5: Brachial Plexus+ Nerves in the upper limb

Question 1

Explain the origin of the Axilla nerve in the brachial plexus

Answer 1

It is a terminal branch of the posterior cord of the brachial pexus (C5-T1)

Question 1

Which muscles does the Axilla nerve supply?

Answer 1

It supplies the Deltoid musle + teres minor

Question 2

Which area of the skin gets its sensory innervation from the Axillary nerve?

Answer 2

Question 3

Explain the route of the Axillary nerve

Answer 3

It emerges from the posterior chord of the brachial plexus at approx. level of the shulder joint and runs under the shoulder joint to innervate the deltoid

Question 4

What is a common injury where the Axilla nerve gets damaged?

Answer 4

It gets damaged in shoulder dislocation

Question 5

What are the consequences of damage to the Axillary nerve?

Answer 5

Loss of function of Deltoid

“Regimental batch” anesthesia

Question 6

What is the origino of the radial nerve in the brachial plexus?

Answer 6

It is the terminal branch of the posterior chord

Question 7

Which muscles are innervated by the radial nerve?

Answer 7

Almost all posterior muscles of the Arm and forearm

• Extensor comparment of the Arm
• Extensor compartment of forearm
• Brachioradialis –> supination

Question 8

Explain the sensory innervation of the radial nerve

Answer 8

It supplies many areas of the lower posterior arm, the posterior forearm and hand

Question 9

How does the radial nerve gets damged?

Why?

Answer 9

It runs closely related to the humerus (radial groove on humerus) –> mighe be damaged in #

Question 10

What are the consequences of radial nerve damage?

Answer 10

1. Motor function loss –> Dependant on site of lesion
   
   • Loss of extensor function
     
     • Elbow?
     • Wrist?
     • Finger?
   • –> Wrist drop
   • Loss of power grip –> initial extension needed
2. Sensory:
   
   • Anesthesia in lateral dorsal hand
     3.

Question 11

Explain the pathway of the radial nerve

Answer 11

1. Terminal branch of posterior cord of Brachial Plexus
2. Runs closely related to humerus in radial groove to the lateral epichondyle
3. Devides at the level of the elbow into
   
   • Deep branch
     
     • descends posterior forearm –> externsor muscles innervation
   • Superficial branch
     
     • sensory branch suppliing the arm, forearm, thenar eminence and part of hand, runs close to the antomical snuffbox

Question 12

Explain the origin of the musculocutaneous nerve in the brachial plexus

Answer 12

It is a terminal branch of the lateral chord (C5-7)

Question 13

Explain the route of the musculocuteneous nerve

Answer 13

It supplies and pinches the coracobrachialis muscle, runs deep protected by musces and emerges superficially to run down as the lateral cutaneous branch of the forearm

Question 14

What is the motor function of the musculocuatneous nerve?

Answer 14

C5-7

–> innervates the flexor compartment of the arm

• biceps brachii
• brachialis
• coracobrachialis

Question 15

What is the sensory function of the musculovutaneous nerve?

Answer 15

It supplies the anteriolateral part of the forerm

Question 16

When might the musculocutaneous nerve be damged?

Answer 16

Normally well protected but might be damaged in lymph node removal in breast cancer

Question 17

What is the origin of the ulnar nerve of the brachial plexus?

Answer 17

It is a terminal branch of the median chord (C8,T1)

Question 18

Explain the route of the ulnar nerve

Answer 18

It runs posteriorly in the posterior medial epicondyle groove in the forearm (supercicially, can be palpated)

Runs down forearm medially and enters hand medially

Question 19

What are common sites of damage to the ulnar nerve?

When might they occur?

Answer 19

1. Injuries to medial epicondyle of humerus
2. Injuries at the wrist –> self harm?

Question 20

Which muscles does the ulnar nerve supply?

Answer 20

It supplies the

• flexor carpu ulnaris
• Medial half to flexor digitorium profundus
• Medial 2 lumbricals
• Inerosseus hand muscles
• Hypolthenar comparment

–> Most innervation to the hand (except thenar and lateral lumbricals)

Question 21

Explain the cutaneous innervation of the hand

Answer 21

Medial part of hand (up to medial part of ring finger)

Question 22

What are the consequences of ulnar nerve damage?

Answer 22

“Claw hand”

due to–> loss of lumbrical contraction –> no flexionin MCP joints and no extension in the IP joints

• limited adduction of thumb
• Numbness in medial side of hand

Question 23

What is the ulnar paradox?

Answer 23

A more distal lesion of the ulnar nerve causes a less sever claw hand than a more proximal lesion

• because ulnar also innervates FDP
  
  • in more distal lesion FDP is paralised and Flexion at IP joints is less

Question 24

What is the origin of the median nerve in the brachial plexus?

Answer 24

It is the terminal recombinant of the medial and lateral cord

Question 25

Explain the route of the median nerve

Answer 25

1. Originates from the lateral and median cords of the brachial plexus 2. runs down anteriorly following the brachial artery to the cubital fossa 3. Enters the hand via the carpal tunnel

Question 26

Which muscles does the median nerve supply?

Answer 26

* Most flexors of forearm and hand * thenar compartment of hand * lateral lumbrical muscles

Question 27

Explain the sensory innervation of the median nerve

Answer 27

It supplies most of the lateral palmar surface and finger tips of fingers 1-3

Question 28

What is the commonest cause for damage of the median nerve?

Answer 28

Carpal tunnel syndrome

Question 29

What are the consequences of median nerve injury?

Answer 29

1. Loss of sensation 2. Loss of fine movements --\> most movements of thumb + 1-2 fingers 3. --\> Benediction Sign (Schwurhand) when trying to flex hand

Question 30

What does damage to the long thoracic nerve cause?

Answer 30

Innervation loss of Serratur Anterior --\> Pressing against a wall will lead to “winging” of the scapula resulting from the loss of activity of serratus anterior

Question 31

What is an Erb-Dunchenne Palsy?

Answer 31

Injury to the upper rours of the brachial Plexus --\> C5+6

Question 32

Which situations might lead to an Erb's-palsy?

Answer 32

Overstretch the neck relative to the shoulder (might also happen during childbirth)

Question 33

What are the consequences of an Erb's palsy?

Answer 33

"Waiters Tip" position due to: * suprascapular nerve, musculocutaneous nerve, axillary nerve palsy * paralysis and atrophy of the deltoid, biceps, and brachialis muscles

Question 34

What is a Klupke's palsy?

Answer 34

Damage to the lower roots of the brachial plexus (C8+T1)

Question 35

What is the common cause of a Klupke's palsy?

Answer 35

Over abdcution of the shoulder e.g. * due to gripping overhead to break a fall. * during childbirth

Question 36

How would someone with Klupke's palsy present?

Answer 36

1. Claw hand 2. due to * median and ulnar function loss --\> muscles of the hand * Ulnar: Fingers slightly seperated from one another (no adduction+abduction possible), lumbricals * lumbricals+ thenars

Question 37

Which spinal segments do spproximately allow movement in the 1. Shoulder girdle 2. Shoulder joint 3. Elbow joint 4. Wrist joint 5. Fingers and thumb

Answer 37

Question 38

Explain the formation and organisation of the brachial Plexus

Answer 38

1. C5-T1 **roots** 2. C5+6, T7, C8+T1 combine to form the **upper, middle and lower trunks** 3. Each roots devides into a **Posterior and Anterior devision** 4. The Anterior devisions of the upper and middle trunk joint to give rise to the **lateral cord,** * ​​​Terminal branches: devides into the musculocutaneous nerve and half of the median nerve 5. **​​​**all posterior devisions join to give rise to the **posterior cord** * devides into axillary and radial nerve 6. **​**and the anterior devision of the lower trunk continues as the **medial cord** * **​​**devides into ulnar nerve and half of the median nerve

Question 39

What is the thoracodorsal nerve? Which muscle does it supply and where does it originate?

Answer 39

It originates in the brachial plexus from the posterior chord and supplies **latissimus dorsi**

Question 40

Where do the upper and lower subscapular nerves originate? What do they supply

Answer 40

The originate from the posterior chord of the brachial plexus --\> ## Footnote supply: subscapularis and teres major,

Question 41

Where does the lateral pectoral nerve originate? What does it supply?

Answer 41

It originates from the lateral cords of the brachial plexus and supplies the Pec major+ parts of pec minor

Question 42

Where does the median pectoral nerve originate? What does it innervate?

Answer 42

Is mainly supplies pec minor and arises from the medial cord of the brachial plexus

Question 43

What is the Name of the different sections in the brachial Plexus?

Answer 43

Read That Damn Cadaver Book * Roots * Trunks * Devisions * Chords * Branches

Question 44

What is a somatic nerve?

Answer 44

Somatic= controlls voluntary movement in body

Question 45

What is a branch of the C5 Nerve route of the Brachial Plexus? What does it innervate?

Answer 45

The Dorsal Scapula nerve * supplies Rhomboids

Question 46

What is the anatomical relationship of the roots of the brachial plexus to adjacent structures?

Answer 46

It i in the posterior triangle of neck * between anterior and middle scalene muscle

Question 47

What is the Origin of the Long Thoracic Nerve?

Answer 47

Branch from C5-C7 Roots in the Brachial Plexus

Question 48

What does the Suprascapular Nerve Supply? Where does it originate?

Answer 48

Supplied the Suprespinatus and infraspinatus * branch of superior trunk of brachial plexus

Question 49

What does the Nerve to Subscapularis supply? Where does it originate?

Answer 49

It is a branch of the Superior Trunk of the brachial Plexus * supplies the subscapularis

Question 50

What are the branches of the Lateral chord of the brachial Plexus?

Answer 50

* Lateral pectoral nerve --\> Pec major * + 2 Terminal Branches * Musculocutaneous Nerve * Part of Median Nerve

Question 51

What are the branches of the Posterior chord of the brachial Plexus?

Answer 51

4 Branches + end in radial nerve * Superior Subscapular Nerve * subscapularis * Thoracodorsal Nerve * latissimus dorsi * Inferior Subscapular Nerve * Subscapularis and teres major * Axillary Nerve * deltoid and teres major

Question 52

What are the branches of the Medial chord of the brachial Plexus?

Answer 52

Gives Rise to Ulnar and part of Median Nerve + * Medial Pectoral Nerve (pec minor) * Medial Cutaneous Nerve of Arm * Medial Cutaneous Nerve of Forearm

Question 53

What are the symptoms of carpal tunnel syndrome?

Answer 53

* nocturnal loss of sensation (paresthesia) and pain in lateral volar part of hand * radiation of pain into arm * loss of power grip * Later * atrohpy of thenar compartment * paresis of abductor pollicis brevis and opponens pollicis