Station 1: neurovasculature of limbs

Question 1

Where does the subclavian artery become the axillary artery?

Answer 1

Lateral edge of rib 1 and enter into the axilla

Question 2

Where does the axillary artery become the brachial artery?

Answer 2

Inferior margin of teres major muscle

Question 3

Where does the brachial artery bifurcate into the radial and ulnar nerve?

Answer 3

Apex of cubital fossa at level of radial neck, underneath the brachialis muscle

Question 4

What relation is the brachial artery to the tendon of biceps brachii?

Answer 4

Medial

Question 5

Where is the median nerve in relation to the brachial artery?

Answer 5

Medial and anterior

Question 6

Which is usually larger, the ulnar or radial artery?

Answer 6

Ulnar

Question 7

Where are the radial and ulnar arteries located? What are the anatomical relations?

Answer 7

Forearm
Radial is lateral
Ulnar is medial

Question 8

How are the radial and ulnar arteries injured?

What structures may also be injured?

Answer 8

Radial/ulnar fractures

Slitting of wrist

Question 9

Where does the right subclavian artery arise from?

Answer 9

Brachiocephalic trunk

Question 10

Where does the left subclavian artery arise?

Answer 10

Directly off the arch of the aorta

Question 11

What could an axillary artery aneurysm compress?

Answer 11

The brachial plexus leading to neurological symptoms such as paraesthesia and muscle weakness

Question 12

When could an axillary artery aneurysm occur?

Answer 12

As a result of atherosclerosis, thoracic outlet syndrome or trauma

Question 13

If the brachial artery was completely blocked or severed, what would happen?

Answer 13

This causes a characteristic flexion deformity called Volkmann’s contracture.
Caused by: resulting ischaemia of the forearm can cause necrosis and paralysis of the muscles in the forearm. The affected muscles are replaced by scar tissue and shorten considerably.

Question 14

Which part of the forearm does the radial artery supply?

Answer 14

The posterior aspect

Question 15

Which part of the forearm does the ulnar artery supply?

Answer 15

The anterior aspect

Question 16

What are the common sites for compression of the arteries of the upper limb to prevent haemorrhaging?

Answer 16

Subclavian artery:
At the 1st rib - downward pressure in angle between clavicle and inferior attachment of SCM

Axillary artery:
inferior part of lateral wall of axilla, compress against the humerus

Brachial artery:
compression against the medial humerus

Question 17

What is the route of the basilic vein?

Answer 17

Originates from the dorsal venous network of the hand -> medial aspect of upper limb -> borders teres major -> moves deep into arm and combines with brachial vein to form the axillary vein

Question 18

What is the route of the cephalic vein?

Answer 18

Originates from the dorsal venous network of the hand -> antero-lateral aspect of the upper limb, passing anteriorly at the elbow -> travels in the deltopectoral groove at the shoulder (between deltoid and pec major) -> enters axilla region via clavipectoral triangle -> in the axilla, cephalic vein terminates by joining the axillary vein

Question 19

Which vein passes through the anatomical snuffbox?

Answer 19

Cephalic vein

Question 20

Where do the cephalic and basilic vein connect? What is this vein called and what is commonly used for?

Answer 20

At the elbow, anteriorly at the cubital fossa, they are connected by the median cubital vein.
Commonly used for venipunctures.

Question 21

What type of veins are the cephalic and basilic vein?

Answer 21

Superficial

Question 22

Which spinal nerves make up the brachial plexus?

Answer 22

Anterior rami (divisions) of the cervical spinal nerves: C5, C6, C7, C8 and first thoracic spinal nerve T1

Question 23

What is the brachial plexus divided up into?

Rugby Twats Drink Cold Beer

Answer 23

Roots, trunks, divisions, cords, branches

Question 24

What are the roots of the brachial plexus?

Answer 24

C5, C6, C7, C8, T1 (anterior divisions)

Question 25

How do the spinal nerves leave the spinal cord?

Answer 25

At each vertebral level, paired spinal nerves leave the spinal cord via the intervertebral foramina of the vertebral column. Each nerve divides into the anterior and posterior nerve fibres. The roots of the brachial plexus are formed by the anterior divisions of the spinal nerves. The posterior divisions go on to innervate the skin and musculature of the trunk. The nerves then pass between the anterior and medial scalene muscles to enter the base of the neck.

Question 26

How are the trunks formed?

Answer 26

At the base of the neck, the roots converge forming three trunks: Superior trunk - C5,C6 roots Middle trunk - C7 root Inferior trunk - C8, T1 roots The trunks move laterally, crossing the posterior triangle of the neck

Question 27

How are the divisions formed?

Answer 27

Each trunk divides into two divisions. One anteriorly and the other posteriorly, in relation to the mid clavicle. The anterior divisions supply anterior compartment (flexors) and posterior divisions supply posterior compartment (extensors). They leave the posterior triangle and pass into the axilla region.

Question 28

How are the cords formed?

Answer 28

Once in the axilla, the divisions combine to form three cords. These are named due to their relation to the second part of the axillary artery.

Question 29

How is the lateral cord formed?

Answer 29

Anterior division superior trunk | Anterior middle trunk

Question 30

How is the posterior cord formed?

Answer 30

Posterior division of the superior trunk Posterior division of the middle trunk Posterior division of the inferior trunk

Question 31

How is the medial cord formed?

Answer 31

The anterior division of the inferior trunk

Question 32

The cords give rise to which major branches of the brachial plexus?

Answer 32

``` Musculocutaneous nerve Median nerve Ulnar nerve Axillary nerve Radial nerve ```

Question 33

Which nerve roots and cord supply the musculocutaneous nerve?

Answer 33

C5,C6,C7 | Lateral cord

Question 34

What are the motor functions of the musculocutaneous nerve?

Answer 34

Muscles of anterior compartment: coracobrachialis, biceps brachii, brachialis (BBC) Flexion of upper arm at shoulder and elbow, supination of forearm (biceps)

Question 35

What are the sensory functions of the musculocutaneous nerve?

Answer 35

Gives rise to lateral cutaneous nerve of the forearm - innervates skin of the lateral surface of the forearm

Question 36

Where is the musculocutaneous nerve commonly injured?

Answer 36

Uncommon, well protected within the axilla | Most common - stab wound to the axilla region

Question 37

What motor functions are affected in a musculocutaneous nerve injury?

Answer 37

BBC muscles Flexion at shoulder is weakened (pec major) Flexion at the elbow affected (brachioradialis) Supination weakened (supinator muscle)

Question 38

What sensory functions are affected in a musculocutaneous nerve injury?

Answer 38

Loss of sensation over anterolateral side of the forearm

Question 39

Which nerve roots and cord supply the axillary nerve?

Answer 39

C5, C6 | Posterior cord

Question 40

What are the motor functions of the axillary nerve?

Answer 40

Innervates teres minor (stabilises glenohumeral joint, externally rotates upper limb) and deltoid muscles (abduction of upper limb)

Question 41

What are the sensory functions of the axillary nerve?

Answer 41

Give rises to superior lateral cutaneous nerve of arm, innervates skin of inferior deltoid (regimental badge)

Question 42

Where is the axillary nerve most commonly damaged?

Answer 42

Trauma to shoulder or proximal humerus - such as fracture of humerus surgical neck, shoulder dislocation

Question 43

What motor functions are affected in a axillary nerve injury?

Answer 43

Paralysis deltoid and teres minor muscles - renders patient unable to adbuct the affected limb

Question 44

What sensory functions are affected in a axillary nerve injury?

Answer 44

Upper lateral cutaneous nerve of arm, resulting in loss of sensation over the regimental badge arm.

Question 45

What are the characteristic clinical signs of axillary injury?

Answer 45

Paralysed deltoid muscle rapidly atrophies, the greater tuberosity can be palpated in that area

Question 46

What are the roots of the median nerve?

Answer 46

C6 - T1 (some indiv have C5 fibres too) | From medial and lateral cords

Question 47

What are the motor functions of median nerve?

Answer 47

Flexor muscles in the anterior compartment of the forearm (except flexor carpi ulnaris and medial half of the flexor digitorum profundus) Thenar muscles Lateral two lumbricals in hand

Question 48

What are the sensory functions of the median nerve?

Answer 48

Give rise to palmar cutaneous branch -> Lateral part of palm Digital cutaneous branch -> lateral three and a half fingers on anterior/palmar surface of the hand

Question 49

How is the median nerve commonly injured?

Answer 49

Supracondylar fracture of the humerus (damage at the elbow) | Laceration just proximal to flexor retinaculum (damage at the wrist)

Question 50

What are the motor deficits when the median nerve is damaged at the elbow?

Answer 50

Flexors and pronators of forearm paralysed = forearm constantly supinated and flexion is weak Flexion of thumb prevented Lateral two lumbricals affected - won't be able to flex at MCP joints or extend at IP joints of index and middle fingers

Question 51

What are the sensory deficits when the median nerve is damaged at the elbow/wrist?

Answer 51

Lack of sensation over the areas that the median nerve innervates - lateral part of palm, lateral three and a half fingers on palmar aspect of hand

Question 52

What are the motor deficits when the median nerve is damaged at the wrist?

Answer 52

Thenar muscles and lateral two lumbricals are paralysed | Affects opposition of the thumb and flexion of the index and middle fingers

Question 53

Characteristic signs of median nerve damage

Answer 53

Thenar eminence wasted | Pt makes a fist -> little and ring fingers flex = shape of 'hand of benediction'

Question 54

What are the roots of the radial nerve?

Answer 54

C5-T1 | Posterior cord

Question 55

What is the sensory supply of the radial nerve?

Answer 55

Skin of posterior side of forearm, dorsal surface of lateral side of palm, lateral three and a half digits

Question 56

What is the motor supply of the radial nerve?

Answer 56

``` Triceps brachii (extends at elbow) Majority of extensor muscles in the forearm (extends wrist and fingers and supinates forearm) ```

Question 57

How is the radial nerve damaged in the axilla region?

Answer 57

Dislocation at the shoulder joint | Fracture of the proximal humerus

Question 58

What are the motor and sensory deficits of damage to the radial nerve in the axilla?

Answer 58

Triceps, posterior compartment of forearm- unable to extend forearm, wrist and fingers Unopposed flexion of wrist = wrist-drop Loss of sensation over lateral and posterior upper arm, posterior forearm, dorsal surface of lateral 3.5 digits

Question 59

How is the radial nerve damaged in the radial groove?

Answer 59

Fracture of humeral shaft

Question 60

What are the motor and sensory deficits of damage to the radial nerve in the spiral groove?

Answer 60

Triceps weakened Posterior forearm = wrist drop Loss of sensation to dorsal surface of lateral 3.5 digits, associated palm area

Question 61

What are the MOI to damage to the radial nerve in the forearm and what would be the associated motor/sensory deficit?)

Answer 61

Stabbing/laceration to the forearm: No motor, sensory loss of lateral 3.5 and palm dorsally Fracture of radial head or posterior dislocation of radius: Posterior forearm muscles, wrist drop doesn't occur as extensor carpi radialis longus is unaffected and maintains some extension at the wrist No sensory deficit

Question 62

What are the roots are the ulnar nerve?

Answer 62

C8, T1 | Medial cord

Question 63

What are the motor functions of the ulnar nerve?

Answer 63

Muscles of the hand (except thenar muscles and two lateral lumbricals), flexor carpi ulnaris, medial half of flexor digitorum profundus

Question 64

What is the sensory innervation of the ulnar nerve?

Answer 64

Anterior and posterior surfaces of the medial one and half fingers, associated palm area

Question 65

Where is the ulnar nerve susceptible to injury?

Answer 65

Elbow and wrist

Question 66

How is the ulnar nerve commonly damaged at the elbow?

Answer 66

Medial epicondyle injury - such as a fracture

Question 67

What are the motor and sensory deficits when the ulnar nerve is damaged at the medial epicondyle?

Answer 67

Flexor carpi ulnaris and medial half of flexor digitorum profundus paralysed -> flexion of wrist can occur but is accompanied by abduction Abduction and adduction of fingers can't occur Movement of little and ring fingers greatly reduced Loss of sensation in anterior and posterior surfaces of the medial one and half fingers, associated palm area Patient can't grip paper placed between fingers

Question 68

What are the motor and sensory deficits when the ulnar nerve is damaged by laceration of the wrist?

Answer 68

Abduction and adduction can't occur Movement of little and ring finger reduced but muscles in forearm are unaffected Just the palmar branch and superficial branch affected so sensory loss over palmar medial 1.5 fingers Patient can't grip paper and ulnar claw develops over long term

Question 69

What is ulnar claw?

Answer 69

Hyperextension of MCP joints of little and ring fingers (paralysis of lumbricals) Flexion at ITP joins

Question 70

What is a upper brachial plexus injury? (Erb's palsy/waiter's tip)

Answer 70

Excessive increase in angle between neck and shoulder (stretch or tear of superior nerve roots) -> difficult birth of shoulder trauma Nerves derived from C5 or C6 solely Affected limb hangs limp, medially rotated, pronated

Question 71

What is a lower brachial plexus injury? (klumpke's palsy/claw hand)

Answer 71

Excessive abduction of arm - person catching a branch when fall from tree Nerves derived from T1 - median and ulnar -> clawed hand appearance

Question 72

What is the function of anterior compartment of the forearm?

Answer 72

Flexion at wrist and fingers Pronation Innervated by ulnar and median nerve

Question 73

What is the function of the posterior compartment of the forearm?

Answer 73

Extension at the wrist and fingers Supination Innervated by the radial nerve

Question 74

What is the blood supply to the anterior compartment of the forearm?

Answer 74

Ulnar and radial artery

Question 75

What is the blood supply to the posterior compartment of the forearm?

Answer 75

Anterior and posterior interosseous arteries (branches of short common interosseous artery from the proximal artery)

Question 76

Why is compartment syndrome more common in the anterior compartment of the forearm?

Answer 76

Me don't know