3-4 Forearm and Hand
Muscles of the Forearm
• Anterior Compartment
– Superficial layer
– Intermediate layer
– Deep layer
• Posterior Compartment
– Superficial Layer
– Deep Layer
Anterior Compartment: Superficial
Layer
Flexor Carpi Ulnaris
•Origin
•Humeral head—medial
epicondyle;
•ulnar head—olecranon and
posterior border of ulna
•Insertion
•Pisiform bone (via pisohamate
and pisometacarpal ligaments
into the hamate and base of
metacarpal V)
•Innervation
•Ulna nerve (C7, C8, T1)
•Function
•Flexes and adducts the wrist joint
Palmaris Longus
•Origin
•Medial epicondyle of humerus
•Insertion
•Palmar aponeurosis of hand
•Innervation
•Median Nerve (C7, C8)
•Function
•Flexes wrist joint;
• because the palmar aponeurosis
anchors the skin of the hand,
contraction of the muscle resists
shearing forces when gripping
Flexor Capri Radialis
•Origin
•Medial epicondyle of humerus
•Insertion
•Base of metacarpals II and III
•Innervation
•Median Nerve (C6, C7)
•Function
•Flexes and abducts the wrist
Pronator teres
•Origin:
•Humeral head—medial
epicondyle and adjacent
supraepicondylar ridge
• ulna head—medial side of
coronoid process
•Insertion
•Roughening on lateral surface,
midshaft, of radius
•Innervation
•Median Nerve (C6-C7)
•Function
•Pronation
Anterior Compartment: Intermediate
Layer
Flexor Digitorum
Superficialis
•Origin
•Humero-ulnar head—medial
epicondyle of the humerus and
adjacent margin of coronoid
process
•radial head—oblique line of the
radius
•Insertion
•4 Tendons, which attach to the
palmar surfaces of the middle
phalanges (index, middle, ring,
and little fingers)
•Innervation
•Median nerve (C8, T1)
•Function
•Flexes proximal interphalangeal
joints of the fingers; also flexes
metacarpophalangeal joints
Anterior Compartment: Deep Layer
Flexor Digitorum
Profundus
•Origin:
•Anterior and medial surfaces of
the ulna and anterior medial half
of interosseous membrane
•Insertion
•Four tendons, which attach to
the palmar surfaces of the distal
phalanges of the index, middle,
ring and little finger
•Innervation
•Lateral half by median nerve
(ant. Interosseous nerve); medial
half by ulna nerve (C8, T1)
•Function
•Flexes distal interphalangeal
joints of the fingers; can also flex
metacarpophalangeal joints of
same fingers and wrist joint
Flexor pollicis longus
•Origin
•Anterior surface of the radius
and radial half of interosseous
membrane
•Insertion
•Palmar surface of the base of
distal phalanx of thumb
•Innervation
•Median Nerve (anterior
interosseous n.) (C7, C8)
•Function
•Flexes interphalangeal joint of
the thumb; can also flex
metacarpophalangeal joint of the
Thumb
Pronator quadratus
•Origin
•Linear ridge on distal anterior
surface of ulna
•Insertion
•Distal anterior surface of radius
•Innervation
•Median Nerve (anterior
interosseous nerve) (C7, C8)
•Function
•Pronation
Posterior Compartment: Superficial
Layer
Brachioradialis
•Origin
•Proximal part of lateral
supraepicondylar ridge of
humerus and adjacent
intermuscular septum
•Insertion
•Lateral surface of distal end of
radius
•Innervation
•Radial nerve (C5, C6) before
division into superficial and deep
branches
•Function
•Accessory flexor of elbow joint
when forearm is midpronated
Extensor Carpi Radialis
Longus
•Origin
•Distal part of lateral
supraepicondylar ridge of
humerus and adjacent
intermuscular septum
•Insertion
•Dorsal Surface of base of
metacarpal II
•Innervation
•Radial Nerve (C6, C7) before
division into superficial and deep
branches
•Function
•Extends and abducts the wrist
Extensor Carpi Radialis
Brevis
•Origin
•Lateral epicondule of humerus
and adjacent intermuscular
septum
•Insertion
•Dorsal surface of base of
metacarpals II and III
•Innervation
•Deep branch of radial nerve (C7,
C8) before penetrating supinator
muscle
•Function
•Extends and abducts the wrist
Extensor Digitorum
•Origin
•Lateral epicondyle of humerus
and adjacent intermuscular
septum and deep fascia
•Insertion
•4 tendons, insert via extensor
hoods into the dorsal aspects of
the bases of the middle and distal
phalanges
•Innervation
•Posterior interosseous nerve (C7,
C8)
•Function
•Extends the fingers; also can
extend wrist
Extensor digiti minimi
•Origin
•Lateral epicondyle of humerus
and adjacent intermuscular
septum together with extensor
digitorum
•Insertion
•Extensor hood of the little finger
•Innervation
•Posterior interosseous nerve (C7,
C8)
•Function
•Extends the little finger
•“Tea muscle”
Extensor Carpi Ulnaris
•Origin
•Lateral epicondyle of humerus
and posterior border of ulna
•Insertion
•Tubercle on the base of the
medial side of metacarpal V
•Innervation
•Posterior interosseous nerve (C7,
C8)
•Function
•Extends and adducts the wrist
Anconeus
•Origin
•Lateral epicondyle of humerus
•Insertion
•Olecranon and proximal
posterior surface of ulna
•Innervation
•Radial Nerve (C6, C7, C8)…via
branch to medial head of triceps
brachii)
•Function
•Abduction of the ulna in
pronation; accessory extensor of
the elbow joint
Posterior Compartment: Deep Layer
Supinator
•Origin
•Superficial part—lateral
epicondule of humerus, radial
collateral and unular ligaments
•Deep part—supinator crest of
the ulna
•Insertion
•Lateral surface of radius superior
to the anterior oblique line
•Innervation
•Posterior interosseous nerve (C6,
C8)
•Function
•Supination
Abductor pollicis longus
•Origin
•Posterior surfaces of ulna and
radius (distal to the attachments
of supinator and anconeus), and
intervening interosseous
membrane
•Insertion
•Lateral side of base of
metacarpal I
•Innervation
•Posterior interosseous nerve (C7,
C8)
•Function
•Abducts carpometacarpal joint of
thumb; accessory extensor of the
thumb
Extensor pollics brevis
•Origin
•Posterior surface of radius (distal
to abductor pollicis longus) and
the adjacent interosseous
membrane
•Insertion
•Dorsal surface of base of
proximal phalanx of the thumb
•Innervation
•Posterior interosseous nerve (C7,
C8)
•Function
•Extends metacarpophalangeal
joint of the thumb; can also
extend the carpometacarpal joint
of the thumb
Extensor pollicus longus
•Origin
•Posterior surface of ulna (distal
to the abductor pollicis longus)
and the adjacent interosseous
membrane
•Insertion
•Dorsal Surface of base of distal
phalanx or thumb
•Innervation
•Posterior interosseous nerve (C7,
C8)
•Function
•Extends interphalangeal joint of
the thumb; can also extend
carpometacarpal and
metacarpophalangeal joints of
the thumb
Extensor indicis
•Origin
•Posterior surface of ulna (distal
to extensor pollicis longus) and
adjacent interosseous membrane
•Insertion
•Extensor hood of index finger
•Innervation
•Posterior interosseous nerve (C7,
C8)
•Funtion
•Extends index finger
Vessels
Radial Artery
Radial Recurrent Artery
Radial a. in “Snuffbox”
Ulna Artery
Common Interosseous Artery
Posterior Interosseous Artery
Anterior interosseous artery
Nerves
Median Nerve
Anterior Interosseous Branch
(Median n.)
Radial Nerve
Superficial Branch (Radial n.)
Deep Branch (Radial n.)
Posterior Interosseous Nerve (branch)
Posterior Antebrachial Cutaneous
Flexor Retinaculum
Carpal Tunnel
Extensor Retinaculum
Intertendinous Connections
Extensor Expansion
Hand Structures
Intrinsic Muscles of the Hand
• Thenar Muscles – 3 muscles associated with
the thumb
– Thenar Eminence = the prominent swelling on the
lateral side of the palm at the base of the thumb
• Hypothenar Muscles — 3 muscles associated
with the little finger
– Hypothenar Eminence = The swelling on medial
side of the palm at the base of the little finger
Opponens pollicis
•Origin
•Tubercle of trapezium and flexor
retinaculum
•Insertion
•Lateral margin and adjacent
palmar surface of metacarpal I
•Innervation
•Recurrent branch of median
nerve (C8, T1)
•Function
•Medially rotates thumb
Abductor pollicis brevis
•Origin
•Tubercles of scaphoid and
trapezium and adjacent flexor
retinaculum
•Insertion
•Proximal phalanx and extensor
hood of thumb
•Innervation
•Recurrent branch of median
nerve (C8, T1)
•Function
•Flexes thumb at
metacarpophalangeal joint
Flexor Pollicis Brevis
•Origin
•Tubercle of the trapezium and
flexor retinaculum
•Insertion
•Proximal Phalanx of the thumb
•Innervation
•Recurrent branch of median
nerve (C8, T1)
•Function
•Flexes thumb at
metacarpophalangeal joint
Opponens digiti minimi
•Origin
•Hook of hamate and flexor
retinaculum
•Insertion
•Medial aspect of metacarpal V
•Innervation
•Deep branch of ulna nerve (C8,
T1)
•Function
•Laterally rotates metacarpal V
Abductor Digiti Minimi
•Origin
•Pisiform, the pisohamate
ligament, and tendon of flexor
carpi ulnaris
•Insertion
•Proximal phalanx of little finger
•Innervation
•Deep Branch of ulna nerve (C8,
T1)
•Function
•Abducts little finger at
metacarpophalangeal joint
Flexor digiti minimi brevis
•Origin
•Hook of the hamate and flexor
retinaculum
•Insertion
•Proximal phalanx of little finger
•Innervation
•Deep branch of ulna nerve (C8,
T1)
•Function
•Flexes little finger at
metacarpophalangeal joint
Intrinsic muscles of hand: AdductorInterosseous Compartment
Adductor Pollicis
•Origin
•Transverse head—metacarpal III;
Oblique head—capitate and bases
of metacarpals II and III
•Insertion
•Base of proximal phalanx and
extensor hood of thumb
•Innervation
•Deep branch of ulna nerve
•Function
•Adducts Thumb
Palmar (Unipennate)
Interosseous (4 muscles)
•Origin
•Sides of metacarpals
•Insertion
•Extensor hoods of the thumb,
index, ring and little fingers and
the proximal phalanx of the
thumb
•Innervation
•Deep Branch of ulna nerve (C8,
T1)
•Function
•Adduction of the thumb, index,
ring, and little fingers at the
metacarpophalangeal joints
Dorsal (Bipennate)
Interosseous muscles (4)
•Origin
•Adjacent sides of metacarpals
•Insertion
•Extensor hood and base of
proximal phalanges of index,
middle, and ring fingers
•Innervation
•Deep Branch of ulna nerve (C8,
T1)
•Function
•Abduction of index, middle, and
ring fingers at the
metacarphphalangeal joints
Intrinsic Hand Muscles: Central
Compartment
Tendons of flexor
Digitorum superficialis
Tendons of Flexor
digitorum profundus
Lumbricals (4 Muscles)
•Origin
•Tendons of flexor digitorum
profundus
•Insertion
•Extensor hoods of index, ring,
middle, and little fingers
•Innervation
•Medial 2 by the deep branch of
the ulna nerve; lateral 2 by digital
branches of the median nerve
•Function
•Flex metacarpophalangeal joints
while extending interphalangeal
joints
Vessels: Branches of the Radial Artery
Superficial Palmar branch
(radial a.)
Princeps Pollicis (Radial a.
branch)
P. 416 GA
Deep Palmar Arterial Arch
(Radial a.)
Palmar metacarpal
arteries
Branches of Ulna Artery
Deep Palmar branch (Ulna
a.)
Superficial Palmar arterial
arch (Ulna a.)
Common palmar digital
arteries
Proper palmar digital
arteries
Nerves of the Hand
Common Digital branches
•Lateral 4 Branches are from
the Median n.
•Medial 2 Branches are from
the Ulna n.
Proper Digital Nerves
•Note that the Proper Digital
Nerves in the ring finger are
branched from both the ulna
and medial nerve
Deep Branch of the Ulna
n.
Recurrent Branch of the
Median Nerve
Innervates thenar muscles
Million dollar test
Superficial Branch of
Radial Nerve
Palmar Aponeurosis
Fibrous Digital sheaths