Download Medical Gross Anatomy Movements of the Upper Limb

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Movements of the Upper Limb - Introduction
This module presents the nomenclature of movement at the joints of the
upper limb. When you first approach the upper limb, concentrate on the
motions and less on the names of muscles producing those motions. After your
study of the upper limb, use this module to review and summarize muscle
actions in the upper limb.
The upper limb is our primary tool for manipulating the environment,
and therefore it is highly mobile. There is a great number of joints within the
entire upper limb, allowing for this great mobility.
In comparing the upper and lower limbs, it is evident that the upper limb
is specialized as the organ of manipulation, and the lower limb serves for
locomotion. To serve these purposes, the upper limb emphasizes mobility and
sacrifices stability, while the lower limb emphasizes stability and sacrifices
mobility. The contrast is perhaps most striking when comparing the mobile
pectoral girdle (clavicles and scapulae) to the rigid pelvic girdle (os coxae and
sacrum).
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Scapular Protraction and Retraction
Protraction of the
scapula is sometimes
called abduction of the
scapula. The scapula is
moved laterally and
anteriorly along the chest
wall.
Muscles: serratus
anterior is the prime
mover. Pectoralis minor
and major, the latter
acting through the
humerus, may assist (act
as synergists).
Retraction of the
scapula is sometimes
called adduction of the
scapula. The scapula is
moved posteriorly and
medially along the chest
wall.
Muscles:
rhomboideus major,
minor, and trapezius are
the prime movers.
The muscles that
protract and retract the
scapula are antagonistic,
that is, they have
opposed actions. Used
together, they fix the
scapula in space to
provide a fulcrum from
which to move the
(lever) arm.
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Scapular Elevation and Depression
Elevation of the scapula moves the scapula superiorly. It is not
synonymous with upward rotation of the scapula
Muscles: levator scapulae and the upper fibers of trapezius.
Depression of the scapula moves the scapula inferiorly. It is not
synonymous with downward rotation of the scapula.
Muscles: pectoralis minor, the lower fibers of trapezius, subclavius
(through clavicle), and latissimus dorsi (through the humerus).
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Scapular Upward and Downward Rotation
The scapula can
pivot on its attachment
to the clavicle, and rotate
upward. This is also
called upward rotation of
the glenoid fossa, and it
is an essential motion for
completing abduction of
the arm.
Muscles: trapezius
and serratus anterior are
synergists.
When the arm is
fully abducted,
downward rotation of
the scapula (or glenoid
fossa) occurs first in
adduction of the arm.
Muscles: pectoralis
minor and major
(through humerus),
subclavius, and
latissimus dorsi (through
the humerus).
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Arm Abduction
Abduction of the arm is also called
abduction of/at the shoulder. This motion
actually can be divided into two motions:
true abduction of the arm at the shoulder
and upward rotation of the scapula.
Muscles: supraspinatus (initiates
abduction - first 15 degrees), deltoid (up
to 90 degrees), trapezius and serratus
anterior (scapular rotation, for abduction
beyond 90 degrees).
The deltoid muscle abducts the arm, but at 90 degrees the humerus bumps into the acromion. Beyond this point, further
abduction is the result of upward scapular rotation.
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Arm Adduction
Adduction of the arm is also called
adduction of/at the shoulder. This motion
can be divided into two motions:
downward rotation of the scapula and
true adduction of the arm at the shoulder.
Muscles: pectoralis major and
minor, latissimus dorsi, teres major,
gravity (depending on body position),
and even the lowest fibers of the deltoid
(making deltoid its own antagonist)
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Arm Flexion and Extension
Flexion of the arm
is also called flexion of/
at the shoulder. It is
typically thought of as
an anterior excursion of
the arm, but remember
that any motion away
from full extension is
flexion.
Muscles: pectoralis
major, coracobrachialis,
biceps brachii, anterior
fibers of deltoid.
Extension of the
arm is also called
extension of/at the
shoulder. It is typically
thought of as movement
of the arm posteriorly,
but remember that any
motion away from full
flexion is extension.
Muscles: latissimus
dorsi and teres major,
long head of triceps,
posterior fibers of the
deltoid.
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Arm Medial and Lateral Rotation
Medial rotation of the arm or humerus can best be seen when the
elbow is flexed and the hand is moved toward the midline.
Muscles: subscapularis, latissimus dorsi, teres major, pectoralis
major, anterior fibers of deltoid.
With the elbow flexed, lateral rotation moves the hand away from
the midline.
Muscles: infraspinatus and teres minor, posterior fibers of deltoid.
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Arm Circumduction
Circumduction at a joint is a motion that circumscribes a
cone. The shoulder, being the most mobile joint in the body,
can circumscribe the largest cone.
Muscles: pectoralis major, subscapularis,
coracobrachialis, biceps brachii, supraspinatus, deltoid,
latissimus dorsi, teres major and minor, infraspinatus, long
head of triceps.
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Forearm Flexion and Extension
Flexion of the
forearm is also known as
elbow flexion.
Muscles: biceps
brachii, brachialis, and
brachioradialis.
Extension of the
forearm is also called
elbow extension.
Muscles: triceps
brachii and anconeus.
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Hand Supination and Pronation
Supination of the
hand brings the palm to
face forward in the
anatomical position. It is
the position you would
place your hand in order
to hold "soup".
Muscles: biceps
brachii and supinator.
Brachioradialis can
return the pronated hand
to a position mid-way
between supination and
pronation.
Pronation of the
hand brings the palm to
face posteriorly in the
anatomical position, or
face down when lying
down.
Muscles: pronator
teres and pronator
quadratus.
Brachioradialis can
return the supinated hand
to a position mid-way
between supination and
pronation.
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Wrist Flexion and Extension
Flexion at the wrist
might also be called
flexion of the hand, but
it usually isn't.
Muscles: all of the
flexor muscles crossing
the wrist joint, but
especially the flexor
carpi radialis and flexor
carpi ulnaris.
Extension at the
wrist might also be
called extension of the
hand, but it usually isn't.
Muscles: all of the
extensor muscles that
cross the wrist joint, but
especially the extensor
carpi radialis longus and
brevis and the extensor
carpi ulnaris.
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Wrist Abduction and Adduction
Abduction at the wrist is also called radial deviation
of the hand, because the hand moves toward the radius, or
laterally.
Muscles: flexor carpi radialis and extensor carpi
radialis longus and brevis.
Adduction at the wrist is also called ulnar deviation of
the hand, because the hand moves medially toward the ulna.
Muscles: flexor and extensor carpi ulnaris.
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Finger Abduction and Adduction
Abduction of the digits of the hand is defined as moving away from
the midline of the hand, which is the middle digit. Abduction, then,
spreads the fingers.
Muscles: dorsal interossei.
Adduction of the fingers returns them toward the midline, or the
middle finger. This brings the fingers together.
Muscles: palmar interossei.
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Thumb Abduction and Adduction
The thumb is set at an angle to the plane of the other four digits, so
that thumb abduction brings it slightly palmar as it moves away from the
middle finger.
Muscles: abductor pollicis longus and brevis.
The plane of abduction/adduction of the thumb is at an angle to the
other digits, but thumb adduction returns the thumb to a position beside
the second digit, and toward the third finger.
Muscles: adductor pollicis.
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Opposition
Opposition is the motion of both thumb and little finger that bring their tips to
touch.
Opposition is a fairly complex movement involving multiple muscles. The thumb
is first abducted, and then flexed while the metacarpal is pulled toward the fifth digit.
Muscles: abductor pollicis longus and brevis, opponens pollicis and opponens
digiti minimi, flexor pollicis longus and flexor digitorum profundus.
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Finger flexion and extension
The four fingers have 3 different joints at which they
can flex or extend - the metacarpophalangeal (MP) joint,
the proximal interphalangeal (PIP) joint, and the distal
interphalangeal (DIP) joint. Some muscles may flex one of
these while extending the other two, or flex two and have
no effect on the third.
Muscles: interossei and lumbricals flex the MP while
extending the PIP and DIP joints; flexor digitorum
superficialis flexes the MP and PIP joints only, while
flexor digitorum profundus flexes all three, and is the only
muscle capable of flexing the DIP joint.
Extension of the fingers occurs at the same 3 joints,
but there is no muscle that extends only the DIP joint.
Muscles: interossei and lumbricals extend the PIP and
DIP joints while flexing the MP joint; extensor digitorum
(communis) extends all 3 joints for all 4 digits, although
due to tendinous connections between adjacent extensor
tendons there may not be independent movement of all
fingers; extensor indicis also extends the index finger
(independently) and extensor digiti minimi extends the
little finger (independently)
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Thumb flexion and extension
In contrast to the fingers, the thumb can flex at only
two joints - the metacarpophalangeal joint and an
interphalangeal (IP) joint, since it has only two phalanges.
Flexion of the thumb takes place in a plane at an angle to
the other digits. When flexed, the thumb points generally
toward the 5th MP joint.
Muscles: flexor pollicis brevis flexes the MP joint
only, while flexor pollicis longus flexes both the MP and
IP joints, and is the only muscle to flex the IP joint.
Extension of the thumb also occurs in a plane offset
from that of the fingers, but the motion has the same effect
of taking the thumb posteriorly in the anatomical position.
Muscles: extensor pollicis brevis extends the MP joint
only, while extensor pollicis longus extends the MP and IP
joints, and is the only muscle to extend the IP joint.
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