Humerus

Question 1

What is the humerus?

Answer 1

The bone that forms the upper arm

Question 2

What does the humerus do?

Answer 2

Joints the arm to the shoulder and forearm

Question 3

What does the humerus articulate with?

Answer 3

The proximal region articulates with the scapula and clavicle
The distal region articulates with the forearm bones (radius and ulna)

Question 4

What is formed when the humerus articulates with the scapula and clavicle?

Answer 4

The shoulder joint

Question 5

What is formed when the humerus articulates with the forearm bones?

Answer 5

Elbow joint

Question 6

What does the humerus act as?

Answer 6

The attachment site for many muscles and ligaments

Question 7

What does the humerus’ role as an attachment site result in?

Answer 7

Various raised roughening on the bony surface

Question 8

What does the proximal region of the humerus articulate with?

Answer 8

The scapula

Question 9

What is formed when the humerus articulates with the scapula?

Answer 9

The glenohumeral (shoulder) joint

Question 10

What are the important anatomical features of the proximal humerus?

Answer 10

The head
 Anatomical neck
 Surgical neck
 Greater and lesser tubercles
 Intertubercular sulcus

Question 11

What is a tubercle?

Answer 11

A round nodule

Question 12

What does a tubercle signify?

Answer 12

An attachment site of a muscle or ligament

Question 13

Where does the head of the humerus project?

Answer 13

Medially and superiorly

Question 14

What does the head of the humerus do?

Answer 14

Articulates with the glenoid cavity of the scapula

Question 15

How is the head of the humerus connected to the tubercles?

Answer 15

By the anatomical neck

Question 16

Describe the anatomical neck of the humerus?

Answer 16

Short in width, nondescript

Question 17

Where is the greater tubercle of the humerus located?

Answer 17

Laterally

Question 18

What does the greater tubercle of the humerus have?

Answer 18

An anterior and posterior face

Question 19

What is the function of the greater tubercle?

Answer 19

It serves as attachment sites for three of the rotator cuff muscles

Question 20

What muscles is the greater tubercle the attachment site for?

Answer 20

Supraspinatus
Infraspinatus
Teres minor

Question 21

How does the lesser tubercle differ from the greater?

Answer 21

It is much smaller, and more medially located. It only has an anterior face

Question 22

What is the purpose of the lesser tubercle?

Answer 22

It is the site of attachment for the last rotator cuff muscle- the subscapularis

Question 23

What separates the two tubercles of the humerus?

Answer 23

A deep depression, called the intertubercular sulcus (or groove)

Question 24

What runs through the intertubercular sulcus?

Answer 24

The tendon of the long head of the biceps brachii

Question 25

What are the edges of the intertubercular sulcus known as?

Answer 25

Lips

Question 26

What attaches to the lips of the intertubercular sulcus?

Answer 26

Tendons of the pectoralis major, teres major and latissimus dorsi

Question 27

Where does the surgical neck of the humerus run?

Answer 27

From the tubercles to the shaft of the humerus

Question 28

What is a frequent site of fracture of the proximal part of the humerus?

Answer 28

The surgical neck

Question 29

How does a fracture of the surgical neck of the humerus occur?

Answer 29

By a direct blow to the area, or by falling on an outstretched hand

Question 30

What are the key structures of concern in a surgical neck of the humerus fracture?

Answer 30

Axillary nerve  | Posterior circumflex artery

Question 31

Where does the axillary nerve innervate?

Answer 31

The skin over the lower deltoid (known as the regimental badge area)

Question 32

What will damage to the axillary nerve result in?

Answer 32

Paralysis to the deltoid and teres minor muscles, and so the patient will be unable to abduct their arm  Sensory innervation to the regimental badge area could be lost

Question 33

What important landmarks does the shaft of the humerus contain?

Answer 33

The deltoid tuberosity  | The radial groove

Question 34

What is the shaft of the humerus the site for?

Answer 34

Attachment for various muscles

Question 35

What is found on the lateral side of the humeral shaft?

Answer 35

The deltoid tuberosity

Question 36

What is the deltoid tuberosity?

Answer 36

A roughened surface where the deltoid muscle attaches

Question 37

What is the radial groove?

Answer 37

A shallow depression

Question 38

Where does the radial groove run?

Answer 38

Diagonally down the surface of the humerus, parallel to the deltoid tuberosity

Question 39

What lies in the radial groove?

Answer 39

The radial nerve and the profunda brachii artery

Question 40

What muscles attach anteriorly to the humerus?

Answer 40

Coracobrachialis Deltoid  Brachialis  Brachioradialis

Question 41

What muscles attach posteriorly to the humerus?

Answer 41

Medial and lateral heads of the triceps

Question 42

What is the problem with a mid shaft fracture of the humerus ?

Answer 42

It could easily damage the radial nerve and profunda brachii artery

Question 43

Why could a mid shaft fracture of the humerus easily damage the radial nerve and profunda brachii artery?

Answer 43

As they are tightly bound in the radial groove

Question 44

What does the radial nerve innervate?

Answer 44

Extensors of the wrist

Question 45

What would be the result of a damaged radial nerve?

Answer 45

The extensors of the wrist would be paralysed, resulting in unopposed flexion of the wrist, known as ‘wrist drop’  There is also some sensory loss over the dorsal (posterior) surface of the hand, and proximal ends of the lateral 3 and a half fingers dorsally

Question 46

What does the dorsal region of the humerus articulate with?

Answer 46

The ulna and radius

Question 47

What is formed when the dorsal region of the humerus articulates with the radius and ulna?

Answer 47

The elbow joint

Question 48

What shape does the bone adopt in the dorsal region?

Answer 48

A flattened, almost 2D shape

Question 49

What do the lateral and medial borders of the humerus form?

Answer 49

Medial and lateral supraepicondylar ridges

Question 50

How does the lateral supraepicondylar ridge differ from the medial?

Answer 50

It is more roughened

Question 51

Why is the lateral supraepicondylar ridge more roughened than the medial?

Answer 51

Because it is the site of attachment for many of the extensor muscles in the posterior forearm

Question 52

What is found immediately distal to the supraepicondylar ridges?

Answer 52

The lateral and medial epicondyles

Question 53

What are epicondyles?

Answer 53

Projections of the bone

Question 54

Where can the epicondyles be palpated?

Answer 54

At the elbow- the medial more so because it is much larger

Question 55

Where can the ulnar nerve be palpated?

Answer 55

Along the posterior side of the medial epicondyle

Question 56

Why can the ulnar nerve be palpated at the medial epicondyle?

Answer 56

Because this is where it passes into the forearm

Question 57

What articulates with the ulna?

Answer 57

The trochlea

Question 58

Where is the trochlea located?

Answer 58

Medially

Question 59

Where does the trochlea extend to?

Answer 59

The posterior of the bone

Question 60

What is found lateral to the trochlea?

Answer 60

The capitulum

Question 61

What does the capitulum article with?

Answer 61

The radius

Question 62

What is found along the distal portion of the humerus?

Answer 62

Three depressions, known as the coronoid, radial and olecrannon fossae

Question 63

What do the coronoid, radial and olecrannon fossae accommodate?

Answer 63

The forearm bones during movement at the elbow

Question 64

Where are the common fracture sites of the distal humerus?

Answer 64

Supracondylar fractures  | Medial epicondyle fractures

Question 65

How does a supraepicondylar fracture occur?

Answer 65

By falling on a flexed elbow

Question 66

What kind of fracture is a supraepicondylar?

Answer 66

A transverse fracture, spanning between the two epicondyles

Question 67

What can distal humerus fractures lead to?

Answer 67

Interference to the blood supply of the forearm from the brachial artery  Damage to the medial, ulnar or radial nerve

Question 68

How can a distal humerus fracture lead to interference of the blood supply from the brachial artery?

Answer 68

Direct damage, or swelling

Question 69

What can interference in forearm blood supply lead to?

Answer 69

Ischaemia, which can cause Volkmann’s ischaemic contracture

Question 70

What is Volkmann’s ischaemic contracture?

Answer 70

Uncontrolled flexion of the hand

Question 71

Why does Volkmann’s ischaemic contracture occur?

Answer 71

Because the flexor muscles become fibrotic and short

Question 72

What could a medial epicondyle fracture damage?

Answer 72

The ulnar nerve

Question 73

What results from damage to the ulnar nerve?

Answer 73

A deformity known as the ulnar claw  | Loss of sensation over the medial 1 and a 1/2 fingers of the hand, on both the dorsal and palmar surfaces