Shoulder girdle is also known as “pectoral girdle,shoulder girdle is formed by two bones,clavicle and scapula.Their function is to connect the upper limb to trunk
Bones
• landmarks – Acromion process
– Coracoid process
– Clavicle
– Manubrium
– Glenoid fossa
– Lateral border
– Inferior angle
Bones
• landmarks
– Acromion process
– Superior angle
– Glenoid fossa
– Spine of the scapula
– Lateral border
– Medial border
– Inferior angle
Joints
• Shoulder girdle (scapulothoracic)
– scapula moves on the rib cage
– joint motion occurs at sternoclavicular
joint & to a lesser amount at the
acromioclavicular joint
• Scapulothoracic
– not a true synovial joint
– does not have regular synovial features
– movement depends on SC & AC joints
which allows the scapula to move
• 25-degrees abduction-adduction
• 60-degrees upward-downward rotation
• 55-degrees elevation-depression
– supported dynamically by its muscles
– no ligamentous support
Joints
• Sternoclavicular (SC)
– (multiaxial) arthrodial
classification
– Movements
• anteriorly 15 degrees with protraction
• posteriorly 15 degrees with retraction
• superiorly 45 degrees with elevation
• inferiorly 5 degrees with depression
Joints
– Ligamentous support
• anteriorly by the anterior SC ligament
• posteriorly by the posterior SC ligament
• costoclavicular & interclavicular
ligaments provide stability against
superior displacement
Joints
• Acromioclavicular (AC)
– arthrodial classification
– 20- to 30-degree total gliding
& rotational motion
accompanying other shoulder girdle
& shoulder
joint motions
– supported by
• Coracoclavicular ligaments
• Superior acromioclavicular ligament
• Inferior acromioclavicular ligament
– often injured
5 muscles primarily involved in shoulder girdle movements
Muscles
• 5 muscles primarily involved in shoulder
girdle movements
– All originate on axial skeleton & insert on
scapula and/or clavicle
– Do not attach to humerus & do not cause
shoulder joint actions
– Essential in providing dynamic stability of
the scapula so it can serve as a relative
base of support for shoulder joint activities
such as throwing, batting, & blocking
Shoulder Girdle Muscles
• 5 muscles primarily
involved in shoulder
girdle movements
– Trapezius – upper,
middle, lower
– Rhomboid – deep
– Levator scapula
– Serratus anterior
– Pectoralis minor –
deep
Shoulder Girdle Muscles
• Location & action
– Anterior
• Pectoralis minor – abduction, downward
rotation, &
depression
• Subclavius – depression
– Posterior & laterally
• Serratus anterior – abduction & upward rotation
Shoulder Girdle Muscles
• Location & action
– Posterior
• Trapezius
• Upper fibers – elevation & extension of the head
• Middle fibers – elevation, adduction, & upper
rotation
• Lower fibers – adduction, depression, & upper
rotation
• Rhomboid – adduction, downward rotation, &
elevation
• Levator scapulae – elevation
ORIGIN INSERTION OF SHOULDER GIRDLE MUSCLES
Origin Insertion Innervation Action Blood supply of Trapezius muscle
The trapezius (r, I), a muscle of the posterior thorax that acts on the
pectoral girdle, is a flat, triangular muscle covering the upper and
back part of the neck and shoulders.
Origin: Occipital bone; ligamentum nuchae; spinous processes of
T01-T12
Insertion: Lateral third of clavicle, acromion and scapular spine of
the scapula
Innervation: Accessory nerve (CN11) and cervical plexus (C03, C04)
Action: Rotation, retraction, elevation, and depression of scapula,
levitate clavicle; extends the neck; stabilizes the shoulder
Blood supply: Transverse cervical artery
Origin Insertion Innervation Action Blood supply of levator scapulae muscle
The levator scapulae (r, I), a posterior muscle of the
thorax, is situated at the back and side of the neck and
acts on the pectoral girdle.
Origin: Transverse processes of C01-C04
Insertion: Superior part of the medial (spinal) border of
the scapula
Innervation: Dorsal scapular nerve (C05) and direct
branches from spinal nerves CO3, C04
Action: Elevates the scapula medially and upward
Blood supply: Dorsal scapular artery
Origin Insertion Innervation Action Blood supply of Rhomboideus major muscle
The rhomboideus major (rhomboid major)
(r, I) is a muscle of the posterior thorax
that acts on the pectoral girdle.
Origin: Spinous processes of T02-TOS
Insertion: Medial (vertebral) border of the
scapula below scapular spine
Innervation: Dorsal scapular nerve (C05)
Action: Steadies scapula; moves the
inferior angle backward and upward
Blood supply: Dorsal scapular artery
Origin Insertion Innervation Action Blood supply of Rhomboideus minor muscle
The rhomboideus minor (rhomboid minor) (r, I) is a
muscle of the posterior thorax that acts on the
pectoral girdle.
Origin: Spinous processes of C07 T01
Insertion: Medial (vertebral) border of the scapula
above scapular spine
Innervation: Dorsal scapular nerve (C05)
Action: Steadies scapula; moves the inferior
angle backward and upward
Blood supply: Dorsal scapular artery
Origin Insertion Innervation Action Blood supply of Serratus anterior muscle
The serratus anterior (D), an anterior muscle of the thorax, is a thin
muscular sheet situated between the ribs and the scapula at the
upper and lateral part of the chest.
Origin: Upper 8-9 ribs
Insertion: Medial border of the scapula
Innervation: Long thoracic (CO5-C07)
Action: Protracts scapula; upward rotation of the scapula (glenoid
cavity moves superiorly); holds scapula close to the thoracic wall;
elevates ribs when scapula is fixed
Blood supply: Lateral thoracic artery (upper part), thoracodorsal
artery (lower part)
Origin Insertion Innervation Action Blood supply of Pectoralis minor muscle
The pectoralis minor (r, I), an anterior muscle of the
thorax, is a thin, triangular muscle situated beneath
the pectoralis major at the upper part of the
thorax.
Origin: Ribs 3-5
Insertion: Coracoid process of the scapula
Innervation: Medial pectoral nerve (C08-T01)
Action: Elevates ribs, draws the scapula down and
medially
Blood supply: Thoracoacromial trunk (pectoral
branch)
Origin Insertion Innervation Action Blood supply of Subclavius muscle
The subclavius (D) is a muscle in the anterior thorax
that depresses the shoulder. It is small and
triangular and is located between
the clavicle and the first rib.
Origin: Junction of the first rib and its cartilage
Insertion: Subclavian groove of the clavicle between the
costoclavicular and conoid ligaments
Innervation: Filaments from the fifth and sixth cervical nerves (C05
and C06)
Action: Depresses the clavicle down and forward
Blood supply: Thoracoacromial trunk (clavicular branch)
Shoulder gridle Movements
• Abduction
(protraction)
– scapula moves
laterally away from
spinal column
Scapula Abduction
• Scapula move laterally away from
spinous processes without rotation
• EX. Push-up & bench press
• Agonists
– Pectoralis minor
– Serratus anterior
• Adduction (retraction)
– scapula moves
medially toward spinal
column
Scapula Adduction
• Return from
abduction
• Occurs with
retractions
• Agonists
– Middle Trapezius
– Rhomboids
Movements
• Depression
– downward or inferior
movement, as in
returning to normal
position
Scapula Depression
• EX. Dip
• Agonists
– Lower Trapezius
– Pectoralis Minor
• Elevation
– upward or superior
movement, as in
shrugging shoulders
Scapula Elevation
• Lifting scapula without rotation in anatomic position
• Shoulder Shrug
• Agonists
– Levator Scapulae
– Rhomboid
– Upper Trapezius
Shoulder gridle Movements
Movements
• Downward rotation
– returning inferior angle
inferomedially toward
spinal column & glenoid
fossa to normal position
Scapula Downward Rotation
• Downward & Medial Movement
• Glenoid Fossa is rotated downward when
downward
movement of shoulder joint occurs
• EX. Lat Pulls –
pulling wt. down
• Agonists
– Pectoralis Minor
– Rhomboid
• Upward rotation
– turning glenoid fossa
upward & moving inferior
angle superolaterally
away from spinal column
Scapula Upward Rotation
• Lateral & upward movement
• Agonists
– Middle Trapezius
– Lower Trapezius
– Serratus anterior
Movements
• Shoulder joint & shoulder girdle work
together in carrying out upper extremity
activities
• Shoulder girdle movement is not
dependent upon the shoulder joint & its
muscles
Shoulder gridle Movements
Movements
• Shoulder girdle muscles
– Stabilize scapula so the shoulder joint
muscles will have a stable base from which
to exert force for moving the humerus
– Contract to maintain scapula in a relatively
static position during shoulder joint actions
– Contract to move shoulder girdle & to
enhance movement of upper extremity
when shoulder goes through extreme
ranges of motion
Movements
• For some shoulder girdle movements,
scapula must rotate or tilt on its axis
• Lateral tilt (outward tilt)
– during abduction
– scapula rotates about its vertical axis resulting in
posterior movement of medial border & anterior
movement of lateral border
• Medial tilt (return from lateral tilt, inward tilt)
– during extreme adduction
– scapula rotates about its vertical axis resulting in
anterior movement of medial border & posterior
movement of lateral border
Shoulder gridle Movements
Movements
• Anterior tilt (upward tilt)
– rotational movement of scapula about frontal axis
occurring during glenohumeral hyperextension
– superior border moving anteroinferiorly & inferior
angle moving posterosuperiorly
• Posterior tilt (downward tilt)
– rotational movement of scapula about frontal axis
occurring during glenohumeral hyperflexion
– superior border moving posteroinferiorly & inferior
angle moving anterosuperiorly
Movements
• Synergy with muscles of glenohumeral joint
– As shoulder joint goes through more extreme
ranges of motion, scapular muscles contract to
move shoulder girdle so that its glenoid fossa will
be in a more appropriate position from which the
humerus can move
– Without the accompanying scapula movement
humerus can only be raised into approximately 90
degrees of total shoulder abduction & flexion
Movements
• Synergy with muscles of glenohumeral joint
– This works through the appropriate muscles of
both joints working in synergy to accomplish the
desired action of the entire upper extremity
– Ex. to raise our hand out to the side laterally as
high as possible, the serratus anterior & trapezius
(middle & lower fibers) muscles upwardly rotate
scapula as supraspinatus & deltoid initiate
glenohumeral abduction
– This synergy between scapula & shoulder joint
muscles enhances movement of entire upper
extremity