L4: Shoulder Anatomy & Physiology

Question 1

How is the shoulder joint anatomically and functionally classified?

Answer 1

Anatomically, it is a synovial ball and socket joint. Functionally, it is a diarthrosis and multiaxial joint.

Question 2

What bones are involved in the articulation of the shoulder joint?

Answer 2

The glenoid cavity of the scapula and the head of the humerus.

Question 3

What is the primary function of the shoulder joint?

Answer 3

To provide the greatest range of motion in the body, allowing upper limb movement across different planes for everyday tasks.

Question 4

what physiological movements take place at the shoulder

Answer 4

flexion
extension
abduction
adduction
medial rotation
lateral rotation

Question 5

what is the range of flexion at the shoulder

Answer 5

0-180°

Question 6

what is the range of extension at the shoulder

Answer 6

0-45°/60°

Question 7

what is the range of abduction at the shoulder

Answer 7

0-150°

Question 8

what is the range of adduction at the shoulder

Answer 8

30-50°

Question 9

what is the range of medial rotation at the shoulder

Answer 9

0-70/90°

Question 10

what is the range of lateral rotation at the shoulder

Answer 10

0-90°

Question 11

What four articulations make up the shoulder girdle

Answer 11

sternoclavicular (SCJ),
acromioclavicular (ACJ),
glenohumeral (GHJ),
and scapulothoracic (STJ)

Question 12

which bones articulate in the shoulder joint

Answer 12

clavicle
scapula
humerus

Question 13

define diarthrosis

Answer 13

a freely moveable joint

Question 14

label key bony points of the shoulder

Answer 14

Question 15

describe the sternoclavicular joint

Answer 15

• saddle shaped
• articulated between medial espect of the clavicle and menubrium of the sternum
• has small amount of movement in scapular elevation/depression when humerus is flexed above 90°

Question 16

desrcibe the acromioclavicular joint

Answer 16

• the articulation between the lateral aspect of the clavicle and the acromion of the scapula
• allows ROM for scapula to glide during shoulder movements
• combination of joint capsule, ligaments and muscle attachments provide joint stability

Question 17

describe acromioclavicular joint stability

Answer 17

• weak fibrous capsule lined with synovial fluid
• stability is maintained by coracoclavicular (made of trapezoid and conoid ligaments) and the acromioclavicular ligaments
• the attachments of deltoid, trapezius and pectoralis major also contribute to joint stability

Question 18

what are the major ligaments of the shoulder joint

Answer 18

biceps tendon
coracohumeral ligament
SGHL direct
MGHL

Question 19

label the major ligaments of the shoulder joint

Answer 19

Question 20

describe the glenohumeral joint

Answer 20

• synovial ball and socket joint
• it is the most mobile and consequently the least stable joint in the body
• the articulation between head of humerus and glenoid fossa

Question 21

describe glenohumeral joint stability

Answer 21

• concavity compression (thick suction cup)
  
  • the labrum increases depth of fossa and increases contact with the humeral head
• ligaments within joint capsule to maintain contact between head and fossa (static stability)
  
  • superior, middle and inferior glenohumeral ligaments as well as the coracohumeral ligament and the transverse humeral ligament
• the rotator cuff tendons and long head of biceps tendon attach around the humeral head to provide stability (dynamic stability)

Question 22

describe the scpulothoracic joint

Answer 22

• not a ‘true’ joint-dependent on congruity of AC and SC joints
• scapula attaches to thoracic wall via fascia and is able to ‘glide’ in a variety of movements
• multiple muscular attachments
• movement of the scapula is integral to normal shoulder kinesiology (scapulohumeral rhythm)
• scapula provides stable base for controlled movements between humeral head and glenoid fossa

Question 23

label borders of scapula

Answer 23

Question 24

label bony points of the scapula

Answer 24

Question 25

what muscles allow flexion of the shoulder

Answer 25

major muscles: anterior deltoid, pectoralis major assisting: biceps brachii, coracobrachialis,

Question 26

what muscles allow extension of the shoulder

Answer 26

major muscles: posterior deltoid, latissimus dorsi, teres major assisting: long head of triceps

Question 27

what musces allow abduction of the shoulder

Answer 27

major muscles: middle fibres of deltoid (15-90°) assisting: supraspinatus (0-15°), trapezius/ serratus anterior produce scapula rotation (90°+)

Question 28

what muscles allow adduction of the shoulder

Answer 28

major muscles: pectoralis major, latissimus dorsi, teres major

Question 29

what muscles allow medial rotation of the shoulder

Answer 29

major muscles: subscapularis, teres major assisting: pectoralis major, latissimus dorsi, anterior deltoid

Question 30

what muscles allow lateral rotation of the shoulder

Answer 30

major muscles: infraspinatus, teres minor assisting: posterior fibres of deltoid

Question 31

what muscles allow scapular elevation

Answer 31

levator scapulae, upper fibres of trapezius

Question 32

what muscles allow scapula depression

Answer 32

gravity! and the actions of the trapezius and latissimus dorsi

Question 33

what muscle allows scapula protraction

Answer 33

serratus anterior

Question 34

what muscles allow scapula retraction

Answer 34

rhomboid major, minor and middle fibres of trapezius

Question 35

what muscles allow upward rotation of the scapula

Answer 35

trapezius and serratus anterior

Question 36

what muscles allow downward rotation of the scapula

Answer 36

gravity, and rhomboids

Question 37

what is the origin and insertion of the anterior deltoid

Answer 37

origin: anterior border of lateral edge of clavicle insertion: deltoid tuberosity of humerus

Question 38

what is the origin and insertion of medial deltoid

Answer 38

origin: lateral margin of acromion process insertion: deltoid tuberosity of the humerus

Question 39

what is the origin and insertion of posterior deltoid

Answer 39

origin: inferior edge of spine of scapula insertion: deltoid tuberosity of humerus

Question 40

what is the origin and insertion of the coracobrachialis

Answer 40

origin: tip of coracoid process insertion: medial aspect of the humerus

Question 41

what is the origin and insertion of pectoralis major

Answer 41

origin: clavicle and anterior surface of sternum insertion: intertubercular sulcus of the humerus

Question 42

what is the origin and insertion of biceps brachii

Answer 42

origin: Long head = supraglenoid tubercle of scapula. short head: tip of coracoid process insertion: radial tuberosity

Question 43

what is the origin and insertion of latissimus dorsi

Answer 43

origin: spinous processes of thoracic T7–T12, thoracolumbar fascia, iliac crest and inferior 3 or 4 ribs insertion: intertubercular sulcus of humerus.

Question 44

what is the origin and insertion of teres major

Answer 44

origin: posterior surfacce of inferior angle of scapula insertion: medial lip of intertubercular sulcus on anterior surface of humerus

Question 45

what is the origin and insertion of teres minor

Answer 45

origin: lateral bored of scapula insertion: greater tubercle of humerus

Question 46

what is the origin and insertion of long head of triceps

Answer 46

origin: infraglenoid tubercle of scapula insertion: posterior part of alecranon process of unla

Question 47

what is the origin and insertion of supraspinatus

Answer 47

origin: supraspinatus fossa of scapula insertion: greater tubercle of humerus

Question 48

what is the origin and insertion of the trapezius

Answer 48

origin: from nuchal line of occipital bone to spinous processes of T1-12 and C7 insertion: cest of spine of scapula and acromion.

Question 49

what is the origin and insertion of serratus anterior

Answer 49

origin: lateral surfaces of upper 8 ribs insertion: medial border of scapula

Question 50

what is the origin and insertion of levator scapulae

Answer 50

origin: transerse process of C1-4) insertion: medial border of scapula from superior angle to bottom of spine of scapula

Question 51

what is the origin and insertion of infraspinatus

Answer 51

origin: infraspinatus fossa of scapula insertion: greater tubercle of humerus

Question 52

what is the origin and insertion of rhomboid major

Answer 52

origin: spinous process of T2-5 insertion: medial border of scapula to bottom of spine of scapula

Question 53

what is the origin and insertion of rhomboid minor

Answer 53

origin: spinous process of C7 and T1 insertion: medial border of sapula at the bottom of the spine of scapula

Question 54

what is a bursa

Answer 54

a fluid filled sac found within the joint space

Question 55

what is the purpose of a bursa

Answer 55

It contains synovial fluid whihc prevents friction during movement

Question 56

what bursa is found in the shoulder joint

Answer 56

subacromial bursa

Question 57

where is the bursa found in the shoulder joint

Answer 57

located between the acromion, corocoacromial ligament and the rotator cuff

Question 58

what nerves innervates the anterior part of the shoulder joint

Answer 58

Subscapular (C5/6) axillary, and lateral pectoral (C5/6 also)

Question 59

which nerves innervate the posterior part of the shoulder joint

Answer 59

suprascapular and small branches of axillary (C5/6)

Question 60

which nerves innervate scapula depression and elevation

Answer 60

Dorsal scapula nerve (C3-5)

Question 61

label the bony landmarks of the shoulder girdle