Forearm and wrist Flashcards
What are the bones in the wrist and name the carpal bones
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
What is important about muscles leading to the wrist?
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
What are the types of joint in the hand
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
What are the anterior muscles of the arm in the superficial layer
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
Describe flexor carpi ulnaris
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
Describe palmaris longus
Palmaris longus
Origin – medial epicondyle
Insertion – continuous with palmar
aponeurosis
Innervation – median n. (C7, C8)
Action – tightening of palm skin (+
some wrist flexion)
Describe flexor carpi radialis
Flexor carpi radialis
Origin – medial epicondyle
Insertion – bases of metacarpals II
and III
Innervation – median n. (C6, C7)
Action – flexion and abduction of
wrist
Describe pronator teres
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
Describe the muscle in the intermediate layer of the anterior arm
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
What are the deep muscles in the anterior forearm- flexor pollicus longus
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
Anterior deep layer- describe pronator quadratus
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
List the muscles in the superficial posterior forearm
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
Posterior superficial forearm- describe brachoradialis
Brachioradialis
Origin – lateral supraepicondylar
ridge
Insertion – lateral surface of distal
radius
Innervation – radial nerve (C5, C6)
Action – flexes elbow when arm is
partially pronated
Posteriorm superficial forearm- extensor carpi radialis longus and brevis
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
posterior superficial forearm- extensor digitorium
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
posterior superficial forearm- extensor digiti minimi
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
posterior superficial forearm- extensor carpi ulnaris
Extensor carpi ulnaris
Origin – lateral epicondyle
Insertion – base of metacarpal V
Innervation – radial nerve, posterior
interosseous (C7, C8)
Action – extends and adducts the
wrist
posterior superficial forearm- anconeous
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
What are the muscles in the deep layer of the posterior forearm
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
Deep layer posterior forearm- abductor pollicis longus
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
Deep layer posterior forearm- extensor pollicis brevis and longus
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
Deep layer posterior forearm- extensor indicus
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
What are the blood vessels of the forearm
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
What is the significance of the pulses in the forearm
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
What are the nerves in the forearm
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)
What is carpal tunnel syndrome
- 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
