Arm muscles

Question 2

What is the location of the pectoral region?

Answer 2

Anterior chest wall

The pectoral region contains muscles that exert force on the upper limb.

Question 3

Name the four muscles found in the pectoral region.

Answer 3

• Pectoralis major
• Pectoralis minor
• Serratus anterior
• Subclavius

These muscles are responsible for various movements and stabilization of the upper limb.

Question 4

What is the shape and size of the pectoralis major muscle?

Answer 4

Large and fan shaped

It is the most superficial muscle in the pectoral region.

Question 5

What are the two heads of the pectoralis major?

Answer 5

• Sternal head
• Clavicular head

Both heads contribute to the muscle’s overall function.

Question 6

What is the primary function of the pectoralis major?

Answer 6

Adducts and medially rotates the upper limb

It also draws the scapula anteroinferiorly.

Question 7

What nerves innervate the pectoralis major?

Answer 7

Lateral and medial pectoral nerves

These nerves are responsible for the muscle’s motor function.

Question 8

Where is the pectoralis minor located?

Answer 8

Underneath the pectoralis major

It forms part of the anterior wall of the axilla region.

Question 9

What is the main function of the pectoralis minor?

Answer 9

Stabilises the scapula by drawing it anteroinferiorly against the thoracic wall

This action helps maintain scapular positioning during arm movements.

Question 10

What nerve innervates the pectoralis minor?

Answer 10

Medial pectoral nerve

The medial pectoral nerve provides motor function to this muscle.

Question 11

What is the location of the serratus anterior muscle?

Answer 11

More laterally in the chest wall

It forms the medial border of the axilla region.

Question 12

What are the attachments of the serratus anterior?

Answer 12

• Originates from the lateral aspects of ribs 1-8
• Attaches to the costal surface of the medial border of the scapula

These attachments allow the muscle to perform its functions effectively.

Question 13

What is the function of the serratus anterior?

Answer 13

Rotates and protracts the scapula

It allows the arm to be raised over 90 degrees and holds the scapula against the ribcage.

Question 14

What nerve innervates the serratus anterior?

Answer 14

Long thoracic nerve

This nerve is crucial for the muscle’s function.

Question 15

What is the size and location of the subclavius muscle?

Answer 15

Small muscle located directly underneath the clavicle

It runs horizontally and provides some protection to underlying structures.

Question 16

What is the function of the subclavius?

Answer 16

Anchors and depresses the clavicle

This function is important for shoulder stability.

Question 17

What nerve innervates the subclavius?

Answer 17

Nerve to subclavius

This nerve supplies motor function to the subclavius muscle.

Question 18

What clinical sign is associated with long thoracic nerve palsy?

Answer 18

Winging of the scapula

This occurs when the scapula protrudes out of the back due to paralysis of the serratus anterior.

Question 19

What is a common cause of long thoracic nerve palsy?

Answer 19

Traction injuries where the upper limb is stretched violently

Such injuries can lead to significant muscle dysfunction.

Question 21

What are the two groups of shoulder muscles?

Answer 21

Extrinsic and intrinsic muscles

Extrinsic muscles originate from the torso, while intrinsic muscles originate from the scapula and/or clavicle.

Question 22

What do extrinsic muscles of the shoulder attach to?

Answer 22

Clavicle, scapula, or humerus

Extrinsic muscles originate from the trunk.

Question 23

What are the two layers of extrinsic shoulder muscles?

Answer 23

Superficial layer and deep layer

The superficial layer includes the trapezius and latissimus dorsi.

Question 24

What shape does the trapezius muscle form?

Answer 24

Trapezoid shape

The trapezius is broad, flat, and triangular.

Question 25

What are the actions of the upper fibres of the trapezius?

Answer 25

Elevate and rotate the scapula during arm abduction ## Footnote The middle fibres retract the scapula and lower fibres pull it inferiorly.

Question 26

What nerve provides motor innervation to the trapezius?

Answer 26

Accessory nerve ## Footnote Proprioceptor fibres also come from C3 and C4 spinal nerves.

Question 27

What is a common cause of accessory nerve damage?

Answer 27

Iatrogenic causes, such as cervical lymph node biopsy ## Footnote Trauma can occur during medical procedures.

Question 28

How can trapezius function be assessed clinically?

Answer 28

By asking the patient to shrug their shoulders ## Footnote Other signs of accessory nerve damage include muscle wasting and partial paralysis of the sternocleidomastoid.

Question 29

What actions does the latissimus dorsi perform?

Answer 29

Extends, adducts, and medially rotates the upper limb ## Footnote The latissimus dorsi covers a wide area of the lower back.

Question 30

What is the innervation of the latissimus dorsi?

Answer 30

Thoracodorsal nerve ## Footnote This nerve controls the latissimus dorsi muscle.

Question 31

What are the muscles in the deep layer of extrinsic shoulder muscles?

Answer 31

Levator scapulae, rhomboid major, rhomboid minor ## Footnote These muscles are situated in the upper back underneath the trapezius.

Question 32

What is the action of the levator scapulae?

Answer 32

Elevates the scapula ## Footnote The levator scapulae is a small strap-like muscle.

Question 33

What is the innervation of the levator scapulae?

Answer 33

Dorsal scapular nerve ## Footnote This nerve is responsible for the motor function of the levator scapulae.

Question 34

What are the actions of rhomboid major and minor?

Answer 34

Retracts and rotates the scapula ## Footnote Both rhomboid muscles perform the same actions.

Question 35

What is the innervation of rhomboid major and minor?

Answer 35

Dorsal scapular nerve ## Footnote Both muscles are innervated by the same nerve.

Question 36

What are the intrinsic muscles also known as?

Answer 36

Scapulohumeral group

Question 37

How many muscles are in the scapulohumeral group?

Answer 37

Six muscles

Question 38

Name the six muscles in the intrinsic muscles group.

Answer 38

* Deltoid * Teres major * Supraspinatus * Infraspinatus * Subscapularis * Teres minor

Question 39

What shape does the deltoid muscle resemble?

Answer 39

Inverted triangle

Question 40

What are the three parts of the deltoid muscle?

Answer 40

* Anterior * Middle * Posterior

Question 41

What actions do the anterior fibres of the deltoid perform?

Answer 41

Flexion and medial rotation

Question 42

What actions do the posterior fibres of the deltoid perform?

Answer 42

Extension and lateral rotation

Question 43

What is the major action of the middle fibres of the deltoid?

Answer 43

Abduction of the arm

Question 44

What nerve innervates the deltoid muscle?

Answer 44

Axillary nerve

Question 45

What is the role of the teres major in relation to the quadrangular space?

Answer 45

Forms the inferior border

Question 46

What actions does the teres major perform?

Answer 46

* Adducts * Extends at the shoulder * Medially rotates the arm

Question 47

What nerve innervates the teres major?

Answer 47

Lower subscapular nerve

Question 48

How many muscles are in the rotator cuff group?

Answer 48

Four muscles

Question 49

What is the collective function of the rotator cuff muscles?

Answer 49

Pull the humeral head into the glenoid fossa for stability

Question 50

What are the individual actions of the supraspinatus?

Answer 50

* Abduction of the upper limb at the shoulder * Assists deltoid from 15-90 degrees

Question 51

What nerve innervates the supraspinatus?

Answer 51

Suprascapular nerve

Question 52

What action does the infraspinatus perform?

Answer 52

Laterally rotates the arm

Question 53

What nerve innervates the infraspinatus?

Answer 53

Suprascapular nerve

Question 54

What action does the subscapularis perform?

Answer 54

Medially rotates the arm

Question 55

What nerves innervate the subscapularis?

Answer 55

* Upper subscapular nerve * Lower subscapular nerve

Question 56

What action does the teres minor perform?

Answer 56

Laterally rotates the arm

Question 57

What nerve innervates the teres minor?

Answer 57

Axillary nerve

Question 58

What is rotator cuff tendonitis?

Answer 58

Inflammation of the tendons of the rotator cuff muscles

Question 59

Which muscle is most commonly affected by rotator cuff tendonitis?

Answer 59

Supraspinatus

Question 60

What causes rotator cuff tendonitis?

Answer 60

Repetitive use of the shoulder joint

Question 61

What conservative treatments are recommended for rotator cuff tendonitis?

Answer 61

* Rest * Analgesia * Physiotherapy

Question 62

What additional treatments can be considered for severe cases of rotator cuff tendonitis?

Answer 62

* Steroid injections * Surgery

Question 63

What is the location of the upper arm?

Answer 63

Between the shoulder joint and elbow joint

Question 64

How many muscles are contained in the upper arm?

Answer 64

Four muscles

Question 65

What muscles are found in the anterior compartment of the upper arm?

Answer 65

Biceps brachii, brachialis, coracobrachialis

Question 66

What muscle is found in the posterior compartment of the upper arm?

Answer 66

Triceps brachii

Question 67

Which nerve innervates the muscles in the anterior compartment of the upper arm?

Answer 67

Musculocutaneous nerve

Question 68

What is a mnemonic to remember the muscles in the anterior compartment?

Answer 68

BBC – biceps, brachialis, coracobrachialis

Question 69

What provides arterial supply to the anterior compartment of the upper arm?

Answer 69

Muscular branches of the brachial artery

Question 70

How many heads does the biceps brachii have?

Answer 70

Two heads

Question 71

Does the biceps brachii attach directly to the humerus?

Answer 71

No, it has no attachment to the bone itself

Question 72

What is formed by the connective tissue sheet given off by the biceps brachii tendon?

Answer 72

Bicipital aponeurosis

Question 73

What is the main function of the biceps brachii?

Answer 73

Supination of the forearm and flexion at the elbow and shoulder

Question 74

What spinal cord segment does the bicep tendon reflex test?

Answer 74

C6

Question 75

Where does the coracobrachialis muscle lie in relation to the biceps brachii?

Answer 75

Deep to the biceps brachii

Question 76

What is the function of the coracobrachialis muscle?

Answer 76

Flexion of the arm at the shoulder and weak adduction

Question 77

What is the function of the brachialis muscle?

Answer 77

Flexion at the elbow

Question 78

Which nerves innervate the brachialis muscle?

Answer 78

Musculocutaneous nerve and contributions from the radial nerve

Question 79

What is a characteristic sign of a complete rupture of the long head of the biceps brachii?

Answer 79

Popeye Sign

Question 80

What does the rupture of the biceps tendon affect in terms of upper limb strength?

Answer 80

Little noticeable weakness due to the action of the brachialis and supinator muscles

Question 81

What artery supplies the posterior compartment of the upper arm?

Answer 81

Profunda brachii artery

Question 82

How many heads does the triceps brachii have?

Answer 82

Three heads

Question 83

What is the function of the triceps brachii?

Answer 83

Extension of the arm at the elbow

Question 84

Which nerve innervates the triceps brachii?

Answer 84

Radial nerve

Question 85

What spinal segment does a tap on the triceps tendon test?

Answer 85

C7

Question 86

In some individuals, which nerve innervates the long head of the triceps brachii?

Answer 86

Axillary nerve

Question 87

What are the 3 layers of the anterior compartment of the arm?

Answer 87

Superficial, intermediate, deep

Question 88

What muscles make up the superficial layer of the anterior forearm?

Answer 88

flexor carpi ulnaris, palmaris longus, flexor carpi radialis, pronator teres

Question 89

What muscles make up the intermediate layer of the anterior compartment of the forearm?

Answer 89

flexor digitorum superficialis

Question 90

What muscles make up the deep layer of the anterior compartment of the forearm?

Answer 90

flexor pollicis longus, flexor digitorum profundus and pronator quadratus

Question 91

Flexor carpi ulnaris action

Answer 91

Flexion and adduction at the wrist

Question 92

Flexor carpi ulnaris innervation

Answer 92

Ulnar nerve

Question 93

Plamaris longus action

Answer 93

Flexion at the wrist

Question 94

Palmaris longus innervation

Answer 94

Median nerve

Question 95

Flexor carpi radialis action

Answer 95

Flexion and abduction at the wrist

Question 96

Flexor carpi ulnaris innervation

Answer 96

Median nerve

Question 97

Pronator teres action

Answer 97

Pronation of foreatm

Question 98

Pronator teres innervation

Answer 98

Median nerve

Question 99

Flexor digitorum superficialis action

Answer 99

Flexes MCP and PIP of 4 fingers, flexes at wrist

Question 100

Flexor digitorum superficialis innervation

Answer 100

Median nerve

Question 101

Flexor digitorum profundus action

Answer 101

Flexes DIPs and MCPs of fingers, flexes wrist

Question 102

Flexor digitorum profundus innervation

Answer 102

Medial half- ulnar nerve, lateral half- anterior interosseous branch of median nerve

Question 103

Flexor pollicis longus action

Answer 103

Flexes IP and MCP of thumb

Question 104

Flexor pollicis innervation

Answer 104

Anterior interosseous branch of median nerve

Question 105

Pronator quadratus action

Answer 105

Pronates forearm

Question 106

Pronator quadratus innervation

Answer 106

Anterior interosseous branch of median nerve