PERSONAL FITNESS 10

Musculoskeletal System Notes

HCS1050

Anatomical, Directional & Regional Terms

Skeletal System Functions

Support soft tissues & provide attachment sites for muscles

Movement at joints when muscles are contracted

Protects organs (e.g., skull encases brain)

Stores calcium, phosphorous, fat, sodium & other minerals

Production of blood cells

Bones

Continuously being remodeled via osteoclasts & osteoblasts Osteoclasts break down bone Osteoblasts build bone

“When bone is subjected to stress, more tissue is created (bone density increases)”

Joints of the body & Planes of Movement

Fibrous Joints

Cartilaginous Joints

Synovial Joints Joint movement occurs within 3 planes of

motion Sagittal Frontal Transverse

Sagittal Plane

Frontal Plane

Transverse Plane

Proprioception

The sense of knowing where the body is in relation to its various segments and the external environment. Receptors in the skin, in and around the

joints and muscles, and in the inner ear transmit the information

Types of Muscles

Skeletal Attaches to the skeleton via tendons, contracts to move

bones Voluntary Striated appearance

Smooth Found on walls of hollow organs (stomach, blood vessels) Involuntary & smooth

Cardiac Forms the walls of the heart Involuntary & smooth

Skeletal Muscle Fiber Types (Slow Twitch)

Slow-twitch muscle fibers Also called Oxidative or Type 1 muscle

fibers Contract more slowly Have lower force outputs More efficient More fatigue resistance

Fast Twitch Muscle Fibers

Two types of Fast-twitch muscle fibers Fast-oxidative glycolytic (Type IIa) fibers

Possess speed, fatigue and force production somewhere between Type I and Type IIx

For this reason, type IIa are also called intermediate fibers

Fast-glycolytic (Type IIx) fibers Limited capacity for aerobic metabolism Fatigue the fastest of the 3 types Considerable anaerobic capacity Largest and fastest Capable of producing the most force of all skeletal

muscle fiber types

Two Muscle Proteins & Connective Tissue

Actin Thin myofilament muscle protein

Myosin Thick myofilament muscle protein

Connective Tissue Tendons connect muscle to bone Ligaments connect bone to bone

Muscle Fiber Microanatomy

Skeletal muscle are made up of many muscle fibers

Muscle fibers are made up of myofibrils (protein filaments) composed of a series of repeating segments called sarcomeres

Sarcomeres, made up of thick (myosin) and thin (actin) myofilaments, are the functional contracting unit of skeletal muscle

Sliding Filament Theory of Muscle Contraction

Acetylcholine is released from the CNS Once detected, calcium is released

Calcium exposes binding sites along the actin for the myosin to attach to

Cross bridges are formed & the myosin pulls the actin toward the center thereby shortening the sarcomere and the muscle fiber itself

If multiple muscle fibers are stimulated to contract at the same time, the muscle will try to actively shorten by contracting

Sliding Filament Model

Sliding Filament Theory

Factors that Impact Flexibility Soft tissues contribute to the total resistance of

joints as follows (we can impact these by stretching): Joint capsule: 47% Muscle fascia: 41% Tendons: 10% Skin: 2%

Other factors that impact flexibility include (we can minimize these by working on flexibility): Age Gender Joint structure and past injury

Human SkeletonSkull

Mandible (Jaw)Clavicle (Collarbone)SternumHumorous

RibsVertebraePelvisRadiusUlnaCarpalsMetacarpalsPhalangesFemur

Patella (Kneecap)

TibiaFibula

TarsalsMetatarsalsPhalanges

Muscles of the Body

The Shoulder Girdle

Upper Trapezius

Middle Trapezius

Serratus Anterior

Lower Trapezius

Levator Scapulae

Rhomboid Minor

Rhomboid Major

Muscles that act at the Shoulder Girdle

The Rotator Cuff

Supraspinatus

Infraspinatus

Teres Minor

Glenohumeral joint

Greater Tubercle

Lesser Tubercle

Subscapularis

The Shoulder

Medial Deltoid

Anterior Deltoid

Pecs (Clavicular)

Pecs (Sternal)

Posterior Deltoid

Pectoralis MajorMiddle DeltoidLatissimus Dorsi

Posterior Deltoid

Anterior View Lateral View Posterior View

Muscles that act at the Shoulder

The Elbow

Anterior View Posterior View

Muscles that act at the Elbow

The Wrist

Muscles that act at the Wrist

The Trunk

External Abdominal Oblique

Internal Abdominal Oblique

Pectoralis Major

Rectus Abdominal

Transverse Abdominis

Tendinous Transcriptions

The Lower Back

Longissimus

Spinalis

Iliocostalis

Muscle that act on the Trunk

Hip Extensors

Semitendonosus

Semimembranosus

Biceps Femorus

Gluteus Maximus Gluteus

Medius

Illiotibial Band

Muscles that act at the Hip Joint

Hip Flexors and Quadriceps Group

Vastus Lateralis

Vastus Intermedialis

Vastus Medialis

Vastus Lateralis

RectusFemorus

Vastus Medialis

Muscles that act at the Hip Joint

Muscles that act at the Knee Joint

The Calves

Soleus

Achiles Tendon

Gastrocnemius

Muscles that act at the Ankle Joint

Four Types of Postural Alignment

Ideal Kyphosis Flat Back Sway Back