S9: the upper limb (2)

Question 1

Describe the two articulations of the elbow joint

Answer 1

Humeroulnar joint = between trochlea of the humerus & trochlear notch of the ulna
Humeroradial joint = between the capitellum of the humerus & radial head

Question 2

Describe the two ligaments which strengthen the elbow joint

Answer 2

Radial collateral ligament = attaches between the lateral epicondyle of the humerus & annular ligament of the radius
-keeps the head of the radius & capitellum in close association during pronation & supination of the forearm
Ulnar collateral ligament = attaches between the medial epicondyle of the humerus & coronoid process and olecranon of the ulnar

Question 3

What is the function of the annular ligament?

Answer 3

Stabilises the proximal radioulnar joint
Forms a collar around the radial head = radial head can rotate whilst maintaining its contact with the radial notch of the ulna

Question 4

List the movements which occur at the elbow & radioulnar joints

Answer 4

Elbow = flexion & extension
Radioulnar = pronation & supination

Question 5

Describe the anatomy of the cubital fossa

Answer 5

Lateral border = medial border of brachioradialis muscle
Medial border = lateral border of pronator teres muscle
Superior border = hypothetical line between the epicondyles of the humerus
Floor = brachialis
Roof = skin, fascia & bicipital aponeurosis (median cubital vein runs in the roof)
Contents (lateral to medial) = radial nerve, biceps tendon, brachial artery & median nerve

Question 6

Describe the anatomical and clinical features of cubital tunnel syndrome

Answer 6

FCU two heads are united by a tendinous arch -> ulnar nerve passes beneath the tendinous arch to enter the cubital tunnel = common site for ulnar nerve compression
Compression of ulnar nerve in the cubital tunnel results in:
1) Paraesthesia in the cutaneous territory of the ulnar nerve
2) May also result in weakness in the muscles supplied by the ulnar nerve
Treatment = decompress the nerve (surgically move it anterior to the medial epicondyle)

Question 7

Name the origins, insertions, innervations & actions of the superficial muscles of the anterior forearm

Answer 7

Origins = medial epicondyle of the humerus (common flexor origin)
Innervation (except FCU) = median nerve
Flexor carpi ulnaris: origin = humeral head -> common flexor origin, ulnar head -> medial margin of the olecranon of ulna, insertion = pisiform bone, hook of hamate, base of 5th metacarpal bone, action = flexion & adduction of wrist
Palmaris longus: insertion = flexor retinaculum & palmar aponeurosis, action = weak flexion of wrist
Flexor carpi radialis: insertion = base of 2nd & 3rd metacarpals, action = abduction & flexion of wrist
Pronator teres: origin = humeral head -> common flexor origin, ulnar head -> coronoid process of ulna, insertion = mid-shaft of radius, action = pronation of forearm

Question 8

Name the origins, insertions, innervations & actions of the intermediate muscles of the anterior forearm

Answer 8

Flexor digitorum superficialis
Origin = 1) humeroulnar head: common flexor origin, 2) radial head: proximal half of the anterior surface of the radius
Insertion = splits into 4 tendons -> insets onto base of 4 fingers
Action = flexion of MCP joints & PIP joints of four fingers, assists flexion of wrist

Question 9

Name the origins, insertions, innervations & actions of the deep muscles of the anterior forearm

Answer 9

Innervation (all except ulnar half of FDP which is ulnar nerve) = anterior interosseous branch of median nerve
Flexor digitorum profundus: origin = shaft of ulnar & interosseous membrane, insertion = splits into 4 tendons & inserts into base of distal phalanges of 4 fingers, actions = flexion of DIP & MCP joints & assists flexion of wrist
Flexor pollicis longus: origin = radial shaft & interosseous membrane, insertion = base of distal phalanx of the thumb, action = flexion of MCP & IP joints of thumb
Pronator quadratus: origin = anterior surface of distal ulna, insertion = anterior surface of distal radius, action = pronation of forearm

Question 10

List the seven muscles found in the superficial layer of the posterior forearm

Answer 10

Brachioradialis
Extensor carpi radialis longus
Extensor carpi radialis brevis
Extensor digitorum
Extensor digiti minimi
Extensor carpi ulnaris
Anconeus

Question 11

Name the origins, insertions, innervations & actions of brachioradialis, ECRL, ECRB & ED

Answer 11

Brachioradialis: origin = lateral supracondylar ridge of humerus, insertion = distal end of radius, innervation = radial nerve, actions = flexion of elbow at mid-prone position
Extensor carpi radialis longus: origin = lateral supracondylar ridge, insertion = dorsal surface of the base of the 2nd/3rd metacarpal bone respectively, innervation = radial nerve, actions = extension & abduction of the wrist
Extensor carpi radialis brevis: origin = common extensor origin (lateral epicondyle), insertion = dorsal surface of the base of the 2nd/3rd metacarpal bone respectively, innervation = deep branch of radial nerve, actions = extension & abduction of the wrist
Extensor digitorum: origin = lateral epicondyle, insertion = splits into 4 tendons into extensor hood of the four fingers, innervation = posterior interosseous branch, actions = extension of 4 fingers at MCPJs & IPs

Question 12

Name the origins, insertions, innervations & actions of EDM, ECU & anconeus

Answer 12

Extensor carpi ulnaris: origin = 1) humeral head -> lateral epicondyle, 2) ulnar head -> olecranon, posterior surface of proximal ulna & deep fascia, insertion = base of 5th metacarpal, innervation = radial nerve, actions = extension & adduction of wrist
Extensor digiti minimi: origin = lateral epicondyle, insertion = extensor hood of little finger, innervation = posterior interosseous branch, actions = extension of little finger
Anconeus: origin = lateral epicondyle, insertion = radial side of olecranon, innervation = radial nerve, actions = weak extension of elbow

Question 13

Name the origins, insertions, innervations & actions of the deep layer of the posterior forearm

Answer 13

Innervation (except supinator) = posterior interosseous branch of radial nerve
Supinator: origin = 1) humeral head -> common flexor origin, 2) ulnar head -> supinator crest on ulna, insertion = proximal lateral border of radius, innervation = deep branch of radial nerve, actions = supination of forearm
Abductor pollicis longus: origin = interosseous membrane & proximal surface of radius and ulna, insertion = radial side of the base of the first metacarpal, actions = thumb abduction
Extensor pollicis longus: origin = interosseous membrane & proximal surface of ulna, insertion = distal phalanx of thumb, actions = extension of all thumb joints
Extensor pollicis brevis: origin = interosseous membrane& proximal surface of radius, insertion = base of the proximal phalanx of thumb, actions = extension of MCPJ & IP of thumb
Extensor indicis: origin = interosseous membrane & proximal surface of ulna, insertion = extensor hood of the index finger, actions = extension of index finger