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 Skeleton Skull Mandible (Jaw) Clavicle (Collarbone) Sternum Humorous Ribs Vertebrae Pelvis Radius Ulna Carpals Metacarpals Phalanges Femur Patella (Kneecap) Tibia Fibula Tarsals Metatarsals Phalanges

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 Glenohumeral joint Greater Tubercle Lesser Tubercle Subscapularis Supraspinatus Infraspinatus Teres Minor

The Shoulder Medial Deltoid Anterior Deltoid Pecs (Clavicular) Pecs (Sternal) Posterior Deltoid Pectoralis Major Middle Deltoid Latissimus Dorsi

Anterior View Lateral View Posterior View

Posterior Deltoid

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 Illiotibial Band Gluteus Medius

Muscles that act at the Hip Joint

Hip Flexors and Quadriceps Group

Vastus Lateralis Vastus Intermedialis Vastus Medialis Vastus Lateralis Rectus Femorus Vastus Medialis

Muscles that act at the Hip Joint

Muscles that act at the Knee Joint

The Calves Gastrocnemius Soleus Achiles Tendon

Muscles that act at the Ankle Joint

Four Types of Postural Alignment Ideal Kyphosis Flat Back Sway Back