Anatomy Study Guide
BLOCK I
Anatomical Positions: erect, arms at side, face and palms forward and feet together with toes forward
Planes and Axes:
Axes – lines through the body
· Cranial-caudal (or longitudinal)
o Straight down through the body
o Vertical
· Dorsal-ventral (anterior-posterior)
o Straight through the heart
o Front to back
· Left-right
o Through the shoulders
o Side-to-side
Planes – imaginary flat surfaces formed by two intersecting ax
· Sagittal
o Vertical plane
o Made by dorsal-ventral and cranial-caudal axes
o Splits body into right and left sides
o Movements in this plane
§ Flexion
§ Extension
· Frontal
o Splits body into front and back parts
o Perpendicular to the sagittal plane
o Made by cranial-caudal and left-right axes
o Movements
§ Abduction
§ Adduction
· Transverse
o Splits body into upper and lower halves
o Made by left-right and dorsal-ventral axes
o Perpendicular to sagittal and frontal planes
o Referred to as cross-sections
o Movements
§ Pronation
§ Supination
§ Rotation (external and internal)
Skin: layers, thickness & fascia
Layers
· Epidermis
o Derived from embryonic ectoderm
o Avascular -Depends on the blood supply from the dermis for oxygen and nutrients
o Made of stratified squamous epithelium cells
§ Flattened in shape with many layers
§ Very impervious to outside substances
o Stratum Germinativum (also stratum basale)
§ The deepest layer of the epidermis (closest to the blood supply)
§ Products of these cells are pushed towards the surface of the skin were they gradually lose blood supply, become keratinized (protein), and die
o Stratum corneum
§ Outermost layer of dead, keratinized cells
· Basement Membrane
o Non-cellular layer of glycoproteins that separates the dermis and epidermis
· Dermis
o Dense, irregular, connective tissue – very tough
§ Bundles of fibers
· Collagen fibers
· Elasitc fibers
o Scattered Cells
§ Fibrocytes
· Secrete more collagen fibers
· Maintain current collagen fibers
§ Macrophages
§ Melanocytes (produce pigment)
o Capillary Plexus
§ Right below basement membrane
§ Temperature regulation
o Glands and hair follicles extend into here for blood supply
Thickness – refer not to total thickness, but the structure of the epidermis
· Thick skin – palms of hand and back
· Thin skin – everywhere else
Fascia
· Superficial (subcutaneous fascia, hypodermis, subQ)
o Lies underneath dermis
o Contains and supports cutaneous nerves and blood vessels
o Made of loose connective tissue
§ Loose bundles of fibers - Collagen fibers, Elasic fibers
o Fat cells - Lipocytes
· Deep
o Lies under the superficial fascia
o Consists of several thin layers of tough collagen material that adheres tightly to structures
o Compartmentalizes muscles, neurovascular bundles, ligaments and tendons
Cutaneous Structures: Superficial veins/arteries, glands, hair follicles, superficial nerves/dermatomes
Superficial veins and arteries
· Dermal capillary plexus
o Provides nutrients and O2 to integumentary
o Thermoregulation
Glands
· Derive from the epidermis or mucosa (gut lining)
o Grow down from epithelial surface into a connective tissue layer
o Some stay connected to epithelial surface, other do not
o Modes of secretion
§ Merocrine – secretory cell is not damaged
§ Holocrine – entire cell is secreted and new secretory cells are produced
§ Apocrine – lose distal end of cell in secretion but the rest remains intact
· Exocrine glands
o Retain connection to epithelium
o Secrete onto surface or into body cavity
o Types:
§ Sudoriferous – sweat glands
· Tubular gland
· Secretes water, salt and urea
· Merocrine secretion
§ Sebaceous – oil glands associated with hair follicles
· Holocrine secretion
§ Mammary
· Modified sudoriferous with apocrine secretion
· Endocrine glands
o Lose connection with epithelial surface
o Secrete into surrounding capillary beds
o Secrete hormones
Hair follicles
· Derived from the epidermis
· Matrix
o Mass of mitotic cells at the bottom of each follicle in the dermis
o Vascular
o As more cells produce, the others get pushed to the top, keritinize and die because of no blood supply. This forms hair shaft.
· Each type of hair has a specific cycle of growing and resting phases
Superficial Nerves (Cutaneous)
· Carry somatic sensory information
o Touch, pressure, pain, tickle, itch, fine touch
Organization of the Human Skeletal System:
· Axial Skeleton
· Appendicular Skeleton
Functions of the skeletal tissue (5)
Structure and protection
Muscle attachment
Leverage for movement
Hemopoiesis
Calcium and phosphate reservoir
Classification of Bones: Long, Short, Flat, Irregular, Sesamoid
Long
· Upper and lower limbs
· Diaphysis and epiphysis
· Ephiphyseal plate
o Proliferating hyaline cartilage
· Medullary cavity
· Periosteum
o Fibrous connective tissue membrane surrounding bone
o Contains blood vessels and nerves
o Continuous with ligaments and tendons
· Endosteum
o Lines medullary cavity
o Single layer of osteoblasts and clasts
· Articular cartilage at end of each epiphysis
Short
· Cube shaped or round
· Carpals and tarsals
Flat
· Skill bones, ribs and scapulae
Irregular
· Vertebrae and facial
Sesamoid
· Commonly found where tendons cross at the ends of long bones in the limbs to give a greater mechanical advantage
· Patella
Gross Bone Structure
Compact bone
· Densely packed parallel layers (lamina) with lacunae compressed between the layers
Spongy
· Cancellous
· Hydroxyapatite in the form of strands of bone that fuse together
· Found in epiphyses or medullary cavity
Marrow
· Yellow is fatty and associated with distal ends of long bones
· Red is associated with axial skeleton and girdles and with proximal ends of long bones
· Children have more red than adults
Bone Markings (pg. 16-17 of supplemental notes)
Microscopic Anatomy of Support Tissues
Introduction and cell types
· (fibro,chondro,osteo)Blast – secrete more cells
· Cyte – maintains matrix in which it is embedded
· Osteoclast – destroys bone matrix, releasing calcium salts
· Connective tissue supports and protects the remainder of the body
o Acellular material secreted by cells
o Cells are embedded here
o Three types
§ Fibrous (collagen and elasic fibers)
§ Cartilaginous
§ Hydroxyapatite (calcium carbonates and phosphates as in the bone matrix)
Tendons and ligaments
Characteristics
· Bundles of collagen fibers
· Few nerves and blood vessels
· Merge with periosteum, into compact bone or even into cancellous
Hyaline cartilage
· Matrix
o Secreted by chondroblasts
o Bundles of cartilage surrounded by proteoglycans (bottle brushes)
o Proteoglycans take up volume and oppose pressure put on cartilage
o Chondrocytes lie within the matrix in cavities called lacunae
o Nutrients and Blood supply get to matrix by diffusion
· Perichondrium
o Connective tissue membrane surrounding a mass of cartilage
o Outer layer has fibroblasts
§ Contains blood vessels and nerves
o Inner layer has chondroblasts
o Not around articular cartilage
Bone
· Matrix
o Secreted by osteoblasts
o 35% organic material
§ glycoproteins and collagen (osteoid) – soft gel
o 65% inorganic material
§ hydroxyapatites (calcium salts and phosphate)
§ make it hard
o Organized into trabeculae (irregular-shaped rods/spongy) or lamellae (parallel layers/compact)
· Compact Bone design (lamellae matrix)
o Formation of an Osteon
§ Several concentric layers of lamellae around a Haversian canal
§ Volkmann’s Canals
· Network of vessels that connect the Haversian canals along the long axis of the bone
§ Lacunae
· lie between adjacent lamellae in an osteon and contain osteocytes of maintenance
§ Canaliculi
· connect lacunae with other lacunae and the Haversian canal (divides the lamellae into little squares)
· Spongy Bone design (trabeculae matrix)
o Each trabecula has lamellae with osteocytes and canaliculi but no Haverian canal
o Trabeculae are nourished from blood circulating through medullary cavities from blood vessels that penetrate the compact bone into the spongy
Ossification Centers
· Primary – diaphysis
o Prenatal
· Secondary – epiphyses
o First two years after birth
o Pressure epiphyses – due to weight bearing (hips/knees)
o Traction epiphyses – associated with attachment of muscles and tendons (tubercles and tuberosities)
· Synostosis
o Bony union of diaphysis and epiphyses
Blood Supply to the Bone
· Periosteal arteries
o Enter bone at numerous points, Supply compact bone
· Nutrient artery
o Near center of bone
o Passes through compact, divides longitudinally and supplies spongy bone and red marrow
· Metaphyseal and epiphyseal arteries
o Supply ends of bone
o Arise from arteries that supply the associated joint
o Supply growth plates
· Avascular necrosis -Death of bone tissue due to loss of arterial supply
· Osteochondroses -Clinical disorders of epiphyses in children because of avascular necrosis
Bone and Cartilage Development and Growth
Chondrogenesis
· Begins with mesenchymal cells that secrete the matrix and then become trapped in lacunae
· The perichondrium is a cellular membrane that surrounds the mass consisting of chondroblasts that secrete additional matrix on the growing mass
· Nutrients, oxygen and waste products diffuse through the chondroitin sulfate between the chondrocytes on the interiror and vessels on the outside
Osteogenesis
· Membranous bone – forms in the dermis of the skin (include flat bones of the head)
o Mesenchymal cells develop into osteoblasts in areas of the body where the carbon dioxide concentration is higher
o Osteoblasts lay down hydroxyapatitie – this is called ossification
· Endochondral bone – forms all of the long bones and most of the irregular bones. Preceded by cartilage and REPLACED by bone
o Start out as cartilage framework in the embryo
o The chondrocytes arrange themselves in longitudinal rows
o Vascular tissue from the perochondrium penetrate through the matrix bringing in osteoblasts
o Osteoblasts break down the cartilaginous matrix and begin to deposit calcium salts (this is called calcification)
o Then the osteoblasts lay down hydroxyapatite to ossify the bone and a trabecular framework is formed
o The periosteum of the bone is derived from the perichondrium of the cartilage and begins to lay down layers of compact bone around the diaphysis.
o The epiphyses form additional ossification centers later on leaving cartilaginous plates in between the epiphyses and the diaphysis for growth.
o Osteoclasts break down the center of the diaphysis to form a medullary cavity which may be filled with red marrow
o Appositional growth – compact bone increasing in diameter beneath the periosteum
o Interstitial growth – cartilage being replaced by bone, increasing length
Joint Classification
Amphiarthrosis (cartilaginous) – slightly moveable with hyaline cartilage or fibrocartilage as the joining material
· Synchondrosis – held together with hyaline cartilage (i.e. epiphyseal plate)
· Symphysis – held together with fibrocartilage. Allows very little movement. (i.e. pubic symphysis)
Synarthrosis (fibrous) – held together with dense collagen and some fibroelastic tissue.
· Suture (skull)
· Gomphosis (tooth and socket)- Periodontal ligaments hold it together
· Syndesmosis (tibia and fibula)- Interosseous membrane holds these joints together
Diarthrosis (synovial) – synovial fluid, articular cartilage, joint capsule (outer layer is highly innervated and poorly vascularized), synovial membrane (poorly innervated and highly vascularized) and ligaments – designed for movement
· Uniaxial – move through one plane around one axis (flex/ext)
o Hinge joints (elbow and interphalangeals)
o Pivot (atalntoaxial and radioulnar)
· Biaxial – two planes around two axes (flex/ext & abd/add)
o Condyloid (ellipsoid) – concave/convex surfaces – (MCP’s)
o Saddle (sellaris) – (thumb joint) – both surfaces are saddle shaped
· Triaxial – all three planes (flex/ext, abd/add & rotation)
o Ball – and – socket
· Nonaxial – sliding
o Plane – joints between carpals
o
Organization and Microscopic Structure of the Skeletal Muscle
Structural hierarchy
· Myofilament – (actin and myosin) organized into arrangements called sarcomeres
· Myofibrl – chain of sarcomeres
· Myofiber – the muscle cell
o Bundle of myofibrils
o Contains myoblasts
o Multinucleated
o Sarcolemma – cell membrane around each myofiber
o Endomysium – delicate connective tissue layer surrounding the myofibers in a fasicle
· Fasicles - Bundles of myofibers surrounded by perimysium
· Muscle
o Bundles of fasicles
o Epimysium – connective tissue layer that surrounds the muscle
Myofilaments
· Actin and myosin (thin and thick)
· Tropomyosin and troponin
· Sliding filament theory
· Uses ATP
Sarcomere organization
· Z-band – plate of z-actin where the actin filaments attach and is perpendicular. Seperates two sarcomeres.
· A-band – myosin and actin over lapping
· I-band – actin filaments
· H-band – only myosin, no actin overlap
· Sarcoplasmic reticulum
· T-tubles – communication between sarcoplasmic reticulum and sarcolemma
· Cisternae – sacs in the SR that hold calcium for a muscle contraction
Nerve Supply to Skeletal muscles and Motor Units
· Neuromuscular junction
o Post and presynaptic membranes and synaptic cleft
o Neurotransmitter (activating chemical agent)
o All –or-none principle – fiber will contract completely or not at all
· Motor unit
o Motor axon and all of the myofibers is innervates
Muscle Classification and Nomenclature
· Unipennate, bipennate, multipennate
Muscle function
· Contractions
o Isometric
o Isotonic
§ Eccentric
§ Concentric
· Actions
o Agonist – prime muscle of an action
o Antagonist – inactive with agonist is working
o Synergists –if the agonist crosses two joints, these muscles prevent movement in the joint that is not in use.
o Fixators – stabilize the base of attachment for other muscles
The Neuron