Thigh+and+Leg

toc =**Thigh and Leg - Lecture Notes**=

[|Lecture 1] [|Lecture 2]

=**Thigh and Leg**=


 * 1. Identify the bones of the lower limb and the major anatomical features of each.**

The major bones of the lower limb are the femur, tibia, and fibula.

Femur has a head that fits into the acetabulum and a neck connects the head to the shaft. The distal end is expanded by medial and lateral condyle where it meets the knee. At the proximal limb of the shaft is the greater trochanter anteriorly, and the lesser trochanter posteriorly.

Distance of the head of the 2 femurs is usually greater in the female because of the greater width of the female hips. Distally, the femurs angle inward medially when in anatomical position. This angle is called the angle of inclination, and is caused by the angle between the head and the neck. Normally, the angle of inclination is usually between 115-140 degrees. These dimensions vary with sex, age, and individual. Greater than 140 degrees (example: 160 degrees) is called coxa valgus or bow-legged situaton; less than 115 degrees (example: 90 degrees) is called coxa varus. The oscoxa is a synonym for the hip, hence “coxa” meaning regarding the hip; do not confuse with genu valgus and varus (knee).

In the leg, the medial bone is the tibia and the lateral bone is the fibula. The tibia participates in the knee joint, but the fibula doesn’t articlate with the patella or the femur. Both bones participate with the ankle joint.

The continuation of the quadriceps tendon, the patella ligament, attaches to the tibial tuberosity. The lateral and medial melleoli are projections of the tibia and fibula at the distal end that participate in the ankle joint. These are subcutaneous and can easily be palpated. The soleal line is oblique on the posterior tibia. The tibia and fibula are interconnected by an interosseous membrane.


 * 2. Define the boundaries and the contents of the femoral triangle.**

The external iliac vessels pass deep to the inguinal ligament and change its name to the femoral vessels. The femoral nerve does not change its name as it crosses deep to the inguinal ligament. Medial to lateral, the femoral vein, artery and nerve enter the lower limb through the femoral triangle. The base of the triangle is the inguinal ligament. Its lateral side is the sartorius muscle and the medial side is the adductor longus. The floor of the femoral triangle is formed laterally by the iliopsoas and medially by the pectineous muscle.

When the vessels come out of the abdominal cavity, they bring some fascia (mostly transversalis fascia) out into the thigh, forming the femoral sheath that invests the vessels. They run around the external surface of the femoral vessels. However, the femoral nerve is lateral to the femoral vessels and outside of the femoral sheath; the femoral nerve is NOT part of the femoral sheath. The femoral nerve ends in the femoral triangle and gives off several branches to supply the anterior compartment and cutaneous nerves to the anterior thigh.

The femoral sheath blends with the adventitia of the femoral triangle and has extensions that create a medial, intermediate, and lateral compartment. The artery is in the lateral compartment; the vein is in the intermediate compartment; the medial compartment is called the femoral canal and contains some loose CT and a lymph node (Cloquet’s lymph node receiving lymph from deep structures).


 * 3. Explain the anatomy of a femoral hernia and distinguish it from inguinal hernias.**

The femoral canal is the smallest and most medial of the three femoral sheath compartments. The femoral ring is a small proximal opening of the femoral canal that is normally closed by the femoral septum, composed of extraperitoneal fatty tissue. The abdominal surface of the femoral septum is covered by parietal peritoneum and is pierced by lymphatic vessels connecting the inguinal and external iliac nodes.

The boundaries of the femoral ring are the partition between the femoral canal and the femoral vein laterally, the superior ramus of the pubis covered by the pectineus and its fascia posteriorly, the lacunar ligament medially, and the medial part of the inguinal ligament anteriorly.

The femoral ring is a weak area in the anterior abdominal wall where a loop of intestine can herniate down to the thigh. Femoral hernias predominate in females because the pelvis is wider. The hernia can go inferiorly through the saphenous opening and become subcutaneous.

Inguinal hernia is an abdominal hernia through anterior abdominal wall in the inguinal region. It can be direct and indirect, and occurs much more frequently in men than women.


 * 4. Demonstrate the course and primary branching pattern for major vessels and nerves of the lower limb.**

The Femoral artery gives off the deep femoral a. of the thigh right after passing through the inguinal ligament. The deep femoral a. gives rise to lateral and medial circumflex arteries, with the leteral femoral circumflex a. giving off a descending branch, the primary artery of the anterior compartment. The deep femoral artery continues down the thigh giving off perferating branches to the posterior compartment. The femoral a. continues down the thigh and passes through the adductor hiatus to become the popliteal a. The popliteal a. branches to form anterior and posterior tibial arteries. The posterior tibial a. give off the fibular a on the posterior leg. The Femoral nerve gives rise to many branches as it enters the thigh (along not inside the femoral sheeth), one being the saphinous n. which follows the saphinous branch of the descending genicular a. into the anteriomedial knee. The sciatic n. enters the posterior thigh through the greater sciatic foramen just inferior to piriformus. The sciatic nerve continues down the posterior compartment dividing into tibial and fibular components in the popliteal fossa. The tibial n. continues inferiorly as the common fibular n. travels meially to the anterior leg. The fibular n. splits into suprificial and deep branches as it descends the leg.


 * 5. Identify arteries from which a pulse may be palpated.**

A pulse can be palpated easily at the femoral a. where it enters the thigh between the ASIS and pubis, the popliteal a. can be palpated in the popliteal fossa, the posterior tibial a. can be palpated below the medial melleolus, and the dorsal pedis a. can be palpated on the dorsum of the foot.


 * 6. Describe the course of the major superficial veins of the lower limb.**

The Great (long) saphenous v. begins on the dorsum of the foot, ascends the anterior leg, moves medially across the posterior knee, then returns to the anterior thigh to drain into the Femoral v. in the femoral sheeth. The lesser (short) saphenous v. begins on the lateral aspect of the foot and ascend up the posterior leg to reach the popliteal fossa where it joins the popliteal v.


 * 7. List the contents of the subsartorial canal.**

The cleft in the muscle containing the femoral artery and vein is called the subsartorial canal (a.k.a adductor canal or hunter’s canal). The femoral artery and nerve goes deep to sartorius muscle. The collateral circulation for the lower limb can allow the lower limb structures to persist even if the femoral artery is tied off.

There are 2 nerves that branch off the femoral nerve that continue with the femoral vessels in the subsartorial canal. One of those nerves is nerve to vastus medialus. The other nerve is the saphenous nerve. The saphenous nerve continues to the leg and foot and is a pure-sensory nerve in the thigh.


 * 8. Demonstrate the muscles found in each anatomical "compartment" of the lower limb.**

Muscles of the thigh are divided into anterior, medial and posterior compartments. In the anterior compartment of the thigh are Quadriceps femoris (Vastus lateralis, Vastus medialis, Vastus intermedius, Rectus femoris), Sartorius, and Tensor fascia lata. In the medial compartment of the thigh are Adductor longus, Adductor brevis, Adductor magnus, Gracilis, and Pectineus. In the posterior compartment of the thigh are Biceps femoris, Semimembranosus, and Semitendinosus Muscles of the leg are divided into anterior, posterior, deep posterior, and lateral compartments. The Popliteus does not lie in any of the compartments, and is located below the knee joint on the posteriomedial leg. In the anterior compartment are Tibialis anterior, Extensor digitorum longus, Extensor hallicus longus, and Fibularis tertius. In the posterior compartment are Gastrocnemius, Plantaris, and Soleus. In the deep posterior compartment are Tibialis posterior, Flexor digitorum longus, and Flexor hallicus longus. In the lateral compartment are Fibularis longus, and Fibularis brevis.


 * 9. Define active and passive insufficiency as it relates to muscles.**

Active insufficiency refers to the inability of a muscle to act efficiently across two joints at the same time. For example, flexion of the knee after extension of the hip using the hamstring muscles results in reduced range and strength. This is because the muscles have already contracted and have difficulty contracting much more to exert action across the second joint.

Passive efficiency refers to the inability of a muscle to stretch enough to complete the full range of motion across two joints simultaneously. For example, it is difficult to do a high kick (hip flexion) while simultaneously keeping the knee fully extended. This is related with the connective tissue restricting the movement of the muscle.

Generally, the anterior thigh muscles are flex the hip and extend the knee, medial thigh muscles adduct of the hip, superficial gluteal muscles extend, abduct, and medially rotate the hip, deep gluteal muscles laterally rotate the hip, and posterior muscles extend the hip and flex, medially rotate, and laterally rotate the knee.
 * 10. Define the major actions of muscles acting on the hip, knee, ankle, and digital joints.**

The muscles of the leg are also divided into anterior, lateral, superficial posterior, and deep posterior compartments. The muscles of the anterior compartment are mainly dorsiflexors of the ankle and extensors of the toes. The lateral compartment everts the foot and weakly plantarflexes the ankle. Superficial posterior muscles are the powerful plantarflexors of the foot and also have some action in flexing the knee. The deep posterior muscles are inverts and plantarflexes the foot, and flexes the toes except for popliteus which flexes the knee and unlocks it.

The intrinsic muscles of the foot are divided into the dorsum side and the 4 layers on the plantar side. Their actions are basically reflected by their names (abductors adduct, flexors flex, extensors extend) but the primary function of the intrinsic muscles on the plantar side of the foot is to resist flattening or maintain the longitudinal arch of the foot. Like the hand, the 3 plantar interosseous muscles are adductors and the 4 dorsum interosseous muscles are abductors. Lumbricals flex the proximal phalanges while keeping the middle and distal phalanges of the lateral 4 toes extended.

The boundaries of the fossa are: superior and medial: the semitendinosus muscle, inferior and medial: the medial head of the gastrocnemius muscle, superior and lateral: the biceps femoris muscle, inferior and lateral: the lateral head of the gastrocnemius muscle. The contents include: popliteal artery and vein, tibial nerve and the common fibular nerve, and some lymphnodes.
 * 11. Define the boundaries of the popliteal fossa and describe its contents.**

__Anterior:__ The anterior tibial a. continues through the anterior of the ankle becoming the dorsal pedal a. following the path of the deep fibular n. Extensor digitorum longus, extensor hallucis and tibialis anterior also cross at the anterior side of the ankle. __Lateral:__ Fubularus longus, and brevis pass inferior to the lateral malleous to enter the foot. __Medial:__ tibialus anterior, flexordigitorus longus, and flexor hallucis longus pass inferior to the medial malleous to enter the foot. Posterior tibial a. enters the foot medially as well to become the medial and lateral plantar a. The posterial tibial nerve also follows this path. __Posterior:__ The calcaneal tendon crosses porteriorly to attach to the calcaneus.
 * 12. Describe the relationship of muscles, vessels, and nerves as they cross the ankle to enter the foot.**

__Hip:__The illiofemoral ligament (Y ligament of Bigelow) composes the anterior portion of hip joint capsule, the Ishiofemoral ligament the posterior side and the pubofemoral the inferior aspect. Within the capsule is the ligament of head of femur with its accompanying small blood vessle.
 * 13. Identify the major extra- and intra-capuslar ligaments of the hip, knee, and ankle.**

__Knee:__
 * Name || Capsule || From || To || Description ||
 * anterior cruciate ligament (ACL) || inside || lateral condyle of femur || anterior intercondylar area || The critically important ACL prevents the tibia from being pushed too far anterior relative to the femur. ||
 * posterior cruciate ligament (PCL) || inside || medial condyle of femur || posterior intercondylar area || - ||
 * ligamentum patellae || outside || patella || tuberosity of the tibia || - ||
 * medial collateral ligament (MCL) || outside || medial epicondyle of the femur || medial tibial condyle || The MCL protects the medial side of the knee from being bent open by a stress applied to the lateral side of the knee (a valgus force). ||
 * lateral collateral ligament (LCL) || outside || lateral epicondyle of the femur || head of fibula || The LCL protects the lateral side from an inside bending force (a varus force). ||
 * oblique popliteal ligament || outside || medial condyle of tibia || - || - ||
 * arcuate popliteal ligament || outside || Intercondylar area of tibia, and lateral condyle of femur, to below head of fibula || - || - ||

__Ankle:__ Medial colateral ligament (Deltoid) consisting of the anterior talofibular ligament, the posterior talofibular ligament, and the calcaneofibular ligament. Lateral colateral ligament


 * 14. Describe the vessels involved in collateral circulation for the hip, knee, and ankle.**

__Hip__ The hip is supplied primarily by the medial and lateral circumflex femoral arteries that are usually branches of the deep artery of the thigh but can arise as branches of the femoral artery. The artery to the head of the femur also participates, as a branch of the obturator artery entering through the ligament of the head of the femur.

__Knee__ The knee joint is supplied by the genicular branches of the femoral, popliteal, and anterior and posterior recurrent branches of the anterior tibial recurrent and circumflex fibular arteries. These genicular branches form the genicular anastomosis around the knee. The middle genicular branch of the popliteal artery penetrates the fibrous capsule of the knee joint to supply the cruciate ligaments, synovial membrane and peripheral margins of the menisci.

__Ankle__ The blood supply of the ankle is derived from the malleolar branches of the fibular and anterior and posterior tibial ateries.