TBL 5 - Pectoral Muscles, Breasts, Axilla, and Anterior Arm

Question 1

Pectoralis major

Answer 1

sternocostal and clavicular heads to the sternum, superior six costal cartilages and clavicle to the anteromedial aspect of the proximal humerus

Question 2

What do the lateral and medial pectoral nerves innervate and where does the lateral pectoral nerve come from?

Answer 2

Clavicular head of major and pectoralis minor and sternocostal head. The lateral pectoral nerve is from the lateral cord

Question 3

Pectoralis Minor

Answer 3

3rd and 5th ribs to the coracoid process of scapula

Question 4

What muscle stabilizes the scapula against the posterior thoracic wall when stretching to reach something

Answer 4

Pectoralis minor

Question 5

What muscle adducts the upper limb and medially rotates the arm

Answer 5

pectoralis major

Question 6

Serratus Anterior

Answer 6

lateral portions of the first 8 ribs to the medial border of the scapula

Question 7

what muscle protracts the scapula when reaching

Answer 7

the serratus anterior

Question 8

How do the pectoralis minor, serrates anterior, and trapezius all act on the scapula

Answer 8

serratus anterior protracts, pec minor stabilizes it here and trapezius retracts

Question 9

How is serratus anterior involved in abduct with the trapezius

Answer 9

Synergistically helps rotate the scapula upward

Question 10

What does the long thoracic nerve innervate and why is the long thoracic nerve vulnerable to injury and how are abduction and rotation at the glenohumeral joint hindered after its injury?

Answer 10

Serratus anterior. the nerve is vulnerable tot injury because it is superficial to the muscle and therefore exposed when the arms are raised. The glenoid cavity cannot be rotated up so the arm cannot be abducted past 90 degrees.

Question 11

What is the winged scapula deformation

Answer 11

When the serratus anterior is paralyzed by long thoracic nerve injury, the medial border of the scapula moves laterally and posteriorly away from the posterior thoracic wall creating the winged scapula

Question 12

What is the precursor to the pec muscles and what is the poland sequence

Answer 12

Parietal layer of lateral plate mesoderm. The poland sequence is where the pec minor and some of the pec major is missing as are the nipple and areola. the digits are fused and shortened

Question 13

Describe the formation of the mammary glands in embryo

Answer 13

Anterior ridge-like epidermal thickenings (primitive nipples) are in the embryo and one pair in the pec region invaginate the dermis. These are modified sweat glands

Question 14

Describe mammary glands in childhood

Answer 14

15-25 rudimentary lactiferous ducts that open onto the surface of the nipple

Question 15

Mammary glands during puberty

Answer 15

Ovarian estrogen and progesterone cause budding of small terminal ducts from distal end of each lactiferous duct. White fat accumulates around each terminal duct

Question 16

Mammary glands after breast feeding and later after menopause

Answer 16

Return to resting state. After menopause, the acini and terminal ducts regress and the lactiferous ducts become fluid-filled cysts

Question 17

Mammary glands during pregnancy

Answer 17

Ovarian hormones and prolactin (pituitary gland hormone) stimulate secretory acini formation at the distal ends of the terminal ducts. Milk secretion is induced by the hormones into the lumens of the acini during lactation

Question 18

What attaches the breasts to the overlying dermis of skin

Answer 18

Suspensory ligaments

Question 19

Trace the lymph from the lateral quadrates of the breasts

Answer 19

Pectoral lymph node (a constituent of axillary nodes) which drain into the supraclavicular lymph nodes

Question 20

Trace the lymph from the medial quadrants of the breasts

Answer 20

Parasternal lymph nodes into the supraclavicular lymph nodes

Question 21

Where do breast carcinomas typically arise and what is the most common site for metastasis?

Answer 21

Usually adenocarcinomas from the epithelial cells of the lactiferous ducts. Axillary lymph nodes are the main sites of metastasis as most lymph is drained through here

Question 22

The axillary artery is continuous with the

Answer 22

subclavian artery at the lateral border of the 1st rib

Question 23

Where does the axillary artery end and what does it become

Answer 23

Ends at the inferior border of the trees major where it becomes the brachial artery

Question 24

What branch of the axillary artery has the shortest length and the longest diameter

Answer 24

Subscapular

Question 25

What are the two terminal branches of the subscapular artery and which one anastomoses with the suprascapular artery?

Answer 25

Circumflex scapular artery, which anastomoses with the supra scapular artery, and the thoracodoral artery

Question 26

What muscle does the thoracodorsal artery supply

Answer 26

Latissimus dorsi

Question 27

What artery supplies the deltoid and describe where it comes from

Answer 27

The posterior circumflex artery, a branch of the axillary artery, supplies the deltoid, encircles the humerus, and anastomoses with the anterior circumflex artery

Question 28

Where can the axillary artery be ligated without stopping blood flow into the upper limb?

Answer 28

It can be ligated between the 1st rib and subscapular artery. In this case, the direction of blood flow in the subscapular artery is reversed to supply the third part of the axillary artery.

Question 29

Where do the axillary lymph nodes drain?

Answer 29

The supraclavicular lymph nodes

Question 30

What nodes receive lymph from the anterior thoracic wall and breasts

Answer 30

Pectoral lymph nodes

Question 31

What nodes receive lymph from posterior thoracic wall and scapular region

Answer 31

Subscapular lymph nodes

Question 32

What nodes receive lymph from entire upper limb except vessels with cephalic vein

Answer 32

Humeral lymph nodes

Question 33

Where do the pectoral, sub scapular, and humeral lymph nodes drain?

Answer 33

The apical node which drains into the supraclavicular node

Question 34

Which two nerves are at risk during surgical removal of pathologic axillary nodes? Why can removal result in lymphedema?

Answer 34

The long thoracic and thoracodorsal nerves are at risk as they are near the axillary lymph nodes. This affects the serratus anterior and latissimus dorsi. Lymphedema can occur if lymphatic drainage is impeded after removal of the nodes

Question 35

What roots generate the dorsal scapular nerve and what muscle does it innervate

Answer 35

C5 - rhomboids

Question 36

What roots generate the long thoracic nerve and what muscle does it innervate

Answer 36

C5, C6, C7 - serratus anterior

Question 37

What generates the supra scapular nerve and what muscle does it innervate

Answer 37

The superior trunk and it innervates the supraspinous and infraspinous

Question 38

How does avulsion of brachial plexus roots C5 and C6 typically occur in adults and newborns?

Answer 38

If the head and shoulder separate at an awkward angle. Can happen during birth or from a hard fall where shoulder hits something and stops moving and head continues to move forward

Question 39

What strengthens the joint capsule at the articulation of the radius, ulna, and humerus

Answer 39

Lateral side - radial collateral ligament | Medial side - ulnar collateral ligament

Question 40

What does the anular ligament do?

Answer 40

Encircles the head of the radius and holds it in the radial notch of the ulna. Forms a radio-ulnar joint for pronto and supination of the forearm

Question 41

How does posterior dislocation of the elbow joint typically occur and why is the distal humerus driven anteriorly? Which nerve may be damaged?

Answer 41

Fall on hands while elbow is flexed. The ulna is driven posteriorly causing the humerus to go anteriorly. The ulnar nerve is at risk here.

Question 42

What is the most common cause of subluxation of the radial head in preschool children? Which ligament is commonly damaged and how is the injury treated?

Answer 42

Occurs when child is lifted suddenly via upper limb and forearm is pronated. Tears the anular ligament off the radius and is treated with a sling for 2 weeks

Question 43

What forms from the torn blood vessels after a fracture

Answer 43

Hematoma (clot) form the coagulation of the blood

Question 44

Describe the acute inflammatory response

Answer 44

Macrophages are recruited adjacent to the fracture, osteoprogenitors proliferate in the periosteum and endosteum is activated

Question 45

Describe the osteoprogenitor cell differentiation that occurs during fracture repair

Answer 45

The periosteal capillaries induce differentiation. Cells close to capillaries become osteoblasts and those farther away become chondroblasts

Question 46

Describe the resolution of the hyaline cartilage external callus that forms on the ends of the bony fragments

Answer 46

Osteoclasts degrade the cartilage and osteoblasts reconstruct it with trabecular bone. The bone forms an internal callus that restores the marrow cavity and the external callus is transformed into compact bone

Question 47

How might mesenchymal stem cell technology be beneficial for the reconstruction of fractured bones?

Answer 47

The stem cells could differentiate into osteoblasts ex vivo and begin formation of the bone and be inserted into the person

Question 48

Biceps brachii

Answer 48

Long head - guided through the inter tubercular sulcus to the supraglenoid tubercle Short head - coracoid process Distal - radial tuberosity

Question 49

Where is the tendon of the long head of the biceps commonly ruptured and what deformity results?

Answer 49

Ruptured at the supraglenoid tubercle after moving back and forth over the inter tubercular sulcus of the humerus. Forms the popeye deformity where the muscle belly forms a ball in the center of the distal part of the anterior arm

Question 50

Coracobrachialis

Answer 50

Coracoid process to the middle third of the humerus

Question 51

Brachialis

Answer 51

Inferior half of humerus to the coronoid process and tuberosity of the ulna

Question 52

What muscle flexes the forearm when it is pronated or supinated

Answer 52

Brachialis

Question 53

What does the musculocutaneous nerve innervate and where does it come from

Answer 53

coracobrachialis, biceps brachii, and brachialis, and skin of the lateral aspect of the forearm. It is a branch of the lateral cord

Question 54

Which spinal cord segments are tested by the biceps tendon reflex?

Answer 54

C5 and C6. Musculocutaneous nerve

Question 55

What arises from the posterior cord before it bifurcates into the radial and axillary nerve

Answer 55

Thoracodorsal and subscapular nerve

Question 56

What is the spinal segmental origin of the axillary nerve and where does it go?

Answer 56

C5 and C6. It is a terminal branch of the posterior cord. Innervates the teres minor and deltoid and skin over the inferior part of the deltoid

Question 57

Would flexion and supination of the forearm be lost after injury to the musculocutaneous nerve? Where would sensation be lost?

Answer 57

No but severely weakened. The supinator and brachioradilis can cause some supination and flexion. Sensation would be lost on the lateral side of the forearm

Question 58

What does the radial nerve innervate

Answer 58

Supinator and brachioradialis

Question 59

How is an affected upper limb positioned after the onset of Erb-Duchenne palsy?

Answer 59

Superior portions of the brachial plexus are hurt. Adducted shoulder, medially rotated arm, and extended elbow

Question 60

What is the first and largest branch of the brachial artery and where does it course

Answer 60

profunda brachii (deep artery of the arm) courses with the radial nerve along the radial groove

Question 61

What does the brachial artery branch into

Answer 61

The ulnar and radial arteries

Question 62

What is the role of the anastomoses of the brachial, profound brachia arteries with branches of the radial and ulnar arteries

Answer 62

Collateral circulation that allows blood to reach forearm when forearm is flexed

Question 63

Why is laceration or occlusion of the brachial artery proximal to the profunda brachii artery a surgical emergency?

Answer 63

Paralysis of the muscle happens with a few hours of ischemia of the elbow and forearm

Question 64

Why can the brachial artery be blocked at any level distal to the deep artery of the arm without stopping blood flow to the forearm and hand?

Answer 64

The arterial anastomoses around the elbow ensure enough blood reaches the ulnar and radial arteries