Muscles HCS 1050 SLO 2

Types of Muscles Smooth muscles Location: Makes up the walls of hollow body organs, blood vessels, respiratory, passageways Cell Characteristics: Tapered at each end, branching networks, non-striated Control Action: Involuntary Produces peristalsis; contracts and relaxes slowly, may sustain contraction

Smooth Muscle

Types of Muscle Cardiac Muscle Location: Wall of the heart Cell Characteristics: Branching networks; special membranes between cells; single nucleus; lightly striated Control Action: Involuntary Pumps blood out of heart; self-excitatory my nervous system and hormones

Cardiac muscle

Types of Muscle Skeletal Muscle Location: Attached to bones Cell Characteristics: Long and cylindrical; multinucleated; heavily striated Control Action: Voluntary Produces movement at joints; stimulated by nervous system; contracts and relaxes rapidly

Skeletal Muscle

Three Primary Functions of skeletal Muscles Movement of the skeleton - muscles are attached to bones and contract to change position of the bones at a joint Maintenance of posture - a steady partial contraction of muscle, known as muscle tone, keeps the body in position Generation of heat - muscles generate most of the heat needed to keep the body at 37 degrees Celsius

The Mechanics of Muscle Movement Most muscles have two or more points of attachment to the skeleton. Muscles are attached to a bone at each end by a cordlike extension called a tendon. One end of the bone is attached to a relatively stable, less movable attachment called the origin The other end of the muscle attaches to a body part that the muscle puts into action. This is called the insertion

Tendons, origins and insertions

Fascia or Deep Fascia covers, separates and protects skeletal muscle Ligaments are bands of connective tissue that connect a bone to another bone Cartilage is found on the bone surfaces of freely movable joints and form a smooth layer also known as articular cartilage. Some complex joints such as the knee, also have additional cartilage between the bones (crescent-shaped medial and lateral meniscus)

Ligaments of the knee

fascia

cartilage

How Muscles are named Location – using a nearby bone, a position such as lateral, medial, internal or external Size – using terms such as maximus, major, minor, longus, or brevis Shape – such as circular (orbicularis), triangular (deltoid) or trapezoid (trapezius) Direction of fibers – including straight (rectus) or angled (oblique)

How Muscles are named Number of heads (attachment points)- example biceps, triceps and quadriceps Action – as in flexor, extensor, adductor, abductor or levator