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Anatomy of shoulder
1.
2. Prepared by: Dr.Sayed Abdul Qahir
PGR1, Orthopedic surgery
MRH, Kandahar, Afghanistan
Supervisor: Dr. Niamatullah shehzad
Trainer specialist, Orthopedic surgery
MRH, Kandahar, Afghanistan
3. CONTENTS
1. Surface and bone anatomy
2. Articulations and adjoining structures
3. Ligaments and articulating structures
4. Bursae and relation of shoulder
5. Muscular and neurovascular anatomy
6. Range of motion of shoulder joint
7. References
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5. 1.1. Surface anatomy
Anteriorly - Clavicle
- Tip of coracoid process of scapula
- Greater tubercle of humerus
- Deltoid counter
- Axilla and its folds
Posteriorly - Acromion (scapula)
- Crest of spine(scapula)
- Medial and lateral borders (scapula)
- Inferior angle (scapula)
Medial epicondyle shows head of humerus direction while lateral shows greater
tuberosity direction
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6. 1.2. Clavicle
It’s long bone placed horizontally
and is a bridge between upper limb
and trunk
Clavicle is S shaped and has:
Two borders (Anterior and Posterior)
Two surfaces(superior and inferior)
Two ends {medial(quadrangular) and
lateral (flat)}
It has no medullary cavity
It ossifies at 12-19 yrs and fuses at
22-25 years
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Lateral Medial
Surface for
articulation
with acromion
Superior view
Anterior view
Conoid tubercle
Inferior view
Surface for articulation with
Manubrium sterni and
First costal cartilage
Trapezoid line
Conoid tubercle
7. 1.3. Scapula
it’s a large flat triangular bone and
has:
Three angles (Lateral, Superior and
Inferior)
Three borders (Superior, Lateral
and medial)
Two surfaces (costal and posterior)
Three processes (Acromion, spine
and coracoid)
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Articular surface for clavicle
Superior border
Superior angle
Medial border
Subscapular fossa
Inferior angle
Articular surface for clavicle
Acromion
Greater scapular notch
Glenoid cavity
Infraglenoid tubercle
Lateral border
Inferior angle
Anterior view
Posterior view
Infraspinous
fossa
Spine of scapula
Medial border
Supraspinous
fossa
Superior angle
Superior border
Lateral border
Notch
Infraglenoid tubercle
Glenoid cavity
Coracoid process
Acromion
8. 1.4. Proximal Humerus
Proximal part of humerus contains
head, neck(surgical and anatomical)
and proximal shaft
Surgical neck is the weakest part of
humerus therefore its most common
site of fracture, structures around this
neck (Axillary nerve, post.
Circumflex artery) may be damaged
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Superior facet
(supraspinatus)Greater tubercle
Intertubercular sulcus
Lesser tubercle
(subscapularis)
Intertubercular sulcus
Anterior view
Lateral view
Posterior view
Surgical neck
Surgical neck
Head
Anatomical neck
Attachment for
pectoralis major
muscle
Deltoid
Tuberosity
(deltoid)
Greater
tubercle
Superior facet
(supraspinatus)
Middle facet
(infraspinatus)
Inferior facet
(teres minor)
Anatomical neck
Attachment for
coracobrachialis
Deltoid tuberosity
(deltoid
Lateral lip, floor
and medial lip of
intertubercular
sulcus (pectoralis
major, latissimus
dorsi, and teres
major respectively)
10. 2.1. Glenohumeral joint
Type: multiaxial synovial ball and
socket joint
Articulation: head of humerus and
glenoid cavity of scapula
Articular surface is PEAR shaped and
is relatively small and flat
Only 1/4th of humeral head is in
contact with glenoid cavity hence
greater mobility is seen
Nerve supply: Axillary and
suprascapular nerves
Ligaments: Glenohumeral, transverse
humeral and coracohumeral ligaments
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Glenoid labrum
Glenoid cavity
Tendon of long
head of biceps
brachii muscle
Head of
humerus
Transverse
humeral ligament
11. Clinical notes
Dislocation of this joint is so common
1. Anterior dislocation(95%)
This usually occurs by excessive extension and lateral rotation
2. Posterior dislocation(4%)
3. Inferior dislocation(1-2%)
Superior dislocation of shoulder may not occur due to coracoacromial arch
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12. 2.2. Acromioclavicular joint
Type: plane synovial joint
Articulation: articular facets of lateral
end of clavicle and medial acromial
margin
Nerve supply: suprascapular nerve
Movements: gliding movement
Ligaments: superior and inferior
acromioclavicular ligaments
Relations: anteriorly to deltoid M.
posteriorly to trapezius M. and
superiorly to skin
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Trapezoid
ligament
Conoid
ligament Conoid tubercle
Suprascapular notch
Glenoid
cavity
Coracoid
process
Acromion
Acromioclavicular
ligament
13. 2.3. Sternoclavicular joint
Type: synovial plane joint
Articulation: sternal end of clavicle,
manubrium sterni and 1st costal
cartilage
Nerve supply: supraclavicular nerve
and nerve to the subclavius muscle
Ligaments: sternoclavicular ligaments
Movements: forward, backward,
elevation and depression of clavicle
13
Articular disc
(capsule and ligaments
removed anteriorly
to expose joint)
Clavicular notch
Interclavicular
ligament
Anterior
sternoclavicular
ligament
Manubrium of
sternum
Attachment site
for rib II
Sternal angle
Rib I
Costoclavicular
ligament
First costal
cartilage
14. 2.4. Scapulothoracic articulation
It’s not a true joint and has no bony
articulation
Scapula is attaching thorax via muscular
attachments
14
16. 3.1. Glenoid labrum
It’s a fibrocartilagenous rim attached to
margin of glenoid cavity and increase
concavity by 50% and surface area of
humeral attachment by 75%
It further strengthens by long head of
biceps origin and superior glenohumeral
ligament
It’s a static stabilizer of joint and prevents
excessive rollback of humerus
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17. 3.2. Joint capsule
It is lax and attaches along epiphyseal
lines of glenoid and humeral head and
extends onto surgical neck medially (that’s
why infection of upper shaft spreads
directly to joint)
Capsule is surrounded by synovial
membrane which prolongs along tendon
of bicep at tubular sheath
Inferior part is the weakest- mostly
resulting in dislocation
Relations: medially supraglenoid tubercle
and labrum, laterally anatomical neck of
humerus, inferiorly surgical neck
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18. 3.3. Glenohumeral ligament
Superior GH
It’s the most superior capsular thickening
from labrum anterior to long head of
biceps at level of coracoid base
It passes under supraspinatus and
inserts on anatomical neck medial to
anterosuperior base of lesser tuberosity
Middle GH
Most variable in size, arises just inferior
to superior GHL and inserts along middle
area of anatomical neck opposite to
lesser tuberosity
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19. 3.3. Glenohumeral ligament cont.
Inferior GH
it’s the thickest part and is very broad
arising from lower half of labrum
It’s thick superior margin is called superior
band, rest of it is called axillary pouch
Superior band and anterior band insert on
anatomical neck while the posterior pouch
on surgical neck
It limits external rotation at 45-90 degree of
abduction(mainly superior band)
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20. 3.4. Coracohumeral ligament
Arises from lateral base of coracoid
process and extends onto both
tuberosities
It forms roof of bicepital tendon sheath
and strengthens capsule anteriorly
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21. 3.5. Transverse humeral ligament
Bridges upper part of bicipital groove
through which long head of biceps
passes down
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22. 3.6. Coracoacromial ligament
It’s a trapezoidal ligament from base of
acromion to epiphysis of coracoid
It along with coracoid and acromion
forms coracoacromial arch which is
secondary socket to humerus
It plays role in resisting upward
displacement of humerus
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23. 3.7. Coracoclavicular ligament
Very strong ligament from outer and
inferior clavicular surface to coracoid
base
It has two components:
- Conoid and Trapezoid
Conoid portion is primary restraint to
anterior and superior rotation and
anterior and superior displacement of
clavicle
Trapezoid has relatively less role than
conoid part
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25. 4.1. Bursae
Subacromial bursa:
sites superior to rotator cuff tendons in
subacromial space
Subscapularis bursa:
Coracoclavicular bursa:
Subcoracoid bursa:
Supraacromial bursa:
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26. 4.2. Relation of shoulder joint
Superiorly: coracoacromial arch,
subacromial bursa, supraspinatus,
deltoid
Inferiorly: Long head of triceps
Anteriorly: Subscapularis,
coracobrachialis, biceps(short head),
deltoid(ant. fibers)
Posteriorly: Infraspinatus, teres
minor, deltoid
Within joint: long head of biceps
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Subacromial bursa (subdeltoid)
Long head of biceps brachii tendon
Subtendinous bursa
of subscapularis
Coraco-acromial ligament
Pectoralis major
Short head of biceps brachii
and coracobrachialis
Long head of triceps
brachii
Latissimus dorsi
Teres major
Teres minor
Infraspinatus
Supraspinatus
Deltoid
Acromion
37. Teres Major
Origin:
Inferior angle of scapula, Axillary border
of scapula
Insertion:
Medial lip of bicipital groove
Innervation:
Lower subscapular
Action:
Internal rotation, adduction, extension
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38. Long head of Triceps
Origin:
Inferior glenoid tuberosity
Insertion:
Olecranon process
Innervation:
Radial nerve
Action:
Extend elbow, long head adducts and
extends humerus
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Triceps barchii
medius
Lateral head
Tendon
Triceps barchii
medius
Long head
42. Serratus Anterior
Origin:
Anterior portion of ribs 1-8
Insertion:
Vertebral border of scapula from superior
angle to inferior angle
Innervation:
Long thoracic nerve(C)
Action:
Scapular protraction and upward
rotation, fixates vertebral border of scapula
to thorax
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43. Pectoralis Minor
Origin:
Anterior portion of ribs 3-5
Insertion:
Coracoid process
Innervation:
Lateral pectoral
Action:
Anterior tilt of scapula
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44. Trapezius
Upper fibers: Base of occiput/upper cervical
spinous processes to distal clavicle
Action: Elevate and upwardly rotate scapula
Middle fibers: Lower cervicle/upper thoracic
spinous processes to acromion process
Action: Retract scapula
Lower fibers: Lower thoracic spinous processes
to spine of scapula
Action: Depress and upwardly rotate scapula
Innervation:
Accessory nerve (c)
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45. 5.2. Nerve supply
Axillary nerve
Musculocutaneous nerve
Suprascapular nerve(arise directly from brachial
plexus from superior trunk)
Lateral pectoral nerve(arise from lateral cord)
Medial pectoral nerve(arise form medial cord)
Long thoracic nerve(arise from roots)
Dorsal scapular(arise from roots)
Upper and lower subscapular(arise from posterior
cord)
Thoracodorsal(arise from posterior cord)
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46. Axillary Nerve
It’s a major peripheral nerve of the upper
limb
Spinal roots: C5 and C6
Sensory function: gives rise to upper
cutaneous nerve of arm which innervate
the skin over and lower deltoid
Motor function: teres minor and deltoid
muscles
Course: it’s a direct continuation of post.
Cord, it leaves axilla via quadrangular
space and around surgical neck it is
divided into its terminal branches
46
48. Musculocutaneous nerve
It’s another major nerve of upper limb
Spinal roots: C5-C7
Motor function: innervates the muscles of
anterior compartment of arm
Sensory function: gives rise to lateral
cutaneous nerve which innervates skin of
lateral surface of forearm
Course: It’s the terminal branch of lateral
cord, it leaves axilla and pierce the
coracobrachialis muscle then it passes down
the flexor compartment of arm, it then pierce
the deep fascia lateral to bicep and enters
forearm
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49. 5.3. Vascular anatomy
Anterior circumflex humeral artery
subclavian artery becomes axillary artery as it passes first rib, which becomes
brachial artery as it passes distal to teres major
Posterior circumflex humeral artery
Ant. And Post. Arteries are both branches of axillary arteries
Suprascapular(arise from the subclavian artery at the thyrocervical trunk) and
subscapular arteries
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50. 50
Rib I Transverse cervical artery
Suprascapular artery
Clavicle
Subscapular artery
Anterior circumflex
humeral artery
Posterior circumflex
humeral artery
Circumflex scapular artery
Profunda brachii artery
Brachial artery
Deep branch of
transverse
cervical artery
Axillary artery
Right subclavian artery
Thyrocervical trunk
Right common carotid artery
52. Active range of motion
Flexion:
180 degree
Extension:
60 degree
Abduction:
180 degree
Adduction:
45 if shoulder flexed
Internal rotation:
70-80 degree at 90 angle(limited by body in
natural position)
External rotation:
40-50 in natural position, 80-90 at 90 angle
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53. 7. References
Clinical anatomy by regions, Richard S. Snell, 9th edition
Gray’s anatomy for students, Richard L. Drake, 2nd edition
Image source:
- Washington university radiology department
- Orthobullets.com
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