2 Functions of the Muscular System Movement-what examples can you think of?Maintaining posture and body positionStabilizing jointsHeat generation (generates 85% of the body’s heat…especially skeletal muscle)How does this happen?
3 Structures of the Muscular System Muscle fibersLong, slender cells that make up the muscleEach muscle consists of a group of fibers that are held together by a connective tissue and enclosed in a fibrous sheathFasciaSheet of connective tissue that covers, supports, and separates muscles or groups of musclesFlexible tissue but not elastic. Crush injuries can cause compartment syndrome
4 Structures of the Muscular System TendonsNarrow band of non-elastic, dense fibrous connective tissue that attaches a muscle to a bone***do not confuse with a ligament! Ligaments connect bone to bone
5 Types of Muscle Tissue Smooth Located in the walls of internal organs like the digestive tract and blood vessels, and ductsMove and control the flow of fluids through these structuresUnstriatedInvoluntary
6 Types of Muscle Tissue Skeletal Attached to the bones of the skeleton and make movement possibleVoluntaryStriated (appear striped)
7 Types of Muscle Tissue Myocardial (Cardiac) Form the muscular walls of the heartStriatedInvoluntary
8 How do Muscle Move? Muscle innervation Muscles are supplied with motor nervesMotor nerves enable the brain to stimulate a muscle to contractWhen the stimulus stops, the muscle relaxesIf nerve impulse is interrupted due to injury or disease, paralysis occurs
10 Antagonistic Muscle Pairs Muscles are arranged into antagonistic pairsWhen one muscle contracts, it’s antagonist relaxesExample: Biceps and Triceps work as a pair to make arm movement possibleContraction: The tightening of a muscle. As a muscle contracts, it shortens and thickens causing the belly of the muscle to enlargeRelaxation: Occurs when a muscle returns to its original form. As the muscle relaxes, it elongates, thins and the belly is no longer enlarged
11 Contrasting Muscle Motion Abduction: moves away from the midlineAdduction: moves toward the midlineFlexion: decreases an angle as in bending a jointExtension: increases an angle, as in straightening a jointElevation: raises a body part. Ex. SmilingDepression: lowers a body part. Ex. FrowningRotation: turns a bone on its own axisCircumduction: the circular movement at the far end of a limbSupination: turns the palm of the hand upward or forwardPronation: turns the palm of the hand downward or backwardDorsiflexion: bends the foot upward at the anklePlantar flexion: bends the foot downward at the ankleHyperextension: extreme overextension of a limb or body part beyond its normal limit
12 How Muscles are NamedMuscles can be named for their insertion and origin pointsOrigin: the less moveable attachment. The place where the muscle beginsInsertion: the more moveable attachment. This is the place where the muscle ends by attaching to a bone or tendon.Example: the sternocleidomastoid (SCM) muscle is named for its two points of origin (sternum and clavicle) and the one point of insertion (mastoid process).
13 Example: the sternocleidomastoid (SCM) muscle is named for its two points of origin (sternum and clavicle) and the one point of insertion (mastoid process).
14 How Muscles are NamedSome muscles can be named for their location on the body or the organ they are near:Example: pectoralis majorPectoral means pertaining to the chest and the Pectoralis major is the large, fan shaped muscle of the chest.
15 How Muscles are Named Muscles may be named for their action Flexor carpi muscles flex the wristExtensor carpi muscles extend the wristMuscle may be named for fiber directionOblique means slanted or at an angleRectus means in strait alignmentTransverse means in a crosswise fashionSphincter is a ring-like muscle that constricts the opening of a passageway.Ex. Anal sphincter
16 How Muscles are NamedSome muscles are named for the number of divisions forming them.Biceps brachii is formed from 2 divisionsTricps brachii is formed from 3 divisionsMuscles may be named for their size or shapeGluteus maximus is the larges of the gluteal musclesThe Deltoid muscle is shaped like an inverted triangle or the Greek letter Delta
17 How Muscles are Named Some muscles are just named for strange reasons… Example: the hamstring group is the group of muscles located at the back of the upper leg and these are the muscles by which a butcher hangs a slaughtered pig!