Download Muscles of the Shoulder

Myology 2
(HS 201)
Lecture 2
Myology of the
Shoulder
1
Scapular Ranges of Motion
Each student should be able to describe and
demonstrate the following movements:
1.
2.
3.
4.
5.
6.
Scapular Elevation
Scapular Depression
Protraction
Retraction
Upward Rotation
Downward Rotation
2
Humeral Ranges of Motion
Each student should be able to describe and demonstrate
the following movements:
1. Humeral Flexion
2. Humeral Extension
3. Humeral Abduction
4. Humeral Adduction
5. Humeral Lateral (External) Rotation
6. Humeral Medial (Internal) Rotation
3
Palpation of the shoulder
Spine of the scapula: Prone; Lay your hand across the upper back and slide your fingers inferiorly
until they roll over the superficial spine. Palpate from the root of the spine to the acromion process.
Medial border: Prone; Place your partner’s hand on the small of the lumbar spine to lift the medial
border. Follow the medial border superiorly and inferiorly.
Inferior angle: Prone; With the patient’s hand still on the small of the back glide your fingers inferiorly
until the scapula begins to raise superiorly and laterally. This is the inferior angle.
Superior angle: Prone; Scoop the anterior shoulder with your hand and lift it off the table. Again
locate the medial border and locate the superior angle approximately an inch superior to the root of the
scapular angle.
Lateral border: Prone; Again find the inferior angle and slide your fingers laterally in the direction of
the axilla.
Infraspinous and Supraspinous Fossa: Prone; Again find the scapular spine and move inferiorly
placing you on the infraspinous fossa. Cross the scapular spine superiorly and your fingers will be on
the supraspinous fossa.
Subscapular Fossa: Side lying: Place your thumb at the middle of the lateral border. Slowly sink
and
curl your thumb into the surface of the fossa. With the other hand, move the scapula and arm so your
thumb can sink in more easily. You may only sink in about an inch or two.
4
Palpation of the shoulder (cont.)
Acromion process and AC joint: Sitting: locate the high point of the shoulder or find the scapular
spine again and follow it laterally and superiorly to the acromion. Moving your fingers slightly anterior
and inferior find the AC joint. Have the patient shrug their shoulders and feel the AC joint move.
Clavicle and the sternoclavicular joint: Sitting; Find the acromion again and move your fingers
medially and inferior to the shaft of the clavicle. Follow the clavicle to where it articulates with the
manubrium. Again have the patient shrug the shoulders and feel the SC joint move.
Coracoid Process: Sitting; Palpate the lateral half of the clavicle where it is concave. Move your
fingers inferiorly about an inch or so and push in posteriorly.
Deltoid tuberosity: Sitting; Locate the acromion again. Slide down the lateral aspect of the arm.
When you reach the halfway point between the shoulder and elbow there is a small tuberosity on the
lateral arm.
Greater tubercle: Sitting; Again locate the acromion. Slide off the acromion inferiorly and laterally
approximately one inch.
Intertubercular groove: Sitting; From the greater tubercle, move your fingers anteriorly until it sinks
into a narrow canal or groove.
Lesser tubercle: Sitting; Still in the intertubercular groove internally rotate the patient’s humerus and
you will feel your fingers raise slightly. This is the lesser tubercle.
5
6 Muscles that move the scapula
Trapezius
Levator Scapula
Rhomboid Major
Rhomboid Minor
Pectoralis Minor
Serratus Anterior
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Trapezius
O: EOP, Superior Nuchal Line, Nuchal ligament,
and the SP of C7 through T12
I: Upper Traps: Lateral 1/3 of clavicle & Acromion
Middle Traps: Spine of scapula and acromion
Lower Traps: Root of the Spine of the scapula
A: Upper Traps: Elevates, upwardly rotates, and
retracts the scapula
Middle Traps: Retracts the scapula
Lower Traps: Depresses, upwardly rotates, and
retracts the scapula
**Reversed muscle action: Bilaterally allows
for extension of the neck. Unilaterally laterally
flexes the neck to the same side and rotates to the
opposite side.
N: CN XI (Spinal accessory nerve) and posterior
rami of C3 and C4
7
Levator Scapulae
O: TP’s of C1 – C4
I: Medial border of the scapula, from
the superior angle to the root of the
spine of the scapula
A: Elevates retracts, and downwardly
rotates scapula.
**Reversed muscle action:
Bilaterally allows for extension of
the neck. Unilaterally laterally
flexes the neck to the same side
and rotates the to the same side.
N: Dorsal Scapular nerve
8
Rhomboid Major and Minor
O: Rhomboid Major: Sp’s T2-T5
Rhomboid Minor: Sp’s C7-T1
I: Medial border of the scapula from the
root of the spine of the scapula to the
inferior angle of the scapula
A: Retracts, elevates, and downwardly
rotates the scapula.
**Reversed muscle action:
Unilaterally causes contralateral
rotation of the trunk
N: Dorsal scapular nerve
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Pectoralis Minor
O: Anterior borders of ribs # 3 through 5
I: Coracoid process of the scapula
A: Protracts, Depresses, and
downwardly rotates the scapula
**Reversed muscle action
includes elevation of the 3rd
through 5th ribs
N: Medial pectoral nerve
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Serratus Anterior
O: Outer borders of the 1st through 9th
ribs
I: Anterior surface of the entire
medial border of the scapula
A: (PUSS) Protracts, upwardly
rotates, and stabilizes the
scapula
N. Long thoracic nerve (of Bell)
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Muscles that move the humerus
Supraspinatus
Infraspinatus
Teres Minor
Subscapularis
Rotator Cuff Muscles
Deltoid
Biceps
Triceps
Coracobrachialis
Latissimus Dorsi
Teres Major
Pectoralis Major
12
Rotator Cuff Muscles
• Consists of the Supraspinatus, Infraspinatus,
Teres Minor, and Subscapularis (SITS)
• Called “Rotator Cuff” group because their tendons all conjoint
to form a cuff across the greater and lesser tubercles of the
humerus
• These muscles act as a group to stabilize the head of the
humerus into the glenoid fossa during shoulder movement
• Their role as stabilizers are vital because the ligaments of the
shoulder are very loose
13
Supraspinatus
O: Supraspinous Fossa of the
scapula
I: Greater tubercle of the
humerus
A: Initiates abduction of the
humerus
N: Suprascapular Nerve
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Infraspinatus
O: Infraspinous Fossa of the
scapula
I: Greater tubercle of the
humerus
A: Lateral rotation and
extension of
the humerus
N: Suprascapular Nerve
15
Teres Minor
O: Upper lateral border of the
scapula
I: Greater tubercle of the humerus
A: Lateral rotation and extension of
the humerus
N: Axillary Nerve
16
Subscapularis
O: Subscapular Fossa
I: Lesser tubercle of the
humerus
A: Medial rotation of the
humerus
N: Upper and lower subscapular
Nerve
17
Deltoid
O:
Anterior Head: Lateral Clavicle
Middle Head: Acromion process
Posterior Head: Spine of scapula
I: Deltoid tuberosity of the humerus
A: The entire muscle is a powerful
abductor of the arm
Anterior Head: flexes, medially rotates and
horizontally adducts the arm
Middle Head: abducts the arm
Posterior Head: extends, laterally rotates, and
horizontally abducts the arm
N: Axillary nerve
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Biceps Brachii
O:
Long Head: Supraglenoid tubercle
of the scapula
Short Head: Corocoid process of the
scapula
I: Radial tuberosity
A: Shoulder: Flexes the arm
Elbow: Flexes the elbow and assists
in supination when power is
required.
N: Musculocutaneous nerve
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Triceps Brachii
O:
Long Head: Infraglenoid tubercle of the
scapula
Lateral Head: Posterior aspect of the shaft
of the humerus (proximal ½)
Medial Head: Posterior aspect of the
shaft of the humerus (distal ½)
I: Olecranon Process of the Ulna
A: Shoulder: Extends the arm
Elbow: Extends the elbow
N: Radial nerve
20
Coracobrachialis
O: Coracoid process of the scapula
I: Medial aspect of the shaft of the
humerus
A: Flexes and adducts the arm
N: Musculocutaneous nerve
21
Latissimus Dorsi
O: Thoracolumbar aponeurosis, posterior
sacrum, posterior iliac crest, lower 3 or 4
ribs, and inferior angle of the scapula
I: Medial lip of the Bicipital Groove of the
humerus
A: Extends, medially rotates, adducts the arm
(handcuff position)
** Reversed muscle action bilaterally
causes anterior tilt of the pelvis. Unilateral
contraction causes elevation of the pelvis,
contralateral rotation of the trunk, and
lateral deviation of the trunk.
N: Thoracodorsal nerve
22
Teres Major
“Twin to the Lats”
O: Inferior lateral border of the
scapula.
I: Medial lip of the bicipital groove
of the humerus
A: Extends, medially rotates, adducts
the arm (handcuff position)
N: Lower subscapular nerve
23
Pectoralis Major
O: Clavicular Head: Medial clavicle
Sternal Head: Sternum and the upper
costal cartilages
I: Lateral lip of the bicipital groove
A: Adduction, medial rotation, and horizontal
adduction of the arm. The clavicular head
also causes flexion of the arm.
Secondarily depresses and protracts the
scapula.
**Reversed muscle action causes
elevation of the trunk, lateral deviation,
and ipsilateral rotation.
N: Medial and Lateral Pectoral nerves
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