Download MBBS Anatomy PPT 104 Skin & Fascia Notes

OBJECTIVES

? Describe layers of skin.
? Enlist the functions of skin.

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? Define appendages of skin.
? Define Fascia.
? Differentiate between Superficial and Deep

Fascia.

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? Applied Anatomy

Tissues of the body

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The tissue: is a group of cells which

perform a specific function

There are four basic tissues:

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1.Epithelium
2.Connective tissue
3.Muscular tissue
4.Nervous tissue

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Skin

IMPORTANCE OF SKIN

qNormalskinisaverycomplexorgan

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Theskinisoneofthelargestorgansofthe

body:76oosqcm

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FUNCTIONS OF THE SKIN

1-Protection
continuousandcoversthebodyaswellas

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protectsthedeeptissues

abrasion, invasion, water loss, UV protection
2-Vitamin D synthesis

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epidermal keratinocytes when exposed to UV

light

helps maintain health of skeleton by increasing

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absorption of Ca2+

3-Sensation

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receptors for heat, cold, touch,

pressure, vibration and pain

4- Thermoregulation

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thermo receptors and sweat glands
hypothalamus controls cutaneous

arteries and sweat glands to retain or

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dissipate heat
5- Excretion

through the secretion of sweat.

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6- Psychological and social functions
appearance and social acceptance
facial expression and nonverbal

communication

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q Keratinized stratified squamous

epithelium devoid of blood vessels

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Connective tissue

containing (bl. v.

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lymph v., sensory

nerve endings,

smooth m, hair

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follicles, sweat and

sebaceous glands)

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In its deep part the

collagen bundles

are arranged in

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parallel rows

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? Keratinocytes (90%)- waterproofs & protects skin,

nails, hair, stratum corneum

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? Melanocytes (8%)- produce melanin
? Merkel Cells- slow mechanoreceptors
? Langerhans' Cells- immunological defense

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?

Stratum Corneum

?

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Stratum Lucidum

?

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Stratum Granulosum

?

Stratum Spinosum

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?

Stratum Basale-
(Germinativum)

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Epidermis

Thickness is increased:

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The epidermis is generally thin except in :
? The palms of the hand.
? The soles of the feet.

Why?

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To protect these parts and withstand friction,
wear and tear that occurs in these regions.

Dermis

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papillary dermis

reticular dermis

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a. Cellular
Fibroblasts (synthesize collagen, elastin, and reticulin),

histiocytes, endothelial cells, perivascular macrophages and

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dendritic cells, mast cells, smooth muscle, and cells of peripheral

nerves
b. Fibrous
Collagen & reticulin - provide tensile strength

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Elastic fibers- provide for restoration of shape after a deformation
c. Ground substance
glycosaminoglycans: hyaluronic acid, chondroitin sulfate, and

dermatan sulfate.

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Hypodermis

This layer contains adipose tissue and serves to attach the dermis to its underlying tissues.

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Lines of cleavage

? The collagen fibers, arranged in parallel rows,

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called:

Lines of cleavage (langer's lines):

? The direction of the rows of collagen fibers in the

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dermis:

It runs

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?Longitudinally in the limbs.

?Circumferentially in the neck and the trunk.
Lines of cleavage

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These lines are important
to determine the direction
for an incision (cut) during
a surgery to avoid obvious
scars.

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? A surgical incision along or between these lines
causes the minimum disruption of collagen so that the
wound heals with a small scar.

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? Conversely, an incision made across the rows of
collagen makes a disruption resulting in the massive
production of fresh collagen and the formation of a
broad scar.

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Skin creases

Folded skin over the

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joints.

Skin is thin and is

firmly adherent to

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underlying structures.

Some variations in human skin color

Sub-Saharan African, Indian, Southern European, Northwest European

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Skin Color

? Due to Melanin, a pigment in the

epidermis and Carotene,

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? Melanin is synthesized in cells called

Melanocytes (found in basal layer).

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? Number of Melanocytes is essentially the

same in all races.

? The differences in skin color is due to the

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amount of pigment the melanocytes

produce.

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? Cyanotic

? Jaundice

? Erythema

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? Pallor

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? Pigmentation levels usually increase with age.

- exception: premature graying

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? Normal pigmentation may be altered by

genetic defects or by acquired diseases.

-Hyperpigmentation- age spots

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-Hypopigmentation- vitiligo,

albinism

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External agents can also alter skin color.
? lightening agents
? carotene
? dyes
? Some internal compounds--such as the byproducts

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of hemoglobin metabolism--may color the skin.

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SKIN IN ANAEMIA

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CHICKEN POX

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SKIN ERUPTIONS

ACNE

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Skin infections

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Pathogenic organisms can
enter to the tissue through :
? Nail Folds
? Hair Follicles
? Sebaceous Glands

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Staphylococcus:
A type of bacteria that causes
skin infections.

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Ring worm


Malignant melanoma
?

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2% of all cancers

Risks:
1.

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Skin type

2. Sun exposure
3.

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Family history

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4. Age

Normal mole Melanoma

5. Immunological status

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?

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A= asymmetry



?

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B= border

?

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C= color

?

D= diameter

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Skin Cancers


The appendages of the skin

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? Nails
? Hairs
? Sebaceous glands
? Sweat glands

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Nails

A nail is a flat horny plate on

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the dorsal surface of tips of

the fingers and toes

It has:

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Root: proximal edge (part

embedded in skin)

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body: exposed part & has a

free distal edge

Nail fold: folds of skin

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? Nail bed is very vascular causing

surround and overlap the

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pink color of the nail
? The germinative zone lies beneath

nail

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the root& is responsible for growth
of nail


Hair

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Cover whole surface of

the body except some
areas as lips, palms, soles,

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some genital areas



Hair

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Hair follicles: invaginations of the

epidermis into the dermis, the
hair grows out of these follicles

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(hair shaft).

Hair bulb: the expanded extremity

of the follicle, concaved at the

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end (located deep in the dermis).

Hair papilla: a vascular connective

tissue that occupies the

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concavity of the bulb.


Arrector Pilli muscle

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? A band of smooth muscle
connects the undersurface of the
follicle to the superficial part of
the dermis.

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? It is innervated by sympathetic
nerve fibers.

? It is involuntary.

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Arrector Pilli muscle

Functions:

?Its contraction causes the

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hair to move into a more
vertical position.

? It compresses the
sebaceous gland and

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causes it to extrude sebum.

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Sebaceous glands

Function

It secrets sebum to oil

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(lubricate) hair and

skin.

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Sebum

An oily material that

keeps the flexibility of

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the hair and oils the

epidermis around the

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mouth of the follicle.

Sebaceous cyst

It occurs because of the

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obstruction (blocking) of the
sebaceous duct.


Sweat glands

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? long tubular glands with deep
coiled part.

? All over the body except red

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margins of lips, nail beds, glans
penis and clitoris.

? The most deeply penetrated
structure.

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Skin burns

Superficial

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Deep

Heals rapidly from the edges,.

Heals slowly from the edges.

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Heals quickly.

Usually needs skin grafting.

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Doesn't need a skin graft.

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Clinical notes

Graft is transferring tissue from one site to another.

Skin graft is needed when the skin is damaged ( usually by deep

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burning )
Clinical notes

Skin Graft

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Split thickness grafting

Full thickness grafting

Transferring epidermis only

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Transferring both

epidermis and dermis.

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Fascia


Fascia

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Collection of connective tissue

Superficial fascia

Deep fascia

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Superficial fascia


Deep Fascia

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Superficial fascia

Superficial fascia:
?

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Loose, mixture of adipose and loose areolar tissues.

?

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It unites the skin to the underlying structures.

?

It is dense in some places as scalp, palm of hand and sole of foot

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and contains collagen bundles

?

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It is thin in the eyelids, auricle, scrotum (devoid of adipose

tissue).

Functions:

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?

Facilitates movement of skin over underlying structures.

?

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Passage for cutaneous vessels, nerves.

?

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Protects the body against heat loss.


Superficial fascia

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Deep fascia

It is more dense than superficial fascia

Collagenous bundles are more compact and

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more regularly arranged

It is usually present in the form of membranes

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Examples of deep fascia

A. Intermuscularsepta
liebetweenmusclesdividing

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thelimbintocompartments

Examples of deep fascia

B. Investing fascia

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? Covers the surfaces of muscles

? In the neck: it forms well-defined layers,

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bounds fascial spaces so limits spread of
infection or determine the path of infection

? In the abdomen: it is thin

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? In the limbs: forms a definite sheath around the

muscles

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Examples of deep fascia

C. Retinacula

Localized thickening of deep fascia around joints, hold the tendons

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in place, prevent bowstringing of tendons