Chapter 7 Muscular System

Functions and Types of Muscle Has three types Smooth Cardiac Skeletal

Functions and Types of Muscle Smooth Muscle: Wall of hollow internal organs Involuntary contractions Moves materials Single nucleus Parallel lines, forming sheets No striations Sustain prolonged contraction, doesn’t fatigue easy

Functions and Types of Muscle Smooth Muscle:

Functions and Types of Muscle Cardiac Muscle: Wall of heart Uninucleiated Striated, tubular, and branched Intercalated disks = quick contractions Involuntary and rhythmic

Functions and Types of Muscle Cardiac Muscle:

Functions and Types of Muscle Skeletal Muscle: Multinucleated Striated Voluntary

Functions and Types of Muscle Skeletal Muscle:

Functions and Types of Muscle Connective Tissue Coverings: Endomysium: each muscle fiber is surrounded by Fascicles: groups of muscle fibers Perimysium: Connective tissue covering of fascicles Epimysium: Covers the entire muscle

Functions and Types of Muscle Connective Tissue Coverings:

Functions and Types of Muscle Skeletal muscle: Supports the body Makes bones and other body parts move Helps maintain a constant body temperature Contraction assists movement in cardiovascular and lymphatic vessels Protects internal organs and stabilizes joints

Contraction of Skeletal Muscle

Contraction of Skeletal Muscle Muscles acquire ATP in 3 ways Creatine phosphate breakdown Cellular respiration Fermentation

Contraction of Skeletal Muscle Creatine Phosphate Breakdown Creatine Phosphate builds up when muscle is at rest Speediest way to make ATP available 8 seconds of intense energy

Creatine Phosphate Breakdown

Contraction of Skeletal Muscle Cellular Respiration: Completed in mitochondria Only when oxygen is available From glycogen and fatty acids End products are carbon dioxide, water, and heat

Cellular Respiration

Contraction of Skeletal Muscle Fermentation: Anaerobic Glucose breaksdown into lactic acid Build up of lactic acid leads to cramping

Fermentation

Contraction of Skeletal Muscle All or nothing law A single fiber either contracts or rest However, a group of fibers some contract and other will not to appear to have the ability for partial contractions

Contraction of Skeletal Muscle Muscle twitch- single contraction that last for a fraction of a second Latent period: time between stimulation and initiation of contraction Contraction period: muscle shortens Relaxation period: muscle returns to its former length

Contraction of Skeletal Muscle Summation – increase in muscle contraction until maximal sustained contraction is achieved Tetanic contraction- maximum contraction

Contraction of Skeletal Muscle While some muscles are contracting others are resting, this helps prevent fatigue Tone: some fibers are always contracting Helps maintain posture

Contraction of Skeletal Muscle Atrophy- loss of muscle tone due to inactivity or nerve damage Muscle will eventually be replaced by adipose and fibrous tissue Muscles will shorten, leaving parts contracted

Contraction of Skeletal Muscle Pertrophy- increase in muscle size Prolonged period of forceful muscular activity increases myofibrils

Contraction of Skeletal Muscle Slow-twitch muscles Steadier and more endurance Highly resistant to fatigue Substantial reserve of glycogen and fat Abundant mitochondria, few fibers Aerobic

Contraction of Skeletal Muscle Fast-twitch muscles Anaerobic Designed for strength Many fibers, few mitochondria Little or no myoglobin Few blood vessels Vulernable to cramping

Skeletal Muscles Origin – of a muscle is on the stationary bone Insertion- of a muscle in on the bone that moves

Skeletal Muscles

Skeletal Muscles Prime mover- the muscle that does most of the work Synergists- the assisting muscles

Skeletal Muscles Antagonist- pair of muscles working against the synergist

Skeletal Muscles Naming muscles Size Shape Direction of fiber Location Example: gluteus maximus, largest butt muscle Shape Deltoid, shaped like a delta Direction of fiber Rectus abominis, rectus = straight Location Frontalis, overlies the frontal bone

Skeletal Muscles Naming muscles Attachment Number of attachments Ex. Brachioradialis, brachium and the radius Number of attachments Ex. Bicep = two attachments Action Extensor digitorum – extends fingers

Skeletal Muscles Muscles of the Head Frontalis: frontal bone Raising eyebrows, wrinkle brow Orbicularis oculi: encircles eye blinking Orbicularis oris: encircles mouth Pucker lips

Skeletal Muscles Muscles of the Head Buccinator: cheek Compresses to whistle Zygomaticus: cheekbone to corner of mouth Smile

Skeletal Muscles Muscles of Mastication Masseter: zygomatic arch to mandible Ex. chewing Temporalis: overlies temporal bone Ex. Elevates mandible

Skeletal Muscles Muscles of the Neck Deep neck muscles are responsible for chewing Superficial muscles are responsible for moving the head

Skeletal Muscles Muscles of the Neck Sternocleidomastoid Trapezius Turns head from right to left Trapezius Triangular Shrug shoulders

Skeletal Muscles Muscles of the Trunk External intercostal: between ribs Ex. Elevate rib cage during inspiration Diaphragm Ex. Assists in inspirations Internal intercostal Ex. Normally no muscular contraction, only with forced expiration

Skeletal Muscles Muscles of the Abdominal Wall External and internal obliques: Lower ribs and pelvic girdle Ex. Trunk rotation and lateral flexion Transversus abdomininis: horizontal across abdomen Synergist muscles Rectus abdominis: from pubic bones to the ribs and strernum Ex. Flex and rotate lumbar region

Skeletal Muscles Muscles of the Shoulder Serratus anterior: from armpit to chest Ex. Helps elevate arm above head

Skeletal Muscles Muscles of the Arm Deltoid Pectoralis major Abducts arm to horizontal position Pectoralis major Latissimus dorsi: from lower spine to humerus Ex. Swimming, rowing and climbing rope Rotator cuff: muscles over proximal humerus

Skeletal Muscles Muscles of the Arm Biceps brachii: muscles of the forearm Turn a doorknob unscrew a jar Brachilais: humerus to ulna Ex. Flexing the forearm Triceps brachii: scapula to humerus Ex. To punch and in tennis

Skeletal Muscles Muscles of the Arm Flexor carpi and extensor carpi Flexes and extends wrist Flexor digitorum and extensor digitorum Flexes or extends fingers

Skeletal Muscles Muscles of the Hip and Leg Iliopsoas: ilium to lumbar vertebrae Ex. walking, bowing, standing erect Gluteus maximus: large buttocks muscle Ex. Walking, jumping, climbing stairs Gluteus medius: small buttocks muscle Adductor group Ex. Thighs inward

Skeletal Muscles Muscles of the Leg Quadricep femoris: thigh Ex. Extends leg Sartorius: thigh to knee Ex. Sit cross legged Hamstring:Back of thigh Ex. Antagonist muscle group

Skeletal Muscles Muscles of the Ankle and Foot Gastrocnemius Ex. Pushing forward while walking, dancing Tibialis anterior Ex. Inversion of foot Peroneus Ex. Plantar flexion Flexor and extensor digitorum longus Ex. Flexes and extends toes

Effects of Aging Mass and strength decrease Muscle tissue initially replaced by connective tissue then eventually fat

Homeostasis Heartbeat and movement of blood Protect internal organs Moves bones and allows daily activities