Forearm and wrist

Question 1

What are the bones in the wrist and name the carpal bones

Answer 1

27 bones in the hand
8 carpal bones
5 metacarpals
14 phalanges

carpal bones (from radial to ulnar side)
prox. row: scaphoid, lunate, triquetrum, pisiform
distal row: trapezium, trapezoid, capitate, hamate

Question 2

What is important about muscles leading to the wrist?

Answer 2

All muscles involved in
movements of the wrist are
extrinsic to the hand; i.e.,
they have bellies in the
forearm and send tendons
to the hand

Question 3

What are the types of joint in the hand

Answer 3

Wrist joint
- synovial joint between radius and articular disc
overlying ulna, and the proximal carpal bones
- allows abduction/adduction and
flexion/extension (circumduction)

Midcarpal joint
- between proximal and distal row of carpal
bones
- limited flexion/extension

Carpometacarpal (CMC) joints
d2-5: very limited range of motion
d1: articulation is saddle-shaped, permitting
flexion/extension, abduction/adduction, and
opposition

Metacarpo-phalangeal (MP) joints
d2-5: flexion/extension, abduction/adduction,
circumduction
d1: hinge joint, only flexion/extension
Interphalangeal (IP) joints
- hinge joints, flexion/extension

Question 4

What are the anterior muscles of the arm in the superficial layer

Answer 4

Flexor carpi ulnaris
Palmaris longus (variable)
Flexor carpi radialis
Pronator teres

Origin – medial epicondyle of
humerus, with some off ulna
Insertion – hand, except for
pronator teres

Innervation – median nerve (C5-
T1), except flexor carpi ulnaris by
the ulnar nerve (C7-T1)

Action – flexion and
abduction/adduction of wrist,
pronation

Question 5

Describe flexor carpi ulnaris

Answer 5

Flexor carpi ulnaris

Origin – humeral head (medial
epicondyle of humerus) and ulnar
head (olecranon and posterior border
of ulna)

Insertion – pisiform, then to hamate
and base of 5th metacarpal (by
ligaments)

Innervation – ulnar n. (C7, C8, T1)
Action – flexion and adduction of wrist
Relations – ulnar nerve passes
between the two heads of the muscle

Question 6

Describe palmaris longus

Answer 6

Palmaris longus
Origin – medial epicondyle
Insertion – continuous with palmar
aponeurosis
Innervation – median n. (C7, C8)
Action – tightening of palm skin (+
some wrist flexion)

Question 7

Describe flexor carpi radialis

Answer 7

Flexor carpi radialis
Origin – medial epicondyle
Insertion – bases of metacarpals II
and III
Innervation – median n. (C6, C7)
Action – flexion and abduction of
wrist

Question 8

Describe pronator teres

Answer 8

Pronator teres
Origin – humeral head (medial
epicondyle) and ulnar head
(coronoid process of ulna)
Insertion – lateral midshaft of
radius
Innervation – median n. (C6, C7)
Action – pronation of forearm
Relations – median nerve passes
between the two heads

Question 9

Describe the muscle in the intermediate layer of the anterior arm

Answer 9

Intermediate Layer
Flexor digitorum superficialis

Origin – medial epicondyle and coronoid
process (humero-ulnar head) and oblique
line of radius (radial head)
Insertion – margins of middle phalanges
(digits II-V)
Innervation – median nerve (C8, T1)
Action – flexes wrist,
metacarpophalangeal joints, first
interphalangeal joints (II – V)
Relations – ulnar artery and median
nerve run between the heads of the
muscle

Question 10

What are the deep muscles in the anterior forearm- flexor pollicus longus

Answer 10

Flexor pollicis longus
Origin – anterior surfaces of radius and the
interosseous membrane
Insertion – base of the distal phalanx of digit I
Innervation – median nerve (C7, C8)
Action – flexes metacarpophalangeal and
interphalangeal joint of digit I

Question 11

Anterior deep layer- describe pronator quadratus

Answer 11

Pronator quadratus
Origin – anterior surface of distal
part of ulna
Insertion – anterolateral surface of
distal radius
Innervation – median nerve (C7, C8)
Action – pronation of forearm

Question 12

List the muscles in the superficial posterior forearm

Answer 12

Brachioradialis
Extensor carpi radialis longus
Extensor carpi radialis brevis
Extensor digitorum
Extensor digiti minimi
Extensor carpi ulnaris
Anconeus

Origin – lateral supraepicondylar ridge
and epicondyle
Insertion – various
Action – flexes and supinates forearm,
moves wrist, extends fingers

Question 13

Posterior superficial forearm- describe brachoradialis

Answer 13

Brachioradialis
Origin – lateral supraepicondylar
ridge
Insertion – lateral surface of distal
radius
Innervation – radial nerve (C5, C6)
Action – flexes elbow when arm is
partially pronated

Question 14

Posteriorm superficial forearm- extensor carpi radialis longus and brevis

Answer 14

Superficial Layer:
Extensor carpi radialis longus and
brevis
Origin – lateral supraepicondylar
ridge (longus) and lateral
epicondyle (longus and brevis)
Insertion – base of metacarpal II
(longus and brevis) and III (brevis)
Innervation – radial nerve (C6, C7,
C8)
Action – extends and abducts wrist

Question 15

posterior superficial forearm- extensor digitorium

Answer 15

Superficial Layer:
Extensor digitorum
Origin – lateral epicondyle
Insertion – extensor hoods of digits
II - V
Innervation – radial nerve, posterior
interosseous (C7, C8)
Action – extends digits II – V and the
wrist

Question 16

posterior superficial forearm- extensor digiti minimi

Answer 16

Extensor digiti minimi

Origin – lateral epicondyle
Insertion – extensor hood of digit V
Innervation – radial nerve, posterior
interosseous (C7, C8)
Action – accessory extensor of digit
V

Question 17

posterior superficial forearm- extensor carpi ulnaris

Answer 17

Extensor carpi ulnaris
Origin – lateral epicondyle
Insertion – base of metacarpal V
Innervation – radial nerve, posterior
interosseous (C7, C8)
Action – extends and adducts the
wrist

Question 18

posterior superficial forearm- anconeous

Answer 18

Anconeus
Origin – lateral epicondyle
Insertion – olecranon and posterior
surface of ulna
Innervation – radial nerve (C6 – C8)
Action – abducts ulna during
pronation to maintain position of the
hand

Question 19

What are the muscles in the deep layer of the posterior forearm

Answer 19

Supinator
Abductor pollicis longus
Extensor pollicis brevis
Extensor pollicis longus
Extensor indicus

Origin – lateral epicondyle
(supinator only), posterior surfaces
of radius and/or ulna and
interosseous membrane
Insertion – various
Action –extends fingers, supinates
forearm, moves thumb

Question 20

Deep layer posterior forearm- abductor pollicis longus

Answer 20

Abductor pollicis longus

Origin – posterior surfaces of
radius and ulna, and the
interosseous membrane
Insertion – lateral side of
metacarpal I
Innervation – radial nerve,
posterior interosseous (C7, C8)
Action – abducts thumb

Question 21

Deep layer posterior forearm- extensor pollicis brevis and longus

Answer 21

Extensor pollicis brevis and longus
Origin – posterior radius (brevis),
posterior ulna (longus) and
interosseous membrane (both)
Insertion – proximal phalanx of
digit I (brevis) and distal phalanx
digit I (longus)
Innervation – radial nerve,
posterior interosseous (C7, C8)
Action – extends the thumb

Question 22

Deep layer posterior forearm- extensor indicus

Answer 22

Extensor indicus
Origin – posterior ulna and
interosseous membrane
Insertion – extensor hood of digit II
Innervation – radial nerve,
posterior interosseous (C7, C8)
Action – extends digit II

Question 23

What are the blood vessels of the forearm

Answer 23

Radial artery
Down lateral aspect of arm under
brachioradialis, blood to
posterolateral aspect of hand; gives
off the superficial palmer branch
Ulnar artery
Medial side of forearm with nerve,
enters hand superficial to carpal
tunnel, supplies blood to forearm
and hand
Common interosseous
(usually) Branch of ulnar a.
Anterior and posterior branches to
supply both compartments of
forearm

Question 24

What is the significance of the pulses in the forearm

Answer 24

Brachial pulse
medial to biceps tendon in the
cubital fossa (last lecture)
Radial pulse
at the wrist, the radial artery lies
immediately lateral to the
tendon of flexor carpi radialis

Question 25

What are the nerves in the forearm

Answer 25

Median nerve
Innervates anterior forearm muscles
(except FCU and medial ½ of FDP),
passes through cubital fossa, down
anterior aspect of arm and through
carpal tunnel, two branches

Ulnar nerve
Innervates FCU and medial ½ of FDP in
arm; around back of medial
epicondyle of elbow, down medial
edge of arm (with ulnar artery) and
enters hand above carpal tunnel,
two branches

Radial nerve
Anterolateral superficial branch is
sensory; around front of lateral
epicondyle then gives superficial
and deep branch (=post.
interosseus)

Question 26

What is carpal tunnel syndrome

Answer 26

• Compression of median nerve due to
  swelling of tendons and sheath
• Patients report pain and numbness in
  distribution of median nerve
• Weakness and eventual atrophy of thenar
  muscles