Eyebrow structure

Question 1

Eyebrows are located between the ____ and _____.

Answer 1

Superior orbital rim/margin (most superior part of the bony orbit) and superior nuchal line (fossa)

Question 2

How many layers does the skin of the eyebrow have?

Answer 2

5:
S- skin
C- connective tissue (dense)
A- Muscle instead of aponeurosis
L- loose connective tissue
P- periosteum 

(Skin, dense connective tissue, muscle, loose connective tissue and the periosteum)

Question 3

Function of the skin

Answer 3

Barrier to the outside environment. Prevents microbes from causing infections in underlying tissue.

Question 4

What is the skin composed of

Answer 4

Epidermis, dermis, and hypodermis.

Question 5

Characteristics of the epidermis (superficial layer of the skin)

Answer 5

Composed of keratinocytes (90%). There are 4 stages of keratinocytes in progressive stages of differentiation.

Question 6

Keratinocytes

Answer 6

An epithelial cell found in the epidermis that produces keratin, a fibrous protein that provides structure and water resistant properties.

There are 4 layers of keratinocytes within the epithelium that are in progressive stages of differentiation.

Question 7

4 stages of keratinocyte differentiation from bottom to top

Answer 7

Stratum basale (inner)- only these cells can undergo mitosis and then migrate through the other layers.

Stratum spinosum- Cells start degrading/losing organelles

Stratum granulosum- cells lose nucleus and become flattened

Stratum corneum (outer)- dead, flattened cells filled with keratin. Cells are shed every few weeks in a process known as desquamation.

Question 8

Desquamation

Answer 8

Dead, flattened epithelial cells shedding off the stratum corneum and being replaced by cells below.

Question 9

4 layers of the epidermis

Answer 9

Stratum basale (big) 
Stratum spinosum (spiders)
Stratum granulosum (get)
Stratum corneum (crushed)

Question 10

4 Cell types in the epithelium

Answer 10

90% keratinocytes

10% melanocytes, langerhans, and merkel cells

Question 11

Melanocytes

Answer 11

Found in the epidermal layer- usually depicted in a brown color. They produce melanin that filters UV light

Question 12

Langerhans cells

Answer 12

Type of white blood cell found in the epidermis. Play a role in the immune system.

Question 13

Where does the epidermis get it’s blood supply

Answer 13

From the dermis. The epidermis is avascular.

Question 14

What connects the epidermis to the dermis?

Answer 14

The basement membrane connects epithelial cells to the underlying dermis.

Question 15

Role of the basement membrane

Answer 15

Connects the epithelial cells of the epidermis to the dermis. Also seres as a partial barrier- allowing only water and small molecules to pass into the dermis.

Question 16

What is the dermis composed of

Answer 16

Composted of connective tissue (fibroblasts, collagen fibers, elastic fibers, adhesive proteins, and ground substance), white blood cells, and adnexal structures (additional/attached/within an organ)

Question 17

Fibroblasts

Answer 17

The main cells found in the dermis, dense connective tissue, loose connective tissue, and periosteum that produce collagen and elastin

Collagen- protein that provides structure and tensile strength.
Elastin- protein that provides elasticity and enables movement.

Question 18

What cell type produces collagen and elastin?

Answer 18

Fibroblasts of the dermis

Question 19

Ground substance

Answer 19

Transparent gel composed of water, glycosaminoglycans (GAGs) and proteoglycans (GAG + protein). All other connective tissues are embedded in it, such as fibroblasts, collagen fibers, elastic fibers, proteins…)

Question 20

Adnexal structures include

Answer 20

Hair follicles, hair, sebaceous glands, and sweat glands

Question 21

Fun fact about eyebrow growth in the womb

Answer 21

They are the first body hairs produced

Question 22

Three layers of the skin

Answer 22

Epidermis, dermis, and hypodermis

Question 23

Deepest layer of the skin

Answer 23

Hypodermis

Question 24

What is the hypodermic composed of

Answer 24

Adipose and loose connective tissue

Question 25

Another name for the hypodermis

Answer 25

Subcutanous

Question 26

Dense connective tissue

Answer 26

1 layer below the epidermis and composed of fibroblasts, collagenous fibers, elastic fibers, ground substance and adhesive proteins.

Contains arteries, veins, and nerves supplying the eyebrows.

Question 27

What does dense connective tissue connect

Answer 27

Connects the skin (epidermis, dermis, and hypodermis) to the underlying muscle. Arteries, veins, and nerves travel through this layer to reach the hypodermis and dermis.

Question 28

Which four muscles influence eyebrow contour and position

Answer 28

Frontalis, corrugator, procesrus, and orbicularis oculi

Question 29

Frontalis muscle is located where, gives a look of what and is innervated by which nerve

Answer 29

Vertical fibers originate high on the scalp and insert near the supraorbital margin. Elevates the brows and gives a look of surprise.

Innervated by the CN VII (facial nerve)

Question 30

Corrugator muscle is located where, gives a look of what and is innervated by which nerve

Answer 30

Oblique fibers originate from the supracilary arch and insert into the medial forehead.

It depresses the medial brows and forms vertical wrinkles in the glabella.

Look of trouble or concentration.

Innervated by the CN VII (facial nerve)

Question 31

Procerus muscle is located where, gives a look of what and is innervated by which nerve

Answer 31

Vertical fibers originate from the nasal bone and insert into the medial forehead.

Depresses the medial brows forming horizontal wrinkles across the bridge of the nose.

Look of penance or aggression.

Innervated by CN VII (facial nerve)

Question 32

Orbicularis oculi muscle is located where, gives a look of what and is innervated by which nerve

Answer 32

Oblique fibres originate from the medial orbital rim (maximally and lacrimal bones) to encircle the eye and insert into the lateral palpebral ligament.

Depresses the brows and protracts (closes) the eyelids.

Innervated by the CN II (facial nerve)

Question 33

What is loose connective tissue composed of

Answer 33

Composed of fibroblasts, collagenous fibers, elastic fibers, ground substance and adhesive proteins.

Question 34

What is the role of lose connective tissues

Answer 34

Connects the top three layers, which are highly bound to each other, to the underlying periosteum.

Question 35

Why is the loose connective tissue of the skin considered the danger zone

Answer 35

Pus and blood can spread easily in this layer and infections can pass into the cranial cavity through veins.

Question 36

Periosteum

Answer 36

Covers bone

Question 37

What is periosteum composed of

Answer 37

Dense, irregular connective tissue (fibroblasts, collagenous fibers, ground substance, osteogenic cells and osteoblasts.)

Question 38

Osteogenic cells

Answer 38

Stem cells that divide and differentiate into ostebclasts, which form the bone matrix.

Question 39

Function of the eyebrow

Answer 39

Shields liquids from dipping into the eye. Shields from bright lights above and plays a role in aging. Crucial to facial expressions.

Question 40

How does the eyebrow play a role in aging.

Answer 40

Muscle atrophy-eyebrow and eyelids can droop. and wrinkles will form.

Question 41

The lateral palpebral ligament is located where

Answer 41

Between the lateral check ligament and the orbital septum/palpebral fascia