Anatomy - The Posterior Upper Limb

Question 1

Name the 5 superficial back muscles.

Answer 1

1. Trapezius 2. Latissimus dorsi 3. Leavator scapuli superioris 4. Rhomboid minor 5. Rhomboid major

Question 2

What is the innervation of trapezius?

Answer 2

Cn 11 - accessory

Question 3

What is the action of trapezius?

Answer 3

Elevates the scapula and rotates it during abduction of the arm.

Question 4

Which rhomboid muscle lies most superiorly?

Answer 4

Rhomboid minor lies superior to major.

Question 5

Name the 4 rotator cuff muscles.

Answer 5

1. Supraspinatus 2. Infraspinatus 3. Subscapularis 4. Teres minor

Question 6

What is the function of the rotator cuff muscles?

Answer 6

To give the shoulder joint additional stability.

Question 7

Where do the rotator cuff muscles originate from and insert?

Answer 7

Origin: scapula, insertion: humeral head.

Question 8

Why can posterior dislocation of the shoulder result in deltoid weakness and numb skin above the deltoid tendon?

Answer 8

Because it can stretch the axillary nerve.

Question 9

What is the insertion of deltoid?

Answer 9

Deltoid tuberosity of the humerus.

Question 10

What is the function of deltoid?

Answer 10

To abduct, flex and extend the arm.

Question 11

Name the 4 rotator cuff muscles.

Answer 11

1. Supraspinatus. 2. Infraspinatus. 3. Teres minor. 4. Subscapularis.

Question 12

What is the function of the rotator cuff muscles?

Answer 12

To stabilise the shoulder joint.

Question 13

What is the action of supraspinatus?

Answer 13

Abduction.

Question 14

What is the action of infraspinatus?

Answer 14

External rotation.

Question 15

What is the action of teres minor?

Answer 15

External rotation.

Question 16

What is the action of subscapularis?

Answer 16

Internal rotation.

Question 17

What is the innervation of the deltoid muscle?

Answer 17

Axillary nerve.

Question 18

What is the insertion of the deltoid muscle?

Answer 18

Deltoid tuberosity of humerus.

Question 19

What is the action of deltoid?

Answer 19

Abduction of the arm!

Question 20

What type of muscles fibres make up deltoid?

Answer 20

Multi-pennate fibres - these fibres are powerful.

Question 21

What is the function of latissiums dorsi?

Answer 21

Adduction!

Question 22

What is the action of triceps?

Answer 22

Extension of the forearm.

Question 23

What is the axilla?

Answer 23

An area underneath the shoulder joint at the junction between the upper limb and thorax.

Question 24

What structures form the apex of the axilla?

Answer 24

The first rib, clavicle and scapula.

Question 25

What structures form the medial wall of the axilla?

Answer 25

Serratus anterior, ribs and intercostal spaces.

Question 26

What structures form the lateral wall of the axilla?

Answer 26

Upper humerus, biceps brachii and coracobrachialis muscle.

Question 27

What structures form the anterior wall of the axilla?

Answer 27

Pectoralis major and minor.

Question 28

What structures form the posterior wall of the axilla?

Answer 28

Latissimus dorsi, teres major and subscapularis.

Question 29

What structures form the base of the axilla?

Answer 29

Skin and deep fascia.

Question 30

Name 5 things contained within the axilla.

Answer 30

1. Fat. 2. Lymph nodes. 3. Axillary artery. 4. Axillary vein. 5. Brachial plexus.

Question 31

Answer 31

Question 32

Answer 32

Question 33

Answer 33

Question 34

What is the clinical relevance of a frozen shoulder?

Answer 34

• the tendon of supraspinatus passes through a tight gap between the humerus and acromion
• if inflamed it will be painful for the patient to raise their arm past a short distance
• if the arm is raised further there is no pain as the swollen area has passed through the gap
• it is described as the painful arch

Question 35

What is the clinical relevance of axillary nerve palsy?

Answer 35

• axillary nerve runs along the neck of the humerus
• can be damaged by dislocation of the shoulder or fracture of the humerus neck
• paralysis of the deltoid and numbness on the lateral arm

Question 36

What is the clinical relevance of radial nerve palsy?

“Saturday night palsy”

Answer 36

• the radial nerve runs in the spiral groove directly against the humerus
• easily damaged by fracture of the humerus of direct pressure (sleeping on it)

Question 37

Which muscles are responsible for the abduction of the shoulder?

Answer 37

• Initiation is supraspinatus and then it is assisted by deltoid.
• Rotation of the scapula is by trapezius.

Question 38

Describe the movements of the scapula and humerus during abduction of the shoulder?

Answer 38

• Supraspinatus initiates abduction and after 10-15 degrees it is assisted by deltoid.
• As the arm rises the humerus externally rotates to keep the articular surfaces in contact.
• At full abduction (upper limb vertically above the head) the humerus has externally rotated 90 degrees.
• For every 2 degrees of abduction at the glenohumeral joint the scapula rotates by 1 degree over the thoracic wall.
• In full abduction (upper limb vertically above the head) the scapula is rotated so that the glenoid points upwards by 60 degrees.

Question 39

Which nerve supplies trapezius?

Answer 39

Spinal accessory nerve (cranial nerve XI)

Question 40

Which nerve is damaged by a posterior dislocation of the shoulder and what sensory and motor loss is experienced?

Answer 40

Axillary nerve; sensory loss in skin over the insertion of deltoid muscle and paralysis of deltoid.

Question 41

What structures stabilise the shoulder joint?

Answer 41

The rotator cuff muscles; supraspinatus, infraspinatus, teres minor and subscapularis.

Question 42

Which bony parts of the shoulder girdle lie subcutaneously and can be palpated easily?

Answer 42

Manubrium sternum, clavicle, spine of the scapula and acromium.

Question 43

Will “Saturday night palsy” result in a weakness of triceps, explain your answer?

Answer 43

• No.
• Saturday night palsy is loss of function of the radial nerve as it runs against the mid-shaft of the humerus in the spiral groove.
• Although the posterior compartment of the arm, which is formed by triceps, is supplied by the radial nerve the branches leave the nerve before the spiral groove.