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Anterior Thigh Details Background & joint movement -The lower limb consists of several named regions, and proximally, it is contiguous with the back, the abdomen, and the perineum *The lower limb is designed for bipedal locomotion, and to support and balance the weight of the body -The hip joint is multiaxial, and thus capable of rotation, flexion/extension, and abduction/adduction *In concert, these actions produce circumduction -The knee joint is essentially only capable of flexion and extension *Ankle and foot joints are more complex, and will be discussed in further detail in upcoming lectures -In many instances the actions mentioned occur with the lower limb fixed on the ground *In such cases, movement of the pelvis occurs relative to the fixed limb Pictures Details LE plexuses -Somatic motor and general sensory innervation of the lower limb are supplied by two somatic plexuses (which are hidden from our view until block 5) -The lumbar plexus *which primarily serves the anterior aspect of the lower limb *is located on the posterior abdominal wall and is formed by the anterior rami of T12-L4 -The sacral plexus *which primarily serves the posterior aspect of the lower limb *is located on the posterior pelvic wall and is formed by the anterior rami of L4-S3 Pictures Details Fascial compartments -The deep fascia of the thigh (fascia lata) gives rise to lateral and medial intermuscular septa, which create anterior and posterior osteofascial compartments *It is customary to add a third compartment—the medial compartment *However, the medial compartment is not delineated posteriorly by a septum, and thus is truly a part of the posterior compartment Pictures Details Innervation Muscle groups -All anterior compartment muscles are supplied by the femoral nerve *with the exception of psoas major and minor (innervated by anterior rami of L1-L2), and pectineus (sometimes additionally innervated by the obturator nerve) -The anterior compartment of the thigh contains two groups of muscles *The flexors of the hip/thigh *The extensors of the knee/leg Pictures Details Flexors -The flexors of the hip (of the anterior compartment) consist of three muscles—pectineus, iliopsoas, and Sartorius *All of these cross the anterior aspect of the hip joint, thus producing flexion at the hip -Iliopsoas *Acts as a single muscle (it is sometimes referred to as a functional unit) but truly consists of three individual muscles: *iliacus, psoas major, and psoas minor -Iliacus originates in the iliac fossa, while psoas major and minor originate from the lumbar vertebrae *Iliacus and psoas major have a common insertion on the lesser trochanter, while psoas minor inserts on the iliopubic ramus and iliac fascia -Function of Iliopsoas *One of the body’s most powerful muscles, and the only one attaching at once to pelvis, vertebral column, and femur *It is the chief flexor of the thigh, and has the most range amongst flexors *With the thighs fixed it is the main flexor of the trunk *Iliopsoas is an important postural muscle, stabilizing the trunk and helping to maintain normal lumbar lordosis -Psoas Abscess *Abdominopelvic infections—such as spinal tuberculosis, or enteritis of the ileum—can be transmitted to the proximal part of iliopsoas, between the covering (deep) fascia and the muscle *The infection may then drain inferiorly to the inguinal and proximal thigh regions, referring severe pain to the hip, thigh, or knee joint Pictures Details *May be palpated in the inguinal region, and thus mistaken for a femoral, or inguinal hernia -Pectineus *Because pectineus is located in a transitional area between anterior and medial compartments it may receive dual innervation (obturator nerve in addition to the femoral nerve) *Flexes, adducts, and laterally rotates the thigh, but studies have shown it to be most active in flexion -Sartorius *A long, strap-like muscle that passes across the length of the anterior thigh, originating on the ASIS and inserting on the medial tibia *B/c crosses both hip and knee joints, it has several actions, which together produce a cross-legged sitting position, formerly used by working tailors, from which Sartorius got its name (Sartus, L., means patched or repaired) *The relatively small size of Sartorius suggests it acts as a synergist, and in practical terms probably keeps the knee in line -Hip flexion: *translates into acceleration of the thigh at the beginning of the swing phase of walking! Pictures Details Extensors -The quadriceps are the extensors of the knee and the largest muscle group in the body, covering most of the anterior and lateral part of the femur *Consists of four parts—rectus femoris, vastus medialus, vastus intermedius, and vastus lateralis— which converge to form the common quadriceps tendon *The quadriceps tendon envelops the patella, and continues as the patellar ligament, which inserts on the tibial tuberosity *Vastus medialis & vastus lateralis originates on the posterior femur and wraps around to anterior side! -Practical Function *The quadriceps are powerful extensors of the knee, but in practical terms, the most important function of the quadriceps is to accept weight during the loading response (flat foot) of the stance phase *Quadriceps are important in projection (running and jumping) and thus may be ~3X as strong as the hamstrings *For the above reasons, atrophy of the quadriceps is particularly great when they are not in use -Rectus Femoris *Runs straight down the anterior part of the thigh, crossing both hip and knee joints *It originates on the AIIS and inserts with all quadriceps on the tibial tuberosity *It flexes the thigh and extends the leg (soccer kick) *In terms of locomotion it works with hip flexors in accelerating the thigh during the swing phase *strain at the muscle’s origin (often subsequent to rapid contraction following stretch) may lead to anterior hip pain! Pictures Details Pictures Medial Thigh Details “Adductor” compartment -The medial compartment of the thigh consists of adductor muscles, which generally originate on the anteroinferior surface of the pubis and insert on the linea aspera of the femur -With the exception of obturator externus, all muscles of the medial compartment adduct the thigh (i.e., in the anatomical position they return the thigh to the midline) -The adductors are mainly innervated by the obturator nerve -The adductors play a secondary role in maintaining posture (by balancing the trunk on the legs) and in regular gait (where they function as synergists) -In certain activities, forcible adduction is very important *Side-to-side motions (shuffling feet in many sports) *Sweeping thigh motions such as a soccer kick Muscle groups -Though they are termed “adductors”, the muscles of the medial compartment are important contributors to flexion and extension of the femur (thigh) against resistance *Running *Weight-training -Adductor Longus and Brevis *Primarily flexors of the thigh *However, when the insertion of either muscle rises above the origin, their action is reversed, and they become extensors of the thigh *The adductors flex the thigh from neutral to ~70°, and they extend from >70° back to ~70° Pictures Details -Adductor magnus *the largest, most powerful, and most posterior muscle of the adductor group *consists of two parts: -The adductor part flexes the thigh and is innervated by the obturator nerve -The hamstrings part extends the thigh and is innervated by tibial division of the sciatic nerve -Obturator externus is primarily a lateral/external rotator of the femur -Gracilis is a medial/internal rotator of the femur (recall that it also adducts the femur) -Both lateral and medial rotation of the hip are crucial to minimizing vertical shifts in the center of gravity during walking Pictures Details Neurovascular structures and relationships -Femoral Triangle *Like the popliteal fossa and the tarsal tunnel, which we will see later—is an important area of transition between the abdomen and the thigh * A subfascial (i.e., deep to the fascia lata) formation of the superior, anteromedial thigh *In muscular individuals—in which the thigh is flexed, abducted, and laterally/eternally rotated— the femoral triangle is visible as an intermuscular depression -Areas of transition *Often clinically important for two related reasons *They represent a passageway, from region to region, for important neurovascular structures *Such a passageway is often the only available route, so structures within are often grouped tightly together *Lesions can compress the structures, and injury can affect multiple structures at once - Femoral Sheath *The femoral sheath is a fascial tube within the femoral triangle, ~3-4 cm long, containing blood and lymphatic vessels *Divided into three compartments: -The lateral compartment contains the femoral artery -The intermediate compartment contains the femoral vein -The medial compartment (AKA femoral canal) contains lymphatic vessels Pictures Details Femoral Canal -Unlike in the other two compartments, the contents of the medial compartment (the lymphatic vessels)— do not fill out the compartment, & are not adherent to the compartment walls *This leaves space within the femoral canal Pictures Details Femoral Ring -The femoral ring *on the inside of the abdominal wall *represents a potential opening into the femoral canal *This opening is covered by the femoral septum, which consists of peritoneum and extraperitoneal fascia Femoral hernias -Femoral ring is the usual originating site of a femoral hernia, which appears as a tender mass in the femoral triangle *In the early stage, the hernia is contained within the femoral sheath, but it may eventually pass through the saphenous opening into the subcutaneous tissue of the thigh *The hernia can get strangulated by the tough lacunar ligament *Femoral hernias are more prominent in females because of their wider pelves Pictures Details Femoral Artery -The continuation of the external iliac artery inferior to the inguinal ligament *is the primary artery of the lower limb -It enters the femoral triangle at the midpoint of the inguinal ligament, bisects the triangle, and is relatively superficial *Its pulse can be taken, and it is commonly catheterized, but as well, it is easily lacerated -Has one major branch *The deep artery of the thigh (profunda femoris), which arises ~5 cm inferior to the inguinal ligament and passes deeply between pectineus and adductor longus -In turn, the deep artery of the thigh usually gives rise to medial and lateral circumflex femoral arteries *These branches sometimes arise from the femoral artery Pictures Details Veins -Venous drainage is both deep and superficial -The principal deep vein of the lower limb is the femoral vein *Becomes the external iliac vein at the inguinal ligament -The main superficial veins of the lower limb are the great and small saphenous veins *The great saphenous vein enters the saphenous opening and drains into the femoral vein Femoral Nerve -8 cm inferior to the inguinal ligament the femoral nerve divides into multiple cutaneous and muscular branches -The anterior cutaneous branches of the femoral nerve supply the anteromedial aspect of the thigh -Cutaneous supply to the anterolateral thigh is from the lateral femoral cutaneous nerve Pictures Details Obturator Nerve -The obturator nerve is not considered to be a part of the femoral triangle, but it does innervate certain muscles in the area -Upon exiting the pelvis and entering the thigh, the obturator nerve (L2-L4) splits into two divisions: *anterior and posterior—which pass anterior and posterior to adductor brevis -Cutaneous branches of the obturator nerve supply a part of the medial thigh Pictures