LAUS Lower Limb with answers 2023.docx

BSMS MODULE: 204 – THE MUSCULOSKELETAL AND IMMUNE SYSTEMS THEME 2: THE MUSCULOSKELETAL SYSTEM LIVING ANATOMY – THE LOWER LIMB In this living anatomy session, you will study the joints, muscles and movements of the lower limb, as well as use ultrasound to examine the lower limb. Learning Outcomes...

BSMS MODULE: 204 – THE MUSCULOSKELETAL AND IMMUNE SYSTEMS THEME 2: THE MUSCULOSKELETAL SYSTEM LIVING ANATOMY – THE LOWER LIMB In this living anatomy session, you will study the joints, muscles and movements of the lower limb, as well as use ultrasound to examine the lower limb. Learning Outcomes By the end of the session, you should be able to: Identify the skeletal components of the hip, knee, ankle and foot Describe the range of movements for each of the joints of the lower limb Determine the actions of the muscles that perform these movements Determine simple tests that can be used to assess muscle function in the clinic Identify the borders of the popliteal fossa Identify the muscles, vessels and nerves of the lower limb on ultrasound Task 1: Examination of the joints, muscles and movements Each of the tasks can be performed either on a volunteer or yourself. Gluteal region The hip joint is a ball and socket joint that can perform a wide range of movements. Examine the range of movements at the joint. Q1. What movements can you perform at the hip joint? Flexion, extension, abduction, adduction, circumduction, medial (internal) rotation and lateral (external) rotation. Palpate the gluteus medius muscle. It can be palpated immediately superior to the greater trochanter. Try walking a couple of steps. Q2. During which phase of walking does the gluteus medius muscle contract, and what is its function? It contracts to prevent pelvic drop when the opposite foot is off the ground (i.e. during mid stance). The muscle, along with gluteus minimus abducts the thigh. Thigh and knee Stand with one leg forward. Flex the knee joint of the forward leg to at least 30 degrees (such as during a lunge). Palpate the rectus femoris muscle in this limb. In the same posture, palpate the vastus lateralis and vastus medialis muscles. Q3. What would be a consequence of injury to vastus medialis on the patella? The patella would track laterally during locomotion, since the function of the oblique fibres of vastus medialis is to pull the patella medially during extension of the knee. Palpate the hamstring muscles during an isometric contraction of the muscle group. This can be performed by flexing your knee against resistance (e.g. whilst standing with your back towards a wall, flex your knee and simultaneously push your heal against the wall). Q4. Which hamstring muscle may be injured in a patient who experiences weakness of flexion and lateral rotation of the knee? Biceps femoris While sitting with one leg extended, palpate the borders of the popliteal fossa. These are the tendons of the semimembranosus and semitendinosus muscles (upper medial border), the tendon of the biceps femoris muscle (upper lateral border), and the two heads of the gastrocnemius muscle (inferior borders). With both hands cuffed around the knee, use your fingers to feel the pulse of the popliteal artery. You will need to apply sufficient pressure. Q5. Which superficial vein drains into the popliteal vein in the popliteal fossa? Short saphenous vein. Palpate the head and neck of the fibula. The common fibular nerve passes laterally around the neck of the fibula. Q6. How would an injury to the common fibular nerve affect muscle function? An injury to the common fibular nerve could lead to loss of dorsiflexion and eversion of the foot. Patients would present with foot drop. The knee joint is considered a complex hinge joint. Perform flexion and extension of the leg at the knee joint. Palpate the femoral condyles when the knee is flexed. These can be located either side of the patella. Q7. How does the shape of the femoral condyle contribute to the locking mechanism of the knee? The condyles are flat inferiorly, which provides a stable base. While standing with weight on the opposite limb, palpate the patella and observe how it moves from side to side when not weight bearing. Position your fingers on the head of the fibula and the lateral epicondyle of the femur while sitting. Now try standing. Q8. What happens to the femur relative to the fibula when you move from sitting to standing? The femur medially rotates locking the joint At the proximal end of the tibia, locate the tibial tuberosity. The tibial tuberosity provides an attachment site for the patellar ligament. Palpate the adductor tubercle, the bony point on the medial side of the knee. The hamstring portion of adductor magnus inserts in the adductor tubercle. Q9. Which artery passes through the hiatus formed by the tendon of this muscle? Femoral artery. After this point, it becomes the popliteal artery. Leg and foot The ankle (talocrural) joint is formed between the tibia, fibula and talus. Q10. What movements can you perform at the talocrural joint? Dorsiflexion and plantarflexion of the foot. While dorsiflexing the foot, palpate the tibialis anterior muscle. Q11. Following a tear of the tibialis anterior muscle, which movement, in addition to dorsiflexion, would be weakened? Inversion of the foot. Try inverting and everting your feet. Q12. At which joint does eversion and inversion occur? At the subtalar joint. Stand with your feet slightly apart. Twist your body to look over your left shoulder. Q13. While twisting your body to look over your left shoulder, which foot is pronated, and which foot is supinated? Your left foot is supinated (it feels as though you are standing on the lateral edge of your left foot) and your right foot is pronated. During supination, the front part of the foot is inverted and adducted; during pronation, the front part of the foot everted and abducted. Locate the lateral and medial malleoli. The tendons of the tibialis anterior, extensor hallucis longus and extensor digitorum longus muscles can be palpated between these two bony points as they pass under the extensor retinaculum. With the foot dorsiflexed, palpate each of these tendons. On the dorsum of the foot, locate the pulse of the dorsalis pedis artery. Q14. Which tendon lies to the medial side of the dorsalis pedis artery? Extensor hallucis longus. This is a useful landmark for locating the dorsalis pedis pulse. While standing on tiptoes, locate the two muscle bellies of the gastrocnemius muscle. Trace the Achilles tendon (the tendocalcaneus) from the gastrocnemius muscle toward its insertion on the calcaneus. Q15. Which other muscles insert into the Achilles tendon? Soleus and plantaris. Locate the tarsal tunnel between the calcaneus and the medial malleolus. Locate the pulse of the posterior tibial artery within the tarsal tunnel. Q16. What is the importance of the pulse points in the foot? As they are a distance from the heart, they can used to assess peripheral circulation. The tibial nerve also passes through the tarsal tunnel. Q17. Over which area of skin would sensation be altered if the tibial nerve was injured at the tarsal tunnel? Plantar surface of foot. On the lateral side of the leg, palpate the fibularis longus muscle. Q18. Can you devise a simple bedside test to assess the function of the fibularis longus muscle? Ask patient to evert foot against resistance. Task 2: Ultrasound imaging of the lower limb Ultrasound is frequently used in musculoskeletal clinics. It is used to identify muscle, tendon or ligament damage, bursitis, joint effusion (increased intra-articular fluid), vascular pathology, haematomas, abscesses, oedema and masses such as ganglion cysts or lipomas. It is also used as guidance for injections, aspiration or biopsy. As part of point of care ultrasound (POCUS), it is used to map lower limb veins for vascular access. Specific examples of clinical conditions that can be diagnosed by ultrasound, as well as procedures that utilise ultrasound, have been given for each region. For this task, you will use ultrasound to examine the muscles, nerves and vessels of the lower limb. Whilst imaging the muscles, ask the subject to move different joints to work out which muscles you are looking at. IMAGING THE ANTERIOR THIGH Refer to page 152-153 in Gray’s Surface Anatomy and Ultrasound. Imaging is performed with the subject lying supine or sitting facing the operator. Identify the femoral artery and vein, as well as the femoral nerve. Also examine the quadriceps. IMAGING THE KNEE Refer to page 152-156 in Gray’s Surface Anatomy and Ultrasound. Imaging is performed with the subject lying supine (leg extended) or sitting (leg flexed), facing the operator. Identify the quadriceps tendon. Identify the vastus medialis oblique muscle fibres as they insert into the patella. With the leg flexed, locate the anterior cruciate ligament. IMAGING THE POSTERIOR THIGH AND POPLITEAL FOSSA Refer to page 156-159 in Gray’s Surface Anatomy and Ultrasound. Imaging is best performed with the subject lying prone or standing. Identify the hamstring muscles, as well as the sciatic nerve. Within the popliteal fossa, examine the popliteal vessels and the tibial nerve. IMAGING THE ANTERIOR LEG Refer to page 159-160 in Gray’s Surface Anatomy and Ultrasound. Imaging is performed with the subject lying supine, sitting or standing facing the operator. Identify the tibialis anterior, extensor digitorum longus and extensor hallucis longus muscles. IMAGING THE POSTERIOR LEG Refer to page 160-162 in Gray’s Surface Anatomy and Ultrasound. Imaging is performed with the subject lying prone or standing with their back to the operator. Examine the contents of the tarsal tunnel.