Anatomical Position and Terminology

Anatomical Position and Terminology

• Anatomical position involves standing with head level and eyes forward, lower limbs close together, and palms facing forward.

Planes of the Body

• The sagittal plane divides the body into left and right sections.
• The median (midsagittal) plane divides the body into equal left and right halves.
• The coronal (frontal) plane divides the body into anterior (ventral) and posterior (dorsal) sections.
• The horizontal (transverse) plane divides the body into superior (cephalic) and inferior (caudal) sections.

Directional Terms

• Anterior (ventral) refers to the front of the body.
• Posterior (dorsal) refers to the rear of the body.
• Superior (cephalic) indicates above.
• Inferior (caudal) indicates below.
• Proximal means closer to the origin.
• Distal means further from the origin.
• Medial means towards the midline.
• Lateral means away from the midline.
• Superficial means towards the surface.
• Deep means away from the surface.

Planes and Axes of Movement

• Sagittal plane movements occur with a transverse axis like flexion/extension.
• Coronal plane movements occur with an anteroposterior axis like abduction/adduction.
• Transverse plane movements occur with a longitudinal axis like medial/lateral rotation.

Types of Tissue

• Epithelial tissue mainly consists of cells covering surfaces or lining structures, like blood vessels.
• Connective tissue has cells separated by extracellular material found in deep fascia and tendons.
• Muscle tissue is contractile and responsible for movement, examples include skeletal, cardiac, and smooth muscle.
• Neural tissue conducts signals and is found in peripheral nerves.

Osteology

• Osteology is the study of bones

Bone Structure

• Cortical bone covers the entire bone surface and is thickest in the shaft of long bones, providing resistance to bending.
• Cancellous bone is deep to cortical bone, arranged along lines of stress to absorb impact.

Bone Types

• Long bones are longer than they are wide such as the radius, ulna, humerus, tibia, fibula, femur, and phalanges.
• Short bones tend to be box or cube shaped for example the carpals and tarsals.
• Flat bones play a role in protecting the body's organs like the sternum and scapula.
• Irregular bones include the vertebrae.
• Sesamoid bones are sesame seed shaped, found within tendons, such as the patella.

Parts of a Long Bone

• Epiphysis joins to the metaphysis via a plate or cartilage, where bone cells replace cartilage cells during growth.
• When growth stops, the metaphysis unites with the epiphysis.
• The main cell in cartilage is the chondrocyte.
• Articular surfaces consist of cartilage-covered ends of bones at a joint, allowing for smooth movement.

Arthrology - Joints

• Arthrology is the study of joints.
• Joints provide articulation between bones and allow for movement.
• Fibrous joints are united by fibrous tissue, allowing very little movement. Examples include sutures and syndesmosis.
• Cartilaginous joints can be primary, united by hyaline cartilage allowing slight movement, or secondary covered by hyaline cartilage by joined by fibrocartilage, allowing for slight movement.
• Synovial joints are covered by hyaline cartilage, separated by a joint cavity, and surrounded by a capsule, permitting various degrees of movement like the humeroradial joint.

Synovial Joint Classification

• Ball and socket joints are multiaxial, allowing movement in three axes like hips and shoulders.
• Plane joints are multiaxial, allowing gliding in multiple directions, such as intercarpal joints.
• Saddle joints are biaxial, allowing movement in two axes like the thumb.
• Ellipsoid/condyloid joints are biaxial like the wrist, allowing movement in two axes.
• Hinge joints are uniaxial, allowing movement in one axis, for example the elbow joint.
• Pivot joints are uniaxial, allowing movement in one axis like the proximal radioulnar joint.

Synovail Joints Movement and Function

• Active movement is the range a person can move their joint unassisted.
• Passive movement is the range when an outside force is applied, usually more than the active range.
• Bursae are enclosed sacs that secrete lubricating liquid for smoother movement of the joints.

Ligaments

• They attach bone to bone.
• Mechanical ligaments prevent unwanted movement and limit wanted movement to a safe level
• Sensory ligaments tell the brain what position a joint is in
• Ligaments can be capsular forming thick parts of the capsule or extracapsular being external and separate from the capsule or intracapsular within the joint, deep to the capsule.

Fascia

• Organized, inelastic connective tissue
• Wraps and packs deep structures of the body.
• Sends intermuscular septa to bone and creates firm compartments for muscle groups.
• Can protect bundles of nerves and blood vessels
• Thick in the palm and sole

Muscle Tissue Types

• Skeletal muscle is found in bones, joints, and eyes, it's voluntary controlled and striated.
• Cardiac muscle is in the walls of the heart, involuntary and striated.
• Smooth muscle is in the walls of hollow organs, blood vessels, and skin, involuntary and non-striated.
• Muscles work by contracting fibers to pull on what the muscle is attached to.
• Action of a muscle is the movement of a joint caused by the contraction

Determining Muscle Action

• Determine where the muscle attaches, what joints it crosses, and what the direction of the muscle fibers are.

Nerves and Vessels

• Central nervous system is made up of the brain and spinal cord
• Peripheral nervous system includes all nerves coming off CNS to the rest of the body.
• Motor nerves carry signals from the brain to muscles.
• Sensory nerves carry signals from the skin to the brain.
• Nerves are collections of axons

Vascular System

• Arteries carry blood away from the heart, distributing oxygen and nutrients, at high pressure, and have firm, muscular walls.
• Veins carry blood towards the heart, carry carbon dioxide and wastes, at low pressure, and have thin, walls.
• Arterioles contract/dilate to change size.
• Venules are thin walled

Microscopic Bone Tissue

• Chondro refers to cartilage.
• -cyte means cell.
• Lacuna is a small cavity or space.
• Matrix is the substance between cells.
• Peri means surrounding or enclosing.
• Endo means inside or within.
• Canaliculi are little tunnels

Structure of Bone Tissue

• Bone is made up of cells, mineralized matrix and neurovascular supply.
• Osteoclasts are responsible for bone reabsorption, releasing enzymes which create an acidic environment

Compact Bone Details

• Haversian systems/osteons are cylindrical, functional units containing vessels and nerves.
• Volkmann's canals are small channels connecting blood vessels to the periosteum and Haversian canals.
• Lacunae are small spaces containing osteocytes.
• Concentric lamellae are the rings of compact bone tissue surrounding the central canal of an osteon.
• Canaliculi are tunnels between osteocytes.
• Periosteum covers bone, containing dense, irregular connective tissue and stem cells.
• Trabeculae are network of rods and columns of tissues

Cartilage

• Avascular, it receives nutrients through diffusion.
• Composed of chondrocytes, which arranged in clusters, rows or singular cells and secrete the matrix components
• Extracellular matrix contains Collagen fibres, proteins and 70% water

Cartilage types

• Hyaline cartilage can be found is synovial joints, its chondrocytes in lacunae maintain collagen and the matrix
• Elastic cartilage is found in ear and epiglottis.
• Fibrocartilage is found in intervertebral discs, wrist, its collagen fibers provide strength and support, and help the tissue resist compression. Chondrocytes in lacunae maintain collagen and the matrix

Articular cartilage

• Smooth, white tissue covering the ends of bones in joints such as the knees, which reduces friction and absorbs shock.

Muscle Tissue types

• Myofilament: actin and myosin and arranged to form fibrils
• Sarcomere- the repeating, overlapping arrangement of myofilaments that create the myofibril
• Myofibrils- located inside the cytoplasm of a muscle cell. Are thread-like structures in muscle fibers that contract to enable movement.
• Sarcoplasm- smooth endoplasmic reticulum organelle. The organisation of the sarcomere means that cells can stack on top of one another when the muscle contracts

Neurons

• They conduct electrical impulses to form a communicating network

Peripheral nerve

• Made up of a bundle of axons and schwann cells

Anatomical Features of Vessels

• Dendrites are extensions of cytoplasm that receive the action potential
• Cell body is a region where the nucleus sits
• Axon- single cytoplasmic extension that transmits the action potential.
• Myelin sheath insulates the axon to increase the speed of the message
• Terminal end releases neurotransmitter chemicals.

Artery Vs Vein

• Shape of lumen: Arteries have more rounded lumen
• Size of lumen: Arteries have a smaller lumen
• Thickness of wall: Arteries have a thicker wall. Veins have a thicker tunica adventitia.

Blood Vessel Function

• Capillary slows blood flow for diffusion
• Arteriole contract/dilate to change size
• Venule thin walled