Human Anatomy Unit 2 MUSCULAR SYSTEM

Human Anatomy Unit 2 MUSCULAR SYSTEM

In Anatomy Today

Functions Movements of bones and soft body parts Movements of fluids through a tube (blood, digestive)

Functions Maintain posture Support soft organs

Functions Control movement through a passage or opening Control body temperature

Muscle Fascia

Muscle Tissue Connective tissue layers are continuous with each other Tendon Periostium Epimysium Perimysium Endomysium

Fusiform Parallel Convergent Pennate Circular Fascicle Orientation 5 Muscle Types

Fusiform Muscles Thick in middle Tapered at ends Moderately strong contractions Examples: Biceps brachii Gastrocnemius

Parallel Muscles Straplike with parallel fascicles Uniform width Contract more than other muscle types Weaker than fusiform Examples: Rectus abdominis Sartorius

Pennate Muscles Feather-shaped Fascicle inserts into tendon running through muscle Unipennate Semimembranosus Bipennate Rectus femoris Multipennate Deltoid

Circular and Convergent Muscles Circular Sphincters Ex) Obicularis oris Convergent Fan shaped Narrow at insertion Strong Ex) Pectoralis major

Macrostructure of skeletal muscle Origins attachment of a muscle to a stationary bone Insertions attachment of a muscle to a movable bone

Characteristics of Origins and Insertions Indirect attachments (most common) Tendons cordlike structures of fibrous, regular connective tissue Aponeuroses a wide, thin, tendon Direct attachments the muscle surface is attached directly to the periosteum of bone

Naming Muscles By fiber arrangement Rectus Fascicles (fibers) run parallel to the muscle longitudinal midline axis (LMA) Example Rectus abdominis

Naming Muscles By fiber arrangement Transverse Fascicles are perpendicular to the LMA Transverse abdominis Transversus costarum Oblique Fascicles are at an angle different than parallel or perpendicular Internal/external oblique

Naming Muscles By location Relative location Tibialis anterior Vastus lateralis Serratus dorsalis Scalenius dorsalis Profundus a deep muscle Flexor digitorum profundus

Naming Muscles By size maximus minimus medius brevis longus magnus

Naming Muscles By the number of origins biceps triceps quadriceps

Naming Muscles By shape Deltoideus Triangular Attached at side Trapezius Quadrilateral 2 sides that are parallel Rhomboideus parallelogram

Naming Muscles By origin and insertion Sternocleidomastoid Sternohyoid

Naming Muscles By action flexor pollices longus (pollux = thumb) pronator teres (teres = round) extensor digitorum

Functional Groups of Muscles 1. Prime movers (agonists) 2. Synergists 3. Antagonists 4. Fixators

Prime Movers Muscle produces most of force during movement across a particular joint 11 types Flexor Abductor Extensor Adductor Levator Depressor Supinator Pronator Rotator Sphincter Tensor

Types of Muscle Fibers Classified based on the speed of contraction 1. Slow (Type I, SO) 2. Intermediate (Type IIA, FO: fast oxidative) 3. Fast (Type IIB, FG: fast glycolytic) Other characteristics Primary source of fuel Myoglobin content Diameter of fiber Blood supply Time to fatigue

Small diameter Fatigue resistant Slow Twitch Fibers Type I: SO Fibers Very good blood supply Myoglobin (red meat) Many mitochondria Take a long time to contract after stimulation Develop less tension Primarily aerobic metabolism Lipids, carbohydrates, amino acids

Intermediate Twitch Fibers Type IIA: FO Fibers Fast twitch Intermediate Diameter Fatigue resistance Blood supply Number of mitochondria Myoglobin content Tension Primarily aerobic metabolism Carbohydrates High [glycolytic enzymes] in sarcoplasm

Large diameter Fatigue quickly Poor blood supply Fast Twitch Fibers Type II, FG Fibers No myoglobin (white meat) Few mitochondria Generates a lot of tension (Force) Primarily anaerobic metabolism Creatine phosphate High [glycolytic enzymes] in sarcoplasm

Fiber Type Distribution