Download
1 / 42
420 likes | 527 Views
Movement Unit. Skeletal System: Anatomy Chapter 6. Components. Includes all of the bones (206 in adults). Includes the cartilage and ligaments that occur at the joints (Articulations System). Functions. Support of the entire body ’ s weight. Protection of the viscera.
E N D
Movement Unit Skeletal System: Anatomy Chapter 6
Components • Includes all of the bones (206 in adults). • Includes the cartilage and ligaments that occur at the joints (Articulations System).
Functions • Support of the entire body’s weight. • Protection of the viscera. • Production of blood cells (Hemopoesis) • Storage of minerals and fat • Allows for flexible body movement
Types of Bones • Long: longer than wide (femur) • Short: cube shaped L=W (talus- foot) • Flat: platelike and have broad surfaces (parietal- skull) • Irregular: varied shapes with many places for connections (vertebra) • Round: circular (patella- knee)
Long bone Anatomy • Periosteum – continuous with ligaments and tendons. Area where blood vessels enter the bone. Fibrous connective tissue. • Epiphysis – expanded portions at each end. Contains cancellous bone wrapped in a thin layer of compact bone covered by hyaline cartilage (articular cartilage). • Diaphysis – “shaft” of the bone – not solid contains the medullary cavity with yellow marrow. Compact bone wraps this cavity.
Review of Histology: • Compact Bone: Osteons, osteocytes, Lacunae, Lamellae, hydroxyapatite ([Ca(OH2)]+Ca3(PO4)2 crystals), central or Haversian canal, canaliculi. • Spongy Bone or Cancellous bone: trabeculae, red bone marrow. • New term- Ossification- process of bone formation
The Skeletal System Articulations
Classification • Classified based on the type of movement they allow. • 3 major types: Fibrous Joint – immovable and connected by fibrous connective tissue (ex: plates in skull, periodontal ligaments) Cartilaginous Joint – slight movement and fibrocartilage is between the 2 bones (ex: betw. spinal vertebrae & pubic bones) Synovial Joint – free motion no direct contact of bones associated with synovial membranes (Ex: elbow, ankle, shoulder)
Fibrous Joints: minimal movement • Sutures: seams between bones, found between skull bones, form fontanels in children (e.g. coronal) • Syndesmoses: bones farther apart than in a suture and are joined by ligaments (e.g. radioulnar) • Gomphoses: specialized joints consisting of pegs that fit in sockets (e.g. dentoaveolar)
Cartilaginous Joints: Growth • Synchondroses: 2 bones joined by hyaline cartilage (e.g. epiphyseal plates- cartilaginous region betw. epiphysis & diaphysis of a growing bone) • Symphyses: fibrocartilage uniting 2 bones (e.g. symphyses pubis, manubriosternal (ribcage))
Synovial Joints: Movable • Plane or gliding: 2 opposed flat surfaces, movement confined to one plane (e.g. intervertebral) • Saddle: 2 saddle-shaped articulating surfaces oriented at right angles (e.g. carpometacarpel- wrist/hand) • Hinge: convex cylinder in one bone applied to a corresponding concave portion on another bone (e.g. elbow and knee) • Pivot: rotation around a single axis. A process that rotates within a ring (e.g. atlantoaxial-neck)
Synovial Joints • Ball and Socket: ball (head) at the end of one bone and a socket on another bone (e.g. coxal-hip and glenohumeral-shoulder) • Ellipsoid: modified ball-and-socket the head is more ellipsoid in shape rather than round (e.g. atlanooccipital- betw.head & neck i.e. allows nodding)
Types Movements • Flexion (anterior or ventral direction) and extension (posterior or dorsal direction) • Dorsiflexion (flex toes) and plantar flexion (point toes) • Abduction (away from midline) and adduction (toward midline) • Medial and lateral rotation (turning around long axis) • Circumduction (combination of flexion, extension, abduction, and adduction) • Elevation (superior motion) and depression (inferior motion) • Protraction (moving in anterior direction) and retraction (moving in posterior direction) • Supination (face up palm) and pronation (face down palm) • Opposition (thumb to finger) and reposition • Lateral excursion (bottom jaw lateral) • Inversion (ankle medial turn) and eversion (ankle lateral turn)
Muscular System Chapter 7 Movement Unit
Review: Fig. 7.1
Functions of Skeletal Muscle: • Support the body (opposes the force of gravity) • Make bones and other body parts move • Maintain a constant body temperature • Assist movement in cardiovascular and lymphatic vessels • Protect internal organs and stabilize joints
Microscopic Anatomy of Skeletal Muscle: • What do we already know from histology? Striations. • Arrangement of myofilaments in a muscle fiber (cell). • Normal cell with some specialized terms for cell parts. (Plasma membrane = sarcolema, endoplasmic reticulum = sarcoplasmic reticulum)
Microscopic Anatomy of Muscle (Sarcoplasmic Reticulum) • Remember this is the ER for muscle cells. • Sarcoplasmic reticulum has specialized pockets to store calcium ions (Ca2+) which is essential for muscle contraction. • The sarcoplasmic reticulum encases hundreds of myofibrils which allow for contraction of the muscle cell.
Microscopic Anatomy of Muscle: • Myofibrils run the length of the muscle fiber. • Striations are formed by the placement of these myofibrils forming sarcomeres. • Sarcomeres contain two types of protein fibers: actin (thin and intertwined) and myosin (thick and shaped like golf club).
Muscles Move Skeletal Parts • Skeletal Muscle • Each muscle fiber is a single cell with many nuclei • Each fiber is composed of a bundle of myofibrils which contain myofilaments • Thin filaments—2 strands of actin • Thick filaments—staggered arrays of myosin • Striated appearance due to sarcomeres (basic functional unit)
Muscle Contractions: Sliding-Filament Model • Thin and thick filaments of the sarcomere slide past one another to shorten the length of the muscle
Muscle Contractions • Motor Unit: A single nerve ending and all the muscle fibers attached to it • With a nerve impulse- muscle fibers contract completely. “all or none”- the amt. of fibers contracting can vary! • Does a muscle have to contract completely? • Partial contraction of a muscle comes from only contracting a portion of the fibers (see above)
Calcium is the so called "trigger" for muscle contraction. Calcium aids in the formation of action potential in the motor end plate, and is later released from the terminal cisternae of the sarcoplasmic reticulum into the cytosol of a striated (cardiac and skeletal) muscle cells. Next the calcium ions bind to troponin which causes a change in the conformation of the troponin-tropomyosin complex that exposes the myosin binding sites on the actin filament. The myosin heads then attach to the actin filament and a muscle contraction occurs.
Chemical energy in muscle fibers is in the form of ATP. In order to produce physical energy, ATP is hydrolyzed to become ADP and Pi (adenosine diphosphate and inorganic phosphate). When ATP is broken down into ADP and Pi the cross bridges are energized which allows for the "power stroke", or force production of a muscle contraction. Source: http://www.cartage.org.lb/en/themes/sciences/zoology/animalphysiology/muscles/muscles.htm
Microscopic Anatomy of Muscle: • Sliding Filaments – when the muscles are triggered by motor nerve cells, impulses travel down the T-tubule of the sarcomere (see following picture). Calcium is then released from the sarcoplasmic reticulum. This causes the sarcomere to shorten. The actin slides across the myosin. ATP provides the power for this contraction.
Connective coverings • Muscles are covered with fascia (dense regular connective) which separates muscles. Deep fascia separates muscles from each other, superficial fascia-from skin. • Fascia are continuous with tendons which are continuous with the bone periosteum.
Smaller picture • Muscles are grouped in to fascicles that are covered with a sheath of connective tissue called perimysium. • Fascicles are divided into muscle fibers, each surrounded by the endomysium • Blood and nerves reach the muscle through the endomysium
Exercise • Atrophy- from lack of use, muscle fibers are replaced with adipose and fibrous tissue • Can cause muscle fibers to shorten enough to force the body to contort. • Hypertrophy-more myofibrils develop with more use
Going the Distance, or not? • Slow twitch- less fibers per motor unit- better for endurance sports • Largely aerobic-extra mitochondria, extra capillaries • Presence of Myoglobin • A dark, red oxygen carrying pigment • Fast Twitch- more fibers per motor unit- better for powerful, short muscle bursts • Few mitochondria • Largley anerobic • Easily hits maximum tension
Macroscopic Anatomy of Muscle: • 3 Layers of connective tissue are part of each muscle: Epimysium – surrounds entire muscle, dense layer of collagen fibers. Perimysium – divides muscle into compartments called fascicles. Endomysium – delicate connective tissue that surrounds each muscle cell or fiber. • Where these connective tissues run together at the end of muscles they form tendons or aponeurosis.
