UE Part 3: Nerves

Question 1

1.
• Passes posteriorly through the quadrangular space accompanied by the posterior circumflex humeral artery and winds around the surgical of the humerus (may be injured when this part of the bone is fractured).
2. What does it innervate?
3. What does it give rise to?

Answer 1

1. Axillary Nerve (C5-C6)
2. Deltoid, Teres minor
3. Lateral Brachial Cutaneous Nerve

Question 2

Innervates the lower part of the subscapularis and teres major muscles. Runs downward behind the subscapular vessels to the teres major muscle.

Answer 2

Lower Subscapular Nerve (C5-C6)

Question 3

Runs behind the axillary artery and accompanies the thoracodorsal artery to enter the latissimus dorsi muscle.

Answer 3

Thoracodorsal Nerve (C7-C8)

Question 4

What innervates the upper portion of the subscapularis muscle?

Answer 4

Upper Subscapular Nerve (C5-C6)

Question 5

What are the Branches from the Posterior Cord of brachial plexus?

Answer 5

1. Upper Subscapular Nerve (C5-C6)
2. Thoracodorsal Nerve (C7-C8)
3. Lower Subscapular Nerve (C5-C6)
4. Axillary Nerve (C5-C6)
5. Radial Nerve (C5-T1)

Question 6

1.
• Runs down the anteromedial aspect of the arm, and at the elbow, it lies medial to the brachial artery on the brachialis muscle (has no muscular branches in the arm).
• Passes through the cubital fossa, deep to the bicipital aponeurosis, and medial to the brachial artery.
• Enters the forearm between the humeral and ulnar heads of the pronator teres muscle, passes between the flexor digitorum superficialis and the flexor digitorum profundus muscles, and then becomes superficial by passing between the tendons of the flexor digitorum superficialis and flexor carpi radialis near the wrist.
2. In the cubital fossa, what does it give rise to?
3. Muscles innervated?
4. Motor functions?
5. Sensory innervation?
6. Nerve injury to hand?

Answer 6

1. Median Nerve (C5-T1)
2. anterior interosseous nerve
3. Anterior muscles of forearm (Pronator teres (PT), Pronator quadratus (PQ), flexor carpi radialis (FCR), flexor digitorum superficialis (FDS), FDP, Flexor pollicis longus (FPL), Thenar muscles (AFO), Lumbricals
4. Thumb flexion and opposition; Flexion of digits 2 & 3, Wrist flexion and abduction; Forearm pronation
5. Skin over anterolateral surface of hand
6. Ape Hand deformity

Question 7

What are the branches of the Medial and Lateral Cords of brachial plexus?

Answer 7

Median Nerve (C5-T1)

Question 8

1.
• Runs down the medial aspect of the arm but does not branch in the brachium.
• Arises from the medial cord of the brachial plexus, runs down the medial aspect of the arm, pierces the medial intermuscular septum at the middle of the arm, and descends together with the superior ulnar collateral branch of the brachial artery.
• Terminates by dividing into superficial and deep branches at the root of the hypothenar eminence.
2. Where can it be palpated and most commonly injured that produces what symptoms?
3. Where is it vulnerable to cuts or stabs?
4. Muscles innervated?
5. Motor functions?
6. Sensory innervation?
7. Nerve injury to hand?

Answer 8

1. Ulnar Nerve (C7-T1)
2. medial epicondyle in a groove or tunnel (cubital tunnel); Funny bone symptoms
3. superficial to the flexor retinaculum and lateral to the pisiform bone
4. Flexor carpi ulnaris, Flexor digitorum profundus, Adductor pollicis, small digital muscles
5. Finger abduction and adduction; Flexion of digits 4 & 5; Wrist flexion and adduction
6. Skin over medial 1/3 surface of hand via superficial branch
7. Claw Hand deformity

Question 9

1. It runs between the axillary artery and vein and then runs medial to the brachial artery.
2. What does it innervate?

Answer 9

1. Medial Antebrachial Cutaneous Nerve (C8-T1)

2. Skin on the medial side of the forearm

Question 10

1.
• Runs along the medial side of the axillary vein.
• May communicate with the (3), which arises as a lateral branch of the second intercostal nerve.
2. What does it innervate?

Answer 10

1. Medial Brachial Cutaneous Nerve (C8-T1)
2. Skin on the medal side of arm
3. intercostobrachial nerve

Question 11

1.
• Passes forward between the axillary artery and vein and forms a loop in front of the axillary artery with the lateral pectoral nerve.
• Enters and supplies the __ muscle and reaches the overlying pectoralis major muscle.
2. What does it innervate?

Answer 11

1. Medial Pectoral Nerve (C8-T1)

2. Pectoralis minor, some part of pectoralis major muscle

Question 12

What are the Branches from the Medial Cord of brachial plexus?

Answer 12

1. Medial Pectoral Nerve (C8-T1)
2. Medial Brachial Cutaneous Nerve (C8-T1)
3. Medial Antebrachial Cutaneous Nerve (C8-T1)
4. Ulnar Nerve (C7-T1)

Question 13

1. It pierces the coracobrachialis muscle, descends between the biceps brachii and brachialis muscles
2. What does it innervate?
3. It continues in the forearm as?

Answer 13

1. Musculocutaneous Nerve (C5-C7)
2. Coracobrachialis, Biceps brachii, Brachialis muscles (flexor muscles in the anterior compartment of the arm)
3. Lateral antebrachial cutaneous nerve

Question 14

1. • Innervates the \_\_ muscle primarily and also supplies the \_\_ muscle by way of a nerve loop.
   • Sends a branch over the first part of the axillary artery to the medial pectoral nerve and forms a nerve loop through which the lateral pectoral nerve conveys motor fibers to the pectoralis minor muscle.
   • Pierces the costocoracoid membrane of the clavipectoral fascia.
   • Is accompanied by the pectoral branch of the thoracoacromial artery.

2. What does it innervate?

Answer 14

1. Lateral Pectoral Nerve (C5-C7)

2. Pectoralis major & minor muscles

Question 15

What are the Branches from the Lateral Cord?

Answer 15

1. Lateral Pectoral Nerve (C5-C7)

2. Musculocutaneous Nerve (C5-C7)

Question 16

1. • Descends in front of the brachial plexus and the subclavian artery and behind the clavicle to reach the subclavius muscle.
   • Also innervates the \_\_ joint.
   • Usually branches to the \_\_\_, which enters the thorax to join the phrenic nerve.

2. What does it innervate?
3. What does it give branch to?

Answer 16

1. Nerve to Subclavius (C5)
2. Subclavius muscle, Sternoclavicular joint
3. Accessory phrenic nerve (C5)

Question 17

1.         • Runs laterally across the posterior cervical triangle.
   • Passes through the scapular notch under the superior transverse scapular ligament, whereas the suprascapular artery passes over the ligament. (Thus, it can be said that the army [artery] runs over the bridge [ligament], and the navy [nerve] runs under the bridge.)
   • Supplies the\_\_ muscle and the shoulder joint and then descends through the notch of the scapular neck to innervate the \_\_\_ muscle.

2. What muscles do this innervate?

Answer 17

1. Suprascapular Nerve (C5-C6)

2. Supraspinatus, Infraspinatus

Question 18

What are the Branches from the Upper Trunk of brachial plexus?

Answer 18

1. Suprascapular Nerve (C5-C6)

2. Nerve to Subclavius (C5)

Question 19

It is commonly caused by a stab wound or during radical mastectomy or thoracic surgery. It results in paralysis of the serratus anterior muscle and inability to elevate the arm above the horizontal.

It produces a winged scapula in which the vertebral (medial) border of the scapula protrudes away from the thorax.

Answer 19

Injury to the long thoracic nerve

Question 20

What are the Branches from the Roots of Brachial plexus?

Answer 20

1. Dorsal Scapular Nerve (C5)

2. Long Thoracic Nerve (C5-C7)

Question 21

1. it descends behind the brachial plexus and runs on the external surface of the serratus anterior muscle
2. What does it innervate?

Answer 21

1. Long Thoracic Nerve (C5-C7)

2. Serratus anterior muscle

Question 22

1. It pierces the scalenus medius muscle to reach the posterior cervical triangle and descends deep to the levator scapulae and the rhomboid minor and major muscles.
2. What does it innervate?

Answer 22

1. Dorsal Scapular Nerve (C5)

2. Rhomboids, Levator scapulae muscles

Question 23

• Is formed by the ventral primary rami of the lower four cervical nerves and the first thoracic nerve (C5-T1). Has roots that pass between the scalenus anterior and medius muscles.
  
  • Is enclosed with the axillary artery and vein in the axillary sheath, which is formed by a prolongation of the prevertebral fascia.

Answer 23

Brachial Plexus

Question 24

It may be caused during a difficult breech delivery (birth palsy or obstetric paralysis), by a cervical rib (cervical rib syndrome), or by abnormal insertion or spasm of the anterior and middle scalene muscles (scalene syndrome). The injury causes a claw hand.

Answer 24

Lower trunk injury (Klumpke paralysis)

Question 25

It is caused by a birth injury during a breech delivery or a violent displacement of the head from the shoulder such as might result from a fall from a motorcycle or horse. It results in a loss of abduction, flexion, and lateral rotation of the arm, producing a ---waiter's tip hand---, in which the arm tends to lie in medial rotation resulting from paralysis of lateral rotator muscles.

Answer 25

Upper trunk injury (Erb-Duchenne paralysis or Erb palsy)

Question 26

Another median nerve injury of inability to flex at the MCP and IP joints of the middle and index finger.

Answer 26

Hand of Benediction / Bishop's Hand

Question 27

1. • Arises from the posterior cord and the largest branch of the brachial plexus. • Descends posteriorly between the long and medial heads of the triceps, after which it passes inferolaterally with the profunda brachii artery in the spiral (radial) groove on the back of the humerus between the medial and lateral heads of the triceps. • Pierces the lateral intermuscular septum to enter the anterior compartment and descends anterior to the lateral epicondyle between the brachialis, and brachioradialis muscles to enter the cubital fossa, where it div into superficial and deep branches. • Gives rise to muscular branches (which supply the brachioradialis and extensor carpi radialis longus), articular branches, and posterior brachial and posterior antebrachial cutaneous branches. 2. Muscles innervated? 3. Motor functions? 4. Sensory innervation? 5. Nerve injury to hand?

Answer 27

1. Radial Nerve (C5-T1) 2. Triceps, Extensor carpi radialis and ulnaris, Supinator, Extensor pollicis 3. Extension of arm, wrist, and proximal finger joints below shoulder; Forearm supination; Thumb abduction in plane of palm 4 . Skin over posterolateral surface of the arm, forearm, and radial half of hand 5. Wrist drop

Question 28

It may be caused by a supracondylar fracture of the humerus or a compression in the carpal tunnel. It results in the loss of pronation, opposition of the thumb, and flexion of the lateral two interphalangeal joints and impairment of the medial two interphalangeal joints. It also produces a characteristic flattening of the thenar eminence, often referred to as the ape hand.

Answer 28

Injury to the median nerve

Question 29

It is commonly caused by a fracture of the surgical neck of the humerus or anteroinferior dislocation of the humerus. It results in weakness of lateral rotation and abduction of the arm (the supraspinatus can abduct the arm but not to a horizontal level).

Answer 29

Injury to the axillary nerve

Question 30

It is caused by the pressure of the crosspiece of a crutch, resulting in the paralysis of the arm called crutch palsy. It results in the loss in function of the extensors of the arm, forearm, and hand and produces a wrist drop.

Answer 30

Injury to the posterior cord

Question 31

1. • Arises from the posterior cord and the largest branch of the brachial plexus. • Descends posteriorly between the long and medial heads of the triceps, after which it passes inferolaterally with the profunda brachii artery in the spiral (radial) groove on the back of the humerus between the medial and lateral heads of the triceps. • Pierces the lateral intermuscular septum to enter the anterior compartment and descends anterior to the lateral epicondyle between the brachialis, and brachioradialis muscles to enter the cubital fossa, where it div into superficial and deep branches. • Gives rise to muscular branches (which supply the brachioradialis and extensor carpi radialis longus), articular branches, and posterior brachial and posterior antebrachial cutaneous branches. 2. Muscles innervated? 3. Motor functions? 4. Sensory innervation? 5. Nerve injury to hand?

Answer 31

1. Radial Nerve (C5-T1) 2. Triceps, Extensor carpi radialis and ulnaris, Supinator, Extensor pollicis 3. Extension of arm, wrist, and proximal finger joints below shoulder; Forearm supination; Thumb abduction in plane of palm 4 . Skin over posterolateral surface of the arm, forearm, and radial half of hand 5. Wrist drop