Introduction and Anatomical Terms

Mahindra Kumar Anand

Section-1

1General and Systemic Anatomy

Introduction and Anatomical Terms ………………… 3–12
Cell ……………………………………………………………….. 13–18
Tissues ………………………………………………………….. 19–26
Organization of Body …………………………………….. 27–66
Skeletal System and Joints ……………………………… 67–80
Muscular System …………………………………………… 81–82
Nervous System ………………………………………….. 83–112
Cardiovascular System ……………………………….. 113–134
Blood and Its Components ………………………….. 135–142
Lymphatic System ………………………………………. 143–154
Respiratory System …………………………………….. 155–166
Digestive System ………………………………………… 167–176
Urinary System …………………………………………… 177–180
Endocrine System ……………………………………….. 181–186
Reproductive System ………………………………….. 187–194
Skin and Its Appendages …………………………….. 195–198
Review of General and Systemic Anatomy ….. 199–208

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Introduction and Anatomical TermsChapter 1

Anatomy is the oldest medical science. History of anatomy traces its origin to early Greek civilizations around 400 B.C. The word anatomy is derived from Greek word “anatome” which means taking apart. Anatomy is the study of various structures and their relations in the body.

SUBDIVISIONS OF ANATOMY

Gross Anatomy or Macroscopic Anatomy

It is the study of various structures of human body (usually carried out by dissection of cadavers or dead bodies) usually with naked eyes. Gross anatomy can be studied under the subdivisions of systemic anatomy and regional anatomy.

Systemic Anatomy (Fig. 1.1)

It is the study of structure of various systems in the body.

Skeletal system: It consists of bones, ligaments, cartilage and joints.

Functions of skeletal system
1. Supports body
2. Forms framework of body
3. Protects internal organs
4. Transmits body weight
Muscular system: It consists of muscles and tendons.

Functions of muscular system
1. Responsible for of skeleton and various hollow viscera of the body.
2. Is the site of heat production in body.
Nervous system: It includes brain, spinal cord, spinal nerves, cranial nerves and sympathetic and parasympathetic ganglia.

Functions of nervous system
1. Receives and interprets sensory information
2. Regulates voluntary and involuntary body functions.
Endocrine system: It consists of endocrine glands namely thyroid gland, suprarenal gland, pituitary gland, ovaries, testes and pancreas, etc.

Functions of endocrine system

Regulates various body functions by secreting hormones. It is responsible for normal growth, development and metabolism of the body.
Cardiovascular system: It includes heart, arteries, veins, blood, lymphatics and lymphoid organs.

Functions of cardiovascular system
1. Transports oxygen and nutrients to tissues and removes waste products from tissues.
2. Lymphatic system
  1. Carries macromolecules
  2. Returns tissue fluids to blood
  3. Destroys pathogens that enter the body, i.e., it provides the immunity.
Respiratory system: It consists of larynx, trachea, bronchi, lungs.

Functions of respiratory system

Responsible for exchange of O₂ and CO₂ between air and blood. O₂ is taken up and CO₂ is excreted out.
Gastrointestinal or digestive system: It includes oral cavity, oesophagus, stomach, small intestine, large intestine, anal canal and associated glands.

Functions of digestive system
1. Ingestion of food
2. Digestion and absorption of food: Changes food to simple chemicals that can be absorbed and assimilated or used by the body.
3. Detoxification and elimination of waste (by liver and large intestine).
Urinary system: It includes kidney, urinary bladder, ureters and urethra.

Functions of urinary system
1. Removes waste products from blood in the form of urine.
2. Regulates the volume and pH of extra cellular fluid.
  
  4
  
  Fig. 1.1: Different systems of the body
Reproductive system: It is formed by a pair of testis, prostate gland, vas deferens, ejaculatory duct and penis in male; vagina, uterus, uterine tubes and a pair of ovaries in female.

Functions of reproductive system

Propogation of species for survival and existence.
Integumentary system: It consists of skin, hair, nails and subcutaneous tissue.

Functions of integumentary system
1. Protects internal structures from physical and chemical excesses
2. Is a barrier to pathogens and chemicals.
3. Prevents excessive water loss.
4. Is a major sense organ.

Regional Anatomy

It is the study of the structure and organisation of a definitive part of the body (Figs 1.2 and 1.3). The various parts or regions of the body studied are

Head and neck
Thorax
Abdomen
Pelvis
Back
Extremities: Upper and lower limbs

Fig. 1.2: Anterior aspect of human body showing different regions

Functional Anatomy

Study of anatomy which provides correlation between structure and function of various organs.

Developmental Anatomy

Study of prenatal and postnatal developmental changes of the human body.

Histology and Cytology

Study of various body structures, organs, tissues and cells in greater details with the help of microscope. It includes functions of these structures also.

Surface Anatomy

Study of projection of internal body parts on the corresponding external surface of the body. This helps in clinical correlation with normal and abnormal anatomy.

Radiographic Anatomy

Study of anatomy of various organs of the body with the help of plain or contrast radiography (X-ray, CT scan, MRI).

Fig. 1.3: Posterior aspect of human body showing different regions

Physical Anthropology

Study of external features and variations in their measurements of different races and groups of people and their comparison with the prehistoric remains.

Clinical Anatomy

It emphasizes the structure and function of a part or the entire body in relation to the practice of medicine and other health related professions.

Experimental Anatomy

Study of factors, with the help of experiments, which determine the form, structure and function of different parts of the body.

Comparative Anatomy

Study of structural variation between other animals and human beings. This helps to trace the sequence of events in the structural evolution of human beings.

TERMINOLOGY USED IN ANATOMY

Anatomical Position

This is the conventional position of the body according to which all anatomical descriptions are made.

“Body is erect, the eyes face forward, arms are kept by the side with palms facing forward. The legs are kept together with feet directed forwards” (Fig. 1.4).

Importance of Anatomical Positon

All structures of our body are described in relation to this position, irrespective to any body posture in space.

Fig. 1.4: Anatomical position

Other Positions of the Body

Supine position: Person lies straight on the back with face directed upwards (Recumbent) (Fig. 1.5).
Prone position: Person lies straight on the abdomen and face is directed downwards (Fig. 1.6).
Lithotomy position: Person lies supine with hips and knees semiflexed, thighs abducted and feet strapped in position (Fig. 1.7). This position is useful in the examination of pelvic viscera of female and is commonly practiced for delivery of a baby.

Fig. 1.5: Supine position

Fig. 1.6: Prone Position

Fig. 1.7: Lithotomy position

Anatomical Planes (Fig. 1.8)

Description of the various parts of the body is based on the following four imaginary planes that divide the body

Midsagittal or median plane: It is a vertical plane that passes between anterior midline and posterior midline of the body dividing it into left and right halves.
Sagittal planes: These are planes passing parallel to the median plane on either side.
Coronal or frontal plane: It is a vertical plane which is perpendicular to midsagittal plane. Mid coronal plane divides the body into equal anterior and posterior halves.
Transverse planes: These are planes that pass perpendicular to the midsagittal and coronal planes, dividing the body transversely.

Commonly used anatomical terms to describe the position of a body part and structure (Figs 1.9 to 1.11).

Anterior: Towards the front aspect of the body.
Posterior: Towards the back of the body.
Superior: Towards the head of the body.
Inferior: Towards the feet of the body.
Central: Towards the centre of mass of body.
Peripheral: Away from the centre of mass of body.

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Fig. 1.8: Anatomical planes
Medial: Towards the median plane.
Lateral: Away from the median plane.
External: Close to the surface of the body.
Internal: Close to the centre or interior of the body.
Ventral: Towards the anterior aspect of the body (in reference to belly).
Dorsal: Towards the posterior aspect of the body (in reference to back of the trunk).
Proximal: This term is used for limbs. Proximal structure is the one which is nearer to the trunk.
Distal: This term is used for limbs. Distal structure is the one which is away from the trunk.
Radial border: It is the outer border of forearm.
Ulnar border: It is the inner border of forearm.
Tibial border: It is the inner border of leg.
Fibular border: It is the outer border of leg.

Fig. 1.9: Anatomical terms

Fig. 1.10: Anterior or ventral aspect of body (Anatomical terms)

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Fig. 1.11: Posterior or dorsal aspect of body (Anatomical terms)
Preaxial border: The outer border in the upper limb, and the inner border in the lower limb.
Postaxial border: The inner border in the upper limb, and the outer border in the lower limb.
Palmar or volar aspect of hand: This pertains to the palm of hand.
Plantar aspect of foot: This pertains to the sole of foot.
Superficial: Location of a structure towards the surface of the body.
Deep: Location of a structure inner to the surface of the body.
Ipsilateral: This term denotes any two structures lying on the same side of the body.
Contralateral: This term denotes any two structures lying on the opposite sides of the body.

Terms Used for Various Body Movements

Flexion: In this two flexor surfaces come in approximation and angle of the joint is reduced (Fig. 1.12).

Fig. 1.12: Flexion of forearm
Extension: In this there is approximation of extensor surfaces whereby angle of joint increases (Fig. 1.13).

Fig. 1.13: Extension of forearm
Abduction: It describes the away from the median plane moving away upper limb from trunk (Fig. 1.14).

Fig. 1.14: Abduction of upper limb
Adduction: This describes the towards the median plane, moving upper limb towards the trunk (Fig. 1.15).

Fig. 1.15: Adduction of upper limb
Medial rotation: Medial rotation denotes towards median plane or inward rotation, medial rotation of arm at shoulder joint (Fig. 1.16).

Fig. 1.16: Medial rotation of arm
Lateral rotation: Lateral rotation denotes rotation away from the median plane or outward rotation, lateral rotation of arm at shoulder joint (Fig. 1.17).

Fig. 1.17: Lateral rotation of arm

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Circumduction: Combined movement of flexion, extension, adduction and abduction in a circular manner is termed as circumduction.
Elevation: Raising or moving a body part towards the cephalic (head) end is termed as elevation.
Depression: Lowering or moving a body part caudally (toe) is termed as depression.
Protrusion: It is the forward of a body part.
Retraction: It is the backward from protrusion.
Pronation: It is the medial rotation of forearm so that the palm comes to face backwards (Fig. 1.18).

Fig. 1.18: Pronation of forearm
Supination: It is the lateral rotation of forearm so that the palm comes to face anteriorly (forwards) (Fig. 1.19).

Fig. 1.19: Supination of forearm
Inversion of foot: It is the that causes the plantar surface of foot to face inwards and downwards (Fig. 1.20).

Fig. 1.20: Inversion of foot
Eversion of foot: It is the that causes the plantar surface of foot to face laterally and downwards (Fig. 1.21).

Fig. 1.21: Eversion of foot
Opposition: It is a combination of abduction, medial rotation and flexion. This characteristically occurs in the thumb (Fig. 1.22).

Fig. 1.22: Opposition of thumb

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Chapter Notes

Introduction and Anatomical TermsChapter 1