Anatomy-I: Introduction to Anatomy

• The presentation is named Anatomy-I
• It is presented by Dr. Rida Zahid, MBBS, DMRD*

Topics covered:

• Brief history of anatomy
• Main subdivisions and disciplines of anatomy with branches
• Different approaches of gross anatomy
• Different regions of the body
• Two main subdivisions of microscopic anatomy
• Developmental anatomy and embryology
• Anatomical terms
• Anatomical regions
• Anatomical positions
• Anatomical planes, sections, directions, and movements

History of Anatomy

• The study of anatomy began as early as 300 BC
• A major tool of anatomy is the use of cadavers
• Anatomists experiment and practice on cadavers to understand the detail of structure
• Cadavers are embalmed, preserved dead bodies intended for dissection by medical students
• Cadavers are positioned flat on their backs to make dissection easier

Literary Meaning of Anatomy

• The term "anatomy" is derived from two Greek words: Ana (up) and Tome (cutting), meaning cutting up
• A synonym for anatomy in Latin is Dissecare, meaning dissection (cutting)
• The literary meaning of anatomy is the study of body structure by cutting up (dissection)

Main Subdivisions and Branches of Anatomy

• Gross Anatomy
• Microscopic Anatomy
• Developmental Anatomy

Branches of Anatomy

• Gross Anatomy: the study of dissected body structure with the naked eye
• Microscopic Anatomy: the study of thin sections of body structures visualized with a microscope
• Developmental Anatomy: the study of developmental changes of the body structure before birth (during intrauterine life) and after birth

Approaches to Gross Anatomy

• Systemic Anatomy
• Regional Anatomy
• Surface Anatomy
• Systemic Anatomy: The study of structures of different systems in the entire body via osteology (bones), angiology (blood vessels, lymphatic system); sometimes called macroscopic anatomy
• Surface Anatomy: The study of internal structures by marking them on the overlying skin without dissection
• Regional Gross Anatomy: The study of structures of different systems present in specific regions of the body, such as the foot

Different Regions of the Body

Features of the body can be labeled as belonging to:

• Head, Trunk, Lower Extremity, and Upper extremity
• Specific identifiable features or zones are: Cranium, Face, Mandible, Neck, Shoulder, Arm, Elbow, Forearm, Wrist, Hand Thorax, Abdomen, Pelvis, Thigh, Knee, Leg, Ankle, Foot

Microscopic Anatomy

• Microscopic anatomy is the study of body structures by making thin slices and viewing them under a microscope; the subdivisions are cytology and histology
• Cytology: The study of cells and their structures
• Histology: The study of tissues and their structures

Developmental Anatomy

• Developmental anatomy explores the structural changes in a human from fertilization to adulthood
• Prenatal Development Anatomy(Embryology): The study of developmental body structure change from fertilization to birth.
• Postnatal Development Anatomy: The study of developmental body structure change after birth

Specialized Disciplines of Anatomy

• Pathological anatomy is the study of structural changes caused by diseases
• Imaging anatomy is the study of internal structures visualized by imaging modalities
• Molecular biology examines anatomical structures at a sub-cellular level

Significance and Classification of Anatomical Terms

• Correct understanding of anatomical terms facilitates effective communication of anatomical knowledge
• Terms for different regions of the body
• Terms for important body positions
• Terms for plane and section of body

Synonyms for Body Regions

• Cephalon (head) refers to the cephalic region
• Cervicis (neck) refers to the cervical region
• Thoracis (thorax or chest) refers to the thoracic region
• Brachium (arm) refers to the brachial region
• Antebrachium (forearm) refers to the antebrachial region
• Carpus (wrist) refers to the carpal region
• Manus (hand) refers to the manual region
• Abdomen refers to the abdominal region
• Lumbus (loin) refers to the lumbar region

Important Body Positions

Terms to describe body position:

• Standard Anatomical Position
• Supine Position
• Prone Position
• Lateral Recumbent
• Trendelenburg Position
• Lithotomy Position

Standard Anatomical Position

• The human stands erect with eyes looking forward, feet together and toes pointing forward, with upper limbs hanging by the sides, palms facing forward, fingers straight and together, and thumbs pointing away from the body

Supine Position

• The body is lying on its back with arms at the sides, palms facing upwards, and feet together

Prone Position

• The body is lying on the abdomen

Lateral Recumbent Position

• A person is lying on their side

Trendelenburg Position

• The patient's feet and legs are higher than the head

Lithotomy Position

• The person is lying on their back with hips and knees flexed and thighs apart
• It is often used for childbirth

Anatomical Planes and Sections

• Anatomical planes are imaginary lines that cut/slice/divide/separate the whole body or its parts into specific sections
• Anatomical sections are flat surfaces resulting from different planes cutting through different planes

Terms for Different Planes/Sections

• There are three major anatomical planes: two vertical and one horizontal
• The two vertical planes are coronal/frontal and sagittal (median plane/mid-sagittal and parasagittal/paramedian)
• Coronal/Frontal: Vertical
• Sagittal: (median plane /mid-sagittal and parasagittal/paramedian)
• Transverse, axial, or cross-sectional: one horizontal plane

Minor Anatomical Planes

• The Oblique plane divides the body at an angle between the horizontal and vertical planes

Median Plane/Mid-Sagittal

• The sagittal plane is a vertical plane
• It passes anteroposterior at the mid or center of the body
• It divides the body into two equal right and left halves

Paramedian Sagittal/Parasagittal Plane

• The paramedian sagittal vertical plane passes from front to back at either side the median plane
• It divides the body into two unequal right and left halves
• e.g. left or right lateral lines of abdomen

Coronal/Frontal Plane

• The coronal/frontal plane is vertical
• It is perpendicular to the median plane
• It passes from one side to the other side of the body
• It divides/separates the body into anterior and posterior parts

Transverse/Axial Plane

• The transverse/axial plane is parallel to the floor and perpendicular to the median and coronal plane
• It separates the body into superior and inferior parts
• e.g. the transpyloric or transtebecular line of abdomen

Terms in Reference to Cranial/Tail End of Body

• Superior/Cranial: In comparison between two points, one is towards or closer to the head
• e.g. the head is superior to the abdomen
• Inferior/Caudal: In comparison between two points, one is towards or closer to the feet
• e.g. the navel is inferior to the chin

Terms Relative to the Midline or Center of the Body

• Medial is toward/closer to the midline of the body (the nose is medial to the eyes)
• Lateral is away from the midline of the body (the ears are lateral to the eyes)
• Median is at the midline (the nose exists in the median of the body)
• Intermediate is between medial and lateral (the collarbone is intermediate between the breastbone)

Terms of Laterality

• Ipsilateral refers to the same side
• e.g. (the spleen and descending colon are ipsilateral, the left hand and left foot are ipsilateral)
• Contralateral refers to the opposite side
• e.g. (the spleen and gallbladder are contralateral, the left biceps and right rectus muscles)
• Unilateral involves any structure, organ, or condition occurring on one side
• e.g. vermiform appendix unilateral
• Bilateral involves structures or organs occurring on both sides
• e.g. ears are bilateral

Terms of Direction to Point of Attachment of the Appendage: Proximal/Distal

• Proximal refers to toward or closer to the origin/root of the body part or the point of attachment of a limb to the body trunk
• e.g. the proximal end of the femur is part of the hip joint, the elbow is proximal to the wrist
• Distal refers to away from the origin of a body part or the point of attachment of a limb to the body trunk
• e.g. the knee is distal to the thigh

Superficial/Deep

Reference point is surface of body

• Superficial is skin to muscle
• Deep is lungs to the skin

External/Internal

• These terms are relevant in terms of describing hollow structures; external indicates outside, while internal indicates being inside
• External intercostal muscles are responsible for forced and quiet inhalation
• Internal intercostal muscles are responsible for forced exhalation

Combination of Relative Terms

• Supero medial
• Infero-lateral
• Postero-superior
• Antero inferior
• The neck is supero-medial to the shoulder, while the shoulder is inferolateral to the neck

Types of Movements

• Nonangular/linear/sliding movements
• Angular/straight movements
• Rotational movements

Nonangular/Linear/Sliding/Gliding Movements

• Gliding movements occur on relatively flat articular surfaces of a joint
• Bones move past/slide each other in any direction without any change of angle between the bones
• E.g., major gliding joints include the intervertebral joints and the bones of the wrists (intercarpal joint)

Angular Movements

• Produced when the angle between the bones of a joint changes
• 6 Types: Flexion, Extension, Hyperextension, Abduction, Adduction, and Circumduction.
• The maximum change in the angle in these movements is 180°; if beyond this range, then the term hyper is added
• The path of movement is straight; this is why these movements are called straight movements

Flexion, Extension, Adduction, Abduction

• Flexion: there is forwarding, bending, decreasing of angle of two surfaces
• Extension: straightening/ increasing of angle between two surfaces
• Adduction: Moving the part towards the midline of the body
• Abduction: Moving parts away from the midline of the body

Reference Books

• Richard S. Snell
• Clinical anatomy
• . Gray's anatomy