3.4. Innervation of Brachia, Antebrachia, and Hands

Question 1

Sort the muscles according to their innervations

Answer 1

Question 2

Identify the nerves that innervate each cutaneous region

Answer 2

Question 3

Which muscles and cutaneous regions are innervated by the axillary nerve? What movements are caused at each muscle?

Answer 3

See notes for movements

Lateral Muscles of Brachia and Antebrachia

• Teres Minor (Posterior Pectoral Girdle)
• Deltoid (Anterior Brachia)
• Upper lateral arm

Question 4

Which muscles and cutaneous regions are innervated by the musculocutaneous nerve? What movements are caused at each muscle?

Answer 4

See notes for movements

MUSCLES: MOST Flexors/Anterior of Brachia Excluding pectoralis major and deltoid

• Biceps Brachii (ant brachia)
• Brachialis (ant brachia)
• Coracobrachialis (ant brachia)

CUTANEOUS:
CONTINUES INTO THE LATERAL CUTANEOUS NERVE OF THE FOREARM

• Lateral antebrachia

Question 5

Which muscles and cutaneous regions are innervated by the radial nerve? What movements are caused at each muscle?

Answer 5

See notes for movements

MUSCLES:

MOST Flexors/Anterior of Brachia Excluding pectoralis major and deltoid

• Biceps Brachii (ant brachia)
• Brachialis (ant brachia)
• Coracobrachialis (ant brachia)

CUTANEOUS:

• Post and lateral brachia
• Post antebrachia
• Posterior lateral palm excluding thumb
• Skin covering thenars

Question 6

Which muscles and cutaneous regions are innervated by the median nerve? What movements are caused at each muscle?

Answer 6

See notes for movements

Muscles:

• MOST Flexors/Anterior of Antebrachia, AND thenars and some lumbricals*
• Except flexor carpi ulnaris and medial half of flexor digitorum profundus*
• Pronator Teres (Ant sup antebrach)
• Flexor Carpi Radialis (Ant sup antebrach)
• Palmaris Longus (Ant sup antebrach)
• Flexor Digitorum Superficialis (Ant mid antebrach)
• Flexor Pollicis Longus (Ant deep antebrach)
• LATERAL half of flexor digitorum Profundus (ant deep antebrach)
• Pronator Quadratus (ant deep antebrach)
• SOME lumbricals

CUTANEOUS:

• Anterior digits 1-3
• Posterior digit tips 1-3

Question 7

Which muscles and cutaneous regions are innervated by the ulnar nerve? What movements are caused at each muscle?

Answer 7

See notes for movements

MUSCLES:

SOME Flexors/Anterior of Brachia AND palmar interossei, dorsal interossei, and most lumbricals

• Flexor Carpi Ulnaris (ant sup antebrachia)
• MEDIAL half of flexor digitorum Profundus (ant deep antebrachia)
• MOST lumbricals (ant and post hand)
• Palmar Interossei (ant hand)

Dorsal Interossei (ant hand)

CUTANEOUS:

• Anterior and posterior digits 4-5

Question 8

Which nerve innervates the extensor muscles of the arm?

Answer 8

Radial

Question 9

Which artery supplies the arm?

Answer 9

Brachial

Question 10

What movements can be performed at the distal interphalangeal joints?

Answer 10

Flexion/extension

Question 11

Name the superficial veins of the upper limbs

Answer 11

Basilic and Cephalic

Question 12

The muscles that cross the anterior aspect of the wrist joint contract to produce…

Answer 12

Flexion

Question 13

The skin on the anterior aspect of the little finger (5th digit) is supplied by which nerve?

Answer 13

Ulnar nerve provides cutaneous innervation to the medial palm and medial 1.5 digits

Question 14

Name the four muscles that form the rotator cuff of the glenohumeral (shoulder) joint.

Answer 14

Supraspinatus, Infraspinatus, Teres Minor, and Subscapularis

Question 15

Name the three muscles innervated by the musculocutaneous nerve

Answer 15

Coracobrachialis, Brachialis, Biceps Brachii

All located in anterior brachia and are flexors of the glenohumeral and/or elbow joints

Question 16

What is the action(s) of the flexor carpi radialis muscle at the wrist?

Answer 16

Flexion because it crosses the anterior aspect of the wrist joint. It performs this action with flexor carpi ulnaris

Abduction (radial deviation) because it crosses the lateral aspect of the wrist joint. It performs this action with the extensor carpi radialis longus and extensor carpi radialis brevis.

Question 17

Describe the articular surfaces, joint classification and movements of the elbow joint.

Answer 17

Classification: Synovial Hinge

Articular Surfaces: Capitulum of humerus with head of radius (humeroradial joint) and trochlea of the humerus with trochlear notch of the ulna (humeroradial). The proximal radioulnar joint between the radius’ head with radial notch of the ulna shares the joint capsule.

Movements: Flexion and Extension

Question 18

A carpenter cuts his forearm while using an electric band saw. The doctor examined his arm and forearm, and noticed he had what is called a ‘wrist drop’ (cannot extend the wrist). Which nerve might have been damaged?

Answer 18

He is likely to have cut his radial nerve (which supplies the extensor muscles of the wrist that are located in the posterior forearm). Therefore he cannot extend his wrist and the wrist goes into unopposed flexion. I.e. Wrist drop.

Question 19

At the cafe you take a drink of your soy decaf latte with an orange twist.

a. What movements are you making to get the glass from the table to your mouth?
b. What muscles are you using at the shoulder and elbow joints?

Answer 19

Elbow flexion- Biceps brachii, brachialis, brachioradialis

Shoulder flexion- Deltoid, coracobrachialis, biceps brachii, and pectoralis major

Also, to hold the glass:

Flexion of the metacarpophalangeal and interphalangeal joints and wrist/radiocarpal joint - flexor digitorum profundus, fleor digitorum superficialis, flexor carpi radialis, and flexor carpi ulnaris

Question 20

One of your friends tells you that he is unable to abduct his glenohumeral (shoulder) joint.

a. Which muscle(s) are most likely to be affected? (i.e. which muscles abduct the shoulder joint?)
b. Which nerve is most likely to be affected? (i.e. which nerve innervates the abductor muscles of the shoulder joint?)

Answer 20

a. Deltoid, supraspinatus
b. Axillary nerve (innervates deltoid)
* Don’t need to know that suprascapular nerve innervates supraspinatus*

Question 21

1. What muscle attaches to the region labelled A?
2. Identify the ligament or tendon labelled B?

Answer 21

1. Subscapularis
2. Coracoacromial Ligament

Question 22

1. Identify the three muscles bordering the anatomical snuff box: from lateral to medial
2. Identify the artery labelled A

Answer 22

1. Abductor pollicis longus, extensor pollicis brevis, extensor pollicis longus
2. Radial Artery

Question 23

1. Identify the bony landmark labelled A
2. List the muscles, ligaments, and bursae that attach onto A

Answer 23

1. Olecranon
2. Triceps Brachii’s distal tendon and the medial collateral ligament of the elbow joint _{(between humerus epicondyle and ulna’s coronoid process)} and the subtendnous bursa (between ulna’s olecranon and the biceps brachii tendons)

Question 24

1. Identify the muscle labelled A
2. What is B innervated by?

Answer 24

1. Palmaris Longus (notice that it divides into 4 tendons under the flexor retinaculum!)
2. Radial Nere (radial nerve innervates ALL extensors/posterior of antebrachia)

Question 25

1. Which movements are possible at the joint labelled A?
2. Identify the bone labelled B

Answer 25

1. Abduction/adduction and flexion/extension (rotation, or pronaton/supination is at the proximal and distal radioulnar joints!)
2. Hamate

Question 26

1. What movement is occurring at the left glenohumeral joint?
2. What muscle is the major contributor to the movement occurring at the left glenohumeral joint?

Answer 26

1. Abduction
2. Deltoid

Question 27

1. Identify the nerve labelled A
2. What cutaneous region is innervated by A?

Answer 27

1. Radial
2. Posterior lateral brachia, posterior antebrachia, posterior lateral hand excluding thumb, and skin covering thenars

Question 28

1. Identify the vein labelled A
2. What vein connects the cephalic and basilic veins at the cubital (elbow)

Answer 28

1. Basilic (medial superficial)
2. Median cubital vein

Question 29

1. The five major arteries of the upper limb, from proximal to distal, are:
2. Identify the artery labelled A

Answer 29

1. Subclavian, axillary, brachial, radial, and ulnar
2. Brachial (is distal to the inferior border of the teres major)

Question 30

1. Identify the structures labelled A
2. What digit of the hand does abduction/adduction occur in reference to?

Answer 30

1. Lumbricals
2. 3rd