tricuspid

  • Between the right atria and the right ventricle
  • Three cusps open into the right ventricle
  • Three papillary muscles (extensions of trabeculae carne) - anterior, posterior, and septal
  • Synchronization of papillary muscles handled by conduction system
  • Cusps are stabilized by chorda tendeneae - fibrous cords between cusps and papillary muscles
  • Ventricular contraction raises pressure - blood pools on ventricular side of cusps causing the cusps to approximate each other and close the valve
  • Adjustments by the papillary muscles and chorda tendeneae provide support and prevent eversion of the cusps into the atria
  • Note - contraction of the papillary muscles, in the absence of ventricular contraction, open, not close, the atrioventricular valves

Atrioventricular valve - Biscuspid (Mitral Valve)

  • Between the left atria and the left ventricle
  • Two cusps open into the left ventricle
  • Two papillary muscles - anterior and posterior
  • Resists extreme pressure generated by left ventricular contraction

Semilunar valve - aortic valve

  • Located at the base of the aortic trunk
  • Prevents reverse flow from the aorta to the left ventricle during diastole
  • Negative pressure of left ventricle and elastic recoil of systemic arteries move aortic blood toward the valve
  • Opened by blood flow during systole - cusps move toward aortic wall and block coronary ostia
  • Three cusps - no papillary muscles or chorda tendeneae
  • Left and right coronary cusps and a non-coronary cusp
  • Nodule - weighted fibrous thicking at the midline of the free edge of each cusp aids in approximating the cusps and closing the valve
  • Aortic sinus - space between the wall of the aorta and each cusp
  • Valve closed by pressure - blood pools in the aortic sinuses during diastole and aproximates the nodules

Semilunar valve - pulmonary valve

  • Located at base of pulmonary trunk
  • Prevents reverse flow from the pulmonary trunk to the right ventricle during diastole
  • Operation is the same as aortic valve except that there are not coronary cusps (no ostia in pulmonary trunk)

Blood flow to the coronary vessels

  • Coronary arteries are perfused during diastole when heart muscle is relaxed
  • During systole the coronary ostia are blocked by the open cusps of the aortic valve
  • During diastole blood pools in the aortic sinuses and closes the aortic valve.
  • Blood driven into the left and right aortic sinuses enters into the ostia of the coronary arteries.


Knee Joint - August 31, 2006

Review the anatomy of the knee joint and include bones, articulations, ligaments, cavities and bursa, vasculature, muscles, fascial specializations, and stability of the joint. Explain the tenderness on the medial side of the knee, and the abnormal forward movement of the tibia in relationship to the femur. (12 pts)

Bones and Articulations

  • Synovial hinge joint between the femoral and tibial condyles.
  • Tibial plateau is cupped by the medial and lateral menisci.
  • Femoral condyles - shape
  • Tibial condyles - shape
  • Patella articulates anteriorly as a sesamoid bone in the quadriceps tendon.
  • Articular cartilage


  • Medial collateral ligament (attached to medial meniscus).
    • medial femoral epicondyle to the medial tibial condyle.
    • resists abduction of tibia
  • Lateral collateral ligament (interval between lateral meniscus and ligament transmits popliteus tendon
    • From lateral femoral epicondyle to the head of the fibula
    • resists adduction of tibia
  • Anterior cruciate ligament
    • from lateral posterior femoral condyle to anterior aspect of tibial intercondyler eminence.
    • resists forward displacement of the tibia.
    • Alar fold
  • Posterior cruciate ligament
    • from posterior medial femoral condyle to posterior aspect of tibial intercondyler eminence.
    • resists posterior displacement of tibia
    • Alar fold
  • Oblique popliteal and arcuate ligaments strengthen the posterior joint capsule.
    • Semibranosus
    • Popliteus
  • Coronary, transverse genicular, and meniscofemoral ligaments secure the menisci.
    • Tibial plateau

Cavities and bursae

  • Synovial joint cavity
    • attaches to edges of menisci - articular surface is intrasynovial
    • Alar folds anterior to anterior crucial ligament - posterior limit of midsaggital synovial cavity
    • reflections of the synovial membrane along the intercondylar fossa - cruciate ligaments are extrasynovial.
    • continuous with suprapatellar bursa (quadriceps bursa)
      • Articularis genu
  • prepatellar bursa
    • bursitis
  • infrapatellar bursa
    • Superficial and deep
  • Joint Capsule
    • ligaments making up the capsule (above)
    • intercondylar area is extrasynovial
    • popliteus tendon within cavity
    • patellar retinaculum
    • patellar and quadraceps tendon

Muscles, Movements and limitations of movement

  • Primarily flexion and extension (hinge joint).
  • Some rotation (30-40 degrees) is possible when the knee is flexed
  • Flexion is primarily by the hamstrings, short head of biceps, gracilis, and sartorius.
    • innervated by tibial portion sciatic, peroneal portion sciatic, obturator, and femoral nerves respectively.
    • minor flexion by popliteus, gastrocnemius, and plantaris.
    • flexion is limited by quadriceps, cruciate ligaments, and by opposing soft tissues (calf and thigh).
  • Extension is primarily by the quadriceps and tensor fascia lata.
    • innervation by femoral nerve and superior gluteal nerve.
    • extension is limited by hamstrings, cruciate ligaments, collateral ligaments, posterior joint capsule.
  • Medial rotation of tibia is primarily by popliteus, semitendonosus, gracilis, and sartorius.
    • innervation by tibial nerve, tibial portion sciatic, obturator, and femoral nerves respectively.
    • limitation of movement by collateral ligaments
  • Lateral rotation of tibia is primarily by biceps femoris.
    • innervation by tibial and peroneal portions of sciatic nerve.
  • limitation of movements by collateral ligaments.
    • Abduction and adduction is limited by the medial and lateral collateral ligaments.
  • Fascial Specializatons
    • patellar retinaculum
    • iliotibial tract
    • investing fascia
  • vascular supply
    • Genicular anastomosis
      • Superior and inferior, medial and lateral genicular arteries, and middle genicular from the popliteal artery.
        • Middle genicular artery and intercondylar space
      • Descending genicular artery from femoral artery and descending branch from lateral femoral circumflex artery.
      • Fibular circumflex artery, and anterior and posterior tibial recurrent arteries from the anterior and posterior tibial artery
      • Accompanying veins
  • Innervation (Hilton's Law)
    • small branches of the femoral, obturator, and sciatic, and tibial nerves pierce the joint capsule.
  • "Screw Home"
    • Consider when the knee is extended with the foot planted on the ground. In this case, the tibia is fixed by virtue of the planted foot. Thus, rotation of the knee occurs as movement of the femur. The femur rotates medially as the knee "locks" in extension. The lateral femoral condyle is smaller than the medial femoral condyle. As the knee is extended the smaller condyle moves through its arc before the medial condyle. Thus, movement stops at the lateral condyle while the femoral medial condyle continues to move further posteriorly. This movement results in a medial rotation of the femur.
    • This medial rotation torques the joint capsule and it's ligamentus specializations (medial and later collateral ligs). The "twisting" of the capsular ligaments causes the region to tighten. This firmly approximates the femoral condyles to the tibial plateau and "locks" the knee. The femur "screws" medially onto the tibial plateau due to the larger medial condyle and the twisting of the capsular ligaments. On extension, the knee goes through a "screw home" rotation that results in "close packing."
    • The final medial rotation of the femur is driven by the line of gravity moving anterior to the axis of the knee joint. Thus, locking the knee is driven by gravity. Unlocking the knee requires muscular involvement. The popliteus, having lateral superior to medial inferior attachments, posterior to the axis of the knee, can to lateral rotate the femur (reverse origin and insertion) and, thus, unlock the knee joint.


Femoral Triangle - August 31, 2006

Review the boundaries (6 in number) and contents (vasculature, nerves, lymphatics) of the femoral triangle. State the relationship of structures entering and leaving this region. (12 pts)

Superior boundary: Inguinal ligament spanning the anterior superior iliac spine and pubic tubercle (including a figure would help)

  • contents of the muscular and vascular lacunae enter the femoral triangle (discuss relations)
  • Vascular lacuna.
    • The vascular lacuna is located posterior to the inguinal ligament, medial to the iliopectineal arch, lateral to the lacunar ligament, and anterior to the pectineal fascia.
    • The contents include, from the lateral to medial, the femoral artery, the femoral vein, and the femoral canal.
    • These contents are contained within compartments of the femoral sheath. These compartments are separated by septa that run between the inguinal ligament and the pectineal fascia.
    • Femoral hernias occur in this region.
    • abdominal viscera may enter the femoral canal through the femoral ring.
  • Muscular lacuna
    • posterior to inguinal ligament and lateral to iliopectineal arch
    • femoral nerve enters femoral triangle deep to iliacus fascia
    • lateral femoral cutaneous nerve enters femoral triangle lateral to femoral nerve and near anterior superior iliac spine

Lateral boundary: sartious

  • lateral femoral circumflex a/v exits laterally deep to sartious and between rectus femoris and vasti

medial boundary: adductor longus

  • profunda femoral a/v exits posteromedial deep to super border of adductor longus and continues between adductor longus and adductor magnus

Inferior boundary: adductor canal at the apex

  • Adductor canal.
  • At the apex of the femoral triangle is the beginning of the adductor canal.
  • The femoral artery and vein, and the saphenous nerve enter the adductor canal.
  • The femoral artery is anterior to vein - note: this relation betrays relation of popliteal vessels
  • The adductor canal is bounded anteromedially by the sartorius muscle. Anterolaterally, it is bounded by the vastus medialis. Posteriorly it is bounded by adductor longus and adductor magnus.
  • nerve to vastus intermedius enters adductor canal
  • deep lymphatics ascend adductor canal to femoral triangle

Posterior boundary: iliopsoas, pectineus, and possibly parts of adductor brevis and adductor longus

  • the medial femoral circumflex a/v exits between iliopsoas and pectineus
  • the deep femoral artery exits between iliopsoas and adductor longus

Anterior boundary: fascia lata and saphenous hiatus (show relations fig)

  • the contents of the cribriform fascia exit the femoral triangle at this location
  • superficial/external pudendal a/v
  • superficial epigastric a/v
  • superficial circumflex iliac a/v
  • the great saphenous vein
  • anterior femoral cutaneous nn pierce fascia lata anterior.

Further discussion

  • The saphenous hiatus
    • is a specialization of the fascia lata located in the anteromedial thigh just inferior to the inguinal ligament and superficial to the femoral sheath. The lateral margin overlies the femoral artery. The medial aspect overlies the femoral canal. Superiorly is the inguinal ligament. Approximately 2cm inferior to the inguinal ligament is the inferior cornu over which the great saphenous vein forms an arch as it leaves superficial fascia and enters the femoral vein. Notable tributaries of the great saphenous vein within the saphenous hiatus are the external pudendal vein coursing medially, the superficial epigastric vein coursing superiorly, and the superficial circumflex iliac vein coursing laterally and superiorly. Accompanying these veins are branches of the femoral artery. These vessels are piercing through the surrounding cribriform fascia. The distinct lateral margin of the saphenous hiatus is the falciform edge. There are superior and inferior borders referred to as the superior and inferior cornu. Medially, the hiatus is indistinct and blends with the pectineus fascia. The femoral ring is located immediately deep to the medial aspect of the saphenous hiatus. A femoral hernia, if present, can be palpated at this location. Additionally, a femoral pulse can be located and, thus, easy surgical access to a major artery or vein is possible.
  • Femoral canal
    • Lymph funnel shaped lymph channel located in the most medial compartment of the femoral sheath.
    • Femoral ring is at the superior opening of this canal.
    • Formed by an 1.5cm extension of transversalis fascia from the abdominal cavity into the thigh.
    • Exposed to superficial fascia by the saphenous hiatus.
    • Site of femoral hernia
    • more common in females because of wider pelvic bones and larger femoral ring.



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Topic revision: r1 - 31 Aug 2012, UnknownUser
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