PBL Night Starvation
Muscular System & Muscles of the Upper Limb
Understand the concepts & associated principles, functional & clinical applications of muscle structure,
tendons and attachments. Be able to identify the major muscles in the upper limb. Comprehend the
organisation of muscles within different compartments of the upper limb, their nerve supply and actions.
The upper limb is designed for its’ mobility and ability to grasp, strike and conduct fine motor skills. The upper
limb is characterised into four segments.
Shoulder: includes the pectoral, scapular and lateral supraclavicular regions. The pectoral girdle is formed
posteriorly by the scapulae and clavicles and anteriorly by the manubrium of the sternum.
Arm: between shoulder and elbow and is centred around the humerus. Includes posterior and anterior
regions.
Forearm: is between the elbow and wrist and contains the ulna and radius. Consists of anterior and posterior
regions of the forearm.
Hand: distal to forearm and contains carpus, metacarpus and phalanges. It is composed of the wrist, palm,
dorsum of hand and digits (fingers, including the opposable thumb). The hand is richly supplied with sensory
endings for touch, pain and temperature.
ANTERIOR AXIOAPPENDICULAR MUSCLES
Muscle
Medial attachment
Lateral attachment
Pectoralis
major
Pectoralis
minor
Clavicular head:
anterior surface of
medial half of clavicle.
Sternocostal head:
anterior surface of
sternum, superior six
costal cartilages,
aponeurosis of external
oblique muscle.
3rd-5th ribs near their
costal cartilages.
Lateral lip of
intertubercular
sulcus (groove) of
humerus.
Innervation
Lateral and
medial pectoral
nerves; clavicular
head (C5, C6 ),
sternocostal head
(C7, C8, T1).
Main actions
Adducts and medially rotates
humerus; draws scapula
anteriorly and inferiorly.
Acting alone, clavicular head
flexes humerus and
sternocostal head extends it
from the flexed position.
Medial border and
Medial pectoral
Stabilizes scapula by drawing
superior surface of
nerve (C8, T1).
inferiorly and anteriorly
coracoid process of
against thoracic wall.
scapula.
Subclavius Junction of 1st rib and
Inferior surface of
Subclavian nerve Anchors and depresses
its costal cartilage.
middle third of
(C5, C6).
clavicle.
clavicle.
Serratus
External surfaces of
Anterior surface of
Long thoracic
Protracts scapula and holds
anterior
lateral parts of 1st-8th
medial border of
nerve (C5, C6,
against thoracic wall; rotates
ribs.
scapula.
C7).
scapula.
NB: bolded spinal cord segmented innervations refers to main innervation to that region.
POSTERIOR AXIOAPPENDICULAR MUSCLES
Muscle
Trapezius
Medial attachment
Medial third of superior
nuchal line; external
Lateral attachment
Lateral third of
clavicle; acromion
Innervation
Spinal accessory
nerve (CN XI)
Main actions
Descending (superior) part
elevates; ascending (inferior)
PBL Night Starvation
occipital protuberance; and spine of scapula
nuchal ligament;
spinous processes of C7T12 vertebrae
(motor fibres)
and C3, C4 spinal
nerves (pain and
proprioceptive
fibres).
part depresses; and middle
part(or all parts together)
retracts scapula; descending
and ascending parts act
together to rotate glenoid
cavity superiorly
Latissimus
dorsi
Spinous processes of
inferior 6 thoracic
vertebrae,
thoracolumbar fascia,
iliac crest, and inferior 3
or 4 ribs
Floor of
intertubercular
sulcus (groove) of
humerus
Thorocodorsal
nerve (C6, C7, C8)
Extends, adducts, and
medially rotates humerus;
raises body toward arms
during climbing.
Levator
scapulae
Posterior tubercles of
transverse processes of
C1-C4 vertebrae
Medial border of
scapula superior to
root of spine
Dorsal scapular
(C5) and cervical
(C3, C4) nerves
Elevates scapula and tilts its
glenoid cavity inferiorly by
rotating scapula
Rhomboid
minor and
major
Minor: nuchal ligament;
spinous processes of C7
and T1 vertebrae Major:
spinous processes of T2T5 vertebrae
minor: triangular
Dorsal scapular
area at medial end of nerve (C4, C5)
scapular spine
Major: medial
border of scapula
from level of spine to
inferior angle
SCAPULOHUMERAL (INTRINSIC SHOULDER) MUSCLES
Muscle
Medial attachment Lateral attachment
Deltoid
Lateral third of
Deltoid tuberosity of
Retract scapula and rotate it
to depress glenoid cavity; fix
scapula to thoracic wall
Innervation
Main actions
Axillary nerve (C5, Clavicular (anterior) part flexes
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clavicle; acromion
and spine of scapula
humerus
C6)
and medially rotates arm;
acromial (middle) part abducts
arm; spinal (posterior) part
extends and laterally rotates
arm
Suprapinatus
Supraspinous fossa
of scapula
Superior facet of
greater tubercle of
humerus
Suprascapular
nerve (C4, C5, C6)
Initiates and assists deltoid
in abduction of arm and acts
with rotator cuff muscles
Infraspinatus
Infraspinous fossa of
scapula
Middle facet of
greater tubercle of
humerus
Suprascapula
nerve (C5, C6)
Laterally rotates arm: and
acts with rotator cuff
muscles.
Teres minor
Middle part of lateral Inferior facet of
border of scapula
greater tubercle of
humerus
Axillary nerve (C5,
C6)
Laterally rotates arm: and
acts with rotator cuff
muscles.
Teres Major
Posterior surface of
inferior angle of
scapula
Medial lip of
intertubercular
sulcus of humerus
Lower
Adducts and medially rotates
subscapular nerve arm
(C5, C6)
Subscapularis
Subscapular fossa
(most anterior
surface of scapula)
Lesser tubercle of
humerus
Upper and lower
subscapular
nerves (C5, C6,
C7)
Medially roates arm; as part
of roator cuff, help hold
head of humerus in gelnoid
cavity
PBL Night Starvation
MUSCLES OF THE ARM
Muscle
Proximal attachment
Distal attachment
Innervation
Tuberosity of radius
and fascia of forearm
via bicipital
aponeurosis
Musculocutaneous nerve
(C5, C6 )
Middle third of
medial surface of
humerus
Muscle action
Supinates forearm and,
when it is supinated, flexes
forearm; flexes arm; short
head resists dislocation of
shoulder
Distal half of anterior
surface of humerus
Coronoid process
and tuberosity of
ulnar
Musculocutaneous nerve
(C5, C6 ) and
radial nerve (C5,
C7)
Flexes forearm in all
positions
Triceps
brachii
Long head: infraglenoid
tubercle of scapula
Lateral head: posterior
surface of humerus,
superior to radial
groove Medial head:
posterior surface of
humerus, inferior to
radial groove
Proximal end of
olecranon of ulnar
and fascia of forearm
Radial nerve (C6,
C7, C8)
Chief extensor of forearm;
long head extends arm and
resists dislocation of
humerus (especially
important during abduction)
Anconeus
Lateral epicondyle of
humerus
Lateral surface of
olecranon and
superior part of
posterior surface of
ulnar
Radial nerve (C7,
C8, T1)
Assists triceps in extending
forearm; stabilizes elbow
joint; abducts ulna during
pronation
Biceps
brachii
Short head: tip of
coracoid process of
scapula Long head:
supraglenoid tubercle of
scapula
Coracobrac
hialis
Tip of coracoid process
of scapula
Brachialis
Helps flex and adduct arm;
resists dislocation of
shoulder
PBL Night Starvation
MUSCLES OF ANTERIOR COMPARTMENT OF FOREARM
Muscle
Medial attachment
Lateral attachment
Superficial (first) layer
Innervation
Main actions
Median nerve
(C6, C7)
Pronates and flexes forearm (at
elbow)
Pronator teres
Coronoid process
Ulnar head
Middle of convexity of
lateral surface of radius
Humeral head
Flexor carpi
radialis
Medial epicondyle of
humerus (common
flexor origin)
Palmaris
longus
Flexor carpi
ulnaris
Humeral head
Ulnar head
Olecranon and
posterior border (via
aponeurosis)
Base of 2nd metacarpal
Flexes and abducts hand (at
wrist)
Distal half of flexor
retinaculum and apex of
palmar aponeurosis
Median nerve
(C7, C8)
Flexes hand (at wrist) and
tenses palmar aponeurosis)
Pisiform, hook of hamate,
5th metacarpal
Ulnar nerve
(C7, C8)
Shafts of middle
phalanges of medial four
digits
Median
nerve (C7,
C8, T1)
Flexes middle phalanges at
proximal interphalangeal
joints of middle four digits;
acting more strongly, it also
flexes proximal phalanges at
metacarpophalangeal joints
Bases of distal phalanges
of 4th and 5th digits
Ulna nerve
(C8, T1)
Flexes distal phalanges 4 and
5 at distal interphalangeal
joints
Bases of distal phalanges
of 2nd and 3rd digits
Anterior
interosseous
nerve, from
median
nerve (C8,
Flexes distal phalanges 2 and
3 at distal interphalangeal
joints
Flexes and adducts hand (at
wrist)
Intermediate (second) layer
Flexor
digitorum
superficialis
Humeroulnar
head
Radial head
Medial epicondyle
(common flexor
origin and coronoid
process)
Superior half of
anterior border
Deep (third) layer
Flexor
digitorum
profundus
Medial
part
Proximal ¾ of medial
and anterior surfaces of
ulna and interosseous
membrane
Lateral part
Flexor
pollicis
Anterior surface of
radius and adjacent
Base of distal phalanx of
Flexes phalanges of 1st digit
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longus
interosseous membrane
thumb
T1)
Pronator
quadratus
Distal quarter of
anterior surface of ulna
Distal quarter of anterior
surface of radius
(thumb)
Pronates forearm; deep
fibers bind radius and ulna
together
TENDONS
Tendons and muscles work together. A tendon is
a tough yet flexible band of fibrous connective
tissue connecting muscle to bone and is capable
of withstanding tension.
Ligaments are similar (both made of collagen)
except ligaments join one bone to another.
PBL Night Starvation
MUSLCE OF POSTERIOR COMPARTMENT OF FOREARM
Muscle
Proximal
Distal Attachment
Attachment
Superficial layer
Brachioradialis
Proximal 2/3 of
Lateral surface of
supraepicondylar
distal end of
ridge of humerus
radius proximal to
styloid process
Extensor carpi
radialis longus
Lateral
supraepicondylar
Dorsal aspect of
base of 2nd
metacarpal
Extensor carpi
radialis brevis
Lateral epicondyle
of humerus
(common extensor
origin)
Lateral epicondyle
of humerus
(common extensor
origin).
Dorsal aspect of
base of 3rd
metacarpal
Extensor
digitorum
Extensor digit
minimi
Extensor carpi
ulnaris
Deep layer
Supinator
Extensor indicis
Innervation
Main Action
Radial nerve (C5,
C6, C7)
Weak flexion of
forearm; maximal
when forearm is in
mid-pronated
position
Extend and abduct
hand at the wrist
joint; ECRL active
during first clenching
Radial nerve (C6,
C7)
Extensor
expansions of
medial 4 digits
Extensor
expansion of 5th
digit
Deep branch of
radial nerve (C7,
C8)
Extends medial 4
digits primarily at
metocarpophalangeal
joints
Extends 5th digit
primarily at
metacarpophalangeal
joint, secondarily at
interphalangeal joint
Extends and adducts
hand at wrist joint
(also active during fist
clenching)
Lateral epicondyle
of humerus;
posterior border of
ulna via a shared
aponeurosis
Dorsal aspect of
base of 5th
metacarpal
Lateral epicondyle
of humerus; radial
collateral and
anular ligaments;
supinator fossa;
crest of ulna
Posterior surface
of distal third of
ulna and
interosseous
membrane
Lateral, posterior,
and anterior
surfaces of
proximal third of
radius.
Deep branch of
radial nerve (C7,
C8)
Supinates forearm;
rotates radius to turn
palm anteriorly or
superiorly (if elbow is
flexed)
Extensor
expansion of 2nd
digit
Posterior
interosseous
nerve (C7, C8),
continuation of
deep branch of
radial nerve
Extends 2nd digit
(enabling its
independent
extension); helps
extend hand at wrist.
Base of 1st
metacarpal
Posterior
interosseous
nerve (C7, C8),
continuation of
deep branch of
radial nerve.
Abducts thumb and
extends it at
carpometacarpal
joint
Outcropping muscles of deep layer
Abductor pollicis
Posterior surface
longus
of proximal halves
of ulna, radius, and
interosseous
membrane
Extensor pollicus
Posterior surface
longus
of middle third of
ulna and
interosseous
Dorsal aspect of
base of distal
phalanx of thumb
Extends distal
phalanx of thumb at
interphalangeal joint;
extends
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membrane
Extensor pollicis
brevis
Posterior surface
of distal third of
radius and
interosseous
membrane
INTRINSIC MUSCLES OF HAND
Muscle
Proximal Attachment
metacarpophalangeal
and carpometacarpal
joints
Extends proximal
phalanx of thumb at
metacarpophalangeal
joint; extends
carpometacarpal
joint
Dorsal aspect of
base of proximal
phalanx of thumb
Distal attachment
Innervation
Main Action
Thenar muscles
Opponens
pollicis
Abductor
Lateral side of 1st
metacarpal
To oppose thumb it
draws 1st metacarpal
medially to center of
palm and rotates it
medially
Recurrent branch
Abducts thumb,
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pollicis brevis
Flexor pollicis
brevis
Superficial
head
of median nerve
(C8, T1)
Flexor retinaculum
and tubercles of
scaphoid and
trapezium
helps oppose it
Lateral side of
base of proximal
phalanx of thumb
Flexes thumb
Deep head
Adductor
pollicis
Oblique head
Transverse
head
Bases of 2nd and 3rd
metacarpals, capitate
and adjacent carpals
Anterior surface of
shaft of 3rd
metacarpal
Deep branch of
ulnar nerve (C8,
T1)
Adducts thumb
toward lateral border
of palm
Medial side of
base of proximal
phalanx of thumb
Hypothenar muscles
Abductor digiti
minimi
Medial side of
base of proximal
phalanx of 5th digit
Flexor digiti
minimi brevis
Opponens
digiti
Abducts 5th digit;
assists in flexion of its
proximal phalanx
Pisiform
Hook of hamate and
flexor retinaculum
Deep branch of
ulnar nerve (C8,
T1)
Flexes proximal
phalanx of 5th digit
Draws 5th metacarpal
anterior and rotates it,
bringing 5th digit into
opposition with thumb
Medial border of
5th metacarpal
Short Muscles
Lumbricals
1st and 2nd
Lateral two tendons
of flexor digitorum
profundus
3rd and 4th
Medial three tendons
of flexor digitorum
profundus
Dorsal
interossei, 1st4th
Adjacent sides of two
metacarpals
Bases of proximal
phalanges;
extensor
expansions of 2nd4th digits
Palmar
Palmar surfaces of
Bases of proximal
Lateral sides of
extensor
expansions of 2nd5th digits
Median nerve (C8,
T1)
Branch of ulnar
nerve (C8, T1)
Flex
metacarpophalangeal
joints; extend
interphalangeal joints
of 2nd-5th digits
Abducts 2nd-4th digits
from axial line; act
with lumbricals in
flexing
metacarpophalangeal
joints and extending
interphalangeal joints
Adducts 2nd, 4th and
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interossei, 1st3rd
2nd, 4th, 5th
metacarpals
phalanges;
extensor
expansions of 2nd,
4th, 5th digits
5th digits toward axial
line; assist lumbricals
in flexing
metacarpophalangeal
joints and extending
interphalangeal joints;
extensor expansions
of 2nd-4th digits