3. Anatomy of the shoulder region

Question 1

Skeletal components of shoulder region

Answer 1

Pectoral girdle - clavicle and scapula
humerus

Two joints: glenohumeral joint and acromioclavicular joint

Important aspects: acromion, coricoid, greater tubercle of humerus, lesser tubercle of humerus, bicepital groove

Question 2

ligaments of shoulder

Answer 2

stabilise/support shoulder region

coracoclavicular

acromioclavicular

coracoacromial

glenohumeral (superior, middle, inferior)

Question 3

Coracoclavicular ligament

Answer 3

two parts

major stabilising ligament

Question 4

Coracoacromial ligament

Answer 4

• Forms arch
• Provides support for head of humerus
• Prevents superior dislocation

Question 5

Glenohumeral joint

Answer 5

Highly mobile ball and socket joint

• Abduction/adduction
• Flexion/extension
• Lateral/medial rotation
• Circumduction

between head of humerus and glenoid fossa

Question 6

Abduction of arm

Answer 6

Performed by deltoid
Origin: spine of scapula & acromion & clavicle

Insert: deltoid tuberosity

Innervation: axillary nerve (from posterior chord of brachial plexus)

Posterior fibres: extension and lateral rotation
Anterior fibres: flexion and medial rotation

Question 7

Adduction of arm

Answer 7

lattisimus dorsi

• origin spinal processes of T6-T12
• inserts into bicepital groove

pectoralis major

• origin sternum, clavicle, costal cartilages
• inserts into bicepital groove’s lateral lip

Question 8

What components accommodate abduction/adduction of arm

Answer 8

Glenohumeral joint accommodates parts of movement

Rotation of scapula increases range of movement

Question 9

Which muscles move the scapula during abduction of the arm and in what direction?

Answer 9

Upper fibres of trapezius moves acromion medially superiorly
lower fibres of trapezius moves spine inferiomedially
serratus anterior moves lower angle superiorly distally

Question 10

Which muscle(s) move the scapula during adduction of the arm and in what direction?

Answer 10

levator scapular moves top of scapula medially and upright

Rhomboids move medial border medially and upright

Question 11

Flexion of the arm

Answer 11

Short head of biceps, long head of biceps, coracobrachialis

also anterior fibres of deltoid

Brachialis flexes forearm

Question 12

Extension of arm

Answer 12

Long head of triceps

Posterior fibres of deltoid
Lattisimus dorsi

Lateral head of triceps and medial head of triceps extend forearm

Question 13

Forearm flexion

Answer 13

Brachialis

Question 14

Forearm extension

Answer 14

lateral head of triceps and medial head of triceps

Question 15

Glenohumeral joint stability

Answer 15

Between large humeral head and shallow glenoid fossa

unstable structure

most frequently dislocated joint - anterior dislocation common (humeral head descends inferiorly and ends up anterior

Question 16

Factors increasing glenohumeral joint stability

Answer 16

1. Coracoacromial arch
2. Glenohumeral ligaments
3. Deepening of glenoid fossa by glenoid labrum
4. Long heads of biceps (above) and triceps (below)
5. Tendons of rotator cuff muscles

Question 17

Glenohumeral arch

Answer 17

prevents superior dislocation of joint

Question 18

Glenohumeral ligaments

Answer 18

Supports anterior of joint

Question 19

Glenoid labrum

Answer 19

Deepens the glenoid fossa

Question 20

Long head of biceps and triceps

Answer 20

Splint joint - prevent movement of head of humerus out of glenoid fossa
Long head of biceps origin in supraglenoid tubercle, passes through joint capsule
Origin of long head of triceps in infraglenoid tubercle

Question 21

Tendons of rotator cuff muscles

Answer 21

Four muscles

Insert on humerus close to joint

Fuse with the joint capsule

Forms cuff around joint

Question 22

Rotator cuff muscles origin

Answer 22

supraspinatus - origin from supraspinous fossa

Intraspinatus - origin from infraspinatus fossa

Teres minor - posterior of scapula near lateral border

Question 23

Rotator cuff muscles - insertion

Answer 23

Supraspinatus, infraspinatus and teres minor insert into the greater tubercle

SIT - upper, middle and lower facets of greater tubercle

Question 24

Subscapularis

Answer 24

Originates from subscapular fossa, forms a tendon, passes across anterior of joint to insert into lesser tubercle

Question 25

Rotator cuff function

Answer 25

Supraspinatus - initiate abduction Infraspinatus - lateral rotation Teres minor - lateral rotation Subscapularis - medial rotation

Question 26

Teres major

Answer 26

Should also be considered with the rotator cuff muscles Performs medial rotation Stabilises the humerus during abduction - Eccentric contraction Originates: inferior angle of scapula Insertion: medial lip of bicepital groove

Question 27

Rotator cuff injuries

Answer 27

Supraspinatus impingement: Supraspinatus most commonly injured Limited space for tendon under coracoacromial arch - Impingement due to repetitive overhead activities - Common in athletes (throwers)

Question 28

Blood supply

Answer 28

Rich blood supply Scapula anastomosis Allows continuous supply of blood to shoulder region during movement From subclavian and axillary arteries

Question 29

Scapula anastomosis

Answer 29

From subclavian and axillary Subclavian -> thyrocervical trunk -> suprascapular -> subscapular subscapula -> dorsal scapula -> subclavian

Question 30

Nerve supply to the shoulder

Answer 30

From brachial plexus Suprascapular nerve -> supraspinatus and infraspinatus from posterior cord

Question 31

Cords of brachial plexus

Answer 31

Within axilla | below pectoralis major

Question 32

Posterior cord

Answer 32

Deltoid and teres minor - axillary triceps brachii - radial subscapularis, teres major - upper/lower subscapular nerves Thoracodorsal nerve - lattisimus dorsi

Question 33

Quadrangular space

Answer 33

Formed by teres minor (superior), humerus (lateral), teres major (inferior), long head of triceps (medial)

Question 34

What is found in the quadrangular space?

Answer 34

Nerve supply to : deltoid teres minor badge area Axillary nerve and posterior circumflex humeral artery

Question 35

Clinical significance of quadrangular space

Answer 35

Fracture of surgical neck can damage axillary nerve and posterior circumflex humeral artery

Question 36

Lateral cord

Answer 36

lateral pectoral nerve -> pectoralis major Musculocutaneous - arm flexors

Question 37

Medial cord

Answer 37

Medial pectoral nerve - Pectoralis major/minor Medial cutaneous nerves to arm and forearm