Superficial layers of the upper limb

Question 1

What are the 2 layers of skin?

Answer 1

Dermis and epidermis

Question 2

What is the function of the epidermis?

Answer 2

Physical and chemical barrier between the body and its exterior environment

Question 3

What is the function of the dermis?

Answer 3

Provides structural and nutritional support

Question 4

What percentage of the total body mass comes from the skin?

Answer 4

16%

Question 5

What is the average total surface area of the skin?

Answer 5

1.8m2

Question 6

Why is the epidermis known as a stratified squamous epithelium?

Answer 6

It consists of many layers of closely packed cells, the most superficial of which are flattened and filled with keratin.

Question 7

What are the 4 layers of epidermis from superficial to deep?

Answer 7

Stratum corneum

Stratum granulosum

Stratum spinosum

Stratum basale

Question 8

What is the additional layer of epidermis only found in some areas?

Where is it located?

Answer 8

Stratum lucindum

Hands and feet, between corneum and granulosum

Question 9

Describe the stratum basale

Answer 9

Single layer of cells which continually divide to replace those shed from skin

Question 10

Where re melanocytes located?

What is their function?

Answer 10

Stratum basale

Produce the pigment melanin to protect from UV rays

Question 11

Describe the stratum spinosum

Answer 11

Thickest layer with ‘prickle cells’ which are linked by numerous processes

Question 12

Describe the stratum granulosum

Answer 12

Cells gradually accumulate keratohyalin granules which eventually overfill cells, destroying the nuclei and organelles

Question 13

Describe the stratum corneum

Answer 13

Thickest in palms and soles and contains dead keratinocytes or squames which are continually shed from the surface

Question 14

Describe the stratum lucindum

Answer 14

Only present in hands and feet. Contains tonofibrils (densely packed keratin filaments)

Question 15

Which layer of the epidermis contains the most flattened cells?

Answer 15

Stratum corneum

Question 16

How is the epidermis attached to the dermis?

Answer 16

Interlocking of its downward projections (epidermal ridges or pegs) with upward projections from the dermis (dermal papillae) at a site referred to as the dermoepidermal junction

Question 17

Why are epidermal pegs structurally important?

Answer 17

They allow the skin to withstand abrasive forces and prevent the formation of blisters

Question 18

What gives the dermis its strength?

Answer 18

The arrangement of its elastic and collagen fibres

Question 19

Where is the dermis thin?

Answer 19

Eyelids

Question 20

Where is the dermis thick?

Answer 20

The back

Question 21

What causes the appearance of the skin in old age?

Answer 21

Thinning of the dermis and loss of elasticity

Question 22

What are the 2 layers of the dermis from superficial to deep?

Answer 22

Papillary and reticular layers

Question 23

What is the thickest layer of the dermis?

Answer 23

The reticular layer

Question 24

What is the purpose of nails?

Answer 24

They provide a firm base for the pulp of the digit

Question 25

Why does the nail bed appear pink?

Answer 25

The underlying capillaries supplying from the dermis

Question 26

What are the 2 types of sweat glands?

Answer 26

Eccrine and apocrine

Question 27

What is the function of eccrine sweat glands? What are they controlled by?

Answer 27

Control body temperature and are controlled by the sympathetic nervous system

Question 28

Where are apocrine sweat glands located?

Answer 28

Axilla, mammary areola and the anogenital region

Question 29

What is the function of sebaceous glands and where are they found?

Answer 29

Produce sebum which provides a protective covering for the skin Present throughout the skin except in the palms and soles

Question 30

How is the blood supply to the skin mediated?

Answer 30

Arteriovenous anastomoses

Question 31

What do Meissner's corpuscles detect? Where are they located?

Answer 31

Light touch Fingers and lips

Question 32

What to pacinian corpuscles detect? Where are they located?

Answer 32

Pressure and vibration Deep in palms, soles and genitalia

Question 33

What is a dermatome?

Answer 33

An area of skin supplied by a single spinal nerve

Question 34

What is the clinical importance of dermatomes?

Answer 34

Diagnosis of problems associated with nerve related disorders, peripheral nerves of spinal injuries Administration of local anaesthetic

Question 35

What is the superficial fascia composed of?

Answer 35

Loose connective tissue and subcutaneous fat

Question 36

Is the superficial fascia thicker in men or women?

Answer 36

Women

Question 37

Where is fat built up when weight is gained?

Answer 37

Subcutaneous fat in the superficial fascia

Question 38

Where is superficial fascia absent?

Answer 38

The eyelids, scrotum and penis

Question 39

Is the superficial fascia homogenous?

Answer 39

No, it can be differentiated into layers by fibrous tissue

Question 40

Give an example of where superficial fascia is differentiated into layers

Answer 40

The anterior abdominal wall Consists of: - fatty layer (Camper's fascia) - membranous layer (Scarpa's layer)

Question 41

What is another term for deep fascia?

Answer 41

Investing fascia

Question 42

What is the deep fascia composed of?

Answer 42

Collagen fibres arranged into lines of stress

Question 43

Describe the appearance of deep fascia in the limbs

Answer 43

Tough white sheet of fibrous tissue which forms a non-elastic tight fitting sleeve

Question 44

What is the function of the deep fascia?

Answer 44

Keeps underlying structures in position Assists in venous return Separates muscles and neurovascular bundles into compartments which limits the spread of infection

Question 45

What are the 2 main superficial veins of the upper limb?

Answer 45

Cephalic and basilic

Question 46

How is blood received from the fingers and hand?

Answer 46

Dorsal venous arch on the dorsum of the hand formed from the cephalic and basilic veins

Question 47

What is the path taken by the cephalic vein?

Answer 47

Begins on the lateral aspect of the hand Crosses the anatomical snuffbox Runs up the lateral aspect of the forearm and arm to lie in the deltopectoral groove Pierces clavipectoral fascia to join the axillary vein

Question 48

What is the path taken by the basilic vein?

Answer 48

Begins on medial aspect of wrist Runs up forearm on medial aspect of cubital fossa Pierces deep fascia in mid-arm to join venae comitantaes of the brachial artery to form the axillary vein

Question 49

What is the connection between the cephalic and basilic veins?

Answer 49

Median cubital vein in the cubital fossa