general anatomy (2)

Dr. SAMINA SHAHEEN

Human Anatomy:Its is defined in various ways :-a)It is concerned with the consideration of

Various structures which make up the human body.

b)In the restricted sense , the anatomy deals with the parts , which from the fully developed individual and can be demonstrated to the naked eye by various methods of dissection.

c) Its is defined as an important scientific

discipline which is concerned with the investigation of biological structure by :

i) Dissection ;ii) Microdissection ;iii) Light microscopy ;iv)Electron microscopy ;v) Radiology ; andvi)Autoradiography etc

Topographical anatomy or regional anatomy :

Its deals with anatomy of various structures as they lie in relationship with one another in different region of the body . It is valuable for surgeons.

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invisible Surface anatomy: It deals with the study and identification of various structures in the living person by methods of inspection and palpation It helps to enhance the knowledge acquired through dissection of the cadaver by either of line of study, Regional or systematic. It is helpful both in health and disease and is daily used in medical practice.

Radiological Anatomy It deals with the study of structure of human body with the aid of X-Rays. It helps to investigate the anatomical facts which cannot be understood by any other method. It is very useful both in health and disease and is in current use in modern medical practice.

Morphology It is a branch of anatomy which deals with

factors which have influenced and determined the form, structure and functions of the constituent parts of the body (or) it explains the changes in form of human beings and different animals.

Comparative Anatomy It is the study of anatomy of various animals. It

helps to understand and correlate the morphological differences between various animal groups including man. It reflects the evolutionary trends among various animal forms.

Ontogeny (or) Ontogenetic History The changes through which any organism

passes from the fertilization of the ovum up to the adult form are collectively called as ontogeny (or) ontogenetic history.

Phylogeny (or) Phylogenetic History It comprises the evolutionary history of the

group to which the organism belong (or) it deals with developmental changes in ancestors from which the human beings evolved.

Embryology It is the study of various changes in the

developing organism from the fertilization of ovum up to the birth of the baby.

Comparative Embryology It is the study of intrauterine development of

the lower but allied animal forms. It helps to interpret many of the features of human development, e.g., study of 10 mm pig embryo helps to understand many features of the human embryogenesis.

Experimental Embryology It is the study of various casual mechanisms

like proliferation, growth, differentiation, induction, metamorphosis, cell death and removal, potency, determination and integration which operate during development. This branch of embryology is limited to lower vertebrates and inveretbrates.

Teratology It is the study of developmental abnormalities,

including their nature, causation and mechanism of genesis, e.g., cleft lip, patent foramen ovale etc.

Statistical Anatomy It deals with Fact and figures (data) on

variations in measurements structures and relationship of different parts of human body .

Cross-sectional Anatomy It is study of human structure with the help of

cross-sections of various regions of the body. It is pofitable but to a limited extent.

Cytology It is the study of the cells by various biological

methods. The cell is defined as the structural unit of a multicellular organism like man.

Histology It is the study of various tissues by various

scientific method (microscopy ; histochemistry ; radio autography ; etc.). A tissue may be defined as a combination of various cells performing a certain function.

Applied (or) Clinical Anatomy It is the direct application of facts of human

anatomy to medicine and surgery. The students are advised to lay the stress on applied aspects while they are studying gross anatomy in dissection hall.

Systematic Anatomy The description of several systems of organs

separately and in logical order comes under the head of systematic anatomy. The several parts of each system not only show a certain similarity of structure but are also associated in specialized functions.

Basic organization of the body A collection of cells of similar morphology

performing a specific function is termed tissue.

There are four basic tissues: i) Epithelium ii) Connective tissueiii) Muscle tissueiv) Nervous tissue

Organs and systems An association of different tissues which

perform certain function is called Organ e.g., bone, muscle, heart, stomach and urinary bladder.

A group of organs working harmoniously to

discharge a specific function forms a system. The following systems are formed in the

human body.

Body Systems-11IntegumentarySkeletalCirculatoryDigestiveRespiratoryUrinaryReproductiveNervousMuscularEndocrineLymphatic

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The IntegumentThe skin that covers your body. Skin is also known as the cutaneous

membrane. Integumentary system consists of the skin

and its derivatives—nails, hair, sweat glands, and sebaceous glands.

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The IntegumentIs the body’s largest organ. Its surface is covered by an epithelium that

protects underlying body layers. The connective tissues contain blood vessels that

provide nutrients and provide strength and resilience to the skin.

Smooth muscle controls both blood vessel diameter and hair position.

Neural tissue supports and monitors sensory receptors in the skin

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2 Distinct LayersA layer of stratified squamous epithelium

called the epidermis. A deeper layer of dense irregular connective

tissue called the dermis. deep to the dermis is a layer of areolar and

adipose connective tissue called the subcutaneous layer, or hypodermis

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Thick SkinThick epidermis is found on the palms of the

hands, the soles of the feet, and corresponding surfaces of the fingers and toes.

All five epidermal strata occur in thick skin.

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Thin SkinThin epidermis covers most of the body.Lacks the stratum lucidum

Has only four specific layers. Contains the following accessories: hair

follicles, sebaceous glands, and sweat glands.

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Functions of Skinprotectionprevention of water losstemperature regulationmetabolic regulationimmune defensesensory receptionexcretion

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Skin Color Hemoglobin is an oxygen-binding protein

present in red blood cells. Upon binding with oxygen, hemoglobin exhibits a bright red color.

Melanin is a pigment produced and stored in cells called melanocytes. the two types of melanin occur in various

yellow, reddish, tan, brown, and black shades

Carotene comes primarily from diet.

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Friction RidgesFound on the fingers, palms, soles, and

toes. Formed from large folds and valleys of

both dermal and epidermal tissue.Help us to grasp objects, and they Increase friction so that items do not slip

easily from our hands. Our feet do not slip on the floor when we

walk.

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Friction RidgesFriction ridges can leave noticeable prints on touched

surfaces.Each individual has a unique pattern of friction ridges.Fingerprints have become a valuable tool for law

enforcement in identifying individuals.Their unique Pattern for an indvidual is genetically determined at 3-4 month of i.u life and remain constant through outLife.Dermatoglyphics,a science which deals with the

study of analysis of ridge pattern. There are 3 basic patterns arches , loops and whorl.

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Skin MarkingsNevus (mole) Freckles Hemangioma

capillary hemangiomas (“strawberry-colored birthmarks”)

cavernous hemangiomas (“port-wine stains”)

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Layers of the DermisComposed of cells of the connective tissue

proper and primarily of collagen fibers, although both elastic and reticular fibers are also present.

Other components of the dermis are blood vessels, sweat glands, sebaceous glands, hair follicles, nail roots, sensory nerve endings, and muscular tissue.

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2 Major Regions of DermisSuperficial papillary layer Deeper reticular layer

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Lines of CleavageTension lines in the skin identify the

predominant orientation of collagen fiber bundles.

Clinically and surgically significant because cuts can result in slow healing and increased scarring.

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Innervation and Blood Supply The dermis has extensive innervation. Monitor sensory receptors in the dermis and

epidermis, and control both blood flow and gland secretion rates.

Tactile corpuscles and tactile (Merkel) cells perceive touch sensations, and work with a variety of other sensory nerve endings in the skin.

This rich innervation allows us to be very aware of our surroundings and to differentiate among the different kinds of sensory signals from receptors in the skin.

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NailsScalelike modifications of the epidermis that

form on the dorsal surfaces of the tips of the fingers and toes.

Protect the exposed distal tips and prevent damage or distortion during jumping, kicking, catching, or grasping.

Hard derivatives formed from the stratum corneum layer of the epidermis.

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HairFound almost everywhere on the body except

the palms of the hands, the sides and soles of the feet, the lips, the sides of the fingers and toes, and portions of the external genitalia.

Most of the hairs on the human body are on the general body surface rather than the head.

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Functions of Hair Protection Heat retention Prevents the loss of conducted heat from

the scalp to the surrounding air Facial expressionSensory reception Visual identification Chemical signal dispersal

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Hair ColorResult of the synthesis of melanin in the

matrix adjacent to the papillae. Variations in hair color reflect genetically

determined differences in the structure of the melanin.

Environmental and hormonal factors Age

Gray hair

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Hair Growth and ReplacementSometimes hair loss may be temporary as a

result of one or more of the following factors: exposure to drugs, dietary factors, radiation, high fever, or stress.

Thinning of the hair, called alopecia can occur in both sexes, usually as a result of aging.

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Exocrine Glands of the Skin Sweat (sudoriferous) glands produce a watery

solution that performs several specific functions. merocrine (eccrine) sweat glands apocrine sweat glands

Sebaceous glands produce an oily material that coats hair shafts and the epidermal surface.

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Other Integumentary GlandsCeruminous glands Mammary glands

modified apocrine sweat glands

Points of interest about the skinThe skin for the ANATOMIST is the first

dissecting layer. The skin for the SURGEON is the first layer to

be incised on the living body. The skin for the PHYSIOLOGIST is a functional

membrane to control the output of body water. The skin for the CLINICIAN is the part of the

body to be noted first on inspection to see anemia, cyanosis and jaundice.

The skin for the GENETIST is the part of the body the finger print of which form a useful diagnostic tool.

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Superficial fascia The subcutaneous tissue (superficial fascia) is

the second layer of the body beneath the skin. It is combination of loose connective tissue and adipose tissue. Its character varies in different regions of the body. The fatty tissue is most abundant in the buttocks and absent in the eyelids, pinna of the ear, penis and scrotum.

In some regions like scalp, face and scrotum it is characterized by presence of muscle fibers forming the subcutaneous muscles of these regions.

Hypodermis The subcutaneous layer is a sort of fibrous

membrane attached firmly to the dermis of the skin and also to the deeper structures, like deep fascia, periosteum and the perichondrium. In it nerves, blood vessels and lymphatics pass to the skin. Its main functions are:

i) Padding ii) Space filling among others anatomic structures

and organs. iii) Storage of fuel in the form of fat, to be used at

the time of starvation.

Deep fascia It is the third layer covering the body in the same

manner as the skin and superficial fascia. It is the real fascia. The fascia is the sheet like connective tissue structure and is continuous everywhere in the body.

It either invests the anatomic structure or binds together two or more structures.

It sends partitions and thus forms fascial compartments in the body to isolate other structures like muscles, nerves and blood vessels. The deep fascia is named according to the area of body. It covers or the function it performs, i.e., pectoral fascia and the extensor or flexor retinacula.

Clinical Importance of Deep Fascia A general understanding of the fascia of the

whole body will make the clinician to know about where and how certain fluids like pus, blood accumulate and will permit the surgeon to FIND AND FOLLOW the cleavage planes for easy separation of the anatomic structures.

Since lymphatics are carried on the fascia, therefore its knowledge will aid in knowing the extent of resection in case of malignancy of any organ.

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BurnsMajor cause of accidental death, primarily

as a result of their effects on the skin. Usually caused by heat, radiation, harmful

chemicals, sunlight, or electrical shock. The immediate threat to life results

primarily from fluid loss, infection, and the effects of burned, dead tissue.

Burns are classified according to the depth of tissue involvement.

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Classification of BurnsFirst- and second-degree burns are called

partial-thickness burns. Third-degree burns are called full-thickness

burns.first-degree burns involve only the epidermis

and are characterized by redness, pain, and slight edema an example is sunburn

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Classification of BurnsSecond-degree burns involve the epidermis

and part of the dermis. The skin appears red, tan, or white, and is

blistered and painful. An example is a scald.

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Classification of BurnsThird-degree burns involve the epidermis,

dermis, and subcutaneous layer, which are often destroyed.

Regeneration may occur from the edge only, due to the absence of dermis.

Skin grafting is required to prevent abnormal connective tissue fibrosis and disfigurement.

Dehydration is a major concern because the entire portion of skin has been lost, and water cannot be retained.

Must be aggressively treated for dehydration.

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Aging of the Integument Skin repair processes take longer due to

reduced number and activity of stem cells. Skin forms wrinkles and becomes less

resilient. Skin’s immune responsiveness is

diminished.Skin becomes drier due to decreased

sebaceous gland activity.Altered skin and hair pigmentation.

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Aging of the IntegumentSweat production diminishes. Blood supply to the dermis is reduced

leading to impaired thermoregulation. Hair thinning and loss. Integumentary production of vitamin D3

diminishes. Development of skin cancers.

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Skin Cancer The most common type of cancer. The greatest risk factor is exposure to UV

rays of the sun. The highest incidence is in people who have

had severe sunburns, especially as children.