S7) The Upper Arm Flashcards

1
Q

Where is the upper arm?

A

The upper arm is located between the shoulder joint and elbow joint

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2
Q

What are the muscles of the upper arm?

A
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3
Q

Identify the 3 muscles in the anterior compartment of the upper arm

A
  • Biceps brachii
  • Coracobrachialis
  • Brachialis
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4
Q

Describe the neurovascular supply of the anterior compartment of the upper arm

A
  • Innervated by the musculocutaneous nerve
  • Arterial supply via muscular branches of the brachial artery
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5
Q

Describe the structure and function of the biceps brachii muscle

A
  • Structure: two-headed muscle, bicipital aponeurosis forms the roof of the cubital fossa and blends with the deep fascia of anterior forearm

- Function: supination, elbow flexion, shoulder flexion

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6
Q

State the origin and attachment of the biceps brachii muscle

A
  • Origin:

I. Long head – supraglenoid tubercle

II. Short head – coracoid process

  • Attachment: radial tuberosity and the fascia of the forearm via the bicipital aponeurosis
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7
Q

Describe the structure and function of the coracobrachialis muscle

A
  • Structure: lies deep to biceps brachii

- Function: shoulder flexion

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8
Q

State the origin and attachment of the coracobrachialis muscle

A
  • Origin: coracoid process of the scapula
  • Attachment: medial side of the humeral shaft, at the level of the deltoid tubercle
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9
Q

Describe the structure and function of the brachialis muscle

A
  • Structure: lies deep to biceps brachii, found more distally than the other and forms the floor of the cubital fossa

- Function: elbow flexion

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10
Q

State the origin and attachment of the brachialis muscle

A
  • Origin: medial and lateral surfaces of the humeral shaft
  • Attachment: ulna tuberosity, distal to the elbow joint
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11
Q

Identify the muscle in the posterior compartment of the upper arm

A

Triceps brachii

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12
Q

Describe the neurovascular supply of the posterior compartment of the upper arm

A
  • Innervated by the radial nerve
  • Arterial supply via the profunda brachii artery
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13
Q

Describe the structure and function of the triceps brachii muscle

A
  • Structure: three heads; medial head lies deeper than the other two

- Function: elbow extension

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14
Q

State the origin and attachment of the triceps brachii muscle

A
  • Origin:

I. Long head – infraglenoid tubercle

II. Lateral head – above radial groove of humerus

III. Medial head – below radial groove of humerus

  • Attachment: olecranon of the ulna
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15
Q

What is the cubital fossa?

A

The cubital fossa is triangular depression on the anterior surface of the elbow joint as the anatomical arm transitions to become the forearm

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16
Q

The cubital fossa is triangular in shape, and thus has three borders.

What are they?

A
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17
Q

Describe the structure of the floor and roof of the cubital fossa

A
  • The floor is formed proximally by the brachialis, and distally by the supinator muscle
  • The roof is formed of skin and fascia and is reinforced by the bicipital aponeurosis
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18
Q

Which structure runs in the roof of the cubital fossa?

A

Median cubital vein is located superficially within the roof of the cubital fossa and can be accessed for a venepuncture

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19
Q

Identify and describe contents of the cubital fossa

A
  • Radial nerve passes underneath the brachioradialis muscle

- Biceps tendon runs through to attach to the radial tuberosity

- Brachial artery bifurcates at the apex of the cubital fossa

- Median nerve leaves the cubital fossa between the two heads of the pronator teres

20
Q

Where can the brachial pulse be felt?

A

The brachial pulse can be felt by palpating immediately medial to the biceps tendon in the cubital fossa

21
Q

What is the humerus and what does it do?

A
  • The humerus is the bone that forms the upper arm and joins it to the shoulder and forearm
  • It acts as an attachment site for many muscles and ligaments
22
Q

Describe the proximal and distal articulations of the humerus

A
  • The proximal region articulates with the scapula and clavicle to form part of the shoulder joint
  • The distal region articulates with the radius and ulna to form the elbow joint.
23
Q

Identify the anatomical features observed in the proximal region of the humerus

A
24
Q

Describe the anatomical position of the head and anatomical neck of the humerus

A
  • The head of the humerus projects medially and superiorly to articulate with the glenoid cavity of the scapula
  • The anatomical neck is short in width and connects the head to the tubercles
25
Q

What is a tubercle?

A

A tubercle is a round nodule, and signifies an attachment site of a muscle or ligament

26
Q

Describe the anatomical position of the greater and lesser tubercles of the humerus

A
  • The greater tubercle is located laterally on the humerus and serves as an attachment site for 3 rotator cuff muscles – supraspinatus, infraspinatus, teres minor
  • The lesser tubercle is located medially on the humerus and serves as an attachment site 1 rotator cuff muscle – subscapularis
27
Q

How are the the greater and lesser tubercles of the humerus separated?

A

Separating the two tubercles is a deep depression, called the intertubercular sulcus/groove and its edges are known as lips

28
Q

Describe the anatomical position of the surgical neck of the humerus

A

The surgical neck runs from the tubercles to the shaft of the humerus

29
Q

The shaft of the humerus contains some important bony landmarks.

Identify and describe them

A
  • Deltoid tuberosity is a roughened surface on lateral side of humeral shaft
  • Radial groove is a shallow depression running diagonally down the posterior surface of the humerus, parallel to the deltoid tuberosity
30
Q

Which structures run along the radial groove?

A
  • Profunda brachii artery
  • Radial nerve
31
Q

Which muscles attach to the shaft of the humerus?

A

- Anteriorly: deltoid, coracobrachialis, brachialis, brachioradialis

- Posteriorly: medial and lateral heads of the triceps

32
Q

Identify the anatomical features observed in the distal region of the humerus

A
33
Q

Describe the structure of the lateral and medial supraepicondylar ridges

A
  • The supracondylar ridges are formed from the lateral and medial borders of the humerus
  • The lateral supraepicondylar ridge is more roughened as many extensor muscles in the posterior forearm attach there
34
Q

Describe the structure of the lateral and medial epicondyles

A
  • The lateral and medial epicondyles are projections of bone immediately distal to the lateral and medial supracondylar ridges
  • The medial is much larger and can be palpated more easily
35
Q

What passes along the medial epicondyle?

A

The ulnar nerve passes into the forearm along the posterior side of the medial epicondyle, and can also be palpated there

36
Q

Describe the anatomical position and articulations of the trochlea and capitulum

A
  • The trochlea is located medially and articulates with the ulna
  • The capitulum is located laterally and articulates with the radius
37
Q

Three depressions are also found on the distal portion of the humerus.

Identify and describe them

A

The coronoid, radial and olecranon fossae are 3 depressions which accommodate the forearm bones during movement at the elbow

38
Q

What is a biceps tendon rupture?

A

Biceps tendon rupture is the complete rupture of the biceps brachii tendon after the very strong contraction of the muscle and presents with a characteristic Popeye sign on elbow flexion

39
Q

After the rupture of the biceps tendon, why would the patient not notice much weakness in the upper limb?

A

Due to the action of the brachialis and supinator muscles

40
Q

Which structures are at risk of damage in a mid-shaft humeral fracture?

A
  • Radial nerve
  • Profunda brachii artery
41
Q

What is a mid-shaft humeral fracture?

A
  • Mid-shaft humeral fractures are fractures within the shaft of the humerus, occuring from FOOSH, which damage the profunda brachii artery and radial nerve
  • It presents with the unopposed flexion of the wrist (wrist drop) due to paralysis of the extensor muscles of the wrist and some sensory loss over the dorsum of the hand
42
Q

Identify two common fracture types of the distal humerus

A
  • Supracondylar fractures
  • Medial epicondyle fractures
43
Q

What is a supracondylar fracture?

A
  • Supraepicondylar fractures are transverse fractures, spanning between two epicondyles, which occur by falling on a flexed elbow
  • It presents with Volkmanns ischaemic contracture which is ischaemia causing the uncontrolled flexion of the hand, as flexor muscles become fibrotic and short
44
Q

Which nerves might be damaged in a supracondylar fracture?

A
  • Median nerve
  • Ulnar nerve
  • Radial nerve
45
Q

What is a medial epicondyle fracture?

A
  • A medial epicondyle fracture is a fracture which damages the ulnar nerve producing a deformity known as ulnar claw due to the paralysis of the lateral lumbricals
  • It presents with a loss of sensation over the dorsal and palmar hand surfaces and the medial 1½ fingers