Session 7: Osteology of the Scapula, Clavicle and Proximal Humerus

Question 1

What type of bone is the scapula?

Answer 1

Irregular bone

Question 2

What does the scapula articulate with?

Answer 2

Humerus at the glenohumeral joint

Clavicle at the acromioclavicular joint

Question 3

What is the subscapular fossa?

Answer 3

A large concave depression on the anterior surface of the scapula.

Question 4

What muscle originates from the subscapular fossa?

Answer 4

Subscapularis

Question 5

What is the coracoid process?

Which muscles originate and insert here?

Answer 5

A hook-like projection which can be found at the superolateral surface of the scapula.

Origination: short head of the biceps brachii

Insertion: pectoralis minor, coracobrachialis

Question 6

Describe the glenoid fossa.

What does it articulate with?

Answer 6

Shallow cavity, superior on the lateral border.

Articulates with the head of the humerus to form the glenohumeral joint.

Question 7

Describe the supraglenoid tubercle.

What muscle originates from here?

Answer 7

Roughening which is superior to the glenoid fossa.

Long head of biceps brachii originate here.

Question 8

Describe the infraglenoid tubercle.

What muscle originates here?

Answer 8

Roughening which is inferior to the glenoid fossa.

Long head of the triceps brachii originate here.

Question 9

There are some important bony landmarks of the scapula. Describe the spine of the scapula.

Answer 9

The most prominent feature of the posterior scapula which runs transversely across the scapula.

Question 10

Describe the acromion.

What does it articulate with?

Answer 10

A large projection arising from the lateral end of the scapula spine.
The acromion arches laterally over the glenohumeral joint and articulates with the clavicle at the acromioclavicular joint.

Question 11

Describe the infraspinous fossa.

What muscle originates here?

Answer 11

A depression found below the spine of the scapula.

Origination of infraspinatus.

Question 12

Describe the supraspinous fossa.

What muscle originates here?

Answer 12

A depression located above the spine of the scapula.
Smaller than the infraspinous fossa and more convex as well.
Origination of supraspinatus.

Question 13

What are the joints of the scapula?

Answer 13

Glenohumeral joint between the glenoid fossa and the head of the humerus.
Acromioclavicular joint between the acromion and the clavicle.

Question 14

What is the scapulathoracic joint.

Answer 14

An articulation between the anterior surface of the scapula and the rib cage which cannot be classified as a joint.
It is an articulation of the scapula with thorax that depends on the integrity of the acromioclaviuclar and sternoclavicular joint.

Question 15

Clavicle.

Type and three main functions.

Answer 15

Long bone.

Attaches the upper limb to the trunk.
Protects the underlying neuromuscular structures supply the upper limb.
Transmits force from the upper limb to the axial skeleton.

Question 16

Structure of the clavicle.

Answer 16

A long bone with a slight ‘S’ shape.
The medial aspect is convex anteriorly and the lateral aspect is concave anteriorly.
The medial end is called the sternal end and the lateral end is the acromial end.
Between the ends is the shaft.

Question 17

Insertion and origins of muscle on the clavicle.

Answer 17

Insertion of:
Trapezius (anterior surface of the acromial end)
Subclavius muscle (in middle of the shaft at the superior surface)

Origination of: 
Deltoid muscle (posterior surface of the acromial end) Pectoralis major (posterior surface of the middle to sternal end)
Sternocleidomastoid muscle at the superior surface of the sternal end)
Sternohyoid muscle (posterior surface oft the sternal end).

Question 18

What does the acromial end of the clavicle articulate with?

Answer 18

The acromion of the scapula at the acromioclavicular joint.

Question 19

What does the sternal end of the clavicle articulate with?

Answer 19

The sternum at the sternoclavicular joint.

Question 20

What two ligaments attach at the acromial end of the clavicle?

Answer 20

The conoid ligament which attach at the conoid tubercle of the clavicle and the coracoid process.
The trapezoid ligament which attach at the trapezoid line of the clavicle and the coracoid process.

Question 21

What are the conoid ligament and the trapezoid ligament collectively known as?
What is its main function?

Answer 21

The coracoclavicular ligament.

To effectively suspend the weight of the upper limb from the clavicle.

Question 22

What type of joint is the acromioclavicular joint?

Answer 22

A plane-type synovial joint.

Question 23

Where can the acromioclavicular joint be palpated?

Answer 23

Approx. 2-3 cm medially from the tip of the shoulder.

Question 24

What are the two atypical features of the acromioclavicular joint?

Answer 24

The articular surfaces of the joint are lined with fibrocartilage instead of hyaline cartilage which is usually found in a synovial joint.

The joint cavity is partially divided by an articular disc. This is a wedge of fibrocartilage that is suspended from the upper part of the capsule.

Question 25

What is the acromioclavicular joint reinforced by?

Answer 25

A loose fibrous layer which encloses the two articular surfaces. The posterior aspect of the joint capsule is reinforced by fibres from the trapezius muscle as well.

Question 26

What are the three main ligaments that strengthen the acromioclavicular joint?

Answer 26

Intrinsic: Acromioclavicular ligament which runs horizontally from the acromion to the lateral clavicle. Lies superficial to the joint capsule and reinforce the superior aspect. Extrinsic: Conoid ligament which runs vertically from the coracoid process of the scapula to the conoid tubercle of the clavicle. Trapezoid ligament which runs from the coracoid process of the scapula to the trapezoid line of the clavicle.

Question 27

What movements does the acromioclavicular joint allow?

Answer 27

A small degree of axial rotation and anteroposterior movement.

Question 28

Where can the sternoclavicular joint be found?

Answer 28

Between the sternal end of the clavicle and the manubrium of the sternum. It is the only attachment of the upper limb to the axial skeleton so its very strong.

Question 29

What type of joint is the sternoclavicular joint?

Answer 29

A saddle-type synovial joint.

Question 30

What atypical feature does the sternoclavicular joint have?

Answer 30

The articular surfaces are covered with fibrocartilage.

Question 31

The sternoclavicular joint is separated into two compartments by a fibrocartilaginous articular disc. Why is this important?

Answer 31

It allows the clavicle and the manubrium to slide over each other more freely to allow rotation and movement in a third axis.

Question 32

There are several movements of the shoulder that also require movement at the sternoclavicular joint. Which?

Answer 32

Elevation of shoulder when shrugging or when abducting the arm over 90 degrees. Depression of shoulders when drooping the shoulder or when extending the arm at the shoulder behind the body. Protraction of the shoulders Retraction of the shoulders Rotation when the arm is raised over the head by flexion at the glenohumeral joint.

Question 33

What does the proximal humerus articulate with?

Answer 33

The glenoid fossa of the scapula to form the glenohumeral joint.

Question 34

What does the distal humerus articulate with?

Answer 34

The head of the radius and trochlear notch of the ulna to form the elbow joint.

Question 35

What is the structure of the proximal humerus?

Answer 35

It has a head which articulates with the glenoid fossa. An anatomical neck which separates the head of the humerus from the greater and lesser tubercle of the humerus. The greater tubercle is posterolateral and the lesser tubercle is more medial. The surgical neck of the humerus lies between the two tubercles and the shaft of the humerus. In between the tubercles there is a depression called the intertubercular sulcus. The intertubercular sulcus runs somewhat down the proximal humerus and is defined by two lips; one lateral and one medial.

Question 36

What muscles insert at the greater tubercle?

Answer 36

Three rotator cuff muscles: supraspinatus, infraspinatus and teres minor. Superior to inferior.

Question 37

What muscles insert at the lesser tubercle?

Answer 37

The subscapularis.

Question 38

What muscles insertions can be found by the lips of the intertubercular sulcus and in the intertubercular sulcus itself?

Answer 38

"A lady between two majors" Pectoralis major inserts lateral lip Latissimus dorsi inserts into the intertubercular sulcus Teres major inserts onto the medial lip Also the tendon of the long head of biceps brachii runs through the intertubercular sulcus.

Question 39

Why is the surgical neck of the neck clinically important?

Answer 39

Because it is a frequent site of fractures usually from blunt trauma to the shoulder or from falling on an outstretched hand.

Question 40

Why are fractures of the surgical neck of the humerus a problem?

Answer 40

Because this is where you would find the axillary nerve and the posterior circumflex artery. In the case of a fracture this site can get damaged.

Question 41

What are the consequences of axillary nerve damage?

Answer 41

Axillary nerve damage would result in paralysis of the deltoid and teres minor muscles. This means that abduction would be difficult as well as slight impairment of adduction and lateral rotation but mainly abduction. Also the innervation of skin and therefore sensation would be impaired in the regimental badge area.

Question 42

Where does the deltoid insert on the humerus?

Answer 42

On the lateral side of the humeral shaft called the deltoid tuberosity. This is a roughened area.

Question 43

Explain the radial groove.

Answer 43

A shallow depression that runs diagonally on posterior surface of the humerus at the level of the deltoid tuberosity. In this groove the radial nerve and profound brachii artery can be found.

Question 44

What muscles attach along the humeral shaft?

Answer 44

Anteriorly: Coracobrachialis, deltoid, brachialis and brachioradialis Posteriorly: medial and lateral heads of triceps.

Question 45

What are the extrinsic muscles of the shoulder?

Answer 45

Superficial: Trapezius and latissimus dorsi Deep: levator scapulae, rhomboid major, rhomboid minor

Question 46

Location, origination, insertion, innervation and action of trapezius.

Answer 46

Most superficial of all the back muscles. Originates from the external occipital protuberance of the skull, the nuchal ligament and the spinous processes of C7-T12. Inserts onto the clavicle, acromion and the spine of the scapula. Innervated by spinal accessory nerve (Cranial nerve XI) and receives proprioceptor fibres from C3 and C4. Action: Upper fibres of the trapezius elevate the scapula and rotate it during abduction of the arm above 90 degrees. Middle fibres retract the scapula Lower fibres pull the scapula inferiorly

Question 47

How can you test the power of the trapezius muscle clinically?

Answer 47

Ask patient to shrug their shoulders while you attempt to push them back down.

Question 48

Location, origination, insertion, innervation and action of latissimus dorsi.

Answer 48

Covers a wide area on the lower back inferior to the trapezius. Originates from spinous processes of T6 to T12, the iliac crest and the thoracolumbar fascia and the three inferior ribs. Fibres converge into a tendon and inserts into the intertubercular sulcus of the humerus. Innervated by thoracodorsal nerve. Actions: Latissimus dorsi extends, adducts and medially rotates the upper limb.

Question 49

What are the deep muscles of the extrinsic muscles?

Answer 49

Levator scapulae, rhomboid major and rhomboid minor.

Question 50

Location, origination, insertion, innervation and action of levator scapulae.

Answer 50

Small strap-like muscles found deep to trapezius and superior rhomboid minor. Originates from the transverse processes of the C1-C4 vertebrae. Inserts on the medial border of the scapula. Innervated by dorsal scapular nerve. Action: elevates the scapula.

Question 51

Location, origination, insertion, innervation and action of rhomboid minor.

Answer 51

Deep to trapezius, inferior to levator scapulae and superior to rhomboid major. Originates from spinous processes C7-T1. Inserts onto medial border of the scapula at the level of the spine of the scapula. Innervated by dorsal scapular nerve same as levator scapulae. Actions: Retracts the scapula and rotates the medial border such that the glenoid fossa is rotated inferiorly.

Question 52

Location, origination, insertion, innervation and action of rhomboid major.

Answer 52

Inferior to rhomboid minor and deep to trapezius. Originates from spinous processes of the T2-T5 vertebrae. Inserts onto the medial border of the scapula between the scapular spine and the inferior angle of the scapula. Innervated by the dorsal scapular nerve like the levator scapulae and rhomboid minor. Actions: Retracts the scapula and rotates the medial border such that the glenoid fossa is rorated inferiorly.

Question 53

What are the intrinsic muscles of the shoulder?

Answer 53

Deltoid Teres major Four rotator cuff muscles: SITS = Supraspinatus, infraspinatus, teres minor and subscapularis.

Question 54

Location, origination, insertion, innervation and action of deltoid.

Answer 54

Originates from the anterior border and upper surface of the lateral third of the clavicle and from the acromion and spine of the scapula. Inserts into the deltoid tuberosity on the lateral surface of the humerus. Innervated by the axillary nerve (C5,C6 from the posterior cord of the brachial plexus) Actions: Anterior fibres flex and medially rotate the arm at the shoulder Middle fibres abducts the arm from 15-90 degrees. Posterior fibres extend and laterally rotate the arm at the shoulder.

Question 55

Location, origination, insertion, innervation and action of teres major.

Answer 55

Forms the inferior border of the quadrangular space. Originates from the posterior surface of the inferior angle of the scapula. Passes anterior to the long head of triceps. Inserts onto the medial lip of the intertubercular groove of the humerus. Innervated by the lower subscapular nerve. Actions: Adducts the arm at the shoulder and medially rotates the arm

Question 56

Location, origination, insertion, innervation and action of supraspinatus.

Answer 56

Originates from the supraspinous fossa of scapula. Inserts onto the greater tubercle of the humerus. Innervated by suprascapular nerve (C5,C6) Actions: Abducts the arm from 0-15 degrees. Assists the deltoid in abducting the arm from 15-90 degrees.

Question 57

Location, origination, insertion, innervation and action of infraspinatus.

Answer 57

Originates from the infraspinous fossa of the scapula. Inserts onto the greater tubercle of the humerus between the supraspinatus and teres minor. Innervation by suprascapular nerve (C5, C6) Action: Laterally rotates the arm.

Question 58

Location, origination, insertion, innervation and action of teres minor.

Answer 58

Originates from the posterior surface of the scapula adjacent to the lateral border. Inserts onto the greater tubercle of the humerus inferior to the infraspinatus. Innervation by the axillary nerve (C5, C6) Actions: laterally rotates the arm and a weak adductor.

Question 59

Location, origination, insertion, innervation and action of subscapularis.

Answer 59

Originates from the subscapular fossa on the costal surface of the scapula. Inserts onto the lesser tubercle of the humerus. Innervated by the upper and lower subscapular nerves. Actions: Medially rotates the arm.

Question 60

Muscles of the anterior compartment of the arm.

Answer 60

BBC: Biceps brachii Brachialis Coracobrachialis

Question 61

Location, structure, origination, insertion, innervation and action of biceps brachii.

Answer 61

Two headed muscle located anteriorly to the humerus. Long head originates from the supraglenoid tubercle and passes through the should joint inside the joint capsule. Short head originates from the coracoid process of the scapula. The head unite into a belly and inserts onto the radial tuberosity and also into the deep fascia of the forearm via the bicipital aponeurosis. Innervated by the musculocutaneous nerve (C5-C7) Actions: Strong supinator of the forearm. Flexes the arm at the elbow and the shoulder joints. Can be remembered as when opening a bottle of win with a corkscrew. Supination to unscrew the work and flexion to pull it out.

Question 62

What purpose does testing the biceps tendon reflex serve and how is it done?

Answer 62

It tests the spinal cord segment C6 because this myotome is predominantly responsible for elbow flexion and for supination. It is done by by tapping the tendon of biceps brachii when it is stretched. This activates a neural reflex arc resulting in contraction of the biceps muscle and flexion of the elbow.

Question 63

What is the bicipital aponeurosis?

Answer 63

A thick fascial band that originates close to the musculotendinous junction of the biceps. This forms the roof of the cubital fossa and ends by blending with the deep fascia of the ulnar border of the anterior forearm.

Question 64

Location, structure, origination, insertion, innervation and action of coracobrachialis.

Answer 64

Lies deep to the short head of the biceps brachii. Originates from the coracoid process of the scapula. Passes through the axilla. Inserts onto the medial side of the humeral shaft at the level of the deltoid tubercle. Innervated by the musculocutaneous nerve (C5-C7) Actions: Flexes the arm at the shoulder and is a weak adductor of the arm.

Question 65

Location, structure, origination, insertion, innervation and action of brachialis.

Answer 65

Lies deep to the belly of biceps brachii in the distal has of the arm. It forms the floor of the cubital fossa. Originates from the anterior surface of the distal half of the humeral shaft. Inserts onto the coronoid process of the ulna and the ulnar tuberosity. Innervated by the musculocutaneous nerve (C5-C7 and contributions from the radial nerve (C5 and C6 fibres)) Actions: Brachialis flexes the forearm at the elbow

Question 66

What are the muscles in the posterior compartment of the arm?

Answer 66

Only the triceps brachii.

Question 67

Location, structure, origination, insertion, innervation and action of triceps brachii.

Answer 67

Three origins since the triceps brachii has three heads. Long head: from the infraglenoid tubercle. Lateral head: shaft of the humerus superior to the radial groove Medial head: from the shaft of the humerus, inferior to the radial groove. The heads converge to form a single tendon that inserts onto the olecranon of the ulna. Innervated by the radial nerve. Actions: Extends the forearm.

Question 68

What purpose does testing the triceps tendon reflex serve? | How is it done?

Answer 68

To test the spinal cord segment C7 because this is the myotome which predominantly is responsible for elbow extension. Taping the triceps tendon results in a reflex contraction of the triceps muscle and extension at the elbow.

Question 69

What are the quadrangular space and the triangular space and the triangular interval?

Answer 69

Passageways between the muscles of the shoulder region.

Question 70

Clinical importance of the quadrangular space.

Answer 70

It is the route via which the axillary nerve and posterior circumflex humeral artery and vein enter the posterior compartment of the arm.

Question 71

``` Superior Inferior Medial Lateral Anterior borders of the quadrangular space. ```

Answer 71

``` Superior: inferior margin of teres minor Inferior: Superior margin of teres major Medially: long head of triceps brachii Laterally: surgical neck of the humerus Anteriorly: Subscapularis ```

Question 72

What passes through the triangular space?

Answer 72

Circumflex scapular vessel to enter the infraspinous fossa. No nerves pass through.

Question 73

Superior Inferior Lateral borders of the triangular space.

Answer 73

Superior: inferior border of teres minor Inferior: Superior border teres major Laterally: long head of triceps brachii

Question 74

Superior Inferior Lateral borders of the triangular interval

Answer 74

Superior: inferior border of teres major Medial: long head of triceps brachii Lateral: Either shaft of the humerus or the lateral head of triceps brachii

Question 75

Artery of the arm.

Answer 75

Brachial artery.

Question 76

Route of the brachial artery.

Answer 76

Continuation of the axillary artery past the inferior border of the teres major muscle. The axillary artery becomes the brachial artery at the inferior border of the teres major muscle. Provides main blood supply to the arm and fore arm. Distal to teres major the brachial artery gives rise to the profunda brachii (deep brachial artery). Brachial artery continues to descend the anterior compartment of the arm. When it passes through the cubital fossa underneath the brachialis muscle the brachial artery will bifurcate into the radial and ulnar arteries.

Question 77

Route of profunda brachii.

Answer 77

A branch of brachial artery distal to teres major. It travels with the radial nerve in the radial groove of the humerus and supplies the structures in the posterior compartment of the arm (like triceps brachii).

Question 78

Where can the brachial pulse be palpated?

Answer 78

In the cubital fossa, medial to the tendon of biceps brachii. In the proximal arm the median nerve lies immediately lateral to the brachial artery. Distally the median nerve crosses the medial side of the brachial artery.