What is anatomy?
Anatomy includes all structures that can be seen with or without the aid of magnification. It’s the
basis for the practice of medicine, as it leads to the understanding of a patient’s disease. Though the
terminology of anatomy is important, an understanding of anatomy requires an understanding of the
context in which the terminology can be placed.
Gross anatomy / macroscopic anatomy: The study of structures that can be seen without a
microscope.
Microscopic anatomy / histology: The study of cells and tissues using a microscope.
How can gross anatomy be studied?
“Anatomy” comes from the Greek “temnein” which means “to cut”.
Anatomy can be studied through dissection, viewing prosected (previously dissected) material and
plastic models or using computer models.
Anatomy can be studied following a regional of a systemic approach.
- Regional approach
Each region of the body is studied separately and all systems and aspects of that region are studied
at the same time. Regions are e.g.: the thorax, abdomen, pelvis, lower limb, etc.. A regional approach
works well if dissection is involved, but it falls short when it comes to giving an understanding of the
continuity of an entire system through the body.
- Systemic approach
Each system of the body is studied and followed through the entire body. Systems are e.g.: the
skeletal-, cardiovascular-, nervous-, respiratory system, etc.. The systemic approach gives a good
understanding of an entire system throughout the body, but it is difficult to coordinate this with a
cadaver dissection and to acquire detail.
Anatomical terms
The anatomical position
The anatomical position is the reference position of the body, used to describe the location of the
structures. The body is in anatomical position while:
- standing upright
- feet together
- hands by the side
- mouth closed
- neutral facial expression
- rim of the bone under the eyes is in the same horizontal plane as the top to the opening of the ear
- eyes open, focussed on something in the distance
- palms of the hands facing forward with fingers together and the thumb to the side
- toes pointing forward
,Anatomical planes
3 major groups of planes pass through the body
in anatomical position:
-Coronal plane
Anterior/ventral: to the front
Posterior/dorsal: to the back
- Sagittal plane
Medial: to the middle
Lateral: to the side (further from the median)
- Transverse / Horizontal / Axial plane
Superior: up
Inferior: down
Other terms:
Proximal: close to a structure’s origin
Distal: further from a structure’s origin
Cronial: toward the head (superior)
Caudal: toward the tail (inferior)
Roastal: position with reference to the nose
Superficial (relative): to the surface of the body
Superficial (absolute): external to the outer layer
of deep fascia
Deep (relative): further from the surface
Deep (absolute): enclosed by the outer layer of
deep fascia.
,Body systems
Skeletal system
The skeletal system can be divided into two subgroups, the axial
skeleton and the appendicular skeleton. The axial skeleton consists
of the bones in the skull, vertebral column, ribs, and sternum. The
appendicular skeleton consists of the bones in the upper and lower
limbs. The skeletal system consists of cartilage and bone.
Cartilage
Cartilage is an avascular (not supplied with blood vessels) form of
connective tissue, consisting of extracellular fibers, embedded in a
matrix that contains cells localized in small cavities.
In heavy weight bearing areas, the amount of collagen is great and
the cartilage is almost inextensible. In low-stress areas, cartilage
contains elastic fibers and few collagen fibers. Cartilage is nourished
by diffusion.
Cartilage functions to:
- support soft tissues
- provide a smooth, gliding surface for bone articulations at joints
- enable the development and growth of long bones.
There are three types of cartilage:
- Hyaline: most common, matrix contains a moderate amount of
collagen fibers (e.g., articular surfaces of bones).
- Elastic: matrix contains both collagen fibers and elastic fibers (e.g.,
external ear).
- Fibrocartilage: matrix contains few cells and ground substance but many collagen fibers (e.g.,
intervertebral discs).
Bone
Bone is a calcified, living, connective tissue that forms the majority of the skeleton. It consists of an
intercellular calcified matrix, which contains collagen fibers, and several types of cells within the
matrix. Bones function as:
- supportive structures of the body.
- protectors of vital organs.
- reservoirs of calcium and phosphorus.
- levers on which muscles act to produce movement.
- containers for blood-producing cells.
There is compact and spongy (trabecular or cancellous) bone. Compact bone is dense bone that
forms the outer shell of all bones and surrounds spongy bone. Spongy bone consists of spicules of
bone enclosing cavities containing blood-forming cells (marrow). Bones are classified by shape:
- long bones are tubular (e.g., humerus in upper limb; femur in lower limb).
- short bones are cuboidal (e.g., bones of the wrist and ankle).
- flat bones consist of two compact bone plates separated by spongy bone (e.g., skull).
- irregular bones are bones with various shapes (e.g., bones of the face).
- sesamoid bones are round or oval bones that develop in tendons (pezen).
, Bones are vascular and innervated. Generally, an adjacent artery gives off a nutrient artery, one per
bone, that directly enters the internal cavity of the bone and supplies the marrow, spongy bone, and
inner layers of compact bone. All bones are covered externally (except in the area of a joint where
articular cartilage is present) by a fibrous connective tissue membrane called the periosteum, which
has the capability of forming new bone. It receives blood vessels that supply the outer layers of
compact bone. A bone can’t survive without it’s periosteum. Nerves accompany the vessels that
supply the bone and the periosteum. Most of the nerves in the internal cavity are vasomotor fibers
that regulate blood flow. Bone itself has few sensory nerve fibers. Periosteum, though, is supplied
with numerous sensory nerve fibers and is very sensitive to injury. All bones develop from
mesenchyme by either intramembranous ossification, in which mesenchymal models of bones
undergo ossification, or endochondral ossification, in which cartilaginous models of bones form from
mesenchyme and undergo ossification.
Joints
Joints: the sites where to skeletal elements come together.
Two categories of joints: synovial- and solid joints
1. Skeletal elements are separated by a cavity (i.e., synovial joints).
2. No cavity, components are held together by connective tissue (i.e., solid joints).
Synovial joints
Synovial joints: connections between skeletal components that are separated by a cavity.
Characteristics:
- (Usually hyaline) cartilage covers the surfaces of the skeletal elements. Bones to not make contact
and on a X-ray, a gap can be seen.
- A joint capsule consisting of an inner synovial membrane and an outer fibrous membrane is
present.
- The synovial membrane attaches to the joint surfaces and encloses the articular cavity. It’s highly
vascular and produces synovial fluid, which percolates into the articular cavity and lubricates the
articular surfaces. It also occurs outside joints where it forms synovial bursae or tendon sheaths.
Bursae often intervene between structures and reduce friction. Tendon sheaths surround tendons
and reduce friction as well.
- The fibrous membrane consists of dense connective tissue and surrounds and stabilizes the joint.
It can form ligaments to further stabilize the joint. Outside the capsule, ligaments provide additional
reinforcement.
Anatomy includes all structures that can be seen with or without the aid of magnification. It’s the
basis for the practice of medicine, as it leads to the understanding of a patient’s disease. Though the
terminology of anatomy is important, an understanding of anatomy requires an understanding of the
context in which the terminology can be placed.
Gross anatomy / macroscopic anatomy: The study of structures that can be seen without a
microscope.
Microscopic anatomy / histology: The study of cells and tissues using a microscope.
How can gross anatomy be studied?
“Anatomy” comes from the Greek “temnein” which means “to cut”.
Anatomy can be studied through dissection, viewing prosected (previously dissected) material and
plastic models or using computer models.
Anatomy can be studied following a regional of a systemic approach.
- Regional approach
Each region of the body is studied separately and all systems and aspects of that region are studied
at the same time. Regions are e.g.: the thorax, abdomen, pelvis, lower limb, etc.. A regional approach
works well if dissection is involved, but it falls short when it comes to giving an understanding of the
continuity of an entire system through the body.
- Systemic approach
Each system of the body is studied and followed through the entire body. Systems are e.g.: the
skeletal-, cardiovascular-, nervous-, respiratory system, etc.. The systemic approach gives a good
understanding of an entire system throughout the body, but it is difficult to coordinate this with a
cadaver dissection and to acquire detail.
Anatomical terms
The anatomical position
The anatomical position is the reference position of the body, used to describe the location of the
structures. The body is in anatomical position while:
- standing upright
- feet together
- hands by the side
- mouth closed
- neutral facial expression
- rim of the bone under the eyes is in the same horizontal plane as the top to the opening of the ear
- eyes open, focussed on something in the distance
- palms of the hands facing forward with fingers together and the thumb to the side
- toes pointing forward
,Anatomical planes
3 major groups of planes pass through the body
in anatomical position:
-Coronal plane
Anterior/ventral: to the front
Posterior/dorsal: to the back
- Sagittal plane
Medial: to the middle
Lateral: to the side (further from the median)
- Transverse / Horizontal / Axial plane
Superior: up
Inferior: down
Other terms:
Proximal: close to a structure’s origin
Distal: further from a structure’s origin
Cronial: toward the head (superior)
Caudal: toward the tail (inferior)
Roastal: position with reference to the nose
Superficial (relative): to the surface of the body
Superficial (absolute): external to the outer layer
of deep fascia
Deep (relative): further from the surface
Deep (absolute): enclosed by the outer layer of
deep fascia.
,Body systems
Skeletal system
The skeletal system can be divided into two subgroups, the axial
skeleton and the appendicular skeleton. The axial skeleton consists
of the bones in the skull, vertebral column, ribs, and sternum. The
appendicular skeleton consists of the bones in the upper and lower
limbs. The skeletal system consists of cartilage and bone.
Cartilage
Cartilage is an avascular (not supplied with blood vessels) form of
connective tissue, consisting of extracellular fibers, embedded in a
matrix that contains cells localized in small cavities.
In heavy weight bearing areas, the amount of collagen is great and
the cartilage is almost inextensible. In low-stress areas, cartilage
contains elastic fibers and few collagen fibers. Cartilage is nourished
by diffusion.
Cartilage functions to:
- support soft tissues
- provide a smooth, gliding surface for bone articulations at joints
- enable the development and growth of long bones.
There are three types of cartilage:
- Hyaline: most common, matrix contains a moderate amount of
collagen fibers (e.g., articular surfaces of bones).
- Elastic: matrix contains both collagen fibers and elastic fibers (e.g.,
external ear).
- Fibrocartilage: matrix contains few cells and ground substance but many collagen fibers (e.g.,
intervertebral discs).
Bone
Bone is a calcified, living, connective tissue that forms the majority of the skeleton. It consists of an
intercellular calcified matrix, which contains collagen fibers, and several types of cells within the
matrix. Bones function as:
- supportive structures of the body.
- protectors of vital organs.
- reservoirs of calcium and phosphorus.
- levers on which muscles act to produce movement.
- containers for blood-producing cells.
There is compact and spongy (trabecular or cancellous) bone. Compact bone is dense bone that
forms the outer shell of all bones and surrounds spongy bone. Spongy bone consists of spicules of
bone enclosing cavities containing blood-forming cells (marrow). Bones are classified by shape:
- long bones are tubular (e.g., humerus in upper limb; femur in lower limb).
- short bones are cuboidal (e.g., bones of the wrist and ankle).
- flat bones consist of two compact bone plates separated by spongy bone (e.g., skull).
- irregular bones are bones with various shapes (e.g., bones of the face).
- sesamoid bones are round or oval bones that develop in tendons (pezen).
, Bones are vascular and innervated. Generally, an adjacent artery gives off a nutrient artery, one per
bone, that directly enters the internal cavity of the bone and supplies the marrow, spongy bone, and
inner layers of compact bone. All bones are covered externally (except in the area of a joint where
articular cartilage is present) by a fibrous connective tissue membrane called the periosteum, which
has the capability of forming new bone. It receives blood vessels that supply the outer layers of
compact bone. A bone can’t survive without it’s periosteum. Nerves accompany the vessels that
supply the bone and the periosteum. Most of the nerves in the internal cavity are vasomotor fibers
that regulate blood flow. Bone itself has few sensory nerve fibers. Periosteum, though, is supplied
with numerous sensory nerve fibers and is very sensitive to injury. All bones develop from
mesenchyme by either intramembranous ossification, in which mesenchymal models of bones
undergo ossification, or endochondral ossification, in which cartilaginous models of bones form from
mesenchyme and undergo ossification.
Joints
Joints: the sites where to skeletal elements come together.
Two categories of joints: synovial- and solid joints
1. Skeletal elements are separated by a cavity (i.e., synovial joints).
2. No cavity, components are held together by connective tissue (i.e., solid joints).
Synovial joints
Synovial joints: connections between skeletal components that are separated by a cavity.
Characteristics:
- (Usually hyaline) cartilage covers the surfaces of the skeletal elements. Bones to not make contact
and on a X-ray, a gap can be seen.
- A joint capsule consisting of an inner synovial membrane and an outer fibrous membrane is
present.
- The synovial membrane attaches to the joint surfaces and encloses the articular cavity. It’s highly
vascular and produces synovial fluid, which percolates into the articular cavity and lubricates the
articular surfaces. It also occurs outside joints where it forms synovial bursae or tendon sheaths.
Bursae often intervene between structures and reduce friction. Tendon sheaths surround tendons
and reduce friction as well.
- The fibrous membrane consists of dense connective tissue and surrounds and stabilizes the joint.
It can form ligaments to further stabilize the joint. Outside the capsule, ligaments provide additional
reinforcement.
