1 THE MUSCULOSKELETAL SYSTEM STRUCTUREANDFUNCTION

2 MUSCLE TISSUE Three types of Muscle tissue Three types of Muscle tissue Skeletal muscle Skeletal muscle Cardiac muscle Cardiac muscle Smooth muscle Smooth muscle Muscle fibers are threadlike, cylindrical cells appearing in bundles with many crosswise stripes and multiple nuclei Muscle fibers are threadlike, cylindrical cells appearing in bundles with many crosswise stripes and multiple nuclei

3 MICROSCOPIC MUSCLE

4 CHARACTERISTICS OF MUSCLE Excitability: irritability, the ability to respond to stimulus such as nerve impulse Excitability: irritability, the ability to respond to stimulus such as nerve impulse Contractibility: fibers stimulated by nerves contract or shorten Contractibility: fibers stimulated by nerves contract or shorten Extensibility: the ability to be stretched or elongate Extensibility: the ability to be stretched or elongate Elasticity: allows the muscle to return to its’ original shape Elasticity: allows the muscle to return to its’ original shape

5 SKELETAL MUSCLE Composed of striated muscle cells and connective tissue Composed of striated muscle cells and connective tissue Attaches to two bones that have a movable joint, under voluntary control Attaches to two bones that have a movable joint, under voluntary control One of the bones is usually stationary, called the “origin” One of the bones is usually stationary, called the “origin” The other bone is usually mobile,called the muscle’s “Insertion” The other bone is usually mobile,called the muscle’s “Insertion” Tendons anchor muscles firmly to bones Tendons anchor muscles firmly to bones

6 TENDONS Made of dense, fibrous connective tissue in the shape of heavy cords Made of dense, fibrous connective tissue in the shape of heavy cords Have great strength Have great strength They do not tear or pull away from the bone easily They do not tear or pull away from the bone easily Bursae lie between some tendons and the bones underneath Bursae lie between some tendons and the bones underneath Bursae makes it easier for a tendon to slide over a bone Bursae makes it easier for a tendon to slide over a bone

7 TENDONS AT WORK

8 FUNCTIONS OF SKELETAL MUSCLE PROVIDE VOLUNTARY MOVEMENT PROVIDE VOLUNTARY MOVEMENT MAINTAIN POSTURE OR MUSCLE TONE MAINTAIN POSTURE OR MUSCLE TONE HEAT AND ENERGY PRODUCTION HEAT AND ENERGY PRODUCTION PROTECT INTERNAL ORGANS PROTECT INTERNAL ORGANS

9 SKELETAL MUSCLE MOVEMENT Muscles move bones by pulling on them Muscles move bones by pulling on them The insertion portion of the muscle moves toward the origin The insertion portion of the muscle moves toward the origin Muscle contraction is responsible for body movements Muscle contraction is responsible for body movements Skeletal muscles contract and become shorter, while others relax Skeletal muscles contract and become shorter, while others relax Muscles Work in coordinated teams, not singly Muscles Work in coordinated teams, not singly This coordinated action makes movement smooth and graceful This coordinated action makes movement smooth and graceful

10 MUSCLES OF ARM FLEXION SEE PAGE 186

11 MEDICAL TERMS: PRIME MOVER: the MUSCLE that is mainly responsible for producing the movement PRIME MOVER: the MUSCLE that is mainly responsible for producing the movement SYNERGISTS: muscles that assist the prime mover SYNERGISTS: muscles that assist the prime mover ANTAGONISTS: muscles that have the opposing actions ANTAGONISTS: muscles that have the opposing actions

12 POSTURE Poor posture makes a person tire more quickly by putting pull on ligaments,joint, and bones Poor posture makes a person tire more quickly by putting pull on ligaments,joint, and bones Poor posture crowds the heart making it harder to contract Poor posture crowds the heart making it harder to contract Poor posture crowds the lungs decreasing breathing capacity Poor posture crowds the lungs decreasing breathing capacity

13 Muscle Tone Muscles are partially contracted at all times Muscles are partially contracted at all times Muscle tone: state of readiness to act Muscle tone: state of readiness to act

14 FATIGUE IF MUSCLE CELLS ARE STIMULATED REPEATEDLY WITHOUT ADEQUATE REST, IF MUSCLE CELLS ARE STIMULATED REPEATEDLY WITHOUT ADEQUATE REST, STRENGTH OF MUSCLE CONTRACTION DECREASES, RESULTING IN FATIGUE STRENGTH OF MUSCLE CONTRACTION DECREASES, RESULTING IN FATIGUE

15 MUSCLE MOVEMENTS FLEXION FLEXION EXTENSION EXTENSION ABDUCTION ABDUCTION ADDUCTION ADDUCTION ROTATION/CIRCUMDUCTION ROTATION/CIRCUMDUCTION SUPRINATION/PRONATION SUPRINATION/PRONATION DORSIFLEXION/PLANTAR FLEXION DORSIFLEXION/PLANTAR FLEXION SEE PAGE 187 SEE PAGE 187

16 HEAT PRODUCTION Normal body temperature: 98.6 F Normal body temperature: 98.6 F (37 C) (37 C) Muscle Contractions produce most heat required to maintain temperature Muscle Contractions produce most heat required to maintain temperature Hypothermia: failure to maintain normal body temperature in cold environment Hypothermia: failure to maintain normal body temperature in cold environment

17 BODY SYSTEMS AFFECTING MOVEMENT Skeletal Skeletal Muscular Muscular Respiratory Respiratory Circulatory Circulatory Nervous Nervous Remember the body is one Remember the body is one large interactive system each large interactive system each part depending on normal part depending on normal function of other parts function of other parts

18 TYPES OF SKELETAL MUSCLE CONTRACTION Twitch..quick, jerky response to stimulus Twitch..quick, jerky response to stimulus Tetanic..sustained and steady response Tetanic..sustained and steady response Isontonic..muscle shortens and produces movement of joints Isontonic..muscle shortens and produces movement of joints Isometric..type contraction where the muscle does not shorten Isometric..type contraction where the muscle does not shorten see page 176 see page 176

19 TONIC CONTRACTION A special type of skeletal muscle contraction used to maintain posture A special type of skeletal muscle contraction used to maintain posture Skeletal muscle tone maintains posture by counteracting the pull of gravity Skeletal muscle tone maintains posture by counteracting the pull of gravity

20 MUSCLE MOVEMENT Before skeletal muscle contracts, it must be stimulated by nerve impulses Before skeletal muscle contracts, it must be stimulated by nerve impulses Motor neuron..nerve fiber that stimulates a muscle fiber Motor neuron..nerve fiber that stimulates a muscle fiber Neuromuscular junction..point of contact between nerve and muscle Neuromuscular junction..point of contact between nerve and muscle Motor unit..single neuron and the muscle cells it innervates Motor unit..single neuron and the muscle cells it innervates

21 MUSCLE STIMULUS Threshold stimulus..minimal level of stimulation required to cause a fiber to contract Threshold stimulus..minimal level of stimulation required to cause a fiber to contract All or none…subjected to a threshold stimulus, muscle contracts completely All or none…subjected to a threshold stimulus, muscle contracts completely

22 SKELETAL MUSCLE GROUPS Muscles of the Head & Neck Upper extremity muscles Muscles of the Trunk Muscles of the lower extremity

23 MUSCLES OF THE HEAD & NECK Muscles of facial expression around eyes, mouth,nose Muscles of facial expression around eyes, mouth,nose Large mastication muscles Large mastication muscles Neck muscles connect skull to trunk, rotate head and bend neck Neck muscles connect skull to trunk, rotate head and bend neck See page 181 See page 181

24 HEAD & NECK MUSCLES Facial Expression: Facial Expression: Frontal raises eyebrows, furrow forehead skin Frontal raises eyebrows, furrow forehead skin Orbicularis oculi closes eyes Orbicularis oculi closes eyes Orbicularis oris puckers lips to kiss Orbicularis oris puckers lips to kiss Zygomaticus elevates corners of mouth & lips (smiling muscles) Zygomaticus elevates corners of mouth & lips (smiling muscles) Mastication: Mastication: Masseter elevates mandible Masseter elevates mandible Temporal closes jaw see page 181 Temporal closes jaw see page 181

25 HEAD & NECK MUSCLES Neck: Neck: Sternocleidomastoids flexes,tilts,rotates head Sternocleidomastoids flexes,tilts,rotates head Trapezius elevates shoulders, extends head backwards Trapezius elevates shoulders, extends head backwards See pages 181 See pages 181

26 UPPER EXTREMITY MUSCLES Pectoralis major flexes upper arm Pectoralis major flexes upper arm Latissinus dorsi extends upper arm Latissinus dorsi extends upper arm Deltoid abducts upper arm Deltoid abducts upper arm Biceps brachii primary flexor of forearm Biceps brachii primary flexor of forearm Triceps brachii extensor of elbow (boxer’s muscle) see page Triceps brachii extensor of elbow (boxer’s muscle) see page

27 MUSCLES OF THE TRUNK ANTERIOLATERAL ABDOMINALS ANTERIOLATERAL ABDOMINALS External oblique External oblique Internal oblique Internal oblique Transversus abdominis Transversus abdominis Rectus abdominis Rectus abdominis RESPIRATORY MUSCLES RESPIRATORY MUSCLES Intercostals Intercostals Diaphragm See page 182 Diaphragm See page 182

28 MUSCLES OF LOWER EXTREMITIES Iliopsoas flexes the thigh or trunk Iliopsoas flexes the thigh or trunk Gluteus maximus supports torso in erect position, forms the buttocks,extends thigh Gluteus maximus supports torso in erect position, forms the buttocks,extends thigh Adductor muscles adduct or press the thighs together Adductor muscles adduct or press the thighs together Hamstrings flexors of the lower leg Hamstrings flexors of the lower leg Quadriceps femoris extend lower leg Quadriceps femoris extend lower leg

29 MUSCLES OF LOWER EXTREMITIES Tibialis anterior dorsiflexes foot Tibialis anterior dorsiflexes foot Gastrocnemius plantar flexes foot Gastrocnemius plantar flexes foot Soleus Plantar flexes the foot Soleus Plantar flexes the foot Peroneus group plantar flexes foot Peroneus group plantar flexes foot

MUSCLE DISORDERS MYALGIA… general muscle pain MYALGIA… general muscle pain MYOSITIS..muscle inflammation MYOSITIS..muscle inflammation SPASMS..Sudden, painful involuntary contraction, cramps due to fluid and electrolyte imbalance SPASMS..Sudden, painful involuntary contraction, cramps due to fluid and electrolyte imbalance STRAIN..Overstretching injury of muscle or tendon STRAIN..Overstretching injury of muscle or tendon 30

MUSCLE DISORDERS MUSCULAR DYSTROPHY..chronic, progressive muscle atrophy resulting in disability & early death MUSCULAR DYSTROPHY..chronic, progressive muscle atrophy resulting in disability & early death POLIOMYELITIS.. A viral infection of the nerves that control skeletal muscle POLIOMYELITIS.. A viral infection of the nerves that control skeletal muscle RIGOR MORTIS… derived from the Latin, it means “stiffness of Death RIGOR MORTIS… derived from the Latin, it means “stiffness of Death 31

MUSCLE DISORDERS MYASTENIA GRAVIS..chronic condition where nerve impulses are not properly transmitted to the muscles. MYASTENIA GRAVIS..chronic condition where nerve impulses are not properly transmitted to the muscles. Affects respiratory system Affects respiratory system Can be fatal Can be fatal Thought to be autoimmune disease Thought to be autoimmune disease Progressive muscle weakness, paralysis Progressive muscle weakness, paralysis No cure, supportive treatment only No cure, supportive treatment only 32

33 THE END