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Question 1
Incorrect
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Due to a traffic accident, a male patient was unable to flex his arm at the glenohumeral joint. Based on the patient’s current condition, which nerve is most likely damaged?
Your Answer: Upper and lower subscapular nerves
Correct Answer: Axillary and suprascapular nerve
Explanation:A suprascapular nerve injury causes numbness in the shoulder, as well as weakness in abduction and external rotation. Damage to the axillary nerve can result in shoulder or arm muscle weakness, as well as difficulty lifting the arm. This is because the deltoid and supraspinatus muscles, which are innervated by the axillary and suprascapular nerves, are responsible for abduction of the arm at the shoulder joint.
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This question is part of the following fields:
- Anatomy
- Upper Limb
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Question 2
Correct
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Which of the following statements accurately describes the flexor digitorum superficialis muscle?
Your Answer: It flexes the middle phalanges of the medial four fingers at the proximal interphalangeal joints
Explanation:Flexor digitorum superficialis is the largest muscle of the anterior compartment of the forearm. It belongs to the superficial flexors of the forearm, together with pronator teres, flexor carpi radialis, flexor carpi ulnaris and palmaris longus. Some sources alternatively classify this muscle as an independent middle/intermediate layer of the anterior forearm, found between the superficial and deep groups.Flexor digitorum superficialis is innervated by muscular branches of the median nerve, derived from roots C8 and T1 that arises from the medial and lateral cords of the brachial plexus. The skin that overlies the muscle is supplied by roots C6-8 and T1.The primary arterial blood supply to the flexor digitorum superficialis is derived from the ulnar artery and its anterior recurrent branch. In addition to branches of the ulnar artery, the anterior and lateral surfaces of the muscle are supplied by branches of the radial artery; and its posterior surface also receives branches from the median artery.The main function of flexor digitorum superficialis is flexion of the digits 2-5 at the proximal interphalangeal and metacarpophalangeal joints. Unlike the flexor digitorum profundus, flexor digitorum superficialis has independent muscle slips for all four digits. This allows it to flex the digits individually at their proximal interphalangeal joints. In addition, flexor digitorum superficialis aids the aids flexion of the wrist.
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This question is part of the following fields:
- Anatomy
- Upper Limb
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Question 3
Incorrect
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Which nerve innervates the brachioradialis muscle?
Your Answer: The musculocutaneous nerve
Correct Answer: The radial nerve
Explanation:Brachioradialis is innervated by the radial nerve (from the root values C5-C6) that stems from the posterior cord of the brachial plexus.
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This question is part of the following fields:
- Anatomy
- Upper Limb
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Question 4
Correct
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A 20-year-old patient had sustained a supracondylar fracture due to falling from a skateboard. The frequency of acute nerve injuries accompanying supracondylar humeral fractures ranges from 10 to 20%. The most common complication is injury to which nerve?
Your Answer: Median nerve
Explanation:According to various studies, the frequency of acute nerve damage associated with supracondylar humeral fractures in children ranges from 10% to 20%. Median nerve injury and anterior interosseous nerve injury are the most common consequences. Damage to this nerve indicated weakening or abnormal extension of the index finger’s distal interphalangeal joint and the thumb’s interphalangeal joint. The absence of sensibility is a distinguishing attribute. A surgical neck humerus fracture may cause injury to the axillary nerve. A midshaft humerus fracture might cause injury to the radial nerve. A medial epicondylar fracture might cause injury to the ulnar nerve.
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This question is part of the following fields:
- Anatomy
- Upper Limb
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Question 5
Correct
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You are reviewing a patient following a fall from a horse. You suspect they may have an Erb's palsy as a result of a brachial plexus injury. Regarding Erb's palsy, which one of the following statements is CORRECT:
Your Answer: Erb's palsy may result in loss of sensation of the regimental badge area.
Explanation:Erb’s palsy is caused by damage to the C5 and C6 nerve roots and thus primarily involves the musculocutaneous, suprascapular and axillary nerves. It commonly result from an excessive increase in the angle between the neck and the shoulder e.g. a person thrown from a motorbike or horseback or during a difficult birth. There is loss or weakness of abduction, lateral rotation and flexion of the arm and flexion and supination of the forearm and loss of sensation on the lateral arm. A characteristic ‘Waiter’s tip’ deformity may be present where the limb hangs limply by the side, medially rotated by the unopposed action of pectoralis major with the forearm pronated due to paralysis of the biceps brachii.
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This question is part of the following fields:
- Anatomy
- Upper Limb
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Question 6
Correct
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Which of the following movements is controlled by the pectoralis major muscle?
Your Answer: Flexion, adduction and medial rotation of the humerus
Explanation:The pectoralis major is a muscle that runs across the top of the chest and connects to a ridge on the back of the humerus (the bone of the upper arm). Adduction, or lowering, of the arm (opposed to the deltoideus muscle) and rotation of the arm forward around the axis of the body are two of its main functions.
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This question is part of the following fields:
- Anatomy
- Upper Limb
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Question 7
Incorrect
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Which of the following statements is false regarding the biceps brachii muscle?
Your Answer: It receives its blood supply from the brachial artery
Correct Answer: It pronates the radioulnar joint in the forearm
Explanation:The biceps brachii muscle is one of the chief muscles of the arm. The origin at the scapula and the insertion into the radius of the biceps brachii means it can act on both the shoulder joint and the elbow joint, which is why this muscle participates in a few movements of the arm. It derives its name from its two heads which merge in one unique distal body, defining the unusual structure of the muscle.The biceps brachii muscle is supplied by the musculocutaneous nerve (C5-C6), a branch of the brachial plexus.Arterial supply to the biceps brachii muscle varies considerably, coming from up to eight vessels originating from the brachial artery in the middle third of the arm.In the shoulder joint both muscle heads partially enforce opposite movements. The long head pulls the arm away from the trunk (abduction) and turns it inwards (inward rotation) whereas the short head pulls the arm back towards the trunk (adduction). When both heads contract simultaneously it leads to an arm bend (flexion). In the elbow joint the muscle bends the forearm (flexion) and rotates it outwards (supination). The supination is most powerful in a flexed elbow. In addition to the movement functions, the biceps has the important task to support the humeral head within the shoulder joint. Its antagonist is the triceps brachii in the posterior compartment of the arm.
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This question is part of the following fields:
- Anatomy
- Upper Limb
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Question 8
Incorrect
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A fracture on which of the following structures is associated with a posterior elbow dislocation?
Your Answer: Olecranon
Correct Answer: Radial head
Explanation:Fracture dislocations of the elbow appear extremely complex, and identification of the basic injury patterns can facilitate management. The simplest pattern of elbow fracture dislocation is posterior dislocation of the elbow with fracture of the radial head. Addition of a coronoid fracture, no matter how small, to elbow dislocation and radial head fracture is called the terrible triad of the elbow.
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This question is part of the following fields:
- Anatomy
- Upper Limb
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Question 9
Incorrect
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An 18-year-old patient was brought to the ER after falling off of his skateboard. He is unable to flex the distal interphalangeal joint of his index finger. You suspect that he suffers from a supracondylar fracture. Which of the following conditions would confirm supracondylar fracture?
Your Answer: Loss of supination of the forearm
Correct Answer: Inability to oppose the thumb
Explanation:A supracondylar fracture is a fracture that occurs through the thin section of the distal humerus above the growth plate. A supracondylar fracture is most usually associated with median nerve injury. A medial nerve damage causes paralysis of the thenar muscles, as well as loss of thumb opposition.
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This question is part of the following fields:
- Anatomy
- Upper Limb
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Question 10
Incorrect
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Which of the following nerves supplies the abductor pollicis brevis?
Your Answer: The ulnar nerve
Correct Answer: The recurrent branch of the median nerve
Explanation:Abductor pollicis brevis is innervated by the recurrent (thenar) branch of median nerve (root value C8 and T1).
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This question is part of the following fields:
- Anatomy
- Upper Limb
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Question 11
Correct
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A man presents to the emergency department with a hand laceration that has damaged the opponens digiti minimi muscle.All of the following statements regarding the opponens digiti minimi muscle is considered correct, except:
Your Answer: It is innervated by the superficial branch of the ulnar nerve
Explanation:Opponens digiti minimi (ODM) is an intrinsic muscle of the hand. It’s a triangular muscle that extends between the hamate bone (carpal bone) and the 5th metacarpal bone. It forms the hypothenar muscle group together with the abductor digiti minimi and flexor digiti minimi brevis, based on the medial side of the palm (hypothenar eminence). These muscles act together in moving the little finger. The opponens digiti minimi is responsible for flexion, lateral rotation and opposition of the little finger.Its origin is the hook of hamate and flexor retinaculum. It inserts into the medial border of 5th metacarpal bone. It is innervated by the deep branch of the ulnar nerve, which stems from the brachial plexus (C8, T1 spinal nerves).Its blood supply is by the deep palmar branch of ulnar artery and deep palmar arch, which is the terminal branch of the radial artery.
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This question is part of the following fields:
- Anatomy
- Upper Limb
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Question 12
Correct
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The following statements are not true of the extensor carpi radialis brevis muscle, except?
Your Answer: It receives its blood supply from the radial artery
Explanation:Extensor carpi radialis brevis is a fusiform muscle found in the lateral part of the posterior forearm. Together with anconaeus, brachioradialis, extensor carpi radialis longus, extensor digitorum, extensor digiti minimi and extensor carpi ulnaris, it belongs to the superficial forearm extensor group. Extensor carpi radialis brevis originates from the lateral epicondyle of humerus via the common extensor tendon. This is a common origin that it shares with the extensor digitorum, extensor digiti minimi and extensor carpi ulnaris muscles. Some fibres also originate from the lateral intermuscular septum, a thick aponeurosis that covers the muscle itself, and from the radial collateral ligament.The muscle courses inferiorly, giving off a long tendon in the middle of the forearm which descends towards the dorsal hand. The tendon passes through a groove on the posterior surface of radius, deep to the extensor retinaculum. After traversing the extensor retinaculum space, the tendon inserts into the posterior aspect of the base of the third metacarpal bone.Extensor carpi radialis brevis is innervated directly by the radial nerve (C5- C8), or sometimes from its deep branch/posterior interosseous nerve. The radial nerve stems from the posterior cord of the brachial plexus.The muscle is vascularized by the radial recurrent artery, radial artery and deep brachial artery (via its radial collateral branch).Extensor carpi radialis brevis works together with extensor carpi ulnaris and extensor carpi radialis longus to extend the hand at the wrist joint. This action is vital in a sequence of muscle contractions needed for clenching a fist or making a grip. When performing these functions, wrist extension blocks the flexor muscles from on acting upon the hand. Instead, flexors act only on the digits, thereby flexing them and producing an effective hand grip, such as that seen in a tennis backhand. When the extensor carpi radialis brevis muscle contracts together with extensor carpi radialis longus and flexor carpi radialis, it contributes to producing hand abduction (radial deviation).
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This question is part of the following fields:
- Anatomy
- Upper Limb
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Question 13
Incorrect
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A 30-year-old carpenter presented to the emergency room with a laceration of his upper volar forearm. Upon further exploration and observation, it was revealed that the nerve that innervates the pronator teres muscle has been damaged. Which of the following nerves is most likely damaged in the case?
Your Answer: The musculocutaneous nerve
Correct Answer: The median nerve
Explanation:Pronator teres syndrome (PTS) is caused by a compression of the median nerve (MN) by the pronator teres (PT) muscle in the forearm. The median nerve, C6 and C7, innervates the pronator teres.
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This question is part of the following fields:
- Anatomy
- Upper Limb
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Question 14
Incorrect
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A 64-year-old woman had a humerus midshaft fracture due to tripping on a curb and falling on her left arm. She might also have damaged which of the following structures?
Your Answer: Axillary nerve and axillary artery
Correct Answer: Radial nerve and deep brachial artery
Explanation:The radial nerve and brachial artery are most likely to be damaged in humerus fractures. They are tethered together to the bone and cannot withstand the forces applied to it as a result of the displacement.
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This question is part of the following fields:
- Anatomy
- Upper Limb
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Question 15
Incorrect
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Which of the following statements is true regarding the extensor pollicis longus?
Your Answer: It extends the thumb at the carpometacarpal joint
Correct Answer: It is innervated by the posterior interosseous nerve
Explanation:Extensor pollicis longus is part of the deep extensors of the forearm together with extensor pollicis brevis, abductor pollicis longus, extensor indicis and supinator muscles. It is located on the posterior aspect of forearm, extending from the middle third of the ulna, and adjacent interosseous membrane, to the distal phalanx of the thumb.Extensor digitorum is innervated by posterior interosseous nerve which is a continuation of a deep branch of radial nerve (root value C7 and C8).Extensor pollicis brevis receives its blood supply from the posterior interosseous artery and perforating branches of the anterior interosseous artery.The main action of extensor pollicis longus is extension of the thumb at the metacarpophalangeal and interphalangeal joints. Extension at the metacarpophalangeal joint occurs in synergy with extensor pollicis brevis muscle. When the thumb reaches the full extension or abduction, extensor pollicis longus can also assist in adduction of the thumb.
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This question is part of the following fields:
- Anatomy
- Upper Limb
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Question 16
Incorrect
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A patient has suffered a nerve injury that has caused weakness of the pectoralis minor muscle.Pectoralis minor receives its innervation from which of the following nerves? Select ONE answer only.
Your Answer: Long thoracic nerve
Correct Answer: Medial pectoral nerve
Explanation:Pectoralis minor is a thin, triangular muscle that is situated in the upper chest. It is thinner and smaller than pectoralis major. It is innervated by the medial pectoral nerve.The origin of pectoralis minor is the 3rdto the 5thribs, near the costal cartilages. It inserts into the medial border and superior surface of the coracoid process of the scapula.The main action of pectoralis minor is to draw the scapula inferiorly and anteriorly against the thoracic wall. This serves to stabilise the scapula.
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This question is part of the following fields:
- Anatomy
- Upper Limb
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Question 17
Incorrect
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A 35 year old man presents with a deep laceration to the proximal part of the forearm. On further assessment, the patient is unable to flex the metacarpophalangeal joints and interphalangeal joints of the index, middle finger and the thumb. The ring and little fingers are intact but there is weakness at the proximal interphalangeal joint.There is also loss of sensation over the lateral palm and the palmar surface of the lateral three and a half fingers. Which of these nerve(s) has most likely been affected?
Your Answer: Ulnar nerve
Correct Answer: Median nerve
Explanation:A median nerve injury affecting the extrinsic and intrinsic muscles of the hand will present with:Loss of sensation to the lateral palm and the lateral three and a half fingers.Weakness of flexion at the metacarpophalangeal joints of the index and middle finger. This is because of paralysis of the lateral two lumbricals. Weakness of flexion of the proximal interphalangeal joints of all four fingers due to paralysis of the flexor digitorum superficialisWeakness of flexion at the distal interphalangeal joints of the index and middle finger following paralysis of the lateral half of the flexor digitorum profundus.Weakness of thumb flexion, abduction and opposition due to paralysis of the flexor pollicis longus and thenar muscles
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This question is part of the following fields:
- Anatomy
- Upper Limb
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Question 18
Incorrect
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A man suffered from a back injury due to a fall from a ladder. Significant bruising was found to be overlying his latissimus dorsi muscle.Which of the following statements regarding the latissimus dorsi muscle is considered correct?
Your Answer: It laterally rotates the humerus as part of its action
Correct Answer: It raises the body towards the arm during climbing
Explanation:The latissimus dorsi muscle is a broad, flat muscle that occupies the majority of the lower posterior thorax. The muscle’s primary function is of the upper extremity but is also considered to be a respiratory accessory muscle.Latissimus dorsi is a climbing muscle. With the arms fixed above the head, it can raise the trunk upwards, together with the help of pectoralis major. Functionally, the latissimus dorsi muscle belongs to the muscles of the scapular motion. This muscle is able to pull the inferior angle of the scapula in various directions, producing movements on the shoulder joint (internal rotation, adduction and extension of the arm). It is innervated by the thoracodorsal nerve (C6 – C8) from the posterior cord of the brachial plexus, which enters the muscle on its deep surface.
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This question is part of the following fields:
- Anatomy
- Upper Limb
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Question 19
Incorrect
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A 27-year-old man presents with a laceration of his forearm that severed the nerve that innervates flexor carpi radialis.Which of the following nerves has been damaged in this case? Select ONE answer only.
Your Answer: The radial nerve
Correct Answer: The median nerve
Explanation:Flexor carpi radialis is innervated by the median nerve.
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This question is part of the following fields:
- Anatomy
- Upper Limb
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Question 20
Incorrect
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The fracture of the medial epicondyle will cause damage to the ulnar nerve. Which of the following motions would be impaired by this type of injury?
Your Answer: Extension of the thumb
Correct Answer: Adduction of the thumb
Explanation:Fracture of the medial epicondyle is most likely to result in damage to the ulnar nerve. The three hypothenar muscles, two medial lumbricals, seven interossei, the adductor pollicis, and the deep head of the flexor pollicis brevis are all innervated by the deep branch of the ulnar nerve.
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This question is part of the following fields:
- Anatomy
- Upper Limb
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Question 21
Incorrect
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After a work-related accident, a 33-year old male is taken to the emergency room with difficulty in adduction and flexion of his left arm at the glenohumeral joint. The attending physician is suspects involvement of the coracobrachialis muscle.The nerve injured in the case above is?
Your Answer: The axillary nerve
Correct Answer: The musculocutaneous nerve
Explanation:The coracobrachialis muscle is innervated by the musculocutaneous nerve (C5-C7) a branch of the lateral cord of the brachial plexus.
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This question is part of the following fields:
- Anatomy
- Upper Limb
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Question 22
Incorrect
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A suicidal patient had lacerated his wrist, which resulted in an ulnar nerve injury. Which of the following will confirm the presence of an ulnar nerve injury?
Your Answer: Loss of flexion of the index and ring fingers
Correct Answer: Claw hand appearance
Explanation:An ulnar injury may result in abnormal sensations in the little finger and ring finger, usually on the palm side, weakness, and loss of coordination of the fingers. A claw like deformity of the hand and wrist is present. Pain, numbness, decreased sensation, tingling, or burning sensation in the areas controlled by the nerve are also possible.
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This question is part of the following fields:
- Anatomy
- Upper Limb
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Question 23
Incorrect
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During bedside rounds, an 82-year old female in the Medicine Ward complains of pain and tingling of all fingers of the right hand. The attending physician is considering carpal tunnel syndrome.Which of the following is expected to undergo atrophy in carpal tunnel syndrome?
Your Answer: The wrist flexors
Correct Answer: The thenar eminence
Explanation:Carpal tunnel syndrome (CTS) is an entrapment neuropathy caused by compression of the median nerve as it travels through the wrist’s carpal tunnel. It is the most common nerve entrapment neuropathy, accounting for 90% of all neuropathies. Early symptoms of carpal tunnel syndrome include pain, numbness, and paraesthesia’s. These symptoms typically present, with some variability, in the thumb, index finger, middle finger, and the radial half (thumb side) of the ring finger. Pain also can radiate up the affected arm. With further progression, hand weakness, decreased fine motor coordination, clumsiness, and thenar atrophy can occur.The muscles innervated by the median nerve can be remembered using the mnemonic ‘LOAF’:L– lateral two lumbricalsO– Opponens pollicisA– Abductor pollicisF– Flexor pollicis brevisIn the early presentation of the disease, symptoms most often present at night when lying down and are relieved during the day. With further progression of the disease, symptoms will also be present during the day, especially with certain repetitive activities, such as when drawing, typing, or playing video games. In more advanced disease, symptoms can be constant.Typical occupations of patients with carpal tunnel syndrome include those who use computers for extended periods of time, those who use equipment that has vibration such as construction workers, and any other occupation requiring frequent, repetitive movement.
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This question is part of the following fields:
- Anatomy
- Upper Limb
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Question 24
Incorrect
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A 30-year-old man suffers from an open fracture of his forearm. As a consequence of his injury, the nerve that innervates the pronator quadratus muscle was severed. Which of the following statements regarding the pronator quadratus muscle is considered correct?
Your Answer: It receives its blood supply from the radial artery
Correct Answer: Its deep fibres bind the radius and ulna together
Explanation:Pronator quadratus is a deep-seated, short, flat, and quadrilateral muscle with fibres running in a parallel direction. It arises from the oblique ridge on the anterior surface of the distal fourth of the Ulna. It is inserted in lateral border and anterior surface of the distal fourth of the radius. It is innervated by the anterior interosseous nerve, a branch of the median nerve (C8-T1). It is vascularized by the anterior interosseous artery.The action of the pronator quadratus muscle along with the pronator teres result in the pronation of the radioulnar joint. Contraction of this muscle pulls the distal end of the radius over the ulna, resulting in the pronation of the radioulnar joint
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This question is part of the following fields:
- Anatomy
- Upper Limb
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Question 25
Incorrect
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A patient presents to ED complaining of pins and needles over the lateral three and a half digits. You suspect carpal tunnel syndrome. Which of the following clinical features would you most expect to see on examination:
Your Answer: Inability to flex the interphalangeal joint of the thumb
Correct Answer: Inability to touch the pad of the little finger with the thumb
Explanation:Compression of the median nerve in the carpal tunnel will result in weakness and atrophy of the thenar muscles – resulting in weakness of opposition, abduction and flexion of the thumb at the metacarpophalangeal joint and anaesthesia or paraesthesia over the distribution of the palmar digital branch of the median nerve (skin over the palmar surface and fingertips of the lateral three and a half digits). The adductor pollicis muscle is innervated by the ulnar nerve, and abduction of the fingers is produced by the interossei, also innervated by the ulnar nerve. Flexion of the interphalangeal joint of the thumb is produced by the flexor pollicis longus, and flexion of the distal interphalangeal joint of the index finger is produced by the flexor digitorum profundus. Median nerve injury at the wrist will not affect the long flexors of the forearm as these are innervated by the anterior interosseous nerve which arises in the proximal forearm.
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This question is part of the following fields:
- Anatomy
- Upper Limb
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Question 26
Incorrect
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A man working as a waiter cuts his arm on a glass while he was working. The palmaris longus muscle was damaged as a consequence of his injury.Which of the following statements regarding the palmaris longus muscle is considered correct?
Your Answer: It arises from the lateral epicondyle of the humerus
Correct Answer: It receives its blood supply from the ulnar artery
Explanation:The palmaris longus is a small, fusiform-shaped muscle located on the anterior forearm of the human upper extremity. The palmaris longus muscle is commonly present but may be absent in a small percentage of the population, ranging from 2.5% to 26% of individuals, depending on the studied population.The palmaris longus belongs to the anterior forearm flexor group in the human upper extremity. The muscle attaches proximally to the medial humeral epicondyle and distally to the palmar aponeurosis and flexor retinaculum. The blood supply to the palmaris longus muscle is via the ulnar artery, a branch of the brachial artery in the human upper extremity.The palmaris longus muscle receives its innervation via branches of the median nerve containing nerve roots C5-T1. Median nerve injury at or above the elbow joint (including brachial plexus and nerve root injury) can lead to deficits in the palmaris longus and other forearm flexor muscles, leading to weakened elbow flexion, wrist flexion, radial deviation, finger flexion, thumb opposition, flexion, and abduction, in addition to the loss of sensory function in the distribution of the median nerve.
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This question is part of the following fields:
- Anatomy
- Upper Limb
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Question 27
Incorrect
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A 29 year old man presents to ED followed an alleged assault whilst out drinking. He received blunt trauma to his right axilla. He is complaining of difficulty abducting his right arm above the level of his shoulder, and on inspection, the inferior angle of his right scapula protrudes more than that of his left scapula. Which of the following nerves has most likely been affected:
Your Answer: Dorsal scapular nerve
Correct Answer: Long thoracic nerve
Explanation:Damage to the long thoracic nerve results in weakness/paralysis of the serratus anterior muscle causing difficulty abducting the upper limb above 90 degrees and giving a ‘winged ‘ scapula appearance where the medial border, particularly the inferior angle, of the scapula moves laterally and posteriorly away from the thoracic wall (this becomes more pronounced if the patient presses the upper limb against a wall).
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This question is part of the following fields:
- Anatomy
- Upper Limb
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Question 28
Incorrect
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Regarding the abductor pollicis longus, which of the following statements is true?
Your Answer: It arises from the lateral epicondyle of the elbow
Correct Answer: It extends the thumb at the carpometacarpal joint
Explanation:Abductor pollicis longus is a muscle found in the posterior compartment of the forearm. It is one of the five deep extensors in the forearm, along with the supinator, extensor pollicis brevis, extensor pollicis longus and extensor indicis.Abductor pollicis longus is innervated by the posterior interosseous nerve (C7, C8), which is a continuation of the deep branch of the radial nerve. The radial nerve is a branch of the posterior cord of the brachial plexus.Blood supply to the abductor pollicis longus muscle comes from the interosseous branches of the ulnar artery.Acting alone or with abductor pollicis brevis, abductor pollicis longus pulls the thumb away from the palm. More specifically, it produces (mid-) extension and abduction of the thumb at the first metacarpophalangeal joint. This action is seen in activities such as bowling and shovelling.Working together with the long and short extensors of the thumb, the muscle also helps to fully extend the thumb at the metacarpophalangeal joint. This action is important for loosening the hand grip, for example, when letting go of objects previously being held. Abductor pollicis longus also helps to abduct the hand (radial deviation) at the radiocarpal joint.
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This question is part of the following fields:
- Anatomy
- Upper Limb
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Question 29
Correct
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A patient suffered from a chest injury while working out in the gym. As a consequence of his injury, his pectoralis minor muscle was damaged.Which of the following statements regarding the pectoralis minor muscle is considered correct?
Your Answer: It stabilises the scapula
Explanation:The pectoralis minor, in comparison to the pectoralis major, is much thinner and triangular in shape and resides below the major. It originates from the margins of the third to fifth ribs adjacent to the costochondral junction. The fibres consequently pass upward and laterally to insert into the medial border and superior surface of the coracoid process. It is crucial in the stabilization of the scapula by pulling it downward and anteriorly against the thoracic wall.Arterial supply to the pectoralis minor also derives from the pectoral branch of the thoracoacromial trunk. Nerve supply of the pectoralis minor is a function of the lateral pectoral nerve and the medial pectoral nerve.
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This question is part of the following fields:
- Anatomy
- Upper Limb
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Question 30
Incorrect
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Which of the following accurately describes the extensor pollicis brevis muscle?
Your Answer:
Correct Answer: It lies on the medial side of abductor pollicis longus
Explanation:Extensor pollicis brevis is a short and slender muscle located in the posterior compartment of the forearm, extending from the posterior surface of radius to the proximal phalanx of thumb. It is one of the deep extensors of the forearm, together with supinator, abductor pollicis longus, extensor pollicis longus and extensor indicis muscles.Extensor pollicis brevis is a deep extensor of the thumb that lies deep to extensor digitorum muscle. It sits directly medial to abductor pollicis longus and posterolateral to extensor pollicis longus muscle. Just above the wrist, extensor pollicis brevis obliquely crosses the tendons of extensor carpi radialis brevis and extensor carpi radialis longus muscles.Extensor pollicis brevis is innervated by posterior interosseous nerve which is a continuation of a deep branch of radial nerve (root value C7 and C8).Extensor pollicis brevis receives its blood supply by posterior interosseous artery and perforating branches from the anterior interosseous artery, which are the branches of common interosseous artery. The common interosseous artery arises immediately below the tuberosity of radius from the ulnar artery.Together with extensor pollicis longus, extensor pollicis brevis is in charge of extension of the thumb in the first metacarpophalangeal joint. It also extends the thumb in the carpometacarpal joint of the thumb. This movement is important in the anatomy of the grip, as it enables letting go of an object. As it crosses the wrist, extensor pollicis brevis also participates in the extension and abduction of this joint.
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This question is part of the following fields:
- Anatomy
- Upper Limb
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SESSION STATS - PERFORMANCE PER SPECIALTY
