Lab 7— Posterior Leg & Foot Skeletal—QuesƟons 1 of 1 1. A 32-year-old carpenter fell from the roof. The lateral 5. A 12-year-old boy is brought to the emergency room by longitudinal arch of his foot was flattened from fracture his mother following being pushed out of the neighbor’s and displacement of the keystone for the arch. Which of tree house, about 10 ft off the ground. He can walk but his the following bones is damaged? right heel hurts every time he puts weight on it. When you A. Calcaneus examine his foot it is tender to pressure on both the medi- B. Cuboid bone al and lateral aspects of the heel inferior to the tibia. You C. Head of the talus order plain films of his right lower extremity because you D. Medial cuneiform suspect he has fractured which of the following? E. Navicular bone A. Calcaneus B. Fibula C. Tibia D. Navicular E. Cuneiform 2. An ossification center is present in which of the follow- 6. A 10-year-old boy falls from a tree house. The resultant ing bones of the foot at six months of intra-uterine life heavy compression of the sole of his foot against the (I.U.L) of the fetus? ground caused a fracture of the head of the talus. Which A. Calcaneus of the following structures is unable to function normally? B. Cuboid A. Transverse arch C. Talus B. Medial longitudinal arch D. Medial cuneiform C. Lateral longitudinal arch E. Lateral cuneiform D. Tendon of the peroneus longus E. Long plantar ligament 3. During recruitment by the local representative for the Marines, a young college student presents with the condi- tion known as flat foot. His foot is displaced laterally and everted, and the head of the talus is no longer supported. Which of the following ligaments probably is stretched? A. Plantar calcaneonavicular (spring) B. Calcaneofibular C. Anterior talofibular D. Plantar calcaneocuboid (short plantar) E. Anterior tibiotalar 4. A 21-year-old man falls from the attic and is brought to the emergency room. Examination and radiogram reveal that the lateral longitudinal arch of his foot is flattened. Which of the following bones is displaced? A. Talus B. Medial three metatarsals C. Navicular D. Cuneiform E. Cuboid 1 Lab 7— Posterior Leg & Foot Skeletal—Answers 1. Answer B. (1) The keystone for the lateral longitudi- 5. Answer A. (7)The calcaneus is the most frequently nal arch is the cuboid bone, whereas the keystone for the broken of the tarsal bones. The weight of the body is medial longitudinal arch is the head of the talus. The cal- transmitted down the tibia and onto the talus, which acts caneus, navicular, and medial cuneiform bones form a as a wedge cracking the calcaneus inferiorly. Unfortunate- part of the medial longitudinal arch, but they are not key- ly, this fracture normally involves the cartilaginous articular stones. The calcaneus also forms a part of the lateral lon- surface, complicating the healing process, increasing the gitudinal arch. likelihood of developing an arthritic subtalar joint. These fractures often must be held together with screws or plates for optimal healing. Since the pain was bilateral, and only the calcaneus is bilateral across the heel, none of the oth- er bones (answers b, c, d, and e) listed are possible sites of fracture. The distal end of the tibia (answer c) would have carried the bulk of the force, but the pain location is inconsistent with a distal tibial fracture. 2. Answer A. (1) Primary ossification centres of tarsal 6. Answer B. (1) The keystone of the medial longitudi- bones appear in the following sequence: nal arch of the foot is the head of the talus, which is locat- Calcaneus - 6th month of intra-uterine life (I.U.L) ed at the summit between the sustentaculum tali and the Talus - 7th month of I.U.L navicular bone. The medial longitudinal arch is supported Cuboid - 9th month of I.U.L (at or around birth in a full term by the spring ligament and the tendon of the flexor hallu- born) cis longus muscle. The cuboid bone serves as the key- Lateral cuneiform - 1 year stone of the lateral longitudinal arch, which is supported Medial cuneiform - 3 years by the peroneus longus tendon and the long and short Intermediate cuneiform - 4 years plantar ligaments. The transverse arch is formed by the Hence, the question of viability of a dead born fetus may navicular, three cuneiform, the cuboid, and five metatarsal be assessed by presence or absence of ossification centre bones and is supported by the peroneus longus tendon in calcaneus. Similarly, the presence of an ossification cen- and the transverse head of the adductor halluces. ter in cuboid also helps in assessing the age of the fetus. 3. Answer A. (5) Flat foot is characterized by disap- pearance of the medial portion of the longitudinal arch, which appears completely flattened. The plantar calcane- onavicular (spring) ligament supports the head of the ta- lus and the medial side of the longitudinal arch. The pla- nar calcaneocuboid (short plantar) ligament supports the lateral portion of the longitudinal arch. The other liga- ments support the ankle joint. 4. Answer E. (5) The lateral longitudinal arch is formed by the calcaneus, cuboid bone, and lateral two metatarsal bones, whereas the medial longitudinal arch of the foot is formed by the talus, calcaneus, navicular bone, cuneiform bones, and medial three metatarsal bones. 2 Lab 7— Posterior Leg & Foot Muscles; Tendons — QuesƟons 1 of 4 1. The process of unlocking the fully extended knee in 5. A 20-year-old college student is brought to the emer- preparation for flexion requires initial contraction of which gency room straight from the soccer field. He had just of the following? started to sprint after the ball, when he heard a loud snap A. Gastrocnemius, soleus, and plantaris muscles and felt sharp pain in his left calf as if somebody had B. Hamstring muscles kicked him in the back of his leg. He cannot stand on tip- C. Popliteus muscle toe and Thompson test is positive on the left, which sug- D. Quadriceps femoris muscle gests rupture of the Achilles tendon. E. Sartorius muscle and short head of the biceps femoris What muscle is affected by this injury? muscle A. M. peroneus longus B. M. triceps surae (soleus and gastrocnemius) C. M. biceps femoris D. M. tibialis anterior E. M. semimembranosus 2. A 19-year-old teenager was dancing in clogs in an eth- 6. What is the function of the M. flexor digitorum longus? nic street festival when she inverted her left foot. She pre- A. Dorsiflexion and inversion sents to your office the next day with a swollen foot, but B. Dorsiflexion and eversion mainly complains about tenderness on the lateral aspect C. Plantarflexion and inversion of the foot along the plantar surface. You carefully palpate D. Plantarflexion and eversion her foot and determine that she has tenderness over the E. Dorsal flexion and both inversion and eversion tuberosity of the fifth metatarsal bone. What muscle has avulsed from its insertion on to the tuberosity of the fifth metatarsal? A. Abductor digiti minimi B. Fibularis (Peroneus) brevis C. Fibularis (Peroneus) longus D. Tibialis anterior E. Tibialis posterior 3. A construction worker is hit on the leg with a concrete 7. The arrow refers to which block and is subsequently unable to plantar flex and invert tendon? his foot. Which of the following muscles is most likely damaged? A. Extensor hallucis longus A. Extensor digitorum longus B. Extensor digitorum longus B. Tibialis anterior C. Tibialis anterior C. Tibialis posterior D. Peroneus tertius D. Peroneus longus E. Peroneus longus E. Peroneus brevis 4. An injury to the leg of a golfer results in loss of the abil- 8. The largest plantar flexors in the superficial layer of the ity to invert the foot. Which of the following muscles is posterior compartment are the triceps surae. The muscles most likely paralyzed? of the triceps surae all insert into the calcaneus. When A. Tibialis posterior evaluating the muscle-tendon for injury, one must test B. Peroneus longus with the knee straight and bent to isolate the muscles for C. Peroneus brevis evaluation. Which one of the muscles originates below D. Peroneus tertius the knee joint? E. Extensor digitorum longus A. Gastrocnemius B. Soleus C. Flexor digitorum longus D. Flexor hallucis longus E. Plantaris 3 Lab 7— Posterior Leg & Foot Muscles; Tendons — Answers 1. Answer C. (7) To unscrew a knee from its locked 5. Answer B. (2) The triceps surae consists of the so- and slightly hyperextended position, the popliteus muscle leus, which origins at the tibia and fibula and the gas- contracts and causes medial rotation of the tibia or, if the trocnemius, which origins at the medial and lateral con- foot is planted, lateral rotation of the femur. This move- dyle of the femur. Both insert to the calcaneus via the ment frees the medial femoral condyle from its posterior Achilles tendon. They are both innervated by the tibial position on the tibial condylar surface. The quadriceps nerve and plantar and it flexes the foot, with the gas- femoris (answer d) then relaxes, and knee flexion occurs trocnemius also flexing the knee. In the Thompson test, by contraction of the hamstring muscles (answer b), as- squeezing the calf results in a passive plantar flexion of sisted by the short head of the biceps femoris, sartorius the foot with intact Achilles tendon. This does not happen (answer e), gracilis, and gastrocnemius muscles (answer with a ruptured tendon and then the test is considered a).