Bony components of the skeletal system
What are the functions of the skeletal system?
Support, movement, protection, mineral storage, electrolyte/pH balance, detox (absorb metals and foreign elements), and blood cell formation
What is osseous tissue and how is it formed/maintained?
Osseous tissue is connective tissue with a hard extracellular matrix. It is formed through ossification (endochondral [cartilage model is replaced by bone] and intramembranous [bone develops from mesenchymal sheet])
What are the different bone classifications? (Think shape)
Irregular, flat, short, long, and sesamoid
What are the connective tissue membranes of bones?
Periosteum, perforating fibers, nutrient foramina, endosteum and articular cartilage
What are the microanatomical structures of compact bone?
Osteons are the structural unit of compact bone, lamella are the rings of the calcified matrix (circumferential are the external and internal surface of compact bone and interstitial lamellae are found in between osteons), the central canal is at the core of the osteon and has the nerve and blood supply, perforating canals extend from the marrow cavity to the periosteum providing blood supply, canaliculi connect neighboring osteocytes and capillaries
What are the microanatomical structures of spongy bone?
Trabeculae are the structural component of spongy bone (porous), it has layers of lamellae but NO osteons, often has bone marrow (yellow is fat and red is blood)
What characteristics of bone prevent breakage?
Trabecular organization is meant to form along stress lines and resist stress with low mass. The structure of lamellae resist breakage because of their spiraling layers of calcified rings
Define bone appositional growth
Bones widen and thicken (circumferential lamellae are added)
Define bone elongation
growth at the epiphyseal plate
How does bone elongation occur?
Starts at the zone of reserve: matrix production. Second stage is the proliferative zone: mitosis takes place. Third is the zone of hypertrophy: lipids, glycogen and alkaline phosphatase accumulate; the matrix calcifies. Fourth is the zone of calcification: chondrocyte cell death. Last is the zone of ossification: where the new bone is.
What is bone marrow? Where are the different marrows found?
It is soft, spongy tissue present in bone. Red marrow is typically found in the epiphysis of bone and yellow marrow is found in the medullary cavity of long bones.
What bones develop through endochondral ossifcation?
All bones from the base of the skull down (aside from the clavicles)
What bones develop through intramembranous ossification?
Flat bones of the skull, the clavicles, and some of the facial bones
What are the functions of bone remodeling?
Functions to respond to mechanical stress/injury (maintain blood calcium and PO43-
What are the processes involved in bone remodeling?
Resorption- osteoclast activity Deposition- osteoblast activity
What are bone fractures?
A broken bone due to trauma (high stress)
What are the processes involved in bone repair?
1. Hematoma formation (fracture hematoma) 2. Soft callus formation 3. Hard callus formation 4. Remodeling
Cartilaginous Components of the Skeletal System
Hyaline Cartilage Characteristics
Most common cartilage with lots of tissue fluid
Elastic Cartilage Characteristics
Contains elastic and collagen fibers
Contains thick collagen fibers
Hyaline Cartilage Functions
Support, cushions, eases movement and is the template for bone growth
Elastic Cartilage Function
Provide flexible support (recoil)
Resist compression and absorb shock
Bones of the Body
What are cranial bones? What are facial bones?
Cranial bones are the flat bones of the skull. Facial bones are any of the bones surrounding the mouth and nose and contributing to the eye socket
What is the vertebral column? What are the different types of vertebrae?
The vertebral column is the central axis of the skeleton, it provides muscle attachments, protects the spinal cord, and supports the trunk. The different types of vertebrae include cervical vertebrae (7), thoracic vertebrae (12), and lumbar vertebrae (5), included is the sacrum and the coccyx.
What are the curves of the spine?
Kyphosis- concave anteriorly Lordosis- concave posteriorly
What bones make up the thoracic cage?
The sternum (manubrium, body, and xiphoid) and 12 pairs of ribs (true are 1-7, false are 8-12, floating are 11-12)
What bones make up the brachium, antebrachium, and the hand?
Brachium: humerus. Antebrachium: ulna and radius. Hand: carpals (8), metacarpals (5), and phalanges (14)
What bones make up the pelvic girdle?
The hip bones (coxal, ossa coxae, pelvic, innominate), the pelvis and articulates (ilium and ischium)
What bones make up the thigh, crura (leg), and feet?
Thigh: femur. Crura: tibia and fibula. Foot: tarsals (7), metatarsals (5), and phalanges (14)
Functional Joint Classification
immobile (short fibers)
limited mobility (long fibers)
Structural Joint Classification
Bony (synarthrotic) joints
The space between two bones ossifies (hip, epiphyseal line, frontal bone)
Fibrous (synarthrotic) joints
Elements are connected by fibrous connective tissue (3 types: sutures [bind bones of the skull], gomphosis [anchors tooth root in socket], and syndesmosis [bones attached via ligaments])
Cartilaginous (ampiarthrotic) joints
Bones are attached via cartilage (synchondroses [hyaline cartilage unites bone] and symphyses [fibrocartilage connects bone])
Synovial (diarthrotic) joints
Bones are structurally complex
What are the characteristics/structures associated with synovial joints?
1. Joint (articular) capsule- encloses the joint cavity and has a fibrous capsule and synovial membrane. 2. Synovial Fluid 3. Articular cartilage Accessory structures include tendons (joint stabilization), ligaments (reinforcing the capsule), and bursae (fluid filled fibrous sacs that ease friction in the joint)
What are the full structural classifications of synovial joints?
Uniaxial diarthrotic joints, biaxial diarthrotic joints, multiaxial diarthrotic joints, and sometimes nonaxial diarthrotic joints
What are the full functional classifications of synovial joints?
Pivot- uniaxial Hinge-uniaxial Condylar-biaxial Saddle- biaxial Plane- biaxial/nonaxial Ball and Socket- multiaxial
Muscle Function and Properties
Movement, posture/joint stabilization, open & close passages, heat production
Properties of muscle tissue
Excitation, conductivity, contractility, elasticity, and extensibility
Histology of Muscles
What are the structures of skeletal muscle fibers?
Sarcolemma, sarcoplasma, myofibrils, t-tubules, sarcoplasmic reticulum, glycogen, and myoglobin
What is the sarcolemma?
plasma membrane of muscle cells (excitable)
What is the sarcoplasm?
the cytoplasm of muscle cells
What is the T-Tubule?
invaginations of sarcolemma
What is the function of a t-tubule?
Conduct nerve impulses throughout muscle
What is the sarcoplasmic reticulum?
Elaborate smooth ER surrounding myofibrils
What is the function of the sarcoplasmic reticulum?
store and release calcium
Structure of Myofibrils
What are myofibrils?
the contractile organelles of skeletal and cardiac muscle
What are the structures of myofibrils?
Actin (thin filaments) and myosin (thick filaments)
What are sarcomeres?
the functional unit of muscle
What proteins/structures make up a sarcomere?
Myofilaments, z disks, m line, titin, a band, h band, and I band
1. Cross-bridge forms: myosin heads binds to actin
2. Myosin "flexes" and pulls on actin
3. Actin pulls Z disk towards each other
Nervous stimulation stops
SR absorbs calcium
Cross-bridges no longer form
Muscle returns to resting length
Muscle Contraction Questions
What is excitation-contraction coupling?
The nerve sends the impulse, the impulse excites the muscle, so the muscle contracts
What is the sliding filament model?
thin filaments pulled past thick (filaments do not shorten
What happens to each element of a sarcomere during contraction?
I Band- narrows, H Zone- narrows A Band- unaffected Z Disk- unaffected
What are the roles of Ca+ and ATP during contraction?
Calcium binds the myosin heads to actin and ATP breaks the binding apart
What happens during relaxation?
Cross-bridges are no longer forming and the muscle returns to its resting length
What are the different types of muscle contraction?
Concentric- muscle shortens (movement upwards) Eccentric- muscle is trying to contact but the load is too heavy (movement downwards) Isometric- muscle remains contracted (0 movement)
fascicles are parallel to each other (sartorius)
a bulging parallel muscle (biceps brachii)
go in a circle around something (orbicularis oris)
broad base to a narrow end, kinda like a triangle (pectoralis major)
attach to CT at an oblique angle; feather like
Muscle Growth & Atrophy
What is hypertrophy and how does it occur?
muscle fibers get bigger, connective tissue development increases
What is atrophy and how does it occur?
number of myofibrils and sarcomeres decrease, reduced use
What is the origin?
Where the muscle is less mobile
What is the insertion?
Where the muscle is more mobile
During normal movement what attachment moves toward the other?
Insertion moves toward the origin
What is a direct attachment?
It looks fleshy, kinda like muscle to muscle
What is an indirect attachment?
Aponeurosis and tendon
How do muscles attach?
CT sheaths fuse/fused sheaths attach to bone (at periosteum)
Protraction, retraction, elevation, depression, and compression
Flexion, extension, adduction, abduction, dorsiflexion, plantar flexion, and lateral flexion
Rotation, medial/lateral rotation
What is the agonist?
the prime mover, it is the muscle doing the action
What is the synergist?
the helper to the prime mover (produces the same action as the agonist)
What is the antagonist?
muscle with the opposite action of the agonist
What is the fixator?
the muscles that stabilize the joint
What is the lever?
the "bar" (bone)
What is the fulcrum?
the point of movement (joint)
What is the effort?
the force exerted (muscle)
What is the load?
what is being moved
What are the benefits of lever systems?
moving a heavy load with less effort and moving a load farther/faster
Describe mechanical advantages
the further the effort arm is from the joint, the better the mechanical advantage
How do you find the mechanical advantage?
effort arm/load arm Higher the number, the higher the advantage