Upper Limb Anatomy Quiz

A 32-year-old man sustains a mild posterior elbow injury. Despite intact triceps brachii function, elbow extension is slightly weakened. Which muscle is most likely contributing as a secondary extensor of the elbow?

• Brachialis

• Brachioradialis

• Anconeus

• Supinator

Which ligament is primarily responsible for preventing downward displacement of the clavicle relative to the acromion?

• Acromioclavicular ligament

• Coracoacromial ligament

• Coracoclavicular ligament

• Glenohumeral ligament

A newborn presents with "claw hand" involving the intrinsic muscles of the hand. Which part of the brachial plexus is most likely injured during a difficult breech delivery?

• Upper trunk (C5-C6)

• Middle trunk (C7)

• Lower trunk (C8-T1)

• Posterior cord

A 6-month-old infant is noted to have a "waiter's tip" posture of the upper limb. Which of the following nerves is most likely affected?

• Axillary and musculocutaneous nerves

• Ulnar nerve and ant. nerve

• Median and radial nerves

• Median and ulnar nerves

A 45-year-old woman presents with numbness and tingling in the lateral three and a half fingers. Which muscle is most likely weakened in this condition?

• Flexor carpi ulnaris

• Flexor pollicis brevis

• Flexor carpi radialis

• Extensor pollicis longus

A 55-year-old woman with breast cancer undergoes axillary lymph node dissection. Which group of lymph nodes drains the majority of the upper limb?

• Pectoral (anterior) nodes

• Lateral (humeral) nodes

• Central nodes

• Apical nodes

A stab wound to the axilla damages the posterior cord of the brachial plexus. Which of the following muscles will be directly affected?

• Biceps brachii

• Triceps brachii

• Pectoralis major

• Pronator teres

A patient with median nerve injury at the elbow is unable to flex the proximal interphalangeal joints of the medial 4 fingers. Which muscle is most directly responsible for this deficit?

• Flexor digitorum profundus

• Flexor digitorum superficialis

• Lumbricals

• Palmar interossei

During a sentinel lymph node biopsy for suspected melanoma of the medial side of the hand, which lymph nodes should be evaluated first?

• Apical nodes

• Lateral (humeral) nodes

• Pectoral (anterior) nodes

• Subscapular nodes

A construction worker sustains an injury that results in weakness of shoulder abduction and elbow flexion. Which part of the brachial plexus is most likely affected?

• Lower trunk (C8-T1)

• Upper trunk (C5-C6)

• Posterior cord (C5-T1)

• Medial cord (C8-T1)