S8) The Forearm Flashcards

1
Q

Describe the structure, location and function of the ulna

A
  • Structure: long bone in the forearm
  • Location: lies medially, parallel to the radius
  • Function: stabilising bone, pivots with the radius to produce movement
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2
Q

Describe the articulations of the ulna

A
  • Proximal: articulates with trochlea of humerus at the elbow joint and head of the radius at proximal radio-ulnar joint
  • Distal: radius at the distal radio-ulnar joint
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3
Q

Identify the important anatomical landmarks in the proximal region of the ulna

A
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4
Q

Describe the structure and purpose of the olecranon, ulna tuberosity and coronoid process

A
  • Olecranon – a large projection of bone that extends proximally, forming part of trochlear notch

- Coronoid process – a ridge of bone projecting outwards anteriorly, forming part of the trochlear notch

  • Tuberosity of ulna – a roughening immediately distal to the coronoid process
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5
Q

Describe the structure and purpose of the trochlear and radial notch

A
  • Trochlear notch is formed by the olecranon and coronoid process and articulates with the trochlea of the humerus
  • Radial notch is located on the lateral surface of the trochlear notch and articulates with the head of the radius
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6
Q

Describe the structure of shaft of the ulna

A

The ulnar shaft is triangular, with three borders and three surfaces and decreases in width distally

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7
Q

The shaft of the ulna has three surfaces.

Identify and describe them

A
  • Anterior – site of attachment for the pronator quadratus muscle distally

- Posterior – site of attachment for many muscles

- Medial – unremarkable

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8
Q

The shaft of the radius has three borders.

Identify and describe them

A
  • Posterior – palpable along the entire length of the forearm posteriorly

- Interosseous – site of attachment for the interosseous membrane

- Anterior – unremarkable

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9
Q

Identify the important anatomical landmarks in the distal region of the ulna

A
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10
Q

Describe the structure, location and function of the radius

A
  • Structure: long bone in the forearm
  • Location: lies laterally, parallel to ulna
  • Function: pivots around the ulna to produce movement at the radio-ulnar joints
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11
Q

The radius articulates in four places.

Identify and describe them

A
  • Elbow Joint – articulation between radial head and capitulum of humerus

- Proximal Radioulnar Joint – articulation between the radial head and radial notch of the ulna

- Distal Radioulnar Joint – articulation between ulnar notch of radius and ulnar head

- Wrist Joint – articulation between the distal radius and carpal bones

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12
Q

Identify the important anatomical landmarks in the proximal region of the radius

A
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13
Q

Describe the structure of the radial head, neck and radial tuberosity.

A
  • Head of radius – disk shaped structure with a concave articulating surface and forms the proximal radioulnar joint
  • Neck – narrow area of bone, which lies between the radial head and radial tuberosity
  • Radial tuberosity – a bony projection
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14
Q

What holds the radial head in place during movement?

A
  • The radial head is held in place by the annular radial ligament, which forms a collar around the joint
  • The is lined with a synovial membrane, reducing friction during movement
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15
Q

Describe the structure of the shaft of the radius

A
  • It is triangular in shape, with three borders and three surfaces and expands in diameter distally
  • The lateral surface has a small roughening for the attachment of the pronator teres muscle
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16
Q

Identify the important anatomical landmarks in the distal region of the radius

A
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17
Q

Describe the structure and purpose of the styloid process, ulnar notch and scaphoid and lunate facets

A
  • Styloid process – distal projection of lateral side of radial shaft
  • Ulnar notch – concavity on medial surface which articulates with the head of ulna, forming the distal radioulnar joint
  • Scaphoid and lunate facets – articulate with the scaphoid and lunate carpal bones to form the wrist joint
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18
Q

The radioulnar joints are two locations in which the radius and ulna articulate in the forearm.

Describe their anatomical position and articulation

A
  • Proximal radioulnar joint is an articulation between the head of the radius, and the radial notch of the ulna (located near the elbow)
  • Distal radioulnar joint is an articulation between the head of the ulna and the ulnar notch of the radius (located proximal to wrist joint)
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19
Q

What type of joint are the radioulnar joints?

A

The radioulnar joint is a pivot type synovial joint

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20
Q

Identify the movements possible at the radioulnar joints and the muscles responsible

A
  • Pronation produced by the pronator quadratus and pronator teres
  • Supination produced by the supinator and biceps brachii
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21
Q

The articular disk is a fibrocartilaginous ligament present in the distal radioulnar joint.

What are its functions?

A
  • Binds the radius and ulna together, and holds them together during movement at the joint
  • Separates the distal radioulnar joint from the wrist joint
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22
Q

What are three major functions of the interosseous membrane?

A
  • Holds the radius and ulna together during pronation and supination

- Acts as a site of attachment for muscles of the forearm

- Transfers forces from the radius to the ulna

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23
Q

Identify the 3 types of muscles in the anterior compartment of the forearm

A
  • Superficial muscles
  • Intermediate muscles
  • Deep muscles
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24
Q

Identify the superficial muscles in the anterior compartment of the forearm

A
  • Flexor carpi ulnaris
  • Flexor carpi radialis
  • Palmaris longus
  • Pronator teres
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25
Q

What is a common characteristic of all superficial muscles in the anterior compartment of the forearm?

A

They all originate from a common flexor tendon, which arises from the medial epicondyle of the humerus

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26
Q

State the function and innervation of the flexor carpi ulnaris muscle

A

- Function: wrist flexion and adduction

- Innervation: ulnar nerve

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27
Q

State the origin and attachment of the flexor carpi ulnaris muscle

A
  • Origin: medial epicondyle
  • Attachment: pisiform carpal bone
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28
Q

State the function and innervation of the palmaris longus muscle

A

- Function: wrist flexion

- Innervation: median nerve

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29
Q

State the origin and attachment of the palmaris longus muscle

A
  • Origin: medial epicondyle
  • Attachment: flexor retinaculum of the wrist
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30
Q

State the function and innervation of the flexor carpi radialis muscle

A

- Function: wrist flexion and abduction

- Innervation: median nerve

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31
Q

State the origin and attachment of the flexor carpi radialis muscle

A
  • Origin: medial epicondyle
  • Attachment: base of metacarpals II and III
32
Q

State the function and innervation of the pronator teres muscle

A

- Function: pronation of the forearm

- Innervation: median nerve

33
Q

State the origin and attachment of the pronator teres muscle

A
  • Origin: medial epicondyle and coronoid process of the ulna
  • Attachment: laterally on mid-shaft of the radius
34
Q

Which muscle is in the intermediate compartment of the anterior forearm?

A

Flexor digitorum superficialis

35
Q

Why is the flexor digitorum superficialis a good anatomical landmark in the forearm?

A

The median nerve and ulnar artery pass between its two heads, and then travel posteriorly

36
Q

State the function and innervation of the flexor digitorum superficialis muscle

A

- Function: MCPJ flexion, PIPJ flexion (4 fingers), wrist flexion

- Innervation: median nerve

37
Q

State the origin and attachment of the flexor digitorum superficialis muscle

A
  • Origin:

I. One head – medial epicondyle of the humerus

II. Other head – radius

  • Attachment: four tendons travel through the carpal tunnel and attach to the middle phalanges of the four fingers
38
Q

Identify the deep muscles in the anterior compartment of the forearm

A
  • Flexor digitorum profundus
  • Flexor pollicis longus
  • Pronator quadratus
39
Q

State the function and innervation of the flexor digitorum profundus muscle

A

- Function: DIPJ flexion (only muscle), MCPJ flexion

- Innervation:

I. Ulnar nerve – medial half

II. Median nerve – lateral half

40
Q

State the origin and attachment of the flexor digitorum profundus muscle

A
  • Origin: ulna and associated interosseous membrane
  • Attachment: splits into four tendons, passes through the carpal tunnel and attaches to distal phalanges of four fingers
41
Q

State the function and innervation of the flexor pollicis longus muscle

A

- Function: IPJ flexion, MCPJ flexion

- Innervation: median nerve

42
Q

State the origin and attachment of the flexor pollicus longus muscle

A
  • Origin: anterior surface of the radius and surrounding interosseous membrane
  • Attachment: base of the distal phalanx of the thumb
43
Q

State the function and innervation of the pronator quadratus muscle

A

- Function: pronates the forearm

- Innervation: median nerve

44
Q

State the origin and attachment of the pronator quadratus

A
  • Origin: anterior surface of the ulna
  • Attachment: anterior surface of the radius
45
Q

Describe the general structure, function and innervation of the extensor muscles of the posterior forearm

A
  • Structure: superficial and deep layers (separated by a layer of fascia)
  • Function: produce extension at the wrist and fingers
  • Innervation: radial nerve
46
Q

Identify the superficial muscles in the posterior compartment of the forearm

A
  • Brachioradialis
  • Extensor carpi radialis longus
  • Extensor carpi radialis brevis
  • Extensor digitorum
  • Extensor digiti minimi
  • Extensor carpi ulnaris
  • Anconeus
47
Q

What is a common characteristic of the extensor carpi radialis brevis, extensor carpi ulnaris, extensor digitorum and extensor digiti minimi muscles?

A

They all originate from the same extensor tendon, which arises at the lateral epicondyle of the humerus

48
Q

State the function and innervation of the brachioradialis

A
  • Function: elbow flexion
  • Innervation: radial nerve
49
Q

State the origin and attachments of the bracioradialis muscle

A
  • Origin: proximal aspect of the lateral supracondylar ridge of humerus
  • Attachment: distal end of the radius (before the radial styloid process)
50
Q

State the function and innervation of the extensor carpi radialis muscles

A
  • Function: wrist extension, wrist abduction
  • Innervation: radial nerve
51
Q

State the origin and attachments of the extensor carpi radialis muscles

A
  • Origin:

I. ECRL – supracondylar ridge

II. ECRB – lateral epicondyle

  • Attachment: metacarpal bones II and III
52
Q

State the function and innervation of the extensor digitorum muscle

A
  • Function: finger extension at the MCPJs and IPJs (not thumb)
  • Innervation: radial nerve
53
Q

State the origin and attachment of the extensor digitorum muscle

A
  • Origin: lateral epicondyle
  • Attachment: extensor hood of each finger
54
Q

State the function and innervation of the extensor digiti minimi muscle

A
  • Function: little finger extension, contributes to wrist extension
  • Innervation: radial nerve
55
Q

State the origin and attachment of the extensor digiti minimi muscle

A
  • Origin: lateral epicondyle of the humerus
  • Attachment: extensor hood of the little finger (with extensor digitorum tendon)
56
Q

State the function and innervation of the extensor carpi ulnaris muscle

A
  • Function: wrist extension, wrist adduction
  • Innervation: radial nerve
57
Q

State the origin and attachment of extensor carpi ulnaris

A
  • Origin: lateral epicondyle of the humerus
  • Attachment: base of metacarpal V
58
Q

Describe the structure, function and innervation of the anconeus muscle

A
  • Structure: blended with the fibres of the triceps brachii (two muscles can be indistinguishable)
  • Function: extends and stablises the elbow joint
  • Innervation: radial nerve
59
Q

State the origin and attachment of the anconeus muscle

A
  • Origin: lateral epicondyle
  • Attachment: posterior and lateral part of the olecranon
60
Q

Identify the deep muscles of the posterior compartment of the forearm

A
  • Supinator
  • Abductor pollicis longus
  • Extensor pollicis brevis
  • Extensor pollicis longus
  • Extensor indicis
61
Q

Describe the structure, function and innervation of the supinator muscle

A
  • Structure: floor of the cubital fossa, two heads – deep branch of the radial nerve passes between
  • Function: supination
  • Innervation: radial nerve
62
Q

State the origin and attachment of the supinator muscle

A
  • Origin:

I. One head – lateral epicondyle of the humerus

II. Other head – posterior surface of the ulna

  • Attachment: posterior surface of the radius
63
Q

Describe the structure, function and innervation of the abductor pollicis longus muscle

A
  • Structure: tendon contributes to lateral border of anatomical snuffbox
  • Function: thumb abduction
  • Innervation: radial nerve
64
Q

State the origin and attachment of the abductor pollicis longus muscle

A
  • Origin: interosseous membrane and adjacent posterior surfaces of the radius and ulna
  • Attachment: lateral side of the base of metacarpal I
65
Q

Describe the structure, function and innervation of the extensor pollicis brevis muscle

A
  • Structure: tendon contributes to lateral border of anatomical snuffbox
  • Function: thumb extension at the MCPJs and CMCJs
  • Innervation: radial nerve
66
Q

State the origin and attachment of the extensor pollicis brevis muscle

A
  • Origin: posterior surface of the radius and interosseous membrane
  • Attachment: base of the proximal phalanx of the thumb
67
Q

Describe the structure, function and innervation of the extensor pollicis longus muscle

A
  • Structure: tendon forms medial border of anatomical snuffbox
  • Function: thumb extension at CMCJs, MCPJs, IPJs
  • Innervation: radial nerve
68
Q

State the origin and attachment of the extensor pollicus longus muscle

A
  • Origin: posterior surface of the ulna and interosseous membrane
  • Attachment: distal phalanx of the thumb
69
Q

State the function and innervation of the extensor indicis proprius

A
  • Function: index finger extension (independent)
  • Innervation: radial nerve
70
Q

State the origin and attachment of the extensor indicis proprius

A
  • Origin: posterior surface of the ulna and interosseous membrane, distal to the extensor pollicis longus
  • Attachment: extensor hood of the index finger
71
Q

Identify the nerves of the forearm

A
72
Q

Describe the arterial supply of the forearm

A
  • Radial artery supplies the posterior aspect of the forearm
  • Ulnar artery supplies the anterior aspect of the forearm

The two arteries anastomose in the hand, by forming two arches, the superficial palmar arch, and the deep palmar arch

73
Q

Identify the veins of the forearm

A
74
Q

What is a Colles’ fracture?

A

A Colles’ fracture is a distal radius fracture caused by a direct blow to the palmar forearm or falling onto extended wrists leading to dorsal displacement

75
Q

What is a Smith’s fracture?

A

A Smith’s fracture is a distal radius fracture caused by a direct blow to the dorsal forearm or falling onto flexed wrists leading to palmar displacement