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