Thigh+and+Leg+-+Lecture+Notes

=**Objectives**=toc

Thigh and Leg

=**Lecture Notes**=

[|Lecture 1] [|Lecture 2]



**Lecture 1**
Inferior gluteal artery is the major artery supplying the gluteus maximus, but it does take some supply from a superficial branch of the superior gluteal artery.

Anterior compartment of the thigh is the flexor compartment.

The dominate dermatomes of the anterior thigh are the L1-L5. L4 is at the patella.

The great (long) saphenous vein is the major vein going up the leg. It starts from the plexus around the foot and ascends medially right up to the region of the inguinal ligament. Just inferior to the inguinal ligament is a hole in the fascia lata called the saphenous opening. The great saphenous vein passes throught the saphenous opening to pass from the superficial fasia to the deep fasia and dump into the femoral vein.

The saphenous vein recieves tribularies from several veins including the external pudendal veins. This vein is a favorite for use in surgery for bypassing an occlusion such as for a coronary bipass. The great saphenous vein does have valves so the direction is important or you can turn it inside out (as blood starts flowing thorough, it will epithelialized). This is ok because the venous flow will be reestablished by new veins.

The lateral cutaneous nerve of the thigh comes into the thigh from the ASIS and give branches to the lateral side of the thigh. Most of the anterior and medial cutaneous innervation comes from the femoral nerve.

There are lymph nodes in the inguinal region. The superficial inguinal lymph nodes cluster around the saphenous opening. There are some that are vertical next to the saphenous vein, as well as some parallel with the inguinal ligament. Superficial structures from all of the lower limb, gluteal region, the inferior anterior wall below the umbilicus, and the lower portion of the anal canal. drain to the superficial inguinal lymph nodes.

The sartorius muscle has origin at the ASIS, going down the anterior thigh, crosses medially, and crosses the knee, attaching to the proximal side of the tibia. This is a very long strap-like muscle. “Sartus” means to fix or repair in Latin; allows a tailor to scissor-cross the legs. The actions of sartorius are flexion of the hip, flexion of the knee, and externally/lateral rotation of the hip. By itself, it’s a very weak muscle and works with other muscles to accomplish those actions.

The tensor fascia lata is innervated by the superior gluteal nerve as is gluteus maximus, medius, and minimus. However, it actually acts on the hip joint as a flexor. It is encased by fascia lata.

The three parts of the quadriceps muscles can be seen anteriorly. The rectus femoris runs the length of the shaft of the femur, taking origin from the anterior inferior iliac spine, crossing the hip joint. The vastus medialus and the vastus lateralis are medial and lateral to the rectus femoris. If rectus femoris is cut and reflected, the fourth quadriceps msucle can be seen.

The muscle just deep to rectus femoris is the vastus intermedius. Non of the vastus muscles attach to the hip joint; all three take origin form the shaft of the femur.

All four quadriceps muscles unite to form a common tendon called the quadriceps tendon, just proximal to the knee. The tendon crosses the knee. The patella is a bone imbedded in the quadriceps tendon. Sesimoid bone are bones imbedded in a tendon; the patella is the largest sesimoid bone in the body. The tendon continues as the patella ligament that attaches on the tibial tuberocity; the patella ligament is the continuation of the quadriceps tendon.

The quadriceps are the most powerful extensor muscles of the knee (leg). Not all of the tendonous fibers attached directly to the patella. Some of the tendons come on to the side of the patella obliquely (especially vastus medialis and vastus lateralis). When the quadriceps pull very forcefully, the patella tends to try to dislocate laterally so the arragement of the tendons around the patella from the vastus medialis helps prevent dislocation.

The iliacus and psoas muscle unites as a common tendon. The iliopsoas leaves the pelvis and enters the anterior thigh and attaches to the lesser trochanter of the thigh. This is the most powerful flexor muscle of the hip joint and the only muscle to attach to the lesser trochantor.

Just medial to iliopsoas is the pectineus muscle. If you reflect pectineus, you expose obturator externis. The pectineus muscle takes origin from the pubis, extending diagonally to the proximal side of the femur. It provides adduction of the hip joint.

The muscles of the anterior compartment (iliopsoas, sartorius, pectineus, etc.) are innervated by the femoral nerve.

The most medial muscle is the gracilis muscle, attached to the pubis proximally, and runs the medial length of the thigh, attaching on the proximal-medial tibia. The tendons of the semitendonosis, sartorius, and gracilis all attach to the proximal-medial tibia. The medial compartment is the adduction compartment. 70% of the adduction compartment can be eliminated without affecting normal gait. These muscles are important for grasping things with the thighs (horseback riding).

Gracilis muscle is frequently used for plastic surgery as a strap-like muscle because it is fairly weak and dispensible. It can be used to replace the external anal sphincter. Between pectineus and gracilis is the adductor longus muscle.

Deeper in the thigh, is a thing sheath-like muscle is the adductor brevis, deep to adductor longus. Both have origin on the pubis, extending laterally to attach to the femur. Obturator externis is exposed underneath pectineous. Its tendon attaches laterally towards the greater trochanter.

The adductor magnus is the huge muscle and forms most of the fleshy part of the medial thigh. It is fan shaped and originates on the pubis, inferior pubic ramus, and ischiotuberocity, attaching mostly on the linea aspera and the supracondylar ridges. It keeps on going to the medial epicondyle of the femur, attaching to the adductor tubercle.

The medial compartment are innervated by the obturator nerve. Adductor magnus, adductor longus, adductor brevis, and obturator externis. The adductor magnus actually has a dual innervation with obturator nerve and tibial nerve. As a result, the adductor magnus has a adductor component and a hamstring component (along with semitendonous, semimembranous, and long head of biceps femoris).

The tendon of adductor magnus has a series of holes in it on its way down the femur. Also there is an opening near its attachment point on the adductor tubercle.

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. Laterally, the iliopsoas, and medially, the pectineous muscle, form the floor of the femoral triangle.

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.

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, outside of the femoral sheath; the femoral nerve is NOT part of the femoral sheath. The femoral sheath bends with the adventitia of the femoral triangle. The femoral sheath has extensions that create a medial, intermediate, and lateral compartments. The artery is in the lateral compartment; the vein is in the intermediate compartment; the medial compartment contains some loose CT and a lymph node (Cloquet’s lymph node receiving lymph from deep structures) in the femoral canal. The femoral canal is where a loop of intestine can herniate down to the thigh and are predominate a female issue because the pelvis and, correspondingly, the femoral canal is wider. The hernia can come up through the saphenous opening and become subcutaneous.

The cleft in the muscle containing the femoral artery and vein is called the subsartial 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 subsartial 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.

The deep artery of the thigh branches off the femoral artery at the femoral triangle. It descends parallel with the femoral artery at a bit deeper plane. It lies on the deep adductor muscles, supplying adductor longus and adductor magnus. The openings in the tendon of adductor magnus let the deep artery of the thigh through to supply the hamstring muscles in the posterior compartment. The deep artery of the thigh ends as the last perforating artery.

The deep artery of the thigh gives off the lateral and medial femoral circumflex arteries right after it branches off the femoral artery. Lateral femoral circumflex is typically larger and gives off a ascending, transverse, and a very large descending branch. The descending branch supplies for the quadriceps muscles in the anterior compartment.

The femoral artery doesn’t itself supply anything; it’s a pipeline that gives off branches (deep artery of the thigh, and femoral circumflex arteries) that supply structures.

Adductor longus is removed to expose adductor brevis just deep to adductor longus. It’s a very thin muscle and lies between adductor longus and adductor magnus. The obturator nerve is the nerve of the medial compartment, entering through the obturator canal. As soon as it enters, the obturator nerve splits into an anterior and posterior division with respect of adductor brevis.

The adductor hiatus is the big aperture in the distal tendon of adductor magnus. It allows the femoral artery and the femoral vein to pass through it. This allows those vessels to go to the posterior aspect of the femur. After it crosses the adductor hiatus, the femoral artery and vein become the popliteal artery and vein as it passes to the popliteal surface of the femur.



In the medial region is the point where the femoral artery and vein pass through the adductor hiatus and become the popliteal artery and vein. These vessels will team up with the sciatic nerve just as the sciatic nerve splits up into its two components.

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

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

The soleal line is oblique on the tibia.

The tibia and fibula are interconnected by an interosseous membrane

There is an deep fascia investing the leg called the crural fascia. The deep fascia send CT septa deep to the bone, subdividing the leg into compartments: the lateral, medial and a very large posterior compartments of the leg. The posterior compartment is further divided into a superficial and deep part.

The crural fascia on the anteror aspect is right up against the shaft of the tibia. Thus, the tibia is subcutaneous for most of its length (the shins).

There is a large vein in the calf called the short (small) saphenous vein. The great saphenous vein starts on the venous arch on the drosal side of the foot ascends medially up the leg and thigh. The short saphenous vein starts on the venous arch of the drosal side of the foot, passing lateral, ascending the calf region, stopping at the knee region. It instead passes through the deep region of the knee and dumps in to the popliteal vein.

Cutaneous nerves are derived from parts of the sciatic, and tibial nerve.



**Lecture 2**
Leg is divided into a lateral, posterior, and anterior parts by fascial compartments.

In the posterior area of the leg, there is a conspicuous short saphenous vein which ends at the knee, where it passes through deep fascia and dumps into the popiteal vein.

The sural nerve is the subcutaneous nerve companion to and just lateral of the short saphenous vein.

Common fibular nerve goes laterally, to take care of the anterior and lateral compartments of the leg.

The tendons of semimembranosis and semitendonosis cross the knee medially. The combined tendons of biceps femoris cross the knee joint laterally. The gastrocnemius muscle has 2 origins on the lateral and medial condyles of the femur and unite into one mass, forming a huge tendon about midway down the leg.

The hamstrings and the gastrocnemius muscle heads produce a diamond shaped structure called the popiteal fossa which contains the popiteal artery and vein (continuation of femoral vessels).

The nerve to vastus medialis and saphenous nerve does not pass through the adductor canal; only the saphenous vessels pass through the popiteal fassa.

The short saphenous vein companion to the sural; the great saphenous vein companion to the saphenous nerve. The sural nerve branches off the tibial and common fibular nerves that join up into a one nerve.

The genicular arteries are small vessels that participates in the collateral circulation at the knee joint.

The popiteal fossa is covered with a deep fascia that can be palpated deep into the deep fossa but only when the knee if partly flexed. You can also find pulse between the ASIS and pubic symphysis and in the anterior compartment of the thigh – good for compressing the femoral artery to stop bleeding.

Formation of the sural nerve is fairly variable and recieves contributions from tibial and common fibular nerves.

Gastrucnemius origin is on the femur and attaches across the ankle, crossing both the knee and ankle joint. It is a weak flexor of the knee and powerful plantarflex of the foot. The tendon of gastrucnemius sometimes can rupture with rapid movement of the foot off the floor. When it ruptures, the tendon sounds like a small caliber rifle shot.

The ankle joint is formed by the medial and lateral malleoli and talis bone of the foot.

Cutting away gastrucnemius, and reflect, the plantaris muscle goes individually from the lateral condyle of the femur to the ankle. The tendon of plantaris is a great source of tendon replacement because its removal is not essential; it is sometimes refered to as the freshman nerve because of its uniform shape. The soleus lies underneath the gastrucnemius. Rupture of the soleus tendon causes initial symptoms similar to the gastrucnemius muscle but the shape of the posterior leg is still symmetric. Rupture of the plantaris tendon is usually not treated with much more than pain relief.

Soleus muscle originates on the soleal line on the tibia. The promence of the calves is made by the soleus which is very thick and much more powerful a plantarflexor than gastrucnemius. The tendon of gastrucnemius and soleus fuse together about midway down the posterior leg. The combined tendon is the tendocalcanius or the “Achilles” tendon.

Tibial nerve supplies the muscles of the superficial posterior compartment: gastrucnemius, soleus, and plantaris muscle. The tibial nerve branches come off fairly high in the popiteal fossa. The arterial supply is from the popiteal artery from the popiteal fossa. Gastrucnemius gets pretty much all its blood by the popiteal artery without much contributions elsewhere to pick up the slack.

The deep posterior compartment is covered by a transverse fascia.

There are 4 muscles in the deep posterior compartment. 3 of them goes down the tibia and pass medially to the ankle.

The most lateral muscle is the flexor hallucis longus and is the flexor of the big toe and the most muscular of the 3 muscles because the big toe is the last thing to leave the floor during locomotion, giving the push off the floor. The flexor hallucis longus originates mostly on the fibula. The most medial muscle is flexor digitorum longus that is responsible for flexing the 4 lateral toes and originates mostly from the tibula. Between the flexor hallucis longus and flexor digitorum longus is the tibialis posterior which originates from the interosseous membrane and is mostly a planarflexor. All can help plantarflex the ankle joint.

Inversion is movement of the sole medially and eversion is the movement of the sole laterally; these are not motions of the ankle joint, but of the bones of the foot. Flexor hallucis longus, flexor digitorum longus, and tibialis posterior can act in inversion.

The popliteal muscle originates on the lateral condyle of the femur, crosses the knee joint posteriorly and attaches to the tibia above the soleal line. This muscle produces the 5 degrees of rotation of the knee that occurs during the last few degrees of extension that helps locks the knee joint so that the muscles that extend the knee (quadriceps) can relax at full extension (standing erect).

The tibial nerve continues down into the deep posterior compartment and innervates the muscles of the deep posterior compartment. Thus, all the muscles of the posterior compartment are innervated by the tibial nerve. It crosses the ankle joint medially. The popiteal artery and tibial nerve lies on posterior aspect of the popliteus muscle. The popiteal artery ends after it crosses the popliteal artery, forming the anterior tibial and posterior tibial arteries. The posterior tibial artery stays in the posterior compartment with the tibial nerve. The anterior tibial artery goes to the anterior compartment by passing through a gap in the interosseous membrane.

The posterior tibial artery gives off the fibular artery which goes laterally and dives into flexor hallusis longus and participates in collateral circulation around the ankle. The fibular artery also gives perforating arteries into the lateral compartment which does not have its own major artery. The fibular artery does not go into the foot; the tibial artery goes to the foot.

The three tendons of the flexor hallucis longus, flexor digitorum longus, and tibialis posterior plus the tibial nerve and the posterior tibial artery cross the ankle joint laterally.

The anterior tibial artery enters through the interosseous membrane.

Anterior compartment tibia has a subcutaneous compartment. Alongside the subcutanous part of the tibia is the tibialus anterior muscle. More lateral to that is the extensor digitorum longus which goes towards the foot and spreads out into 4 tendons to the 4 lateral toes. Between the tibialus anterior and extensor digitorum longus is the extensor hallucis longus. Most of the tibialus anterior attachment is to the tibia; the origin of the extensor digitorum longus is to the fibula; the extensor hallucis longus origin is on the interosseous muscles.

These are the extrinsic foot muscles because they are extrinsic to the foot.

Extensor digitorum longus muscle has 4 tendons that go to the 4 toes but there is a 5th tendon that goes to the metacarpal of the little toe. This tendon is part of fibularis tertius and is part of the anterior compartment.

In the lateral compartment are the fibularis longus and fibularis brevis. Fibularis longus becomes tendonous about half way down and passes laterally to the ankle. On the deep side is the fibularis brevis which parallels the fibularis longus. These are the 2 muscles of the lateral compartment and both originate on the fibula. Both fibularis brevis and fibularis tertius attach to the base of the 5th metacarpal.

The action of the muscles of the lateral compartment are plantarflexors. Thus, the 3 muscles of the deep posterior compartment and 2 muscles of the lateral compartment are plantarflexors. However, the muscles of the anterior compartment help with dorsiflexion.

The tibial nerve goes to the posterior compartment. The common fibular nerve passes laterally out of the popiteal fossa, lying subcutaneously on the neck of the fibula as it crosses the knee laterally. This makes this very prone to trauma, especially because automobile bumpers are right at this level.

The common fibular nerve warps divides as it goes around the knee laterally into a superficial and deep branch. The superficial fibular nerve goes to the lateral compartment. The deep branch goes to the anterior compartment. Remember, the tubial nerve takes care of the posterior compartment.

The superficial fibular nerve becomes cutaneous after it gives off its motor innervation to fibularis longus and brevis. It gives its sensory innervation to the skin of the lateral leg, down the ankle and to almost all of the dorsum of the foot. The only part of the dorsum of the foot that is not have sensory supply by the superficial fibular nerve is the area on the adjacent sides of the first 2 toes which are supplied by the deep fibular nerve instead.

Intermittent Claudication – pain that comes and goes. It is common with the posterior leg due to vascular disease of the arteries of the posterior leg. The pain comes because of the vascular insufficiency associated with the posterior tibial artery.

Anterior Tibial Syndrome, a.k.a. shin splits. The structures in the lateral and posterior compartment of the leg has room for expansion. However, the structures of the anterior compartment are packed tight because the crural fascia on the anterior side is attached to the periosteum of the tibia and is very thick. Thus, there is really no room for expansion in the anterior compartment if there is any edema. This can compromise the blood supply to the muscles and the nerves of the anterior compartment.

The anterior tibial artery comes through the interosseous membrane and become the companion vessel with the deep fibular nerve. Understand that they arrive together in the anterior compartment by different routes. Both of them go to the dorsum of the foot.

There is no companion artery to the superficial fibular nerve so it gets its blood from the perforating arteries from the fibular artery.

Cross section of the ankle.