D312 ANATOMY AND PHYSIOLOGY I - Set 2 - Part 3

Correct Answer: Supraspinatus, infraspinatus, teres minor, subscapularis

Option d is correct because the rotator cuff group consists of the supraspinatus, infraspinatus, teres minor, and subscapularis, which together stabilize the glenohumeral joint during arm movements. Option a is incorrect because the biceps brachii, brachialis, and triceps brachii are arm muscles that flex and extend the elbow joint and do not form the stabilizing cuff around the shoulder. Option b is incorrect because pectoralis major, latissimus dorsi, and deltoid are large superficial muscles that produce powerful arm movements but do not form the deep stabilizing rotator cuff unit. Option c is incorrect because the trapezius, rhomboids, and serratus anterior connect the scapula to the trunk and move the shoulder blade itself rather than stabilizing the glenohumeral joint directly.

Correct Answer: Biceps brachii and brachialis flex, triceps extends

Option a is correct because the biceps brachii and brachialis are the primary anterior arm flexors bending the elbow, while the triceps brachii is the posterior arm extensor that straightens it. Option b is incorrect because the triceps brachii extends the elbow rather than flexing it, and the deltoid primarily abducts the arm at the shoulder rather than performing elbow flexion movements. Option c is incorrect because the deltoid abducts the arm at the shoulder and the supraspinatus initiates abduction, and neither is a primary elbow flexor as described in this exercise context. Option d is incorrect because the trapezius moves the scapula and the pectoralis major acts primarily on the shoulder joint, and neither muscle is a primary flexor at the elbow joint.

Correct Answer: The quadriceps: rectus femoris and three vastus muscles

Option b is correct because the quadriceps group includes the rectus femoris, vastus medialis, vastus intermedius, and vastus lateralis, all located in the anterior thigh and serving as knee extensors. Option a is incorrect because the hamstrings, including biceps femoris and semimembranosus, are located in the posterior thigh compartment and function as knee flexors and hip extensors, not extensors. Option c is incorrect because the adductors including adductor magnus and gracilis occupy the medial thigh compartment and primarily pull the leg toward the midline rather than extending the knee. Option d is incorrect because the gluteal muscles are located in the buttock region and are responsible for hip extension and abduction, not knee extension in the anterior thigh compartment.

Correct Answer: Biceps femoris, semitendinosus, semimembranosus

Option c is correct because the three hamstring muscles of the posterior thigh are the biceps femoris, semitendinosus, and semimembranosus, all of which extend the hip and flex the knee. Option a is incorrect because the rectus femoris, vastus lateralis, and vastus medialis are three of the four quadriceps muscles located in the anterior compartment that extend the knee instead of flexing it. Option b is incorrect because the adductor magnus and gracilis are medial thigh muscles for adduction, and the sartorius is an anterior thigh muscle, none of which are classified as hamstrings. Option d is incorrect because the gluteus maximus, medius, and minimus are gluteal muscles of the buttock region responsible for hip extension and abduction, not the posterior thigh hamstring group.

Correct Answer: Gastrocnemius and soleus in the posterior leg

Option a is correct because the gastrocnemius and soleus are the superficial posterior lower leg muscles that together form the primary plantar flexors, powering activities like walking and jumping. Option b is incorrect because the tibialis anterior performs dorsiflexion, which is the opposite movement of plantar flexion, and the extensor digitorum longus extends the toes rather than pointing them down. Option c is incorrect because the fibularis longus and brevis are located in the lateral compartment of the lower leg and primarily perform eversion of the foot, not plantar flexion movements. Option d is incorrect because the tibialis posterior and flexor hallucis longus are deep posterior compartment muscles that assist with plantar flexion and toe flexion but are not the primary superficial pair.

Correct Answer: Anterior for extension, medial for adduction, posterior for flexion

Option d is correct because the anterior thigh compartment contains the quadriceps for knee extension, the medial compartment holds the adductors, and the posterior compartment houses the hamstrings for flexion. Option a is incorrect because the anterior compartment extends the knee rather than flexing it, and the medial compartment performs adduction rather than extension, reversing the actual functional assignments. Option b is incorrect because the anterior compartment performs knee extension not adduction, the medial compartment performs adduction not flexion, and the posterior compartment performs flexion not extension. Option c is incorrect because none of the thigh compartments are primarily defined by rotation or abduction as their main actions, making every pairing in this answer choice fundamentally wrong.

Correct Answer: Tibialis anterior in the anterior compartment

Option b is correct because the tibialis anterior is the primary muscle of the anterior compartment of the lower leg, and its main action is dorsiflexion, which pulls the foot upward. Option a is incorrect because the gastrocnemius is a superficial posterior compartment muscle that performs plantar flexion, the opposite of dorsiflexion, pushing the foot downward during walking and jumping. Option c is incorrect because the fibularis longus is located in the lateral compartment and primarily performs eversion of the foot, turning the sole outward, rather than the dorsiflexion action described. Option d is incorrect because the soleus is a posterior superficial compartment muscle that works alongside the gastrocnemius to perform plantar flexion, not the dorsiflexion attributed to anterior muscles.

Correct Answer: Trapezius, serratus anterior, and rhomboids

Option c is correct because the trapezius, serratus anterior, and rhomboids are axial-to-upper-limb muscles that connect the scapula to the trunk and control scapular positioning for arm movement. Option a is incorrect because the biceps brachii, triceps brachii, and brachialis are muscles of the arm that act on the elbow joint and do not connect the upper limb to the axial skeleton. Option b is incorrect because the supraspinatus, infraspinatus, and subscapularis are three of the four rotator cuff muscles that stabilize the glenohumeral joint, not axial-to-limb connectors. Option d is incorrect because the flexor carpi radialis and extensor carpi ulnaris are forearm muscles that move the wrist joint and have no role in connecting the upper limb to the trunk.

Correct Answer: Gluteus maximus extends, medius and minimus abduct

Option a is correct because the gluteus maximus is the primary hip extensor providing power for climbing and standing, while the gluteus medius and minimus perform hip abduction to stabilize the pelvis. Option b is incorrect because the gluteus medius primarily performs abduction not extension, and the gluteus maximus is the powerful hip extensor, so this answer reverses their actual primary functional roles. Option c is incorrect because the biceps femoris is a hamstring muscle that flexes the knee and extends the hip secondarily, and the vastus lateralis is a quadriceps muscle that extends the knee. Option d is incorrect because the rectus femoris is a quadriceps muscle that extends the knee, and the adductor magnus pulls the leg toward the midline performing adduction rather than abduction.

Correct Answer: Iliacus and psoas major crossing the hip

Option d is correct because the iliacus and psoas major are the primary hip flexors that originate from the lumbar spine and iliac fossa and merge to cross the hip joint for powerful thigh elevation. Option a is incorrect because while the rectus femoris assists with hip flexion, it is primarily a quadriceps knee extensor, and the sartorius assists multiple actions rather than serving as a primary hip flexor. Option b is incorrect because the gluteus maximus is the primary hip extensor performing the opposite action, and the gluteus medius primarily abducts the hip rather than flexing it toward the chest. Option c is incorrect because the semitendinosus and semimembranosus are two of the three hamstring muscles in the posterior thigh that flex the knee and extend the hip, not flex it.