Elbow, forearm and wrist

Question 1

What are the bones of the elbow, forearm and wrist?

Answer 1

Humerus
Radius
Ulna
Carpal bones (from lateral to medial):
-Proximal row: scaphoid, lunate, triquetrum, pisiform
-Distal row: trapezium, trapeze, capitate, hamate

Question 2

What are the muscles of the anterior compartment of the arm?

Answer 2

Biceps brachii
Brachialis
Coracobrachialis

Question 3

What are the muscles of the posterior compartment of the arm?

Answer 3

Triceps

Anconeus

Question 4

What are the muscles of the superior anterior compartment of the arm?

Answer 4

Pronator teres
Flexor carpi radialis (FCR)
Palmaris longus (PL)
Flexor digitorum superficialis (FDS)
Flexor carpi ulnaris (FCU)

Question 5

What are the muscles of the deep anterior compartment of the arm?

Answer 5

Flexor digitorum profundus (FDP)
Flexor pollicis longus (FPL)
Pronator quadratura (PQ)

Question 6

What are the muscles of the extensor compartment of the arm that move the wrist joint?

Answer 6

Extensor carpi radialis longus (ECRL)
Extensor carpi radialis brevis (ECRB)
Extensor carpi ulnari (ECU)

Question 7

What are the muscles of the extensor compartment of the arm that move the digits?

Answer 7

Extensor digitorum (ED)
Extensor indicis (EI)
Extensor digitorum minimi (EDM)

Question 8

What are the muscles of the extensor compartment of the arm that move the thumb?

Answer 8

Abductor pollicis longus (APL)
Extensor pollicis brevis (EPB)
Extensor pollicis longus (EPL)

Question 9

What type of joint is the elbow joint?

Answer 9

Synovial hinge joint between the humerus proximally and the ulna and radius distally.

Question 10

What does the distal humerus articulate with?

Answer 10

Ulna via trochlea

Radius via capitulum

Question 11

What are the important ligaments at the elbow which contribute to the stability of the joint?

Answer 11

Medial (ulnar) collateral ligaments
Lateral (radial) collateral ligaments
Annular ligament (part of the proximal radio-ulnar joint)

Question 12

What are the main flexors of the elbow?

Answer 12

Brachialis
Biceps brachii
Brachioradialis
Some assistance from pronator teres

Question 13

What are the extensors of the elbow?

Answer 13

Triceps

Anconeus

Question 14

What is the carrying angle?

Answer 14

The deviation of the long axis of the radius and ulna from that of the humerus (in extension). It is greater in women than men and averages 7 degrees.

Question 15

What type of joint is the proximal radio-ulnar joint?

Answer 15

Uni-axial pivot-type synovial joint that allows the head of the radius to rotate within the annular ligament that attaches it to the margins of the radial notch of the ulna.

Question 16

What type of joint is the distal radio-ulnar joint?

Answer 16

Pivot-type synovial joint that allows the radius to rotate around the distal ulna and the articular surfaces are held together by a fibrocartilage articular disc.

Question 17

What movements take place at the proximal and distal radio-ulnar joints?

Answer 17

Supination and pronation

Question 18

What muscles produce supination of the upper limb?

Answer 18

Supinator, biceps brachii

Question 19

What muscles produce pronation of the upper limb?

Answer 19

Pronator quadrates, pronator teres

Question 20

What is the interosseous membrane of the forearm?

Answer 20

Fibrous sheet that connects the radius and ulna, forming a fibrous joint (syndesmosis) between the 2 bones.
Divides the forearm into anterior and posterior compartments, gives rise to muscle attachments and transfers forces from the radius to the ulna to the humerus and vice versa.

Question 21

What type of joint is the wrist joint?

Answer 21

Elipsoid synovial joint between the distal radius and its associated triangular fibrocartilage articular disc, with the proximal row of the carpal bones (scaphoid, lunate and triquetrum).

Question 22

What are the strong ligaments that stabilise the wrist joint?

Answer 22

Ulnar collateral ligament
Radial collateral ligament
Palmar radio-carpal ligament
Palmar ulno-carpal ligament
Dorsal radio-carpal ligament
Inter-carpal ligaments

Question 23

What muscles provide flexion at the wrist joint?

Answer 23

FCR - important
FCU - important
Long flexors of the thumb and fingers
Palmaris longus
APL

Question 24

What muscles provide extension at the wrist joint?

Answer 24

ECRL – important
ECRB – important
ECU – important
Long extensors of the thumb and fingers

Question 25

What muscles provide radial deviation at the wrist joint?

Answer 25

``` FCR ECRL ECRB APL Extensor pollicis brevis ```

Question 26

What muscles provide ulnar deviation at the wrist joint?

Answer 26

ECU | FCU

Question 27

Describe the path of the ulnar artery.

Answer 27

Descends in the anterior compartment of the forearm and passes into the hand anteriorly, on the ulnar side of the wrist (just lateral to FCU). The ulnar nerve lies medial to it at the wrist joint, i.e. from medial to lateral, the relationships are FCU, ulnar nerve, ulnar artery.

Question 28

What does the ulnar artery supply in the forearm?

Answer 28

Medial muscles of the forearm, via branches including the common interosseous artery, the anterior interosseous artery and the posterior interosseous artery.

Question 29

Describe the path of the radial artery.

Answer 29

Descends the lateral aspect of the forearm under the cover of the brachioradialis muscle. It is easily palpable at the wrist where it lies anteriorly on its radial aspect. Crosses the floor of the anatomical snuff box and ultimately anastomosis with branches of the ulnar artery to form the palmar arches.

Question 30

What connects the cephalic and basilic veins at the level of the elbow, and what is its clinical significance?

Answer 30

Median cubital vein- common site for venipuncture, variable in its anatomy.

Question 31

What are the 3 main nerves of the forearm?

Answer 31

Ulnar nerve Median nerve Radial nerve

Question 32

Describe the path of the ulnar nerve (C8,T1).

Answer 32

Has no branches in the arm and initially descends in its anterior compartment, but distally passes into the posterior compartment to lie superficially, posterior to the medial epicondyle of the elbow, where it is at risk of damage. Enters the forearm passing between the heads of flexor carpi ulnaris, then descends on the medial side of the forearm where it supplies the more medial muscles in the anterior compartment.

Question 33

What does the ulnar nerve (C8,T1) supply in the forearm?

Answer 33

Flexor carpi ulnaris (FCU). Medial portion of flexor digitorum profundus (FDP), i.e. to the ring and little fingers. Sensory supply to the medial aspect of the ventral forearm. At the wrist, it lies between the FCU (medially) and the ulnar artery (laterally) and then passes into the hand where it supplies most of the intrinsic muscles.

Question 34

Describe the path of the median nerve (C678,T1).

Answer 34

Descends in the anterior compartment of the arm, within which it does not give any branches. Anterior to the elbow, it lies medial to the brachial artery, where it is at risk of damage by supracondylar fractures of the humerus. Descends into the forearm between the heads of pronator teres to become the principal motor nerve of the anterior compartment. At the anterior wrist, the median nerve lies quite superficially between the tendons of FDS and FDP and deep to palmaris longus (if present), prior to entering the hand through the carpal tunnel.

Question 35

What does the median nerve (C678,T1) supply?

Answer 35

``` Pronator teres FDS Lateral portion of FDP (to the index and middle fingers) FCR Pronator quadratus Palmaris longus ```

Question 36

What does the radial nerve (C5678,T1) supply?

Answer 36

Posterior (extensor) compartment of the arm. In the forearm: brachioradialis, ECL. Deep branch: ECRB, supinator.

Question 37

Describe the path of the radial nerve (C5678,T1).

Answer 37

It lies on the humerus in the radial (spiral) groove where it is at risk in humeral shaft fractures. Just superior to the elbow it divides into the superficial radial nerve (cutaneous sensory) and the deep branch of the radial nerve (motor), which descends into the forearm between the heads of supinator, to be come the posterior interosseous nerve and to supply all of the muscles of the posterior (extensor) compartment of the forearm and it ends as a pseudoganglion below the extensor retinaculum.

Question 38

What does the posterior interosseous nerve supply?

Answer 38

``` ED ED minimi ECU APL EPB EPL E indicis ```