Introduction to Anatomy

Anatomy Beginnings

Man is not the centre of the universe as was naïvely believed in the past, but something much more beautiful — Man the ascending arrow of great biological synthesis.

— P. Teilhard de Chardin

The place of humans amongst the Animalia

Phylum Chordata

diagnostic characteristics

notochord

dorsal hollow nerve cord

pharyngeal pouches

other features

bilateral symmetry

segmentation

body cavities [coelomic cavities]

dorsal cavity

cranial portion

vertebral portion

ventral cavity

thoracic cavity

abdominopelvic cavity

Class Mammalia

diagnostic characteristics

hair

mammary glands [modified apocrine sweat glands]

other features

endothermy

viviparity

Order Primates

diagnostic characteristics

“Primates are a diverse group of mammals that have evolved from a group of insectivorous mammals some 60 million years ago. Indeed it is difficult to define primates since they lack a single feature that separates them from other mammalian groups. At the same time, primates have remained plesiomorphic, retaining many ancestral features, rather than becoming highly apomorphic as did many groups of mammals, for example, the horse with a single digit in each foot.”
— DR Swindler, Primate Dentition. An Introduction to the Teeth of Non-human Primates, Cambridge University Press, 2002. p 1.

most are pentadactyl with an opposible digit I

claws modified to flattened nails

well-developed clavicula

orbital frontation

enlargement of cerebral cortex

usually only two mammary glands, with one birth per gestation

Classification of the great apes

Suborder Haplorhini

Infraorder Catarrhini

Superfamiliy Hominoidea

Family Hominidae

Genus Pongo: orangutans
Genus Pan: bonobos and chimpanzees
Genus Gorilla: gorillas
Genus Homo: humans

Basic terminology

physiology — the science that deals with the functioning of the body

anatomy — the science that deals with the structure of the body

gross anatomy

topographical (surface) anatomy

regional anatomy

systemic anatomy

microscopic anatomy

cytology

histology

organology

developmental anatomy [ontogeny]

embryology

postnatal development

comparative anatomy [phylogeny]

homology

analogy

some specialized nomenclature of body parts

head & neck	orbit — the space in the skull around the eyeball
trunk	thorax — the chest region; the thoracic cavity is separated from the abdominopelvic cavity by the diaphragm back — although part of the trunk, generally considered a separate region; comprises the vertebrae and associated musculature perineum — region inferior to the pelvic diaphragm; pierced by the urethra and anal canal in the male, and additionally by the vagina in the female
upper extremity	arm — the region between the shoulder and elbow; the term brachium is frequently used forearm — the region between the elbow and wrist; the term antebrachium is frequently used cubital fossa — the anterior region of the elbow pollex — digit I, the thumb
lower extremity	thigh — the region between the hip and knee leg — the region between the knee and ankle; the term shank is used in quadrupeds popliteal fossa — the posterior region of the knee hallux — digit I, the great toe

Why do your elbows project backwards and your knees forwards?

[ Image used with permission of the Florida Department of Environmental Protection ]

a Carnegie stage 18 embryo, 44 postovulatory days

directional and relational terms

anatomical position

terms of direction

dorsal	ventral
posterior	anterior
cranial	caudal
rostral
superior	inferior
plantar	volar or palmar
medial	lateral
median
external	internal
superficial	deep or profound
proximal	distal
intermediate

planes of reference

right and left pieces

median [midsagittal]

sagittal [parasagittal]

anterior and posterior pieces

frontal [coronal]

superior and inferior pieces

transverse [horizontal]

The SI [ Système International ] seven basic units of measurement assumed to be mutally independent ¹

mass	kilogram (kg)
length	metre (m)
time	second (s)
thermodynamic temperature	kelvin (K)
amount of a substance	mole (mol)
electric current	ampere (A)
luminous intensity	candela (cd)

Organization of the body

molecules

cells

tissues

epithelial tissues

connective tissues

general

loose [areolar]

dense irregular

dense regular

specialized

cartilaginous tissue

osseous tissue

adipose tissue [fat]

blood

muscle tissues

skeletal muscle

cardiac muscle

smooth muscle

nervous tissue

organs

systems

integumentary

musculoskeletal

circulatory

digestive

respiratory

urinary

reproductive

nervous (including the special sense organs)

immune & reticuloendothelial

endocrine

the organism

Questions for thought

1.		Explain what is meant by the term defining characteristics. Why is the presence of a notochord considered a defining characteristic of the chordates, but bilateral symmetry is not.
2.		Explain why the relational pairs anterior/posterior and superior/inferior are not appropriate in comparative anatomy.
3.		Using examples, distinguish homologous and analogous anatomic structures from each other.
4.		Present a reasoned defense of or rebuttal to this statement: “Anatomy and physiology are very separate disciplines, the province of each being so distinct that it does not overlap that of the other.”

Go to beginning

Links

Referenced sites
- ¹ From the Freie Universität Berlin, a comprehensive overview of SI units and prefixes
  [ oder auf deutsch ]
  
  Frank Tapson’s extensive Dictionary of Units, host by the Centre for Innovation in Mathematics Teaching (CIMT)
  The NIST SI unit rules and style conventions
Other sites
- My new favorite sites to browse: From the National Library of Medicine, Dream Anatomy and Historical Anomalies on the Web
- Yes, it’s outdated, but still, the 1918 edition of Gray’s Anatomy of the Human Body online! Complete text and illustrations
- James McNulty at Loyola University Chicago, Stritch Medical Center, has compiled a list of Internet sites that include educational material for anatomy; beware that, as so often happens, many have moved or become defunct
- The on-line version of the Illustrated Encyclopedia of Human Anatomic Variation; many more fascinating atlases are available from the home site
- The interactive atlases of The Digital Anatomist Project from the Department of Biological Structure, University of Washington, Seattle

Go to beginning