Download MBBS Anatomy PPT 26 Skin Superficial Fascia And Deep Fascia Notes

Download MBBS (Bachelor of Medicine, Bachelor of Surgery) Human Anatomy ppt lectures Topic 26 Skin Superficial Fascia And Deep Fascia Notes. - anatomy ppt free download human anatomy ppt lectures, medicine notes ppt, anatomy handwritten notes pdf, mbbs 1st year anatomy notes pdf download, best anatomy notes pdf, human anatomy notes pdf, anatomy easy notes pdf, anatomy notes online, anatomy short notes, Anatomy ppt, Powerpoint Presentations and lecture notes.


SKIN

DEFINITION

? GENERAL COVERING OF THE EXTERNAL
? SURFACE OF THE BODY
? FORMS 15% OF THE TOTAL BODY WEIGHT
? THICKNESS-1.5 to 5.0 mm
? LARGEST ORGAN OF THE BODY

INTEGUMENTARY SYSTEM



Some Facts about Skin

? Surface area: 1.5-2.0 sq meters
? Growth rate of nail: 0.1mm per day
? Growth rate of hair: 1.5-2.2 mm per week
? Life span of hair:
Eyelashes, axilla- 4 months
Scalp ? 4 years


STRUCTURE OF SKIN

? TWO DISTINCT LAYERS
* EPIDERMIS
* DERMIS
? EPIDERMIS : SUPERFICIAL AND AVASCULAR
? DERMIS : DEEP AND VASCULAR

TERMS USED FOR MOVEMENTS

TYPES OF SKIN

? THICK SKIN - EPIDERMIS VERY THICK
USUALLY HAIRLESS ON
PALMS OF HAND & SOLES
OF FEET
? THIN SKIN ? COVERS GREATER PART OF
BODY & IS USUALLY HAIRY
? EXCEPTION ? SCALP : THICK AND HAIRY


Layers Of Skin

Epidermis:
? Composed of keratinized

stratified squamous epithelium.

Dermis:
? Papillary region composed of

loose connective tissue.

? Reticular region composed of

dense irregular connective tissue.

Hypodermis:
? Composed of areolar tissue with

abundant adipocytes

Cells

? Keratinocytes
? Melanocytes-pigment forming cells from

neural crest cells

? Merkel cells-sensory mechanoreceptors
? Langerhans cells-antigen presenting cells from

bone marrow

? Free nerve endings


LAYERS OF THE EPIDERMIS

Stratum Basale (Germinal/

Malpighian layer):

? Single layer of cuboidal cells resting on

basement membrane.

? High mitotic activity.
Stratum Spinosum:
? Several layers of polygonal cells.
? Cells are held together by

desmosomes.

Stratum Granulosum:
? 3-5 layers of flattened polygonal cells.
? Cells contain keratohyaline granules.

contd....

Stratum Lucidum:

? Seen only in non-hairy or thick skin.

? Cel s are flattened, translucent,

eosinophilic with indistinct

boundaries & nucleus.

? Contains a product of

keratohyaline i.e. eleidin.

Stratum Corneum:

? Composed of structureless

dehydrated dead cel s.

? Flattened & scale-like.

? Fil ed with keratin.

? Superficial layer is continuosly

sloughed off.

Stratum Basale




Stratum Spinosum

Stratum Granulosum

Stratum Lucidum

Stratum Corneum




SPECIALIZED CELLS OF THE EPIDERMIS

Keratinocytes:
? Most common cel s of the epidermis.
? Provides protection and

waterproofing sealant.

Melanocytes:
? Rounded cel s with dendrite-like

branches.

? Present in Stratum basale.
? Produces melanin pigment

responsible for the colour of skin.

? Melanin is a brown/black pigment

that absorbs UV-light.

SPECIALIZED CELLS OF THE EPIDERMIS

Langerhans Cells (antigen presenting

cells):

? Non-pigmented granular dendrocytes.

? Present in Stratum spinosum.

? Nucleus is indented at many places &

cytoplasm contains rod-shaped

granules.

? They participate in immune responses

against bacteria and viruses.

Merkel Cells:

? Found in Stratum basale.

? Sensory cells innervated by sensory

nerves.

? Abundant in fingertips, oral mucosa &

hair follicles.

? Function as mechanoreceptors.


PIGMENTATION OF SKIN

The colour of skin depends upon fol owing factors:

? Carotene: yellow-orange pigment (precursor of vitamin A)

found in stratum corneum & dermis.

? Melanin: produced in epidermis by melanocytes

gives black colour to the skin.

? Hemoglobin (in blood vessels of dermis): gives pink colour

to the skin.

LAYERS OF THE DERMIS

?

Papil ary layer:

-Narrow band of loose connective tissue.

-In contact with basement membrane of

stratum basale.

-Dermal papil ae (finger- like processes)

- provide mechanical anchorage and supply

nerves and blood vessels



?

Reticular layer:

-

4

Dense irregular connective tissue.

Dermal

papil a

-Thick elastic fibres.

-may be involved in development of skin lines

3

1

2

TYPES OF SKIN

Th

Thin Skin

in Skin

Th

Thick i

Skck

in Skin

Layers of epidermis

St. corneum &

St. corneum & spinosum are

spinosum are thin while thick while lucidum is

lucidum is absent.

present.

Thickness of epidermis

0.10-0.15 mm

0.6-4.5 mm

Epidermal ridges

Absent

Present (well developed

dermal paplillae)

Hair fol icles, arrector pili Present

Absent

muscle & sebaceous

gland
Sweat glands

Few

Many

Sensory receptors

Less

More

Distribution

Covers all parts of body Present in palms, palmar

except palms & soles

surface of digits & soles


APPENDAGES OF THE SKIN


HAIRS:

? Keratinized filaments derived from

invagination of the basal layer of

epidermis into the dermis.

? Parts-

a) Root: enclosed by hair follicle.



b) Shaft: projects above the surface.



? Hair fol icle: tubular invagination,
partly epidermal and partly dermal in

origin.



contd.....

Structure of shaft and root:
? Medul a
? Cortex
? Cuticle
Hair fol icle:
? Tubular invagination of epidermis

& dermis in which hair root

resides.

? Layers: 3 (inner root sheath, outer

root sheath, connective tissue

sheath).

contd.....

? Hair bulb: lower expanded

end of hair follicle.

? Hair papil a: the

indentation at the base of
hair bulb by part of the
dermis.

contd.....

Arrector Pilorum Muscle:

? Smooth muscle innervated

by sympathetic nerves.

? Extends from papil ary

layer of dermis to the

connective tissue sheath of

a hair fol icle.

? Contraction of muscle

presses the sebaceous

gland which squeezes out

sebum.

? Formation of "goose flesh".




APPENDAGES OF THE SKIN

NAILS:

? Hardened keratin plates on

the dorsal surface of the

tips of fingers & toes.

? Parts:

a) Root

b) Free border

c) Body

? Nail bed: tissue on which

the nail rests. Made up of

stratum basale & spinosum.

APPENDAGES OF THE SKIN

SEBACEOUS GLANDS:

? Distributed all over the

dermis of the skin, except

for the palms & soles.

? Abundant in the scalp,

face, around the

apertures of the ear, nose,

mouth & anus.

APPENDAGES OF THE SKIN

SEBACEOUS GLANDS:

? Holocrine in nature.

? Number of alveoli

connected to broad duct

that opens into hair

follicle.

? Produces an oily

secretion called sebum.


SWEAT GLANDS (SUDORIFEROUS GLANDS)

? Absent from lips, glans & nail bed.

? Mode of secretion: merocrine

? Simple tubular gland

? 2 parts:

(a) Secretory portion

(b) Excretory duct

Secretory portion:

? Twisted coil like structure with simple

cuboidal epithelium.

? 3 types of cel s: clear cel s, dark cel s,

myoepithelial cel s.

Excretory duct:

? Long & extends from secretory portion to

surface of epidermis.

contd....

2 types:
Eccrine:
? Most numerous in the soles &

palms.

? Produces thin watery secretion.
Apocrine:
? Confined to axil a, eyelids (Moll's

glands), nipple & areola of breast,

perianal region, and the external

genitalia.

? Produces thick odourous secretion.
? Ceruminous glands & lactating

mammary glands are modified

apocrine sweat glands.

Sweat Gland


SURFACE IRREGULARITIES

? FLEXURE LINES - Permanent lines along

which

the skin folds during habitual

movements of joints

? CLEAVAGE LINES - According to arrangement

of fibres in deep fascia, horizontal in

trunk, in old age fibres atrophy and skin

wrinkles

PAPILLARY RIDGES

PAPILLARY RIDGES
? Palms and soles and digits
? Form narrow ridges separated

by fine paral el grooves,

? corrospond to dermal papil ae
? Study is cal ed dermatoglypics
? Pattern of finger prints- loops ,

whorls and arches and

composite

Langer's lines(Cleavage lines)

? Langer lines of skin tension, or

sometimes called cleavage lines

? Correspond to the natural orientation

of collagen fibers in the dermis,

? Are generally parallel to the orientation of

the underlying muscle fibers.

? Langer's lines have relevance to forensic

science and the development of surgical

techniques

Langer's lines

? Langer lines of skin tension, or

sometimes cal ed cleavage

lines

? Correspond to the natural

orientation of collagen fibers

in the dermis,

? Are general y paral el to the

orientation of the underlying

muscle fibers.

? Langer's lines have relevance

to forensic science and the

development of surgical

techniques
Applications of Langer Lines

? Incisions made parallel to Langer's lines may

heal better and produce less scarring than

those that cut across. Conversely, incisions

perpendicular to Langer's lines have a

tendency to pucker and remain obvious,

although sometimes this is unavoidable

? In old age, elastic fibres atrophy and skin

becomes wrinkled

Linea gravidarum

? Rupture of fibre bundles

of dermis due to

excessive stretching

result in prominent

white lines.

? Seen in anterior

abdominal wall in

pregnancy.

Rule of Nine: To estimate

the extent of damaged skin

in burn injuries.

? First degree burn-

only epidermis.

? Second degree burn-

epidermis + upper region of

dermis.

? Third degree burn-

entire thickness of skin.

Dermatomes

? The strip of skin

supplied by a single

spinal nerve is called

dermatome.
FUNCTIONS OF SKIN

? Protective shield for the body
? Barrier to water
? Thermoregulation
? Important sense organ (pain, touch,

temperature & pressure)

? Absorption of ultraviolet radiation from sun

for the production of vitamin D

APPLIED ANATOMY

? Skin is pale in anemia, yel ow in
jaundice and blue in cyanosis

? Skin incisions should be made paral el to

lines of cleavage to have the smal est scar

? Sebaceous cyst is common in scalp
due to obstruction to sebaceous
duct

SUPERFICIAL FASCIA

SUPERFICIAL FASCIA

? DEFINITION- General coating of the body

beneath the skin made up of loose

areolar tissue and fat

? ABUNDANCE OF FAT- Front of thigh and

anterior abdominal wal

? ABSENCE OF FAT- Eyelids & external ear

? In females there is more fat and it is
evenly distributed


TERMS USED FOR MOVEMENTS

IMPORTANT FEATURES

? Most distinct in lower part of
anterior abdominal wal & limbs
? Very thin on dorsal aspect of hands &

feet, sides of neck, face.

? Very dense in scalp, palms and soles.


IMPORTANT FEATURES

? IT CONTAINS
1. Cutaneous nerves &

vessels

2. Groups of lymph nodes
3. Subcutaneous muscle in
neck

FUNCTIONS

? Helps in movements of skin
? Allows for the passage of the vessels &

nerves to the skin

? Conserves body heat as fat is a bad
conductor of heat
? Fat fills hollow spaces like axilla &
orbits

DEEP FASCIA

? Deep fascia is a fibrous sheet which

covers the body beneath the superficial
fascia.

? It is devoid of fat, and is usual y inelastic

and tough


DISTRIBUTION OF DEEP FASCIA

? Best seen in limbs where it forms tough and

tight sleeves

? Well defined in the neck where it
? forms a collar
? Not well formed on the trunk and face
? Blends with periosteum of a subcutaneous

bone

MODIFICATIONS OF DEEP FASCIA

? Inter muscular septa which divides limbs

into compartments

? Thickenings form retinacula around joints

like wrist and ankle

? Forms sheath around large arteries
? In palms & soles form aponeurosis
? Form investing layer of fascia in region of

neck giving it shape.

INTERMUSCULAR SEPTA

RETINACULA


INVESTING LAYER OF FASCIA

FUNCTIONS

? Keeps underlying structures in position
? Provides extra surface for muscle
attachment
? Helps in venous return
? Helps muscles in action by applying tension

and pressure

? Retinacula keep tendons in position

MCQ

Q1. Which layer is present only in thick skin:

a. Stratum basale
b. Stratum spinosum
c. Stratum granulosum
d. Stratum lucidum

MCQ

Q2. The characteristic feature of reticular layer of
dermis is:

a. High mitotic activity
b. Contains keratin granules
c. Dense irregular connective tissue
d. Finger like processes
MCQ

Q3. Secretion of sebaceous glands is aided by
contraction of:

a. Arrector pilorum muscle
b. Myoepithelial cells
c. Papillary layer of dermis
d. Reticular layer of dermis

MCQ

Q4. Langerhans cells are present in:

a. Stratum basale
b. Stratum spinosum
c. Stratum granulosum
d. Stratum lucidum

This post was last modified on 05 April 2022