BMS271 - Arm & Elbow

Question 1

Biceps Brachii

Answer 1

Attachments:
- short head (medial): coracoid process
- long head (lateral): supraglenoid tubercle
- radial tuberosity, deep fascia of forearm via bicipital aponeurosis
Actions:
- flexion and supination of the forearm
- short head: resists shoulder dislocation
Innervation:
- musculocutaneous nerve (C5, C6 and C7)

Question 2

Brachialis

Answer 2

Attachments:
- distal half of anterior surface of humerus
- coronoid process and tuberosity of ulna
Actions:
- flexion of the forearm in all positions
Innervation
- musculocutaneous nerve (C5 and C6)

Question 3

Coracobrachialis

Answer 3

Attachments:
- coracoid process
- middle third of medial humerus
Actions:
- adduction of the humerus
- flexion of the humerus
- resists dislocation of shoulder
Innervation:
- musculocutaneous nerve (C5, C6 and C7)

Question 4

Triceps Brachii

Answer 4

Attachments:
- long head: infraglenoid tubercle
- medial head: posterior surface of humerus inferior to radial groove
- lateral head: posterior surface of humerus superior to radial groove
- proximal surface of olecranon and fascia of forearm
Actions:
- extension of the forearm
- long head may also extend and adduct the humerus
- resists dislocation of the humerus
Innervation:
- radial nerve (C6, C7 and C8)
Radial nerve enters into triceps

Question 5

Elbow Joint and Radioulnar Joints

Answer 5

Humeroulnar joint
Humeroradial joint
Proximal radioulnar joint
Distal radioulnar joint
The first two act together as a hinge joint which permits flexion/extension
The last three act together as a pivot joint which permits supination/pronation

Question 6

Elbow Joint

Answer 6

Humeroulnar joint, Humeroradial joint and Proximal radioulnar joint share one joint capsule and are often referred to as the elbow joint
Elbow Joint is a compound synovial joint - has Anterior and Posterior Fat Pads within the joint capsule
Closed packed is full extension

Question 7

Humeroulnar joint

Answer 7

• trochlea of humerus and trochlear notch of ulnar
• incongruent:
• in full flexion the medial part of the trochlea and trochlear notch are close together,
• in full extension the lateral part of the trochlea and trochlear notch are close together
• This leads to a lateral excursion of the forearm during extension (carrying angle = 5-30°)
• Shape of trochlea varies: in full flexion resting position of hand will vary b/w individuals
• The trochlear notch is deeper than is needed to hold the trochlea: when unloaded only a small area of “contact” exists between surfaces

Question 8

Humeroradial joint

Answer 8

capitulum of humerus and proximal surface of head of radius

has also been classified as a ball and socket joint

Question 9

Proximal radioulnar joint

Answer 9

circumference of head of radius and radial notch of ulna

Question 10

Distal radioulnar joint

Answer 10

head of ulna and ulnar notch of radius

Question 11

Radial collateral ligament

Answer 11

lateral epicondyle > olecranon and annular ligament

Question 12

Ulnar collateral ligament

Answer 12

medial epicondyle > olecranon and coronoid process

Stroner of the 2 collateral ligaments

Question 13

Annular ligament

Answer 13

anterior margin of radial notch > posterior margin of radial notch
has articular cartilage on inside

Question 14

Radioulnar Joints

Answer 14

Proximal radioulnar joint
Distal radioulnar joint:
- head of ulna 3/4 covered by articular cartilage
- Triangular articular disc supports this joint and separates it from the radiocarpal joint
The interosseous membrane
(sometimes named the middle radioulnar joint) is a fibrous joint which binds the radius and ulna together, transmits forces from one to the other and becomes taut at a position midway between supination and pronation