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Terms in this set (70)

The answer is gracilis. All the nerves supplying the lower limb originate within the abdominal and/or pelvic cavities, from the lumbar and/or sacral plexuses. Therefore, all these nerves must have positional relationships to and must penetrate through the abdominal or pelvic walls in order to reach the lower limb. The obturator nerve crosses the lateral wall of the pelvis on its way to the obturator canal and into the lower limb, and may be damaged in surgery or trauma to the lateral pelvic wall. Ultimately, it supplies the muscles in the medial compartment of the thigh, including the gracilis. Trauma to the efferent fibers within the obturator nerve may produce spasms or dysfunction in any of these muscles. Sartorius is incorrect. The sartorius is a member of the anterior compartment of the thigh, controlled by the femoral nerve. The femoral nerve does not cross the lateral pelvic wall in its path to the lower limb. Instead, it runs lateral and parallel to the psoas major muscle, outside the true pelvic cavity. Biceps femoris is incorrect. The biceps femoris is located in the posterior compartment of the thigh. It is supplied by both the tibial and common fibular (peroneal) nerves. These nerves exit the pelvis through the greater sciatic foramen as components of the sciatic nerve. Neither nerve is related to the lateral pelvic wall. Tensor muscle of fascia lata is incorrect. The tensor muscle of fascia lata (tensor fasciae latae) is innervated by the superior gluteal nerve. This nerve also exits the pelvis through the greater sciatic foramen and is well removed from the lateral pelvic wall. Vastus medialis is incorrect. The vastus medialis is part of the quadriceps femoris muscles in the anterior compartment of the thigh. It is supplied by the femoral nerve, which does not cross the lateral pelvic wall in its path to the lower limb. Instead, it runs lateral and parallel to the psoas major muscle, outside the true pelvic cavity. (less)
The answer is vertical group of superficial inguinal. The vertical group of superficial inguinal lymph nodes receives superficial lymph vessels from the territory drained by the great saphenous vein (including the medial aspect of the knee), and lies along its termination near the saphenous hiatus. Efferent lymphatic vessels from this group of superficial inguinal nodes drain into deep inguinal nodes. Given the location of the injury and the patient's presentation, the vertical group of superficial inguinal lymph nodes is most likely to receive the initial drainage from the infected wound. Popliteal is incorrect. The popliteal nodes are located in the popliteal fossa and receive lymphatic drainage from the lateral side of the leg and foot, which corresponds to the area drained by the small saphenous vein, and from deep lymph vessels accompanying the anterior and posterior tibial arteries. External iliac is incorrect. The external iliac lymph nodes lie along the external iliac vessels above the superior pelvic aperture and receive lymphatic drainage from the inguinal lymph nodes, abdominal wall below the level of the umbilicus, and the pelvic viscera. Efferent vessels from the external iliac nodes drain into common iliac nodes. Deep inguinal is incorrect. The deep inguinal nodes receive lymph from deep lymphatic vessels in the lower limb that travel with the arteries, from the superficial inguinal nodes (horizontal and vertical groups), from the popliteal nodes, and from the glans and body of the clitoris or penis. Efferent vessels from the deep inguinal nodes drain into external iliac nodes. Though the deep inguinal nodes could be involved with this infection, they would not be the first nodes affected in this patient due to the site of the injury (medial knee). Horizontal group of superficial inguinal is incorrect. The horizontal group of superficial inguinal lymph nodes is located approximately 2 centimeters below the inguinal ligament and receives lymphatic drainage from the lateral buttocks, lower anterior abdomen wall, and the perineum. An infected cut on the medial knee would not send lymph to this group of lymph nodes. (less)
The answer is meniscus. The menisci are crescent-shaped intraarticular fibrocartilages found in the knees. These cartilaginous structures serve to dissipate force between the femur and the tibia by acting as shock absorbers, to increase knee joint congruence by forming shallow fossae that receive the femoral condyles, and to help distribute the synovial fluid of the knee joint. A meniscus usually tears during abnormal twisting of the flexed knee, usually eliciting a loud pop, as noted by this patient. Patients present with the listed symptoms and also may experience limited range of motion in the knee joint. If a meniscal tear is suspected, a McMurray test can be implemented by the physician by placing a valgus stress on the flexed knee of the patient. A clicking sound or pain along the joint line represents a "positive McMurray test." An MRI is taken to verify the suspected meniscal tear. Although X-rays do not show meniscal tears, it is standard practice to X-ray the affected knee joint to look for other causes of knee pain, such as osteoarthritis. Tibial (medial) collateral ligament (TCL) is incorrect. The TCL supports the medial side of the knee, attaching to the medial femoral epicondyle and the medial tibial condyle. It is tightly stretched in knee extension, resisting medial displacement of these bones. Therefore, the appropriate clinical test for integrity of the TCL is to abduct the leg while placing a valgus stress on the knee joint. Very importantly, the TCL is firmly attached to the medial meniscus. Tearing of the TCL (e.g., due to a blow to the lateral side of the knee) may tear and/or detach the medial meniscus. The ACL, TCL, and medial meniscus are often damaged together in sports injuries resulting from a lateral impact to the knee when the foot is planted and the knee flexed. This combination injury is termed the "unhappy triad" of the knee joint. Due to the absence of considerable impact to the medial aspect of the knee, TCL damage is unlikely. Moreover, a TCL tear would most likely lead to considerable pain, which would have made it unlikely for him to continue playing. Fibular (lateral) collateral ligament (FCL) is incorrect. The FCL supports the lateral side of the knee, attaching to the lateral femoral epicondyle and the head of the fibula. As with the TCL, it is taut in knee extension, resisting that and lateral displacement of the leg. Thus, the appropriate clinical test for integrity of the FCL is to adduct the leg while placing a varus stress on the knee joint. Notably, the FCL does not attach to the lateral meniscus, eliminating damage to that structure in cases of tearing of the FCL. Due the absence of considerable impact to the lateral aspect of the knee, FCL damage is unlikely. Moreover, a FCL tear would most likely lead to considerable pain, which would have made it unlikely for him to continue playing. Anterior cruciate ligament (ACL) is incorrect. An ACL rupture may also elicit a loud pop and lead to instability in the knee joint during descent of stairs. However, the patient would most likely not be able to continue playing and would have sought medical attention immediately. The integrity of the ACL is tested via an anterior drawer test. When the tibia can be displaced abnormally forward away from the femur, damage to the ACL is verified. It is important to note that the ACL is commonly injured (along with the tibial collateral ligament and the medial meniscus) in athletes who receive a blow to the lateral side of the leg, which forcefully twists their flexed knee when the foot is planted on the ground. In this patient, joint line pain and clicking of the knee during the McMurray test indicate damage to the meniscus. Patella is incorrect. The patella (kneecap) is a sesamoid bone within the quadriceps tendon that increases the leverage of the knee joint. This bone can be damaged via a direct blow or fall onto the anterior aspect of the knee. The deep knee bend can differentiate between damage to the patella and the menisci. Patients with patellar issues would experience pain while rising from the deep knee bend position. In this patient, pain was elicited at the bottom of the deep knee bend, which indicates damage to the meniscus. (less)
The answer is saphenous nerve. The cutaneous area indicated in the illustration is that of the saphenous nerve, the longest branch of the femoral nerve. The saphenous nerve becomes cutaneous at the medial aspect of the knee, and descends through the leg into the foot in company with the great saphenous vein. It innervates the skin on the medial side of the leg and foot. Because of its close relationship to the great saphenous vein, this nerve is vulnerable to injury in surgery involving the vein (e.g., harvesting of the vein for coronary bypass or repair of varicosities). Sural nerve is incorrect. The sural nerve is derived from both the tibial and common fibular (peroneal) nerves in the proximal posterior leg. It supplies the skin on the posterior leg and lateral side of the ankle, heel, and foot. It travels in company with the small saphenous vein and is vulnerable in surgery involving that vessel. Obturator nerve is incorrect. The obturator nerve supplies most of the muscles in the medial (adductor) compartment of the thigh and also has a small cutaneous territory in the medial thigh. The cutaneous branches may be damaged in surgery of the upper segment of the great saphenous vein. Deep fibular (peroneal) nerve is incorrect. This nerve is one of the terminal branches of the common fibular (peroneal) nerve. It supplies the muscles in the anterior compartment of the leg and dorsum of the foot and has a small cutaneous area in the contiguous skin between the first and second toes. Superficial fibular (peroneal) nerve is incorrect. This nerve represents the other terminal branch of the common fibular (peroneal) nerve. It supplies the two muscles in the lateral compartment of the leg and has a large cutaneous territory in the lateral side of the lower leg and most of the dorsum of the foot. (less)
The answer is deltoid ligament. The injury in this patient is one of excessive eversion of the foot. Therefore, the ligament damaged is on the medial aspect of the ankle, where it is positioned to resist eversion. The deltoid ligament is a four-part structure that in total resembles the triangular Greek letter Delta. It covers the medial side of the ankle, extending from its apex on the medial malleolus of the tibia down to its base on the navicular, calcaneus, and talus. It functions to resist excessive eversion of the foot. Due to its intrinsic strength, the deltoid ligament may not rupture but instead cause an avulsion fracture of the medial malleolus. Plantar calcaneonavicular (spring) ligament is incorrect. The plantar calcaneonavicular ligament is located in the plantar aspect of the foot, where it connects the sustentaculum tali of the calcaneus to the navicular bone. It helps support the head of the talus and the medial longitudinal arch of the foot. It is termed the spring ligament because it contains a high density of elastic fibers that provide spring to the foot during plantar flexion. Calcaneofibular ligament is incorrect. The calcaneofibular ligament, one of the three ligaments on the lateral aspect of the ankle, runs from the calcaneus to the lateral malleolus of the fibula, as its name indicates. It resists excessive inversion of the foot at the ankle joint, rather than eversion. Anterior talofibular ligament is incorrect. This ligament, like the calcaneofibular ligament, resists excessive inversion of the foot at the ankle joint, rather than eversion. It connects the head and neck of the talus with the lateral malleolus of the fibula. The third component of the lateral ligament is the posterior talofibular ligament. Plantar calcaneocuboid (long plantar) ligament is incorrect. The plantar calcaneocuboid ligament is located in the plantar aspect of the foot. It is a relatively long structure that runs from the plantar side of the calcaneus to the cuboid and bases of the lateral metatarsal bones. It forms a deep canal for the tendon of the fibularis (peroneus) longus muscle and helps to support the lateral longitudinal arch of the foot. (less)
The answer is common fibular nerve. The common fibular (peroneal) nerve, a terminal branch of the sciatic nerve, courses around the neck of the fibula. It is at this site that this nerve is particularly prone to injury via trauma, such as a kick to the side of the leg. Distal to this location, the common fibular nerve divides into the deep and superficial fibular nerves, which supply the motor innervation to the anterior and lateral compartments of the leg, respectively. Damage to the common fibular nerve would lead to all of the symptoms seen in this patient, such as weakness in eversion and dorsiflexion of the foot at the ankle joint, foot drop, and loss of sensation to the dorsum of the foot. Tibial nerve is incorrect. The tibial nerve is a terminal branch of the sciatic nerve that supplies the posterior muscles of the knee joint and leg. Damage to this nerve would cause an inability to stand on one's tiptoes, not the foot drop and other signs and symptoms present in this patient. Deep fibular nerve is incorrect. The deep fibular (peroneal) nerve is a terminal branch of the common fibular nerve that supplies motor innervation to the muscles of the anterior compartment of the leg. These muscles are responsible for dorsiflexion of the ankle, and damage to the deep fibular nerve would result in foot drop, seen in the image. However, the cutaneous innervation of the deep fibular nerve supplies only a small area between the first and second toes, not the entire dorsum of the foot, which is primarily supplied by the superficial fibular nerve. This involvement of the superficial fibular nerve suggests the lesion is more proximal. Superficial fibular nerve is incorrect. The superficial fibular nerve is a terminal branch of the common fibular nerve that supplies motor innervation to the muscles of the lateral compartment of the leg, responsible for eversion of the foot at the ankle joint. It also supplies cutaneous (sensory) innervation to the distal third of the anterior surface of the leg and dorsum of foot. Both motor (weakness in eversion) and sensory (paresthesia on dorsum of foot) symptoms are present in this patient; however, a lesion to the superficial fibular nerve would not explain the foot drop of the patient. This involvement of the anterior leg compartment indicates that the lesion is more proximal. Sciatic nerve is incorrect. The sciatic nerve is formed by the anterior rami of L4-S3 and supplies the muscles in the posterior compartment of the thigh. The sciatic nerve bifurcates into the tibial and common fibular nerves in the popliteal fossa. Because this nerve usually gives off its terminal branches in the popliteal fossa, it is unlikely to be damaged by impact to the fibular neck. (less)
The answer is iliofemoral ligament. In this situation, the hip is pushed into hyperextension with forces directed to produce anterior dislocation of the head of the femur. Thus, the ligament best positioned to resist this force crosses the anterior aspect of the hip joint. The iliofemoral ligament is a large, Y-shaped structure that crosses the front of the hip from the anterior inferior iliac spine and acetabular rim down to the intertrochanteric line of the femur. It is the largest ligament that reinforces the front of the hip joint, and resists hyperextension by tightening the head of the femur into the acetabulum. Pubofemoral ligament is incorrect. This ligament reinforces the hip joint capsule inferiorly and anteriorly as it runs from the pubic part of the acetabular rim to the neck of the femur. Its primary function is to resist hyperabduction of the hip. Ischiofemoral ligament is incorrect. The ischiofemoral ligament is a relatively weak structure that reinforces the posterior aspect of the hip joint. It attaches from the ischial portion of the acetabular rim to the neck of the femur medial to the base of the greater trochanter. Thus, its primary role is to resist medial rotation of the thigh plus aiding in resisting extension. Lacunar ligament is incorrect. The lacunar ligament is a reflection of fibers from the inguinal ligament down to the pubic tubercle. It forms part of the floor of the inguinal canal and the medial wall of the femoral ring (canal). While it is a notable structure in differentiating femoral from inguinal herniae, it is not part of the hip joint. Ligament of the head of the femur is incorrect. This ligament (also called the round ligament of the head of the femur or ligamentum teres capitis femoris) is a relatively weak structure that runs from the floor of the acetabular fossa to the small fovea in the head of the femur. It has little importance in strengthening the hip joint. However, this ligament is notable because in early life it usually carries the small nutrient artery supplying the epiphysis of the head of the femur. (less)
The answer is vertical group of superficial inguinal. The vertical group of superficial inguinal lymph nodes receives superficial lymph vessels from the territory drained by the great saphenous vein (including the medial aspect of the thigh) and lies along its termination near the saphenous hiatus. Efferent lymphatic vessels from this group of superficial inguinal nodes drain into deep inguinal nodes. Given the location of the injury and the patient's presentation, this group of lymph nodes is most likely to receive the initial drainage from the infected wound. Popliteal is incorrect. The popliteal nodes are located in the popliteal fossa and receive lymphatic drainage from the lateral side of the leg and foot, which corresponds to the area drained by the small saphenous vein, and from deep lymph vessels accompanying the anterior and posterior tibial arteries. The efferent lymphatic vessels leaving the popliteal nodes drain into deep lymph vessels of the lower limb that parallel the major vessels before reaching the deep inguinal nodes. External iliac is incorrect. The external iliac lymph nodes lie along the external iliac vessels above the superior pelvic aperture and receive lymphatic drainage from the inguinal lymph nodes, abdominal wall below the level of the umbilicus, and the pelvic viscera. Efferent vessels from the external iliac nodes drain into common iliac nodes. These nodes are not the first nodes affected in this patient due to the site of the injury (medial thigh). Deep inguinal is incorrect. The deep inguinal nodes receive lymph from deep lymphatic vessels in the lower limb that travel with the arteries, from the superficial inguinal nodes (horizontal and vertical groups), from the popliteal nodes, and from the glans and body of the clitoris or penis. Efferent vessels from the deep inguinal nodes drain into external iliac nodes. Though the deep inguinal nodes could be involved with this infection, they would not be the first nodes affected in this patient due to the site of the injury (medial thigh). Horizontal group of superficial inguinal is incorrect. The horizontal group of superficial inguinal lymph nodes is located approximately 2 cm below the inguinal ligament and receives lymphatic drainage from the lateral buttocks, lower anterior abdomen wall, and the perineum. An infected cut on the medial thigh would not send lymph to this group of nodes. (less)
The answer is iliotibial band syndrome (ITBS). ITBS is one of the leading causes of lateral knee pain in runners, and it is often seen in runners who increase the intensity of their workouts too rapidly. The iliotibial band (tract) is a lateral thickening of the fascia lata that extends inferiorly to the anterolateral aspect of the lateral condyle of the tibia and stabilizes the knee during running. When the knee is flexed at approximately 45 degrees, the iliotibial tract passes posterior to the lateral femoral epicondyle. In distance runners and cyclists, repeated flexion and extension of the knee cause friction on the lateral femoral epicondyle due to the iliotibial band rubbing against the bone. ITBS, and its associated pain and inflammation of the lateral knee, is exacerbated by downhill running and chronic repetitive foot strikes during long runs. Sprained fibular (lateral) collateral ligament (FCL) is incorrect. Lateral knee pain can generally be traced to three anatomical sites: ITBS (seen in this patient), a torn lateral meniscus, and a sprained FCL. The latter two scenarios usually follow trauma to the knee joint, which was not reported in this patient and can be ruled out as a diagnosis. FCL sprains are usually due to a blow to the medial side of the knee, which sprains or tears the FCL; however, this type of trauma was not reported in this patient. Patellofemoral pain syndrome is incorrect. Patellofemoral pain syndrome is often seen in runners who increase the intensity of their workouts too rapidly. This syndrome results from imbalances in the forces controlling patellar tracking during knee flexion and extension, and patients present with anterior knee pain that is described as being around, underneath, or behind the patella. While this syndrome is similar in presentation to ITBS, it can be distinguished from ITBS due to the presence of anterior knee pain versus the lateral knee pain seen in this patient. Torn lateral meniscus is incorrect. Though a patient with a torn lateral meniscus would report lateral knee pain, this presentation is usually due to trauma, particularly when the flexed knee is twisted. Patients with torn menisci present with pain, inflammation, tenderness, popping or clicking of the joint, and knee joint instability. Though this patient had lateral knee pain with some of these signs and symptoms, there was no trauma reported, which would make a meniscus tear unlikely. Pes anserinus bursitis is incorrect. The pes anserinus (L: foot of a goose) is the combined tendon insertions of the Sartorius, Gracilis, and semiTendinosus muscles (mnemonics: 1. SGT, an abbreviation for sergeant, and 2. "Say Grace Before Tea," which takes into account the presence of the anserine Bursa) at the medial border of the tuberosity of the tibia. Pes anserinus bursitis is often seen in athletic overuse; however, it would be responsible for medial knee pain, not the lateral knee pain seen in this patient. (less)
The answer is fibularis brevis. The fibularis (peroneus) brevis muscle attaches to the dorsal surface of the tuberosity on the lateral side of the base of the fifth metatarsal, which is where the avulsion fracture is seen in this X-ray. During extreme inversion injuries, force from this muscle can avulse the tuberosity at the base of the fifth metatarsal. When diagnosing fractures of the fifth metatarsal, a physician must distinguish among an avulsion fracture (as seen on this X-ray), a stress fracture normally located at the midshaft, and a Jones fracture, which is a fracture through the proximal fifth metatarsal that enters the intermetatarsal joint. With the fifth metatarsal, blood supply is less than adequate as it progresses distally along this bone, so treatments for each type of fracture will vary. Extensor digitorum longus is incorrect. The extensor digitorum longus inserts into the middle and distal phalanges of the lateral four digits. This muscle extends the lateral four digits and dorsiflexes the ankle. It does not insert into the tuberosity located at the base of the fifth metatarsal, so it would not be involved in the avulsion fracture seen in this patient. Fibularis longus is incorrect. The fibularis (peroneus) longus muscle inserts into the base of the first metatarsal and medial cuneiform bone. This muscle is important in eversion of the foot; however, it can be eliminated due to its medial insertion in the foot. Fibularis tertius is incorrect. The fibularis (peroneus) tertius muscle attaches to the dorsal surface at the base of the fifth metatarsal. Due to its dorsal attachment, an avulsion fracture involving this muscle would not involve the tuberosity located at the base of the fifth metatarsal, which is shown avulsed in this patient. Remember, the fibularis tertius muscle is located in the anterior leg compartment and is important in eversion of the foot during ambulation. Flexor digiti minimi brevis is incorrect. The flexor digiti minimi brevis inserts into the base of the proximal phalanx of the fifth digit. It does not participate in eversion of the foot, so it would not be injured in this inversion ankle injury. (less)
The answer is anterior talofibular ligament. The ankle is the most frequently injured major joint in the body. Torn ligaments (ankle sprains) are commonly seen following inversion injuries, where the joint is twisted on a weight-bearing plantar flexed foot (as described in this patient). The most commonly sprained ankle ligament is the anterior talofibular ligament on the lateral side of the ankle, and this injury results in instability of the joint. If this ankle injury were more severe, additional ligaments of the lateral side of the ankle would also be involved, specifically the calcaneofibular and posterior talofibular ligaments. Calcaneofibular ligament is incorrect. The calcaneofibular ligament is often injured in severe ankle sprains following forced inversion of the foot but only after the anterior talofibular ligament would have incurred damage. However, in this athlete, the ankle sprain was not severe and she was able to continue playing. Therefore, the calcaneofibular ligament was most likely not involved. Posterior talofibular ligament is incorrect. The posterior talofibular ligament would only be damaged in the most severe cases of forced inversion of the ankle joint following injury to the anterior talofibular and calcaneofibular ligaments. Given the nature of this injury, the anterior talofibular ligament was the only ligament involved. Plantar calcaneonavicular ligament is incorrect. The plantar calcaneonavicular (spring) ligament connects the sustentaculum tali of the calcaneus with the plantar surface of the navicular bone. It supports the head of the talus and helps maintain the medial longitudinal arch of the foot. This ligament would not be involved with a sprained (or twisted) ankle. Medial (deltoid) ligament is incorrect. The medial (deltoid) ligament of the ankle reinforces the medial aspect of the ankle joint and would be injured during forced eversion injuries. This ligament is much stronger than the lateral ligaments of the ankle (calcaneofibular, anterior talofibular, posterior talofibular ligaments) and would not be involved in this inversion injury. (less)
The answer is gluteus medius. The given AP X-ray reveals fragmentation of the greater trochanter, a large superolateral projection of the proximal end of the femur. The greater trochanter serves as the insertion site for the gluteus medius and minimus muscles, which are involved with abduction and medial rotation of the hip joint. These two muscles also keep the pelvis level when the ipsilateral hip is bearing weight during gait. Fragmentation of the greater trochanter would most likely include detachment of the gluteus medius and minimus muscles. Moreover, additional muscles insert into the greater trochanter to produce lateral rotation of the hip, such as the piriformis, obturator externus, obturator internus, and superior and inferior gemelli (which attach onto the tendon of the obturator internus and by default onto the greater trochanter). In this discussion, the trochanteric fossa is considered part of the greater trochanter, which explains the inclusion of muscles involved with lateral rotation. Gluteus maximus is incorrect. The gluteus maximus arises from the ilium of the hip (or coxal) bone, sacrum and coccyx, and sacrotuberous ligament. It inserts partly into the gluteal tuberosity of the femur, but mostly into the iliotibial tract, which attaches into the lateral condyle of the tibia. Due to its course, the gluteus maximus is a powerful extensor and lateral rotator of the thigh, with a notable influence on the leg. However, the given X-ray reveals fragmentation of the greater trochanter, so the gluteus maximus muscle is not involved in this fracture. Iliopsoas is incorrect. The given plain film of the hip joint identifies a fragmentation fracture of the greater trochanter of the femur. However, the lesser trochanter is the insertion site for the iliopsoas muscle, so this muscle is not involved. Biceps femoris is incorrect. The two heads of the biceps femoris originate from the ischial tuberosity and the linea aspera and supracondylar line of the femur, respectively. This muscle inserts into the lateral side of the head of the fibula. Because this muscle is not associated with the greater trochanter of the femur, the biceps femoris muscle is not involved in this fracture. Sartorius is incorrect. The sartorius muscle originates from the anterior superior iliac spine and inserts into the medial surface of the tibia. Because this muscle is not associated with the greater trochanter of the femur, the sartorius muscle is not involved in this fracture. (less)
The answer is gluteus maximus. The sacrotuberous ligament runs from the lower lateral sacrum and the coccyx to the ischial tuberosity. It is important in stabilizing the sacroiliac joint and, together with the sacrospinous ligament, defines the lesser sciatic foramen. Furthermore, it provides the gluteus maximus muscle additional firm surface area for origin of its fibers. It is important to notice that skeletal muscle fibers do not always attach only to bone. They may utilize any available structure to increase the surface area for attachment of fibers. Since muscle force production is directly proportional to the physiological cross-sectional area of a muscle, increasing the space available for packing in muscle fibers is an important mechanical aspect of muscle anatomy. Gluteus medius is incorrect. This muscle attaches only to bone, the superior aspect of the greater trochanter. This muscle is not located close to the sacrotuberous ligament. Gluteus minimus is incorrect. The gluteus minimus, like the gluteus medius, attaches to the superior aspect of the greater trochanter. This muscle is not located in proximity to the sacrotuberous ligament. Gemelli is incorrect. The small gemellus superior and inferior muscles originate from bony locales (ischial spine and ischial tuberosity, respectively) and attach onto the tendon of the obturator internus muscle in order to exert their actions against the greater trochanter of the femur. They pass deep to the sacrotuberous ligament, but do not attach onto it. Obturator externus is incorrect. Both the obturator externus and internus muscles take most of their origins from the surfaces of the obturator membrane. Thus, both muscles are additional examples of muscles that use ligaments to increase the surface area available for muscle fiber attachment. (less)
The answer is phalanges. Accutane (retinoic acid; vitamin A) is a useful therapeutic drug in relieving skin disorders such as acne. However, it also is a recognized teratogenic agent that should not be utilized during pregnancy. Both upper and lower limbs follow the same pattern of development, except that corresponding events occur slightly later (by ~2 days) in the lower limb. One aspect of this pattern is that development proceeds along the proximo-distal axis of the limb, with the more proximal skeletal elements differentiating first, followed by the more distal structures. Overall, the major formative events take place from late week 4 to week 8. In this case, the Accutane was used during the later stages of limb development. The structures most likely affected are the most distal elements, the phalanges. Ilium is incorrect. Because of the timing of the mother's use of Accutane, the more distal skeletal components, which are the last to differentiate, are most likely affected. The ilium, a bony component of the coxal or hip bone, would not be affected. Femur is incorrect. Because of the timing of the mother's use of Accutane, the more distal skeletal components, which are the last to differentiate, are most likely affected. The femur would not be affected. Patella is incorrect. Because of the timing of the mother's use of Accutane, the more distal skeletal components, which are the last to differentiate, are most likely affected. The patella, a sesamoid bone in the quadriceps tendon, would not be affected. Tibia is incorrect. Because of the timing of the mother's use of Accutane, the more distal skeletal components, which are the last to differentiate, are most likely affected. The tibia, a long bone in the leg, would not be affected. (less)
The answer is intermittent claudication (ischemia) of the calf muscles. In this case, the limp and pain were most likely due to occlusive disease of the arteries of his right leg, especially the posterior tibial artery. The obstruction caused the decreased blood flow to his calf muscles. Compression of the tibial nerve is incorrect. This nerve is the larger terminal branch of the sciatic nerve. If the nerve were compressed, there would be weakness of the calf muscles, but this symptom would not likely disappear when the person rested. Furthermore, there would likely be paresthesia of the skin of the heel. And there would not be a loss of the posterior tibial pulse. Obstruction of the fibular artery is incorrect. The main blood supply to the leg is from the posterior tibial artery, but the fibular artery assists with the supply. Occlusion of this artery would not likely cause the severe pain experienced by this man. And the patient would still have a posterior tibial pulse. Lymphatic edema of the posterior compartment of the leg is incorrect. Inflammatory or lymphatic edema of the leg could result from an infection or obstruction of lymphatic vessels in the leg. The accumulation of abnormally large amounts of fluid in the intercellular tissue spaces could compress the nerves or vessels of the lower limb, but this would not likely cause the transient symptoms mentioned by the patient. Severe atherosclerosis of the profunda femoris artery is incorrect because this artery does not supply the posterior tibial artery. (less)
The answer is medial collateral ligament. The medial collateral ligament (MCL) runs from the medial condyle of the femur superiorly and to the medial surface of the shaft of the tibia inferiorly. Because the MCL prevents abduction of the tibia at the knee joint, it can be injured during a traumatic blow to the lateral surface of the lower femur, as seen in this patient. In this patient, exaggerated displacement is seen when the physician forcibly abducts the tibia at the knee joint. The physician is performing a valgus stress test, and the abnormal displacement indicated damage to the integrity of the MCL. Lateral collateral ligament is incorrect. The lateral collateral ligament (LCL) runs from the lateral condyle of the femur superiorly and to the head of the fibula inferiorly. The LCL prevents adduction of the tibia at the knee joint, so the clinical test for LCL integrity is a varus stress test in which the physician forcibly adducts the tibia at the knee joint. Anterior cruciate ligament is incorrect. The anterior cruciate ligament is attached to the anterior intercondylar area of the tibia and passes upward, backward, and laterally, to be attached to the posterior part of the medial surface of the lateral femoral condyle. The anterior cruciate ligament prevents posterior displacement of the femur on the tibia. With the knee joint flexed, the anterior cruciate ligament prevents the tibia from being pulled anteriorly. Posterior cruciate ligament is incorrect. The posterior cruciate ligament (PCL) is attached to the posterior intercondylar area of the tibia and passes upward, forward, and medially to be attached to the anterior part of the lateral surface of the medial femoral condyle. The posterior cruciate ligament prevents anterior displacement of the femur on the tibia. With the knee joint flexed, the posterior cruciate ligament prevents the tibia from being pushed posteriorly. Ligamentum patellae is incorrect. The ligamentum patellae represents the terminal end of the quadriceps tendon, attaching these four muscles to the tibial tuberosity. Damage to the ligamentum patellae is indicated by displacement of the patella into the anterior thigh and/or a deficit in knee extension. (less)
The answer is abductor hallucis muscle. The muscles and associated structures in the plantar aspect of the foot are organized into four layers from superficial (layer 1) to deep (layer 4). The first layer includes the abductor hallucis muscle as well as the abductor digiti minimi and the flexor digitorum brevis. Plantar arterial arch is incorrect. The plantar arterial arch (deep plantar arch) is an anastomotic vessel formed by the lateral plantar artery and the deep plantar branch of the dorsalis pedis artery. The lateral plantar artery portion (providing the main flow into the plantar arch) is initially located in the plane between the first and second layers of plantar muscles and then courses deeper, between the third and fourth layers. The contribution of the dorsalis pedis artery pierces between the first and second metatarsals into the deepest plantar layer. Tendons of the flexor digitorum longus muscle is incorrect. These tendons are located in the second layer of plantar muscles, with the quadratus plantae and the tendon of the flexor hallucis longus. The four lumbrical muscles are also found here, attached to the tendons of the flexor digitorum longus. Tendon of the fibularis (peroneus) longus muscle is incorrect. This long tendon crosses the foot deep to the fourth layer of plantar muscles. Some authors include this tendon as a member of the fourth layer. Superficial fibular (peroneal) nerve is incorrect. The superficial fibular nerve emerges from the lateral compartment of the leg and distributes its terminal cutaneous branches across the dorsum of the foot. (less)
The answer is tendon of the flexor hallucis longus (FHL) muscle. The sustentaculum tali is a bony ledge projecting off the medial side of the calcaneus, as seen in the given drawing. It supports the head of the talus and serves as a pulley-like device for the tendon of the FHL. This tendon emerges from the posterior deep compartment of the leg and turns through a groove on the inferior side of the sustentaculum tali to align itself with the hallux. Thus, the FHL uses the sustentaculum tali to change its direction and improve its mechanical efficiency. Likewise, the obturator internus tendon uses the lesser sciatic notch as a pulley to change its line of action. Because of their intimate relationship, a fracture of the sustentaculum tali immediately endangers the FHL tendon. Tendon of the tibialis posterior muscle is incorrect. This tendon accompanies the tendon of the FHL out of the posterior deep compartment of the leg. However, the tibialis posterior tendon crosses the medial side of the ankle by hugging the posterior side of the medial malleolus to reach the medial aspect of the foot. Thus, the tibialis posterior also utilizes a bony prominence as a pulley to alter its line of action. Tendons of the flexor digitorum brevis muscle is incorrect. The flexor digitorum brevis muscle is located in the first muscle layer in the plantar side of the foot and is not related to the sustentaculum tali. However, the flexor digitorum longus is the third member of the posterior deep compartment of the leg. Its tendon does cross the medial side of the ankle in close company with the FHL and tibialis posterior. Small saphenous vein is incorrect. This important cutaneous vein arises from the lateral end of the dorsal venous arch of the foot. It ascends into the leg by crossing the ankle posterior to the lateral malleolus. It is at this location that the small saphenous vein is often harvested for vein grafting procedures. Plantar arterial arch is incorrect. The plantar arterial arch is located deep in the plantar aspect of the foot, crossing the metatarsals. It is formed from the lateral plantar artery and the deep plantar artery (a branch of the dorsalis pedis artery). (less)
The answer is profunda femoris artery. The profunda femoris artery (deep femoral artery; deep artery of the thigh) gives off the perforating arteries that supply blood to the posterior femoral compartment. Arising from the femoral artery, the profunda femoris artery gives off the medial and lateral circumflex femoral arteries before it descends to give off a series of (usually four in number) perforating arteries. These arteries are so named because they pierce (perforate) through the adductor magnus muscle to reach the posterior compartment of the thigh. The perforating arteries supply the adductor magnus and hamstring muscles of the posterior compartment of the thigh. Femoral artery is incorrect. The femoral artery gives rise to the profunda femoris artery, which in turn gives off the perforating branches. Obturator artery is incorrect. The obturator artery is a branch of the internal iliac artery within the pelvic cavity. It enters the thigh through the obturator canal and divides into anterior and posterior branches, which envelope the adductor brevis muscle. The obturator artery supplies the adductor muscles in the medial compartment of the thigh. Popliteal artery is incorrect. The popliteal artery is the direct continuation of the femoral artery in the popliteal fossa. It gives rise to five genicular arteries that form an extensive anastomotic network around the knee. Medial femoral circumflex artery is incorrect. This vessel arises from the femoral or profunda femoris artery high within the femoral triangle. It supplies the muscles in the upper medial thigh and the hip joint. This important vessel is one component of the cruciate anastomosis around the hip and also provides the main supply to the head and neck of the femur. (less)
The answer is femoral hernia. The femoral ring is a weakened aspect in the anterior abdominal wall through which femoral hernias enter the femoral canal. These hernias are more common in females due to a wider pelvis and femoral canal, and they often contain abdominal viscera. The location of the globular mass being located below and lateral to the pubic tubercle helps to distinguish between a femoral hernia, seen in this patient, versus an indirect or direct inguinal hernia. CT imaging can further differentiate between these hernia types. Indirect inguinal hernia is incorrect. An indirect inguinal hernia is usually a congenital hernia that results when abdominal cavity contents herniate through a patent processus vaginalis, or in an adult, the inguinal canal. When the hernial sac emerges through the superficial inguinal ring to start its descent into the scrotum, the swelling will lie above and medial to the pubic tubercle. Direct inguinal hernia is incorrect. A direct inguinal hernia is an acquired hernia that results when abdominal cavity contents herniate through a weakness in the anterior abdominal wall in the inguinal (Hesselbach) triangle. The hernia exits through the superficial inguinal ring, but does not usually descend into the scrotum. Direct inguinal hernias would lie above and medial to the pubic tubercle and are 25 times more likely to occur in men. Swollen superficial inguinal lymph nodes is incorrect. Lymphadenitis (swollen lymph nodes) of the superficial inguinal nodes could be responsible for the globular mass detected in this patient. However, the history of this patient does not include a recent bacterial or viral infection, which would cause these lymph nodes to be tender and swollen. Most importantly, the pain in this patient is acute, which would rule out lymph node involvement, especially due to the patient's history of onset after heavy lifting. Fractured hip joint is incorrect. No trauma was reported by the patient, so a fractured hip can be easily eliminated as a choice, especially due to the location of the globular mass below and lateral to the pubic tubercle. (less)
The answer is cuboid. The given radiograph reveals a fractured cuboid bone, which is identified by the black arrow. The cuboid is a tarsal bone named for its cube-like shape. It is the most lateral bone in the distal row of tarsal bones, where it articulates proximally with the calcaneus and distally with the fourth and fifth metatarsal bones. It is the only bone involved with both the transverse tarsal and tarsometatarsal joints. The tarsus, or proximal foot, consists of seven bones: Talus, Calcaneus, Navicular, Medial cuneiform, Intermediate cuneiform, Lateral cuneiform, and Cuboid. A mnemonic for the tarsal bones is "Tiger Cubs Need MILC," which lists the superior tarsal bones first and then names each distal tarsal bone in the right foot in a clockwise pattern. Navicular is incorrect. The navicular (L: little ship) is a flattened, boat-shaped bone located between the talus proximally and the three cuneiform bones distally. Talus is incorrect. The talus (L: ankle bone) is located between the malleoli of the fibula and tibia and is the only tarsal bone without tendinous or muscular attachments. It articulates with the navicular bone anteriorly and the calcaneus bone inferiorly. Calcaneus is incorrect. The calcaneus (L: heel bone) is the largest and strongest tarsal bone. With its superior surface articulating with the talus, this bone transmits the majority of the forces generated by the weight of the bone from the talus to the ground during standing. Its anterior surface articulates with the cuboid. Lateral cuneiform is incorrect. The lateral cuneiform (L: wedge-shaped) articulates with the navicular located posterior, the third metatarsal located anterior, the cuboid positioned lateral, and the intermediate cuneiform bone located medial. (less)
The answer is tibial (medial) collateral ligament (TCL). The TCL supports the medial side of the knee, attaching to the medial femoral epicondyle and the medial tibial condyle. It is tightly stretched in knee extension, resisting medial displacement of these bones. Therefore, the appropriate clinical test for integrity of the TCL, the valgus test, is to abduct the leg at the knee. Very importantly, the TCL is firmly attached to the medial meniscus. Tearing of the TCL (e.g., due to a blow to the lateral side of the knee) may tear and/or detach the medial meniscus. The ACL, TCL, and medial meniscus are often damaged together in sports injuries resulting from a lateral impact to the knee when the foot is planted and the knee flexed. This combination injury is termed the "unhappy triad" of the knee joint. Fibular (lateral) collateral ligament (FCL) is incorrect. The FCL supports the lateral side of the knee, attaching to the lateral femoral epicondyle and the head of the fibula. As with the TCL, it is taut in knee extension, resisting that and lateral displacement of the leg. Thus, the appropriate clinical test for integrity of the FCL, the varus test, is to adduct the leg at the knee. Notably, the FCL does not attach to the lateral meniscus, eliminating damage to that structure in cases of tearing of the FCL. Anterior cruciate ligament (ACL) is incorrect. The ACL resists anterior sliding of the tibia on the femur when the foot is free (or posterior sliding of the femur on the tibia when the foot is fixed) and hyperextension of the knee. It is commonly injured (along with the tibial collateral ligament and the medial meniscus) in athletes who receive a blow to the lateral side of the leg, which forcefully twists their flexed knee when the foot is planted on the ground. Rupture of the ACL allows the free tibia to be unduly displaced anteriorly under the fixed femur. The integrity of the ACL is tested by looking for an anterior drawer sign, in which the femur is fixed and the physician pulls the free tibia forward, as in opening a drawer, to check the range of movement. A positive drawer test (sign) is one in which the tibia can be displaced abnormally forward, indicating damage to the ACL. Posterior cruciate ligament (PCL) is incorrect. The PCL resists posterior sliding of the tibia on the femur when the foot is free (or anterior sliding of the femur on the tibia when the foot is fixed) and hyperflexion of the knee. Because it is shorter, straighter, and stronger than the ACL, the PCL is injured less frequently. It may tear when the anterior knee hits the ground when flexed. Rupture of the PCL allows the free tibia to be unduly displaced posteriorly under the fixed femur. Thus, in clinical testing, the femur is fixed and the physician pushes the free tibia backward, as in closing a drawer, to check the range of movement. In this case, a positive drawer test (sign) is one in which the tibia can be displaced abnormally backward, indicating damage to the PCL.Patellar ligament is incorrect. The patellar ligament is, in actuality, the terminal end of the quadriceps tendon, attaching those four muscles to the tibial tuberosity. Damage to the patellar ligament is indicated by displacement of the patella into the anterior thigh and/or a deficit in knee extension. (less)
The answer is sciatic nerve. The sciatic nerve is formed by the anterior rami of L4-S3 and is located in the inferior medial quadrant of the buttock. This nerve supplies the muscles in the posterior compartment of the thigh and bifurcates into the tibial nerve and common fibular nerves in the popliteal fossa. The patient exhibits damage to the L4-S1 distribution of this nerve, which would severely limit inversion (L4, L5), eversion (L5, S1), and dorsiflexion (L4, L5) of the foot at the ankle joint. The inability to dorsiflex the foot also has led to foot drop. This prisoner received an improperly placed gluteal IM injection, which either directly damaged his sciatic nerve or the damage to the nerve was caused secondarily due to infection (possibly from an improperly sanitized needle). Properly administered gluteal IM injections are placed posterior to the anterior superior iliac spine and anterior to the tubercle of the iliac crest along the superior border of the gluteus maximus muscle (see diagram on next page). These injections penetrate skin, fascia, and muscles, which allows absorption of the injected substance into the IM veins located in the area of the tensor fasciae latae muscle. Superior gluteal nerve is incorrect. The superior gluteal nerve supplies motor innervation to the gluteus medius, gluteus minimus, and tensor fasciae latae muscles. Loss of this innervation would lead to weakness in abducting and medially rotating the thigh at the hip joint. These muscles are also responsible for keeping the pelvis level during the swing phase of gait. Though the superior gluteal nerve is formed by the anterior rami of L4-S1, damage to this nerve would not cause the paresis (weakness) seen in this patient at the ankle joint. Common fibular nerve is incorrect. The common fibular (peroneal) nerve is a terminal branch of the sciatic nerve that usually does not arise until the sciatic nerve bifurcates in the apex of the popliteal fossa. This nerve further divides into the deep and superficial fibular nerves, which supply the motor innervation to the anterior and lateral compartments of the leg, respectively. Damage to the common fibular nerve would lead to the symptoms seen in this patient (i.e., weakness in inversion, eversion, and dorsiflexion of the foot at the ankle joint as well as foot drop). However, a gluteal IM injection would not affect this nerve directly due to its origin, which is usually in the apex of the popliteal fossa. Tibial nerve is incorrect. The tibial nerve is a terminal branch of the sciatic nerve that usually does not arise until the sciatic nerve bifurcates in the apex of the popliteal fossa. This nerve supplies the posterior compartment of the leg and is important in plantar flexion of the foot at the ankle joint. Weakness in plantar flexion was not noted in this patient, and more importantly, a gluteal IM injection would not affect this nerve directly due to its origin, which is usually in the popliteal fossa. Inferior gluteal nerve is incorrect. The inferior gluteal nerve innervates the gluteus maximus and is formed by the anterior rami of L5-S2. This muscle is involved with lateral rotation and extension of the thigh at the hip joint, especially when the thigh is in a flexed position (rising from a sitting position or climbing stairs). Damage to the inferior gluteal nerve would not produce weakness in movements of the ankle joint. (less)