Upper Limb Anatomy PDF

Question 1 of 601 A 10 year old boy is admitted to the emergency department following a fall. On examination, there is deformity and swelling of the forearm. The ability to flex the fingers of the affected limb is impaired. However, there is no sensory impairment. Imaging confirms a displaced forea...

Question 1 of 601 A 10 year old boy is admitted to the emergency department following a fall. On examination, there is deformity and swelling of the forearm. The ability to flex the fingers of the affected limb is impaired. However, there is no sensory impairment. Imaging confirms a displaced forearm fracture. Which of the nerves listed below is likely to have been affected? Ulnar h Posterior interosseous nerve la Anterior interosseous nerve Axillary Sa Radial Forearm fractures may be complicated by neurovascular compromise. The anterior interosseous nerve may be affected. It has no sensory supply so the defect is motor alone. Please rate this question: C Discuss and give feedback Next question R Anterior interosseous nerve The anterior interosseous nerve (volar interosseous nerve) is a branch of the median nerve that supplies the deep muscles on the front of the forearm, except the ulnar half of the flexor digitorum profundus. M It accompanies the anterior interosseous artery along the anterior of the interosseous membrane of the forearm, in the interval between the flexor pollicis longus and flexor digitorum profundus, supplying the whole of the former and (most commonly) the radial half of the latter, and ending below in the pronator quadratus and wrist joint. Innervation The anterior interosseous nerve classically innervates 2.5 muscles: Flexor pollicis longus  Pronator quadratus The radial half of flexor digitorum profundus (the lateral two out of the four tendons). These muscles are in the deep level of the anterior compartment of the forearm. h la Sa C R M Question 2 of 601 Which of the following nerves supplies the skin on the palmar aspect of the thumb? Ulnar Median h Radial la Musculocutaneous None of the above Sa The median nerve supplies cutaneous sensation to this region. Please rate this question: Discuss and give feedback C Next question Median nerve The median nerve is formed by the union of a lateral and medial root respectively from the lateral R (C5,6,7) and medial (C8 and T1) cords of the brachial plexus; the medial root passes anterior to the third part of the axillary artery. The nerve descends lateral to the brachial artery, crosses to its medial side (usually passing anterior to the artery). It passes deep to the bicipital aponeurosis and the median cubital vein at the elbow. It passes between the two heads of the pronator teres muscle, and runs on the deep surface of M flexor digitorum superficialis (within its fascial sheath). Near the wrist it becomes superficial between the tendons of flexor digitorum superficialis and flexor carpi radialis, deep to palmaris longus tendon. It passes deep to the flexor retinaculum to enter the palm, but lies anterior to the long flexor tendons within the carpal tunnel. Branches  Region Branch Upper arm No branches, although the nerve commonly communicates with the musculocutaneous nerve Forearm Pronator teres Pronator quadratus Flexor carpi radialis Palmaris longus h Flexor digitorum superficialis Flexor pollicis longus Flexor digitorum profundus (only the radial half) la Distal Palmar cutaneous branch forearm Sa Hand Motor supply (LOAF) (Motor) Lateral 2 lumbricals Opponens pollicis Abductor pollicis brevis C Flexor pollicis brevis Hand Over thumb and lateral 2 ½ fingers R (Sensory) On the palmar aspect this projects proximally, on the dorsal aspect only the distal regions are innervated with the radial nerve providing the more proximal cutaneous innervation. M Patterns of damage Damage at wrist e.g. carpal tunnel syndrome paralysis and wasting of thenar eminence muscles and opponens pollicis (ape hand deformity) sensory loss to palmar aspect of lateral (radial) 2 ½ fingers Damage at elbow, as above plus:  unable to pronate forearm weak wrist flexion ulnar deviation of wrist Anterior interosseous nerve (branch of median nerve) leaves just below the elbow results in loss of pronation of forearm and weakness of long flexors of thumb and index finger h Topography of the median nerve la Sa C R M Question 7 of 601 A 63 year old lady is undergoing an axillary sentinel lymph node biopsy as part of her breast cancer treatment. Which of the structures listed below is most likely to be encountered? Subclavian artery h Intercostobrachial nerve la Upper cord of the brachial plexus Lower cord of the brachial plexus Sa Axillary nerve This can be a challenging question. A particularly careless surgeon could encounter all of these. However, during a routine level 1 axillary exploration which is where the majority of sentinel nodes will be located, the nerves most commonly encountered are the intercostobrachial nerves. C Please rate this question: R Discuss and give feedback Next question M Axilla Boundaries of the axilla Medially Chest wall and Serratus anterior Laterally Humeral head  Floor Subscapularis Anterior aspect Lateral border of Pectoralis major Fascia Clavipectoral fascia Content: h Long thoracic nerve (of Derived from C5-C7 and passes behind the brachial plexus to enter the axilla. Bell) It lies on the medial chest wall and supplies serratus anterior. Its location puts it at risk during axillary surgery and damage will lead to winging of the la scapula. Thoracodorsal nerve and Innervate and vascularise latissimus dorsi. thoracodorsal trunk Sa Axillary vein Lies at the apex of the axilla, it is the continuation of the basilic vein. Becomes the subclavian vein at the outer border of the first rib. Intercostobrachial nerves Traverse the axillary lymph nodes and are often divided during axillary C surgery. They provide cutaneous sensation to the axillary skin. Lymph nodes The axilla is the main site of lymphatic drainage for the breast. R M 10 of 601 A 35 year old farm labourer injures the posterior aspect of his hand with a mechanical scythe. He severs some of his extensor tendons in this injury. How many tunnels lie in the extensor retinaculum that transmit the tendons of the extensor muscles? One h Three Four la Five Six Sa There are six tunnels, each lined by its own synovial sheath. Please rate this question: C Discuss and give feedback Next question Extensor retinaculum R The extensor rentinaculum is a thickening of the deep fascia that stretches across the back of the wrist and holds the long extensor tendons in position. Its attachments are: M The pisiform and triquetral medially The end of the radius laterally Structures related to the extensor retinaculum Structures superficial to the Basilic vein retinaculum Dorsal cutaneous branch of the ulnar nerve Cephalic vein Superficial branch of the radial nerve  Structures passing deep to the extensor Extensor carpi ulnaris tendon retinaculum Extensor digiti minimi tendon Extensor digitorum and extensor indicis tendon Extensor pollicis longus tendon Extensor carpi radialis longus tendon Extensor carpi radialis brevis tendon Abductor pollicis longus and extensor pollicis brevis tendons h Beneath the extensor retinaculum fibrous septa form six compartments that contain the extensor muscle tendons. Each compartment has its own synovial sheath. la The radial artery The radial artery passes between the lateral collateral ligament of the wrist joint and the tendons of the abductor pollicis longus and extensor pollicis brevis. Image illustrating the topography of tendons passing under the extensor retinaculum Sa C R M Question 12 of 601 Which of the muscles listed below is not innervated by the median nerve? Flexor pollicis brevis Lateral two lumbricals Pronator teres h Opponens pollicis la Adductor pollicis Sa Adductor pollicis is innervated by the ulnar nerve. Medial two lumbricals innervated by the ulnar nerve. Please rate this question: Discuss and give feedback Next question C Median nerve The median nerve is formed by the union of a lateral and medial root respectively from the lateral (C5,6,7) and medial (C8 and T1) cords of the brachial plexus; the medial root passes anterior to the R third part of the axillary artery. The nerve descends lateral to the brachial artery, crosses to its medial side (usually passing anterior to the artery). It passes deep to the bicipital aponeurosis and the median cubital vein at the elbow. It passes between the two heads of the pronator teres muscle, and runs on the deep surface of flexor digitorum superficialis (within its fascial sheath). M Near the wrist it becomes superficial between the tendons of flexor digitorum superficialis and flexor carpi radialis, deep to palmaris longus tendon. It passes deep to the flexor retinaculum to enter the palm, but lies anterior to the long flexor tendons within the carpal tunnel. Branches Region Branch Upper arm No branches, although the nerve commonly communicates with the musculocutaneous nerve  Region Branch Forearm Pronator teres Pronator quadratus Flexor carpi radialis Palmaris longus Flexor digitorum superficialis Flexor pollicis longus Flexor digitorum profundus (only the radial half) h Distal Palmar cutaneous branch forearm la Hand Motor supply (LOAF) (Motor) Sa Lateral 2 lumbricals Opponens pollicis Abductor pollicis brevis Flexor pollicis brevis Hand Over thumb and lateral 2 ½ fingers C (Sensory) On the palmar aspect this projects proximally, on the dorsal aspect only the distal regions are innervated with the radial nerve providing the more proximal cutaneous innervation. R Patterns of damage Damage at wrist M e.g. carpal tunnel syndrome paralysis and wasting of thenar eminence muscles and opponens pollicis (ape hand deformity) sensory loss to palmar aspect of lateral (radial) 2 ½ fingers Damage at elbow, as above plus: unable to pronate forearm weak wrist flexion ulnar deviation of wrist Anterior interosseous nerve (branch of median nerve) leaves just below the elbow results in loss of pronation of forearm and weakness of long flexors of thumb and index finger Topography of the median nerve h la Sa C R M Question 14 of 601 A 23 year old man is involved in a fight outside a nightclub and sustains a laceration to his right arm. On examination, he has lost extension of the fingers in his right hand. Which of the nerves listed below is most likely to have been divided? Median h Musculocutaneous Radial la Ulnar Axillary Sa The radial nerve supplies the extensor muscle group. Please rate this question: C Discuss and give feedback Next question Radial nerve R Continuation of posterior cord of the brachial plexus (root values C5 to T1) Path M In the axilla: lies posterior to the axillary artery on subscapularis, latissimus dorsi and teres major. Enters the arm between the brachial artery and the long head of triceps (medial to humerus). Spirals around the posterior surface of the humerus in the groove for the radial nerve. At the distal third of the lateral border of the humerus it then pierces the intermuscular septum and descends in front of the lateral epicondyle. At the lateral epicondyle it lies deeply between brachialis and brachioradialis where it then divides into a superficial and deep terminal branch. Deep branch crosses the supinator to become the posterior interosseous nerve. In the image below the relationships of the radial nerve can be appreciated h la Sa Image sourced from Wikipedia Regions innervated Triceps Anconeus C Motor (main nerve) Brachioradialis Extensor carpi radialis Supinator R Extensor carpi ulnaris Extensor digitorum Motor (posterior Extensor indicis interosseous branch) Extensor digiti minimi M Extensor pollicis longus and brevis Abductor pollicis longus The area of skin supplying the proximal phalanges on the dorsal aspect of Sensory the hand is supplied by the radial nerve (this does not apply to the little finger and part of the ring finger) Muscular innervation and effect of denervation  Anatomical location Muscle affected Effect of paralysis Shoulder Long head of triceps Minor effects on shoulder stability in abduction Arm Triceps Loss of elbow extension Forearm Supinator Weakening of supination of prone hand and h Brachioradialis elbow flexion in mid prone position Extensor carpi radialis longus and brevis la The cutaneous sensation of the upper limb- illustrating the contribution of the radial nerve Sa C R M Image sourced from Wikipedia Question 17 of 601 An injured axillary artery is ligated between the thyrocervical trunk of the subclavian and subscapular artery. Subsequent collateral circulation is likely to result in reversal of blood flow in which of the vessels listed below? h Circumflex scapular artery la Transverse cervical artery Sa Posterior intercostal arteries Suprascapular artery Profunda brachii artery C It's an easy question really, we just made the wording difficult (on purpose). It is asking about the branches of the axillary artery and knowledge of the fact that there is an extensive collateral network around the shoulder joint. As a result, the occlusion of the proximal aspect of the circumflex humeral inflow (from the axillary artery) ceases and there is then retrograde flow through it from collaterals. R The circumflex scapular artery is a branch of the subscapular artery and normally supplies the muscle on the dorsal aspect of the scapula. In this instance, flow is reversed in the circumflex scapular and subscapular arteries forming a collateral circulation around the scapula. M Please rate this question: Discuss and give feedback Next question Axillary artery The axillary artery extends from the outer border of the first rib to the lower border of teres major, where it becomes the brachial artery. The vessel is subdivided into three zones; the first part lies above pectoralis minor, the second part is behind the muscle and the third part lies inferior to it. First part Together with the axillary vein, the artery is enclosed within the cords of the brachial plexus. Both vessels are contained within the axillary sheath, a prolongation of the prevertebral fascia. Posteriomedial to the sheath lies the first intercostal space, the superior aspect of the serratus anterior and the long thoracic nerve. Within the sheath, the medial cord of the brachial plexus lies behind the artery. Anteriorly lies the clavipectoral fascia. Superolaterally, lie the lateral and posterior cords of the brachial plexus. Inferomedially lies the axillary vein. h Second part Posterior to the second part lies the posterior cord of the brachial plexus and the subscapularis muscle. Anteriorly, lie pectoralis minor and major. The lateral cord of the brachial plexus lies laterally. Medially, lies the medial cord of the brachial plexus, here it separates the artery from the la vein. Third part Posterior to the artery lie suscapularis, latissimus dorsi and teres major. Interspersed between the Sa vessel and subscapularis are the axillary and radial nerves. Anterior to the vessel is the medial root of the median nerve. Laterally, the lies the median and musculocutaneous nerves and coracobrachialis. The axillary vein is related medially. Branches of the axillary artery Highest thoracic artery Thoraco-acromial artery Lateral thoracic artery C Subscapular artery Posterior circumflex humeral artery Anterior circumflex humeral artery R M Question 23 of 601 A 43 year old typist presents with pain at the dorsal aspect of the upper part of her forearm. She also complains of weakness when extending her fingers. On examination triceps and supinator are both functioning normally. There is weakness of most of the extensor muscles. However, there is no sensory deficit. Which of the following nerves has been affected? Anterior interosseous h Median la Posterior interosseous Palmar cutaneous Sa Ulnar The radial nerve may become entrapped in the arcade of Frohse which is a superficial part of the C supinator muscle which overlies the posterior interosseous nerve. This nerve is entirely muscular and articular in its distribution. It passes postero-inferiorly and gives branches to extensor carpi radialis brevis and supinator. It enters supinator and curves around the lateral and posterior surfaces of the radius. On emerging from the supinator the posterior interosseous nerve lies between the superficial extensor muscles and the lowermost fibres of supinator. It then gives branches to the R extensors. Please rate this question: Discuss and give feedback M Next question Posterior interosseous nerve Emerges from supinator between the superficial extensor muscles and lowest fibres of supinator It gives recurrent branches which innervate extensor digitorum, extensor digiti minimi and extensor carpi ulnaris It then passes with the posterior interosseous artery superficial to the abductor pollicis longus supplying it. It supplies branches to extensor pollicis longus and brevis and extensor indicis and ends as a small gangliform enlargement at the back of the carpus from which the intercarpal joints are supplied. Question 29 of 601 A 23 year old man falls and slips at a nightclub. A shard of glass penetrates the skin at the level of the medial epicondyle, which of the following sequelae is least likely to occur? Atrophy of the first dorsal interosseous muscle Difficulty in abduction of the the 2nd, 3rd, 4th and 5th fingers h Claw like appearance of the hand la Loss of sensation on the anterior aspect of the 5th finger Partial denervation of flexor digitorum profundus Sa Injury to the ulnar nerve in the mid to distal forearm will typically produce a claw hand. This consists of flexion of the 4th and 5th interphalangeal joints and extension of the metacarpophalangeal joints. The effects are potentiated when flexor digitorum profundus is not affected, and the clawing is more pronounced.More proximally sited ulnar nerve lesions produce a milder clinical picture owing to the simultaneous paralysis of flexor digitorum profundus (ulnar half). This is the 'ulnar paradox', due to the more proximal level of transection the hand will typically not C have a claw like appearance that may be seen following a more distal injury. The first dorsal interosseous muscle will be affected as it is supplied by the ulnar nerve. Please rate this question: R Discuss and give feedback Next question Ulnar nerve M Origin C8, T1 Supplies (no muscles in the upper arm) Flexor carpi ulnaris Flexor digitorum profundus Flexor digiti minimi  Abductor digiti minimi Opponens digiti minimi Adductor pollicis Interossei muscle Third and fourth lumbricals Palmaris brevis Path Posteromedial aspect of upper arm to flexor compartment of forearm, then along the ulnar. Passes beneath the flexor carpi ulnaris muscle, then superficially through the flexor h retinaculum into the palm of the hand. la Sa C R M Image sourced from Wikipedia Branches  Branch Supplies Muscular branch Flexor carpi ulnaris Medial half of the flexor digitorum profundus Palmar cutaneous branch (Arises near the Skin on the medial part of the palm middle of the forearm) h Dorsal cutaneous branch Dorsal surface of the medial part of the hand la Superficial branch Cutaneous fibres to the anterior surfaces of the medial one and one-half digits Deep branch Hypothenar muscles Sa All the interosseous muscles Third and fourth lumbricals Adductor pollicis Medial head of the flexor pollicis brevis Effects of injury C Damage at the wrist Wasting and paralysis of intrinsic hand muscles (claw hand) Wasting and paralysis of hypothenar muscles Loss of sensation medial 1 and half fingers R Damage at the elbow Radial deviation of the wrist Clawing less in 4th and 5th digits M Question 31 of 601 A 43 year old man is stabbed outside a nightclub. He suffers a transection of his median nerve just as it leaves the brachial plexus. Which of the following features is least likely to ensue? Ulnar deviation of the wrist Complete loss of wrist flexion h Loss of pronation la Loss of flexion at the thumb joint Inability to oppose the thumb Sa Loss of the median nerve will result in loss of function of the flexor muscles. However, flexor carpi ulnaris will still function and produce ulnar deviation and some residual wrist flexion. High median nerve lesions result in complete loss of flexion at the thumb joint. Please rate this question: C Discuss and give feedback Next question Median nerve R The median nerve is formed by the union of a lateral and medial root respectively from the lateral (C5,6,7) and medial (C8 and T1) cords of the brachial plexus; the medial root passes anterior to the third part of the axillary artery. The nerve descends lateral to the brachial artery, crosses to its medial side (usually passing anterior to the artery). It passes deep to the bicipital aponeurosis and the median cubital vein at the elbow. M It passes between the two heads of the pronator teres muscle, and runs on the deep surface of flexor digitorum superficialis (within its fascial sheath). Near the wrist it becomes superficial between the tendons of flexor digitorum superficialis and flexor carpi radialis, deep to palmaris longus tendon. It passes deep to the flexor retinaculum to enter the palm, but lies anterior to the long flexor tendons within the carpal tunnel. Branches  Region Branch Upper arm No branches, although the nerve commonly communicates with the musculocutaneous nerve Forearm Pronator teres Pronator quadratus Flexor carpi radialis Palmaris longus h Flexor digitorum superficialis Flexor pollicis longus Flexor digitorum profundus (only the radial half) la Distal Palmar cutaneous branch forearm Sa Hand Motor supply (LOAF) (Motor) Lateral 2 lumbricals Opponens pollicis Abductor pollicis brevis C Flexor pollicis brevis Hand Over thumb and lateral 2 ½ fingers R (Sensory) On the palmar aspect this projects proximally, on the dorsal aspect only the distal regions are innervated with the radial nerve providing the more proximal cutaneous innervation. M Patterns of damage Damage at wrist e.g. carpal tunnel syndrome paralysis and wasting of thenar eminence muscles and opponens pollicis (ape hand deformity) sensory loss to palmar aspect of lateral (radial) 2 ½ fingers Damage at elbow, as above plus:  unable to pronate forearm weak wrist flexion ulnar deviation of wrist Anterior interosseous nerve (branch of median nerve) leaves just below the elbow results in loss of pronation of forearm and weakness of long flexors of thumb and index finger h Topography of the median nerve la Sa C R M Question 33 of 601 Which of the structures listed below articulates with the head of the radius superiorly? Capitulum h Trochlea la Lateral epicondyle Ulna Sa Medial epicondyle A useful revision aid : 'Capital Radio' is the articulation of the radial head superiorly. The head of the radius articulates with the capitulum of the humerus. Please rate this question: C Discuss and give feedback R Next question Radius The radius is one of the two long forearm bones that extends from the lateral side of the elbow to the M thumb side of the wrist. It has two expanded ends, of which the distal end is the larger. Key points relating to its topography and relations are outlined below; Upper end Articular cartilage- covers medial > lateral side Articulates with radial notch of the ulna by the annular ligament Muscle attachment- biceps brachii at the tuberosity Shaft Muscle attachment Upper third of the body Supinator Flexor digitorum superficialis Flexor pollicis longus Middle third of the body Pronator teres Lower quarter of the body Pronator quadratus h Tendon of supinator longus la Lower end Quadrilateral Anterior surface- capsule of wrist joint Sa Medial surface- head of ulna Lateral surface- ends in the styloid process Posterior surface: 3 grooves containing: 1. Tendons of extensor carpi radialis longus and brevis 2. Tendon of extensor pollicis longus 3. Tendon of extensor indicis C R M Question 39 of 601 At the level of the wrist joint, which of the statements below best describes the relationship of the ulnar artery to the ulnar nerve? It lies on its radial side h It lies deep to it la It lies superficial to it It lies on its ulnar side Sa None of the above In the middle of the forearm, the artery is overlapped by the flexor carpi ulnaris and on the flexor retinaculum it is covered by a superficial layer from that structure. In its distal two-thirds, flexor digitorum superficialis lies on its radial side, and the ulnar nerve is situated on its ulnar side. C Please rate this question: Discuss and give feedback R Next question Ulnar artery M Path Starts: middle of antecubital fossa Passes obliquely downward, reaching the ulnar side of the forearm at a point about midway between the elbow and the wrist. It follows the ulnar border to the wrist, crossing over the flexor retinaculum. It then divides into the superficial and deep volar arches. Relations Deep to- Pronator teres, Flexor carpi ulnaris, Palmaris longus Lies on- Brachialis and Flexor digitorum profundus Superficial to the flexor retinaculum at the wrist The median nerve is in relation with the medial side of the artery for about 2.5 cm. And then crosses the vessel, being separated from it by the ulnar head of the Pronator teres The ulnar nerve lies medially to the lower two-thirds of the artery Branch Anterior interosseous artery h la Sa C R M Question 40 of 601 Which of the following anatomical structures lies within the spiral groove of the humerus? Median nerve h Radial nerve la Tendon of triceps Musculocutaneous nerve Sa Axillary nerve The radial nerve lies in this groove and may be compromised by fractures involving the shaft. Please rate this question: C Discuss and give feedback R Next question Humerus M The humerus extends from the scapula to the elbow joint. It has a body and two ends. It is almost completely covered with muscle but can usually be palpated throughout its length. The smooth rounded surface of the head articulates with the shallow glenoid cavity. The head is connected to the body of the humerus by the anatomical neck. The surgical neck is the region below the head and tubercles and where they join the shaft and is the commonest site of fracture. The capsule of the shoulder joint is attached to the anatomical neck superiorly but extends down to 1.5cm on the surgical neck. The greater tubercle is the prominence on the lateral side of the upper end of the bone. It merges with the body below and can be felt through the deltoid inferior to the acromion. The tendons of the supraspinatus and infraspinatus are inserted into impressions on its superior aspect. The lesser tubercle is a distinct prominence on the front of the upper end of the bone. It can be palpated through the deltoid just lateral to the tip of the coracoid process. The intertubercular groove passes on the body between the greater and lesser tubercles, continuing down from the anterior borders of the tubercles to form the edges of the groove. The tendon of biceps within its synovial sheath passes through this groove, held within it by a transverse ligament. The posterior surface of the body is marked by a spiral groove for the radial nerve which runs obliquely across the upper half of the body to reach the lateral border below the deltoid tuberosity. Within this groove lie the radial nerve and brachial vessels and both may be affected by fractures involving the shaft of the humerus. The lower end of the humerus is wide and flattened anteroposteriorly, and inclined anteriorly. The h middle third of the distal edge forms the trochlea. Superior to this are indentations for the coronoid fossa anteriorly and olecranon fossa posteriorly. Lateral to the trochlea is a rounded capitulum which articulates with the radius. la The medial epicondyle is very prominent with a smooth posterior surface which contains a sulcus for the ulnar nerve and collateral vessels. It's distal margin gives attachment for the ulnar collateral ligament and, in front of this, the anterior surface has an impression for the common flexor tendon. Sa C R M Question 41 of 601 A 24 year old man falls and sustains a fracture through his scaphoid bone. From which of the following areas does the scaphoid derive the majority of its blood supply? From its proximal medial border h From its proximal lateral border la From its proximal posterior surface From the proximal end From the distal end Sa The blood supply to the scaphoid enters from a small non articular surface near its distal end. Transverse fractures through the scaphoid therefore carry a risk of non union. C Please rate this question: R Discuss and give feedback Next question M Scaphoid bone The scaphoid has a concave articular surface for the head of the capitate and at the edge of this is a crescentic surface for the corresponding area on the lunate. Proximally, it has a wide convex articular surface with the radius. It has a distally sited tubercle that can be palpated. The remaining articular surface is to the lateral side of the tubercle. It faces laterally and is associated with the trapezium and trapezoid bones. The narrow strip between the radial and trapezial surfaces and the tubercle gives rise to the radial collateral carpal ligament. The tubercle receives part of the flexor retinaculum. This area is the only part of the scaphoid that is available for the entry of blood vessels. It is commonly fractured and avascular necrosis may result. Scaphoid bone h la Sa C R M Question 43 of 601 A patient sustains damage to the median nerve during a carpal tunnel release. Which of the following muscles will be affected? Abductor digiti minimi h Abductor pollicis brevis la Adductor pollicis Palmaris brevis Sa Flexor digiti minimi brevis Of the muscles listed, only the abductor pollicis brevis is innervated by the median. In questions like C this one, ensure you don't become confused between adductor and abductor. Please rate this question: R Discuss and give feedback Next question M Abductor pollicis brevis Origin Fleshy fibres from the flexor retinaculum, scaphoid and trapezium Insertion Via a short tendon into the radial side of the proximal phalanx of the thumb Nerve Recurrent branch of median nerve in the palm Actions Abducts the thumb at the carpometacarpal and metacarpophalangeal joints, causing it to travel anteriorly at right angles to the plane of the palm and to rotate medially (e.g. typing). When the thumb is fully abducted there is angulation of around 30 degrees between the proximal phalanx and the metacarpal. Because of the direction of the muscle, abduction involves medial rotation of the metacarpal, and the abductor is used along with opponens pollicis in the initial stages of thumb opposition h Next question la Sa C R M Question 52 of 601 Which of the nerves listed below is directly responsible for the innervation of the lateral aspect of flexor digitorum profundus? Ulnar nerve h Anterior interosseous nerve la Radial nerve Median nerve Sa Posterior interosseous nerve The anterior interosseous nerve is a branch of the median nerve and is responsible for innervation of C the lateral aspect of the flexor digitorum profundus. Please rate this question: R Discuss and give feedback Next question M Forearm flexor muscles Muscle Origin Insertion Nerve supply Action Flexor carpi Common flexor Front of bases of second Median Flexes and abducts the radialis origin and and third metacarpals carpus, part flexes the Muscle Origin Insertion Nerve supply Action surrounding elbow and part fascia pronates forearm Palmaris Common flexor Apex of palmar Median Wrist flexor longus origin aponeurosis h Flexor carpi Small humeral Pisiform and base of the Ulnar nerve Flexes and adducts the ulnaris head arises from fifth metacarpal carpus the common la flexor origin and adjacent fascia. Ulnar head comes from olecranon and Sa medial border of posterior border of ulna Flexor Long linear origin Via tendons in the fibrous Median Flexor of C digitorum from common flexor sheath. At the level metacarpophalangeal superficialis flexor tendon, of the joint and proximal adjacent fascia metacarpophalangeal interphalangeal joint and septa and joint each tendon split R medial border of into two, these bands the coronoid pass distally to their process insertions M Flexor Upper two thirds Via tendons that lie deep Medial part= Flexes the distal digitorum of the medial and to those of flexor ulnar, lateral interphalangeal joints profundus anterior surface digitorum superficialis to part=anterior and the wrist of the ulna, insert into the distal interosseous medial side of the phalanx nerve olecranon, medial half of the interosseous membrane  Next question h la Sa C R M Question 55 of 601 Which of the structures listed below are most closely related to the axillary nerve within the quadrangular space? Posterior circumflex humeral vessels Axillary artery h Anterior circumflex humeral vessels la Radial artery Acromiothoracic artery Sa The posterior circumflex humeral vessels which are branches of the axillary artery are related to the axillary nerve within the quadrangular space. Please rate this question: C Discuss and give feedback Next question Axillary nerve R Terminal branch of the posterior cord of the brachial plexus Root values C5 and C6 Descends posterior to the axillary artery at the lower border of subscapularis and then passes through quadrangular space with the posterior circumflex humeral vessels M Divides into anterior and posterior branches Innervates deltoid and lateral head of triceps and small patch of skin over deltoid  h la Image sourced from Wikipedia Sa Next question Display my notes on this topic C Save my notes R …. M Question 62 of 601 Which muscle initiates abduction of the shoulder? Infraspinatus Latissimus dorsi h Supraspinatus la Deltoid Teres major Sa The intermediate portion of the deltoid muscle is the chief abductor of the humerus. However, it can only do this after the movement has been initiated by supraspinatus. Damage to the tendon of supraspinatus is a common form of rotator cuff disease. Please rate this question: C Discuss and give feedback Next question R Shoulder joint Shallow synovial ball and socket type of joint. It is an inherently unstable joint, but is capable to a wide range of movement. Stability is provided by muscles of the rotator cuff that pass from the scapula to insert in the M greater tuberosity (all except sub scapularis-lesser tuberosity). Glenoid labrum Fibrocartilaginous rim attached to the free edge of the glenoid cavity Tendon of the long head of biceps arises from within the joint from the supraglenoid tubercle, and is fused at this point to the labrum. The long head of triceps attaches to the infraglenoid tubercle Fibrous capsule Attaches to the scapula external to the glenoid labrum and to the labrum itself (postero- superiorly) Attaches to the humerus at the level of the anatomical neck superiorly and the surgical neck inferiorly Anteriorly the capsule is in contact with the tendon of subscapularis, superiorly with the supraspinatus tendon, and posteriorly with the tendons of infraspinatus and teres minor. All these blend with the capsule towards their insertion. Two defects in the fibrous capsule; superiorly for the tendon of biceps. Anteriorly there is a defect beneath the subscapularis tendon. h The inferior extension of the capsule is closely related to the axillary nerve at the surgical neck and this nerve is at risk in anteroinferior dislocations. It also means that proximally sited osteomyelitis may progress to septic arthritis. la Movements and muscles Flexion Anterior part of deltoid Pectoralis major Sa Biceps Coracobrachialis Extension Posterior deltoid Teres major Latissimus dorsi C Adduction Pectoralis major Latissimus dorsi R Teres major Coracobrachialis Abduction Mid deltoid M Supraspinatus Medial rotation Subscapularis Anterior deltoid Teres major Latissimus dorsi  Lateral rotation Posterior deltoid Infraspinatus Teres minor Important anatomical relations Anteriorly Brachial plexus Axillary artery and vein h Posterior Suprascapular nerve Suprascapular vessels la Inferior Axillary nerve Circumflex humeral vessels Sa Next question Display my notes on this topic C R Save my notes M Question 69 of 601 The first root of the brachial plexus commonly arises at which of the following levels? C6 C5 h C3 la C2 C8 Sa It begins at C5 and has 5 roots. It ends with a total of 15 nerves of these 5 are the main nerves to the upper limb (axillary, radial, ulnar, musculocutaneous and median) Please rate this question: Discuss and give feedback C Next question Brachial plexus The brachial plexus extends from the neck to the axilla. It is formed by the ventral rami of the fifth to R the eighth cervical nerves with the ascending part of the first thoracic nerve. Location of the plexus The ventral rami which form the plexus enter the lower part of the posterior triangle of the neck in series with the ventral rami of the cervical plexus. The second part of the subclavian artery lies M immediately anterior to the lower two rami. The upper three rami intermingle and pass inferolaterally towards the axilla and subclavian artery. They are enclosed within an extension of the prevertebral fascia. In the neck the plexus lies deep to platysma, the supraclavicular nerves, inferior belly of omohyoid and the transverse cervical artery. It then passes deep to the clavicle and the suprascapular vessels, to enter the axilla, and thence surround the second part of the axillary artery Composition of the plexus Ventral rami, the roots of the plexus, lie between scalenus medius and anterior. As they enter the posterior triangle, the upper two (C5,6) and lower two (C8, T1) roots of the plexus unite to form the upper and lower trunks of the plexus respectively. Meanwhile, C7 continues as the middle trunk. The lower trunk may groove the superior surface of the first rib posterior to the subclavian artery, and the root from the first ventral ramus is always in contact with it. Each trunk divides into ventral and dorsal divisions which are destined to supply the anterior (flexor) and posterior (extensor) parts of the upper limb. The cords of the plexus are formed in the axilla. The dorsal divisions unite to form the posterior cord (C5-8). The ventral divisions of the upper and middle trunks unite to form the lateral cord (C5-7), while the ventral divisions of the lower trunk continues as the medial cord (C8-T1). The cords are named according to their relationship to the axillary artery. Each cord terminates by dividing into two main branches at the beginning of the third part of the artery. Sympathetic communications The fifth and sixth cervical ventral rami receive grey rami communicantes from the middle cervical h ganglion, while the two or more grey rami communicantes pass from the inferior cervical ganglion to the seventh and eighth cervical ventral rami. The first thoracic ventral ramus receives its grey ramus from the cervicothoracic ganglion. Its for this reason that inferior plexus injury can be complicated by a Horners syndrome. la Summary Origin Anterior rami of C5 to T1 Sa Sections of the Roots, trunks, divisions, cords, branches plexus Mnemonic:Real Teenagers Drink Cold Beer Roots Located in the posterior triangle Pass between scalenus anterior and medius C Trunks Located posterior to middle third of clavicle Upper and middle trunks related superiorly to the subclavian artery R Lower trunk passes over 1st rib posterior to the subclavian artery Divisions Apex of axilla M Cords Related to axillary artery Diagram illustrating the branches of the brachial plexus  h la Image sourced from Wikipedia Sa Cutaneous sensation of the upper limb C R M Image sourced from Wikipedia Next question Display my notes on this topic Save my notes h la Sa C R M Question 72 of 601 When the brachial plexus is injured in the axilla as a result of a crutch palsy, which of the nerves listed is most commonly affected? Thoracodorsal nerve Suprascapular nerve h Radial nerve la Ulnar nerve Long thoracic nerve Sa The radial nerve is most commonly injured and results in a wrist drop. The ulnar nerve arises from the medial cord and is rarely affected as a result of this injury mechanism. Please rate this question: C Discuss and give feedback Next question Brachial plexus R The brachial plexus extends from the neck to the axilla. It is formed by the ventral rami of the fifth to the eighth cervical nerves with the ascending part of the first thoracic nerve. Location of the plexus The ventral rami which form the plexus enter the lower part of the posterior triangle of the neck in M series with the ventral rami of the cervical plexus. The second part of the subclavian artery lies immediately anterior to the lower two rami. The upper three rami intermingle and pass inferolaterally towards the axilla and subclavian artery. They are enclosed within an extension of the prevertebral fascia. In the neck the plexus lies deep to platysma, the supraclavicular nerves, inferior belly of omohyoid and the transverse cervical artery. It then passes deep to the clavicle and the suprascapular vessels, to enter the axilla, and thence surround the second part of the axillary artery Composition of the plexus Ventral rami, the roots of the plexus, lie between scalenus medius and anterior. As they enter the posterior triangle, the upper two (C5,6) and lower two (C8, T1) roots of the plexus unite to form the upper and lower trunks of the plexus respectively. Meanwhile, C7 continues as the middle trunk. The lower trunk may groove the superior surface of the first rib posterior to the subclavian artery, and the root from the first ventral ramus is always in contact with it. Each trunk divides into ventral and dorsal divisions which are destined to supply the anterior (flexor) and posterior (extensor) parts of the upper limb. The cords of the plexus are formed in the axilla. The dorsal divisions unite to form the posterior cord (C5-8). The ventral divisions of the upper and middle trunks unite to form the lateral cord (C5-7), while the ventral divisions of the lower trunk continues as the medial cord (C8-T1). The cords are named according to their relationship to the axillary artery. Each cord terminates by dividing into two main branches at the beginning of the third part of the artery. Sympathetic communications h The fifth and sixth cervical ventral rami receive grey rami communicantes from the middle cervical ganglion, while the two or more grey rami communicantes pass from the inferior cervical ganglion to the seventh and eighth cervical ventral rami. The first thoracic ventral ramus receives its grey ramus from the cervicothoracic ganglion. Its for this reason that inferior plexus injury can be complicated by la a Horners syndrome. Summary Origin Anterior rami of C5 to T1 Sections of the Sa Roots, trunks, divisions, cords, branches plexus Mnemonic:Real Teenagers Drink Cold Beer Roots Located in the posterior triangle Pass between scalenus anterior and medius C Trunks Located posterior to middle third of clavicle Upper and middle trunks related superiorly to the subclavian R artery Lower trunk passes over 1st rib posterior to the subclavian artery M Divisions Apex of axilla Cords Related to axillary artery Diagram illustrating the branches of the brachial plexus  h la Image sourced from Wikipedia Sa Cutaneous sensation of the upper limb C R M Image sourced from Wikipedia Next question Display my notes on this topic Save my notes h la Sa C R M Question 81 of 601 A 56 year old man requires long term parenteral nutrition and the decision is made to insert a PICC line for long term venous access. This is inserted into the basilic vein at the region of the elbow. As the catheter is advanced, into which venous structure is the tip of the catheter most likely to pass from the basilic vein? Subclavian vein h Axillary vein la Posterior circumflex humeral vein Cephalic vein Superior vena cava Sa The basilic vein drains into the axillary vein and although PICC lines may end up in a variety of fascinating locations the axillary vein is usually the commonest site following from the basilic. The C posterior circumflex humeral vein is encountered prior to the axillary vein. However, a PICC line is unlikely to enter this structure because of its angle of entry into the basilic vein. Please rate this question: R Discuss and give feedback Next question Basilic vein M The basilic and cephalic veins both provide the main pathways of venous drainage for the arm and hand. It is continuous with the palmar venous arch distally and the axillary vein proximally. Path Originates on the medial side of the dorsal venous network of the hand, and passes up the forearm and arm. Most of its course is superficial. Near the region anterior to the cubital fossa the vein joins the cephalic vein. Midway up the humerus the basilic vein passes deep under the muscles.  At the lower border of the teres major muscle, the anterior and posterior circumflex humeral veins feed into it. It is often joined by the medial brachial vein before draining into the axillary vein. Next question h la Sa C R M Question 83 of 601 An 8 year old boy falls onto an outstretched hand and sustains a supracondylar fracture. In addition to a weak radial pulse the child is noted to have loss of pronation of the affected hand. Which nerve is compromised? Median h Radial Ulnar la Musculocutaneous Axillary Sa This is a common injury in children. In this case the angulation and displacement have resulted in median nerve injury. Please rate this question: C Discuss and give feedback Next question Median nerve R The median nerve is formed by the union of a lateral and medial root respectively from the lateral (C5,6,7) and medial (C8 and T1) cords of the brachial plexus; the medial root passes anterior to the third part of the axillary artery. The nerve descends lateral to the brachial artery, crosses to its M medial side (usually passing anterior to the artery). It passes deep to the bicipital aponeurosis and the median cubital vein at the elbow. It passes between the two heads of the pronator teres muscle, and runs on the deep surface of flexor digitorum superficialis (within its fascial sheath). Near the wrist it becomes superficial between the tendons of flexor digitorum superficialis and flexor carpi radialis, deep to palmaris longus tendon. It passes deep to the flexor retinaculum to enter the palm, but lies anterior to the long flexor tendons within the carpal tunnel. Branches  Region Branch Upper arm No branches, although the nerve commonly communicates with the musculocutaneous nerve Forearm Pronator teres Pronator quadratus Flexor carpi radialis Palmaris longus h Flexor digitorum superficialis Flexor pollicis longus Flexor digitorum profundus (only the radial half) la Distal Palmar cutaneous branch forearm Sa Hand Motor supply (LOAF) (Motor) Lateral 2 lumbricals Opponens pollicis Abductor pollicis brevis C Flexor pollicis brevis Hand Over thumb and lateral 2 ½ fingers R (Sensory) On the palmar aspect this projects proximally, on the dorsal aspect only the distal regions are innervated with the radial nerve providing the more proximal cutaneous innervation. M Patterns of damage Damage at wrist e.g. carpal tunnel syndrome paralysis and wasting of thenar eminence muscles and opponens pollicis (ape hand deformity) sensory loss to palmar aspect of lateral (radial) 2 ½ fingers Damage at elbow, as above plus:  unable to pronate forearm weak wrist flexion ulnar deviation of wrist Anterior interosseous nerve (branch of median nerve) leaves just below the elbow results in loss of pronation of forearm and weakness of long flexors of thumb and index finger h Topography of the median nerve la Sa C R M Image sourced from Wikipedia Next question Display my notes on this topic Save my notes h la Sa C R M Question 84 of 601 A 40 year old lady trips and falls through a glass door and sustains a severe laceration to her left arm. Amongst her injuries it is noticed that she has lost the ability to adduct the fingers of her left hand. Injury to which of the following nerves is most likely to account for her examination findings? Ulnar Median h Radial la Musculocutaneous Axillary Sa The interossei are supplied by the ulnar nerve. Please rate this question: C Discuss and give feedback Next question Ulnar nerve R Origin C8, T1 M Supplies (no muscles in the upper arm) Flexor carpi ulnaris Flexor digitorum profundus Flexor digiti minimi Abductor digiti minimi Opponens digiti minimi Adductor pollicis Interossei muscle Third and fourth lumbricals  Palmaris brevis Path Posteromedial aspect of upper arm to flexor compartment of forearm, then along the ulnar. Passes beneath the flexor carpi ulnaris muscle, then superficially through the flexor retinaculum into the palm of the hand. h la Sa C R M Image sourced from Wikipedia Branches Branch Supplies Muscular branch Flexor carpi ulnaris Medial half of the flexor digitorum profundus  Branch Supplies Palmar cutaneous branch (Arises near the Skin on the medial part of the palm middle of the forearm) Dorsal cutaneous branch Dorsal surface of the medial part of the hand Superficial branch Cutaneous fibres to the anterior surfaces of the h medial one and one-half digits la Deep branch Hypothenar muscles All the interosseous muscles Third and fourth lumbricals Adductor pollicis Medial head of the flexor pollicis brevis Sa Effects of injury Damage at the wrist Wasting and paralysis of intrinsic hand muscles (claw hand) Wasting and paralysis of hypothenar muscles Loss of sensation medial 1 and half fingers C Damage at the elbow Radial deviation of the wrist Clawing less in 4th and 5th digits R Next question M Question 98 of 601 A 28 year old rugby player injures his right humerus and on examination is noted to have a minor sensory deficit overlying the point of deltoid insertion into the humerus. Which of the nerves listed below is most likely to have been affected? Radial h Axillary la Musculocutaneous Median Sa Subscapular This patch of skin is supplied by the axillary nerve C Please rate this question: Discuss and give feedback R Next question Axillary nerve Terminal branch of the posterior cord of the brachial plexus M Root values C5 and C6 Descends posterior to the axillary artery at the lower border of subscapularis and then passes through quadrangular space with the posterior circumflex humeral vessels Divides into anterior and posterior branches Innervates deltoid and lateral head of triceps and small patch of skin over deltoid  h la Image sourced from Wikipedia Sa Next question C R M Question 104 of 601 A 21 year old man is stabbed in the antecubital fossa. A decision is made to surgically explore the wound. At operation the surgeon dissects down onto the brachial artery. A nerve is identified medially, which nerve is it likely to be? Radial Recurrent branch of median h Anterior interosseous la Ulnar Median Sa Please rate this question: C Discuss and give feedback Next question Median nerve R The median nerve is formed by the union of a lateral and medial root respectively from the lateral (C5,6,7) and medial (C8 and T1) cords of the brachial plexus; the medial root passes anterior to the third part of the axillary artery. The nerve descends lateral to the brachial artery, crosses to its medial side (usually passing anterior to the artery). It passes deep to the bicipital aponeurosis and the median cubital vein at the elbow. M It passes between the two heads of the pronator teres muscle, and runs on the deep surface of flexor digitorum superficialis (within its fascial sheath). Near the wrist it becomes superficial between the tendons of flexor digitorum superficialis and flexor carpi radialis, deep to palmaris longus tendon. It passes deep to the flexor retinaculum to enter the palm, but lies anterior to the long flexor tendons within the carpal tunnel. Branches  Region Branch Upper arm No branches, although the nerve commonly communicates with the musculocutaneous nerve Forearm Pronator teres Pronator quadratus Flexor carpi radialis Palmaris longus h Flexor digitorum superficialis Flexor pollicis longus Flexor digitorum profundus (only the radial half) la Distal Palmar cutaneous branch forearm Sa Hand Motor supply (LOAF) (Motor) Lateral 2 lumbricals Opponens pollicis Abductor pollicis brevis C Flexor pollicis brevis Hand Over thumb and lateral 2 ½ fingers R (Sensory) On the palmar aspect this projects proximally, on the dorsal aspect only the distal regions are innervated with the radial nerve providing the more proximal cutaneous innervation. M Patterns of damage Damage at wrist e.g. carpal tunnel syndrome paralysis and wasting of thenar eminence muscles and opponens pollicis (ape hand deformity) sensory loss to palmar aspect of lateral (radial) 2 ½ fingers Damage at elbow, as above plus:  unable to pronate forearm weak wrist flexion ulnar deviation of wrist Anterior interosseous nerve (branch of median nerve) leaves just below the elbow results in loss of pronation of forearm and weakness of long flexors of thumb and index finger h Topography of the median nerve la Sa C R M Question 109 of 601 Which of the following muscles does not attach to the radius? Pronator quadratus Biceps h Brachioradialis la Supinator Brachialis Sa The brachialis muscle inserts into the ulna. The other muscles are all inserted onto the radius. Please rate this question: Discuss and give feedback Next question C Radius The radius is one of the two long forearm bones that extends from the lateral side of the elbow to the thumb side of the wrist. It has two expanded ends, of which the distal end is the larger. Key points R relating to its topography and relations are outlined below; Upper end M Articular cartilage- covers medial > lateral side Articulates with radial notch of the ulna by the annular ligament Muscle attachment- biceps brachii at the tuberosity Shaft Muscle attachment  Upper third of the body Supinator Flexor digitorum superficialis Flexor pollicis longus Middle third of the body Pronator teres Lower quarter of the body Pronator quadratus Tendon of supinator longus h Lower end la Quadrilateral Anterior surface- capsule of wrist joint Medial surface- head of ulna Lateral surface- ends in the styloid process Sa Posterior surface: 3 grooves containing: 1. Tendons of extensor carpi radialis longus and brevis 2. Tendon of extensor pollicis longus 3. Tendon of extensor indicis C R M Image sourced from Wikipedia Question 110 of 601 A 25 year old man is stabbed in the upper arm. The brachial artery is lacerated at the level of the proximal humerus, and is being repaired. A nerve lying immediately lateral to the brachial artery is also lacerated. Which of the following is the nerve most likely to be? Ulnar nerve h Median nerve la Radial nerve Intercostobrachial nerve Sa Axillary nerve The brachial artery begins at the lower border of teres major and terminates in the cubital fossa by branching into the radial and ulnar arteries. In the upper arm the median nerve lies closest to it in the C lateral position. In the cubital fossa it lies medial to it. R M  h la Sa Image sourced from Wikipedia Please rate this question: C Discuss and give feedback Next question Brachial artery R The brachial artery begins at the lower border of teres major as a continuation of the axillary artery. It terminates in the cubital fossa at the level of the neck of the radius by dividing into the radial and ulnar arteries. M Relations Posterior relations include the long head of triceps with the radial nerve and profunda vessels intervening. Anteriorly it is overlapped by the medial border of biceps. It is crossed by the median nerve in the middle of the arm. In the cubital fossa it is separated from the median cubital vein by the bicipital aponeurosis. The basilic vein is in contact at the most proximal aspect of the cubital fossa and lies medially. Next question Display my notes on this topic Save my notes h la Sa C R M Question 111 of 601 What is the course of the median nerve relative to the brachial artery in the upper arm? Medial to anterior to lateral Lateral to posterior to medial h Medial to posterior to lateral la Medial to anterior to medial Sa Lateral to anterior to medial Relations of median nerve to the brachial artery: Lateral -> Anterior -> Medial The median nerve descends lateral to the brachial artery, it usually passes anterior to the artery to lie on its medial side. It passes deep to the bicipital aponeurosis and the median cubital vein at the C elbow. It enters the forearm between the two heads of the pronator teres muscle. R M Image sourced from Wikipedia Please rate this question:  Discuss and give feedback Next question Brachial artery The brachial artery begins at the lower border of teres major as a continuation of the axillary artery. It terminates in the cubital fossa at the level of the neck of the radius by dividing into the radial and ulnar arteries. Relations Posterior relations include the long head of triceps with the radial nerve and profunda vessels h intervening. Anteriorly it is overlapped by the medial border of biceps. It is crossed by the median nerve in the middle of the arm. In the cubital fossa it is separated from the median cubital vein by the bicipital aponeurosis. la The basilic vein is in contact at the most proximal aspect of the cubital fossa and lies medially. Next question Sa Display my notes on this topic C Save my notes R M Question 124 of 601 The following statements relating to the musculocutaneous nerve are true except? It arises from the lateral cord of the brachial plexus h It provides cutaneous innervation to the lateral side of the forearm la If damaged, then extension of the elbow joint will be impaired Sa It supplies the biceps muscle It runs beneath biceps It supplies biceps, brachialis and coracobrachialis. If damaged then elbow flexion will be impaired. C Please rate this question: Discuss and give feedback R Next question Musculocutaneous nerve Branch of lateral cord of brachial plexus M Path It penetrates the coracobrachialis muscle Passes obliquely between the biceps brachii and the brachialis to the lateral side of the arm Above the elbow it pierces the deep fascia lateral to the tendon of the biceps brachii Continues into the forearm as the lateral cutaneous nerve of the forearm Innervates Coracobrachialis Biceps brachii Brachialis Next question h Display my notes on this topic la Save my notes Sa C R M Question 136 of 601 Which of the muscles listed below is attached to the anterior aspect of the fibrous capsule that encases the elbow joint? Pronator teres Biceps h Brachialis la Triceps Sa Extensor carpi radialis longus The brachialis inserts some of its fibres into the fibrous joint of the elbow capsule and when it contracts, it helps to flex the joint. Please rate this question: C Discuss and give feedback R Next question Elbow joint M This large synovial joint is of the hinge variety of joint, the bones of the forearm articulate with the lower end of the humerus. The upper ends of the radius and ulnar are bound together by the anular ligament of the radius in such a way as to permit movement between these two bones at what is described as the proximal radio-ulnar joint. The elbow and the proximal radio-ulnar joints have a common fibrous capsule and synovial cavity, and though the anular ligament plays a part in the structure of both joints, it is described with the proximal radio-ulnar joint. Articular surfaces The humeral articular surface at the elbow comprises the grooved trochlea, the spheroidal capitulum, and the sulcus between them. This composite surface is covered by a layer of articular cartilage. The capitulum is confined to the anterior and distal aspects of the bone, but the trochea extends round the distal end of the bone from the lower edge of the coronoid fossa on the front of the humerus to the lower edge of the olecranon fossa posteriorly. The articular surface covering the ulnar surface of the elbow joint is interrupted along the deepest part in a transverse line. Then trochlear notch articulates with the trochlea of the humerus forming a saddle shaped joint with it. The radial surface has a slight concavity to the proximal surface of the head which articulates with the capitulum while its raised margin lies on the capitulotrochlear groove. This surface of the head is covered with articular cartilage which is continuous with that round the sides in the radio-ulnar joint. The radial and ulnar surfaces are most fully in contact with the corresponding humeral surfaces when the forearm is in a position midway between full pronation and supination and the elbow is fixed to a right angle. Fibrous capsule The joint is encased within a fibrous capsule that is relatively weak anteriorly and posteriorly, its h strengthened at the sides to form the radial and ulnar collateral ligaments. The anterior part of the capsule is attached to the front of the humerus immediately superior to the radial and coronoid fossae, to the anterior border of the coronoid process of the ulna, and to the anterior part of the anular ligament of the radius. The brachialis muscle covers the greater part of the front of the la capsule, and some of its deep fibres insert into the capsule. The posterior part of the capsule is very weak in its median part. However, the tendon of triceps inserts at this site and supports it and also draws it upwards in extension. The radial collateral ligament is a strong triangular shaped thickening of the fibrous capsule. Its apex Sa is attached superiorly to the antero-inferior aspect of the lateral epicondyle of the humerus in close relation to the common extensor muscles whose common origin overlies this site. Distally, the broad base of the ligament blends with the anular ligament of the radius, and is attached both in front and behind to the margins of the radial notch on the ulna. The ulna collateral ligament is comprised of three capsular condensations which are continuous with one another. An anterior band passes from the front of the medial epicondyle of the humerus to the medial edge of the coronoid process of the ulna; it is closely related to the common origin of the superficial flexor muscles. A posterior band is attached above to the back of the medial epicondyle C and below to the medial edge of the olecranon. A transverse band stretches between the attachments of the anterior and posterior bands on the coronoid process and the olecranon. The lower edge of this transverse ligament is free, a small amount of synovial membrane may protrude through the space between this and the underlying bone. R Synovial membrane The attachments of the synovial membrane generally follow those of the fibrous capsule. Nerve supply M The elbow joint derives its nerve supply from the musculocutaneous, median, radial and ulna nerves. Movements Movement occurs around a transverse axis, a movement of flexion when the forearm makes anteriorly a diminishing angle with the upper arm and extension when the opposite occurs. The axis of movement passes through the humeral epicondyles and is not at right angles with either the humerus or bones of the forearm. In full extension with the forearm supinated, the arm and forearm form an angle which is more than 180 degrees, the extent to which this angle is exceeded is termed the carrying angle. The carrying angle is masked when the forearm is pronated. Next question Question 137 of 601 A 32 year old rugby player is hit hard on the shoulder during a rough tackle. Clinically, his arm is hanging loose on the side. It is pronated and medially rotated. What structure is most likely to have been compromised? Brachial trunks C5-6 Brachial trunks C6-7 h Brachial trunks C8 - T1 la Anterior interosseous nerve Posterior interosseous nerve Sa The patient has an Erb's palsy involving brachial trunks C5-6. Please rate this question: Discuss and give feedback C Next question Brachial plexus The brachial plexus extends from the neck to the axilla. It is formed by the ventral rami of the fifth to R the eighth cervical nerves with the ascending part of the first thoracic nerve. Location of the plexus The ventral rami which form the plexus enter the lower part of the posterior triangle of the neck in series with the ventral rami of the cervical plexus. The second part of the subclavian artery lies M immediately anterior to the lower two rami. The upper three rami intermingle and pass inferolaterally towards the axilla and subclavian artery. They are enclosed within an extension of the prevertebral fascia. In the neck the plexus lies deep to platysma, the supraclavicular nerves, inferior belly of omohyoid and the transverse cervical artery. It then passes deep to the clavicle and the suprascapular vessels, to enter the axilla, and thence surround the second part of the axillary artery Composition of the plexus Ventral rami, the roots of the plexus, lie between scalenus medius and anterior. As they enter the posterior triangle, the upper two (C5,6) and lower two (C8, T1) roots of the plexus unite to form the upper and lower trunks of the plexus respectively. Meanwhile, C7 continues as the middle trunk. The lower trunk may groove the superior surface of the first rib posterior to the subclavian artery, and the root from the first ventral ramus is always in contact with it. Each trunk divides into ventral and dorsal divisions which are destined to supply the anterior (flexor) and posterior (extensor) parts of the upper limb. The cords of the plexus are formed in the axilla. The dorsal divisions unite to form the posterior cord (C5-8). The ventral divisions of the upper and middle trunks unite to form the lateral cord (C5-7), while the ventral divisions of the lower trunk continues as the medial cord (C8-T1). The cords are named according to their relationship to the axillary artery. Each cord terminates by dividing into two main branches at the beginning of the third part of the artery. Sympathetic communications The fifth and sixth cervical ventral rami receive grey rami communicantes from the middle cervical ganglion, while the two or more grey rami communicantes pass from the inferior cervical ganglion to h the seventh and eighth cervical ventral rami. The first thoracic ventral ramus receives its grey ramus from the cervicothoracic ganglion. Its for this reason that inferior plexus injury can be complicated by a Horners syndrome. la Summary Origin Anterior rami of C5 to T1 Sections of the plexus Sa Roots, trunks, divisions, cords, branches Mnemonic:Real Teenagers Drink Cold Beer Roots Located in the posterior triangle Pass between scalenus anterior and medius C Trunks Located posterior to middle third of clavicle Upper and middle trunks related superiorly to the subclavian artery Lower trunk passes over 1st rib posterior to the subclavian artery R Divisions Apex of axilla M Cords Related to axillary artery Diagram illustrating the branches of the brachial plexus  h la Image sourced from Wikipedia Sa Cutaneous sensation of the upper limb C R M Image sourced from Wikipedia Next question Question 139 of 601 A 73 year old man undergoes an excision biopsy of a lymph node that is closely applied to sternocleidomastoid. This muscle is mobilized and a nerve that is present is damaged. Which muscle below is most likely to be affected? Trapezius h Rhomboid major la Deltoid Supraspinatus Rhomboid minor Sa The accessory nerve has a number of lymph nodes applied to it near the sternocleidomastoid muscle. It is particularly at risk if SCM is mobilized. If injured, the trapezius muscle and SCM will be C paralysed. Please rate this question: R Discuss and give feedback Next question M Trapezius Origin Medial third of the superior nuchal line of the occiput External occipital protruberance Ligamentum nuchae Spines of C7 and all thoracic vertebrae and all intervening interspinous ligaments Insertion Posterior border of the lateral third of the clavicle Medial border of the acromion Upper border of the crest of the spine of the scapula Nerve supply Spinal portion of the accessory nerve Actions Elevation of the shoulder girdle Lateral rotation of the scapula h Next question la Sa C R M Question 140 of 601 A 35 year tennis player attends reporting tingling down his arm. He says that his 'funny bone' was hit very hard by a tennis ball. There is weakness of abduction and adduction of his extended fingers. Which nerve has been affected? Ulnar Anterior interosseous h Posterior interosseous la Median Musculocutaneous Sa The ulnar nerve arises from the medial cord of the brachial plexus (C8, T1 and contribution from C7). The nerve descends between the axillary artery and vein, posterior to the cutaneous nerve of the forearm and then lies anterior to triceps on the medial side of the brachial artery. In the distal half of the arm it passes through the medial intermuscular septum, and continues between this structure and the medial head of triceps to enter the forearm between the medial epicondyle of the humerus and the olecranon. It may be injured at this site in this scenario. C Please rate this question: Discuss and give feedback R Next question Ulnar nerve Origin M C8, T1 Supplies (no muscles in the upper arm) Flexor carpi ulnaris Flexor digitorum profundus Flexor digiti minimi Abductor digiti minimi  Opponens digiti minimi Adductor pollicis Interossei muscle Third and fourth lumbricals Palmaris brevis Path Posteromedial aspect of upper arm to flexor compartment of forearm, then along the ulnar. Passes beneath the flexor carpi ulnaris muscle, then superficially through the flexor retinaculum into the palm of the hand. h la Sa C R M Image sourced from Wikipedia Branches  Branch Supplies Muscular branch Flexor carpi ulnaris Medial half of the flexor digitorum profundus Palmar cutaneous branch (Arises near the Skin on the medial part of the palm middle of the forearm) h Dorsal cutaneous branch Dorsal surface of the medial part of the hand la Superficial branch Cutaneous fibres to the anterior surfaces of the medial one and one-half digits Deep branch Hypothenar muscles Sa All the interosseous muscles Third and fourth lumbricals Adductor pollicis Medial head of the flexor pollicis brevis Effects of injury C Damage at the wrist Wasting and paralysis of intrinsic hand muscles (claw hand) Wasting and paralysis of hypothenar muscles Loss of sensation medial 1 and half fingers R Damage at the elbow Radial deviation of the wrist Clawing less in 4th and 5th digits M Question 154 of 601 A 22 year old falls over and lands on a shard of glass. It penetrates the palmar aspect of his hand, immediately lateral to the pisiform bone. Which of the following structures is most likely to be injured? Palmar cutaneous branch of the median nerve h Lateral tendons of flexor digitorum superficialis la Ulnar artery Sa Flexor carpi radialis tendons