Lec 8 Brachium and Plexus

Question 1

Biceps Brachii

Answer 1

MA: Supinates forearm, flexes forearm

PA: Short heard; coracoid process, Long head; Supraglenoid Tubercle and Labrum, Short head resists shoulder dislocation

DA: Radial Tuberosity and Forearm fascia via bicipital aponeurosis

N: Musculocutaneous N C5, *C6, C7

Question 2

Coracobrachialis

Answer 2

MA: Flex and Adduct the Shoulder

PA: Coracoid process

DA: Middle third of Medial surface of humerus

N: Musculocutaneous C5,*C6, C7

Question 3

Brachialis

Answer 3

MA: Flex elbow in pronated forearm position (all positions)

PA: Distal end of anterior humerus

DA: Ulnar tuberosity and Coronoid process of Ulna

N: Musculocutaneous C5 C6 and Small branch from Radial C5 C7

Question 4

Brachioradialis

Answer 4

MA: Flexes elbow in mid-pronated position (thumb up, humeroulnar joint)

Assists in pronating and supinating the forearm when these movements are resisted from the end range

PA: lateral supracondylar ridge of humerus

DA: Lateral distal end of radius proximal to styloid process

N: Radial Nerve C5, *C6, C7

Question 5

Which muscle is the strongest elbow flexor?

Answer 5

Brachialis

Question 6

Triceps Brachii

Answer 6

MA: Chief extensor of forearm/elbow

Long head resists dislocation of humerus, especially during adduction

PA:
- Longhead; infraglenoid tubercle (of scap)
- Lateral Head; posterior surface, superior to radial groove
- Medial Head; posterior humerus, inferior to radial groove

DA: Olecranon of ulna

N: Radial Nerve C6, *C7, *C8

Question 7

Boundaries of the Axilla

Answer 7

“armpit”

apex - armpit

base - formed by skin

anterior wall - pec minor and major

lateral wall - upper portion of humerus

medial wall - serratus anterior and rib cage (*since the pec minor is visible in cross section, the rub must be 3-5)

posterior wall - lat, subscapularis and teres major

Question 8

What muscle that attaches to the axilla region is the farthest away from the axilla region?

Answer 8

Lat

Question 9

Where is the PNS CNS division for spinal nerves

Answer 9

Spinal Nerve (made by anterior and posterior roots) are CNS

Rami are PNS

so if anterior rami are damaged, the CNS is not affected potentially (something like that)

Question 10

How many of each RTDCB are there

Answer 10

5 Rami (C5, 6, 7, 8 T1)
3 Trunks (superior, middle and inferior)
6 Divisions (3 anterior and 3 posterior)
3 Cords (lateral, Posterior and medial)
Branches - 5 main terminal

Question 11

Where do the following nerves come off the brachial plexus?

Dorsal Scapular
Lower and Upper Subscapular
Lateral Pectoral
Thoracodorsal
Long thoracic
Medial Pectoral
First intercostal
Nerve to subclavius
Suprascapular
Medial Cutaneous

Answer 11

Dorsal Scapular - C5 rami

Lower and Upper Subscapular - Posterior Cord

Lateral Pectoral - Lateral Cord

Thoracodorsal - Posterior Cord

Long thoracic - Rami if C5, C6, C7

Medial Pectoral - Medial Cord

First intercostal - T1 rami

Nerve to subclavius - Superior trunk

Suprascapular - Superior trunk

Medial Cutaneous - Medial Cord

Question 12

Where do the 5 terminal branches go? What muscles do they innervate?

Answer 12

Musculocutaneous - anteriorly emerges at armpit and innervates biceps brachii, coracobrachialis and brachialis

Median N - anterior, medial to musculocutaneous, innervates anterior forearm muscles

Ulnar N - anterior, medial, goes all the way down to ulna, also innervates some medial forearm flexors

Axillary N - comes down through posterior scapular and wraps around upper humerus, innervates deltoid and teres minor

Radial N - comes posteriorly through scapula and travels down to posterior humerus, innervates triceps

Question 13

Subclavius

Answer 13

MA: depresses and anchors clavicle

PA: junction of first rib and its costal cartilage

DA: inferior surface of middle surface of clavicle

N: the nerve to subclavius C5 C6

Question 14

Contents of Thoracic Outlet

Answer 14

Brachial Plexus, subclavian vein and artery, (turn into axillary artery and vein after first rib), scalenes

Question 15

Anterior Scalene

Answer 15

MA: Flex neck laterally, elevate first rib during forced inhaltion

SA: TP od C3-6

IA: first rib

N: cervical spinal nerve C4-C6

Question 16

Middle Scalene

Answer 16

MA: flex neck laterally and elevate first rib during forced inhalation

SA: TP of C5-C7

IA: 1st rib

N: anterior rami of cervical spinal nerves

Question 17

Posterior scalene

Answer 17

MA: flex nick laterally and elevate the SECOND rib during forced inhalation

SA: TP of C5-C7 posterior tubercles

IA: external border of second rib

N: anterior rami of cervical spinal nerves C7 and C8

Question 18

Where does the brachial plexus exist in relation to the scalene muscles

Answer 18

exits between the anterior and middle scalene

Question 19

Thoracic Outlet Syndrome

Answer 19

compression of nerves arteries or veins in the thoracic outlet region

typically occurs via compression between the clavicle and 1st rib, pec minor or the presence of a cervical rib (variation in a few people of rib off of C7 very tiny)

causes pain, weakness, numbness, muscle atrophy and swelling

symptoms will be a peripheral nerve distribution because if the brachial plexus is compressed, those are Rami, which begins the PNS division

Question 20

What are the three spaces/intervals of the Upper Extremity

Answer 20

Quadrangular space
Triangular Space
Triangular Interval

Question 21

Quadrangular space fxn and contents

Answer 21

an anatomical conduit for neurovascular strucutures to pass from the anterior axilllary region to the posterior scapular region

axillary nerve, and posterior circumflex HUMERAL artery and vein

Question 22

Quadrangular space borders

Answer 22

pointing in

top; inferior margin of teres minor

lateral side; surgical neck of humerus

bottom: superior border of teres major

apex: lateral margin of the long head of the triceps brachii

Question 23

Triangular space borders and contents

Answer 23

pointing in

lateral side: the medial margin of the long head of the triceps brachii

top: inferior margin of teres minor

bottom: superior border of teres major

content: circumflex SCAPULAR artery and vein

Question 24

Triangular interval borders and contents

Answer 24

upside down

medial border: lateral margin of long head of triceps brachii

lateral border: shaft of humerus

superior border: inferior margin of teres major

contents: profunda brachii artery and radial nerve

Question 25

What are the two divisions of the upper extremity

Answer 25

brachium

antebrachium (forearm)

Question 26

What is the only synovial joint articulation between the UE to the axial skeleton?

Answer 26

sternoclavicular joint

Question 27

What is a Proximal bicep rupture

Answer 27

popeye sign - the muscle belly to slide down and bunch up in arm

For distal ruptures, surgery is not typically done because it is a cosmetic issue

Question 28

Innervation and function of Musculocutaneous nerve AND LEVELS

Answer 28

Has motor AND sensory innervation

Motor innervation to all muscles of the anterior compartment of the upper arm

Sensory innervation to the skin of the lateral forearm

C6, C6 C7

Question 29

Contents of Extensor compartment

Answer 29

one muscles - triceps

deep brachial artery - branch off brachial artery that goes to posterior side

radial nerve C5-T1

Question 30

How can you tell if you are looking at posterior or anterior humerus?

Answer 30

If you see the radial groove, its the posterior side, that where triceps attach around

Question 31

Another name for deep brachial artery (whats its parent structure)

Answer 31

profunda brachii artery

comes off brachial artery

Question 32

What does the radial nerve innervate? what LEVELS

Answer 32

supplies the entire posterior compartment

C5, C6, C7 C8 T1

Question 33

Axillary N Levels

Answer 33

C5 C6