Download MBBS Anatomy PPT 104 Skin & Fascia Notes

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OBJECTIVES

? Describe layers of skin.
? Enlist the functions of skin.
? Define appendages of skin.
? Define Fascia.
? Differentiate between Superficial and Deep

Fascia.

? Applied Anatomy

Tissues of the body

The tissue: is a group of cells which

perform a specific function

There are four basic tissues:

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

IMPORTANCE OF SKIN

qNormalskinisaverycomplexorgan

Theskinisoneofthelargestorgansofthe

body:76oosqcm


FUNCTIONS OF THE SKIN

1-Protection
continuousandcoversthebodyaswellas

protectsthedeeptissues

abrasion, invasion, water loss, UV protection
2-Vitamin D synthesis
epidermal keratinocytes when exposed to UV

light

helps maintain health of skeleton by increasing

absorption of Ca2+

3-Sensation

receptors for heat, cold, touch,

pressure, vibration and pain

4- Thermoregulation
thermo receptors and sweat glands
hypothalamus controls cutaneous

arteries and sweat glands to retain or

dissipate heat
5- Excretion

through the secretion of sweat.

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

communication


q Keratinized stratified squamous

epithelium devoid of blood vessels

Connective tissue

containing (bl. v.

lymph v., sensory

nerve endings,

smooth m, hair

follicles, sweat and

sebaceous glands)

In its deep part the

collagen bundles

are arranged in

parallel rows




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

nails, hair, stratum corneum

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


?

Stratum Corneum

?

Stratum Lucidum

?

Stratum Granulosum

?

Stratum Spinosum

?

Stratum Basale-
(Germinativum)


Epidermis

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

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

Dermis


papillary dermis

reticular dermis

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

histiocytes, endothelial cells, perivascular macrophages and

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

nerves
b. Fibrous
Collagen & reticulin - provide tensile strength
Elastic fibers- provide for restoration of shape after a deformation
c. Ground substance
glycosaminoglycans: hyaluronic acid, chondroitin sulfate, and

dermatan sulfate.


Hypodermis

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

Lines of cleavage

? The collagen fibers, arranged in parallel rows,

called:

Lines of cleavage (langer's lines):

? The direction of the rows of collagen fibers in the

dermis:

It runs

?Longitudinally in the limbs.

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

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

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

? 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.


Skin creases

Folded skin over the

joints.

Skin is thin and is

firmly adherent to
underlying structures.

Some variations in human skin color

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

? Due to Melanin, a pigment in the

epidermis and Carotene,

? Melanin is synthesized in cells called

Melanocytes (found in basal layer).

? Number of Melanocytes is essentially the

same in all races.

? The differences in skin color is due to the

amount of pigment the melanocytes

produce.

? Cyanotic

? Jaundice

? Erythema

? Pallor




? Pigmentation levels usually increase with age.

- exception: premature graying

? Normal pigmentation may be altered by

genetic defects or by acquired diseases.

-Hyperpigmentation- age spots

-Hypopigmentation- vitiligo,

albinism

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

of hemoglobin metabolism--may color the skin.






SKIN IN ANAEMIA




CHICKEN POX


SKIN ERUPTIONS

ACNE




Skin infections

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

Staphylococcus:
A type of bacteria that causes
skin infections.

Ring worm


Malignant melanoma
?

2% of all cancers

Risks:
1.

Skin type

2. Sun exposure
3.

Family history



4. Age

Normal mole Melanoma

5. Immunological status



?

A= asymmetry



?

B= border

?

C= color

?

D= diameter

Skin Cancers


The appendages of the skin

? Nails
? Hairs
? Sebaceous glands
? Sweat glands

Nails

A nail is a flat horny plate on

the dorsal surface of tips of

the fingers and toes

It has:

Root: proximal edge (part

embedded in skin)

body: exposed part & has a

free distal edge

Nail fold: folds of skin

? Nail bed is very vascular causing

surround and overlap the

pink color of the nail
? The germinative zone lies beneath

nail

the root& is responsible for growth
of nail


Hair

Cover whole surface of

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



Hair

Hair follicles: invaginations of the

epidermis into the dermis, the
hair grows out of these follicles
(hair shaft).

Hair bulb: the expanded extremity

of the follicle, concaved at the
end (located deep in the dermis).

Hair papilla: a vascular connective

tissue that occupies the
concavity of the bulb.


Arrector Pilli muscle

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

? It is innervated by sympathetic
nerve fibers.

? It is involuntary.

Arrector Pilli muscle

Functions:

?Its contraction causes the
hair to move into a more
vertical position.

? It compresses the
sebaceous gland and
causes it to extrude sebum.




Sebaceous glands

Function

It secrets sebum to oil

(lubricate) hair and

skin.

Sebum

An oily material that

keeps the flexibility of

the hair and oils the

epidermis around the

mouth of the follicle.

Sebaceous cyst

It occurs because of the
obstruction (blocking) of the
sebaceous duct.


Sweat glands

? long tubular glands with deep
coiled part.

? All over the body except red
margins of lips, nail beds, glans
penis and clitoris.

? The most deeply penetrated
structure.

Skin burns

Superficial

Deep

Heals rapidly from the edges,.

Heals slowly from the edges.

Heals quickly.

Usually needs skin grafting.

Doesn't need a skin graft.




Clinical notes

Graft is transferring tissue from one site to another.

Skin graft is needed when the skin is damaged ( usually by deep
burning )
Clinical notes

Skin Graft

Split thickness grafting

Full thickness grafting

Transferring epidermis only

Transferring both

epidermis and dermis.

Fascia


Fascia

Collection of connective tissue

Superficial fascia

Deep fascia

Superficial fascia


Deep Fascia

Superficial fascia

Superficial fascia:
?

Loose, mixture of adipose and loose areolar tissues.

?

It unites the skin to the underlying structures.

?

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

and contains collagen bundles

?

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

tissue).

Functions:
?

Facilitates movement of skin over underlying structures.

?

Passage for cutaneous vessels, nerves.

?

Protects the body against heat loss.


Superficial fascia

Deep fascia

It is more dense than superficial fascia

Collagenous bundles are more compact and

more regularly arranged

It is usually present in the form of membranes


Examples of deep fascia

A. Intermuscularsepta
liebetweenmusclesdividing
thelimbintocompartments

Examples of deep fascia

B. Investing fascia

? Covers the surfaces of muscles

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

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

? In the abdomen: it is thin

? In the limbs: forms a definite sheath around the

muscles


Examples of deep fascia

C. Retinacula

Localized thickening of deep fascia around joints, hold the tendons
in place, prevent bowstringing of tendons

This post was last modified on 05 April 2022