Muscles are organs They provide tone, move body fluids & food, provide the heartbeat & distribute heat.

Transcription

1 The Muscular System

2 Muscles are organs They provide tone, move body fluids & food, provide the heartbeat & distribute heat. There are 3 types of muscle: 1. Skeletal Muscle 2. Smooth Muscle 3. Cardiac Muscle

3 Types of Muscle:

4 Attached to bones Voluntary Allow movement l_muscle.jpg Striated (striped) Enclosed in endomysium (connective tissue) which forms fibers called fascicles. The fascicles collectively form aponeuroses, tendon-like structures which attach to bones.

5 Smooth Muscle No striations Involuntary Located in CVS and hollow organs (stomach, bladder, etc.) Cardiac Muscle Striated Involuntary Located only in the heart (pump blood) ial/basic%20tissues/imagefll.jpg

6 Movement (contraction & relaxation) Posture Joint stabilization Heat generation

7 Muscle type and innervation of the diaphragm Type musculaire et innervation du diaphragme John Messmer 1998 [Re: Involuntary Diaphragm???] There are three types of muscle in the body: skeletal, smooth and cardiac. Skeletal contracts in response to a nerve impulse at the individual muscle cell's neural plate. It is not propogated to other muscles. Smooth muscle also uses a stimulus to contract, though its type of contraction is less forceful than skeletal muscle and can propogate to other smooth muscle cells. Smooth muscle is in intestines, for example. Cardiac muscle contracts spontaneously, but that's a separate topic. The diaphragm has ONLY skeletal muscle, not smooth muscle - none. It will not contract spontaneously as cardiac muscle. It MUST have an impulse delivered to contract. That impulse can originate in the higher brain centers as when we voluntarily inhale and exhale or in the lower brain as when low oxygen levels or high levels of acid or carbon dioxide are present in the cerebrospinal fluid or blood. There are MANY sites of modulation of breathing in the brain too complicated for this forum. I will repeat what I have said before: the diaphragm muscle is skeletal and *not considered voluntary or involuntary* - it is the NERVOUS SYSTEM which is either voluntary or involuntary depending on whether we are consciously or unconsciously breathing. The phrenic nerve carries motor fibers that originate in the upper brain - the cortex which serves voluntary actions, and lower brain - brainstem which serves involuntary actions. There are NO SYMPATHETIC OR PARASYMPATHETIC nerves to the diaphragm. (Lungs, yes; diaphragm, no.) We determine whether our diaphragms are at rest, contracted or forced up into our thoraces by the proprioceptive (position) sensation in our abdominal and chest walls and the nociceptive (bad feeling) fibers in our intestines and lungs. When it is contracted, our abdominal organs are pushed down and our abdominal walls are pushed out. When relaxed, this reverses. To exhale fully, it requires us to contract the abdominal wall muscles and the intercostal muscles (between the ribs) since our diaphragms can not move any higher than fully relaxed. I hope this clears it up. John John Messmer, MD, Medical Director Penn State Geisinger Health Group, Palmyra, PA

8 Sarcolemma is the plasma membrane. The contractile unit in the muscle is the sarcomere. Myofibrils are the organelles. Myofilaments are the proteins found within the sarcomeres. These form striations. Actin are thin filaments. Myosin are thick filaments.

9 Skeletal Muscle:

10 These striations have a pattern with 2 parts: 1. I bands (light) have actin attached to Z lines. 2. A bands (dark) are myosin overlapping actin, contain an H zone (central thick region) and a M line. Within the sarcoplasm is the sarcoplasmic reticulum (just like the ER of other cells). These are membranous channels.

11 Skeletal Muscle Fiber:

12 %20Biology/muscular/manatomy/images/muscle2.gif

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14 Motor neurons (nervous system) connect to each & every skeletal muscle fiber. The connection between these two forms a neuromuscular junction. This is the reason skeletal muscles contract. Motor neurons branch; their ends contain a lot of mitochondria & synaptic vesicles (responsible for synapses). They store neurotransmitters.

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16 The basic movement of skeletal muscle is a result of a stimulus (via a neurotransmitter). The actin & myosin filaments slide past each other, shortening the muscle fiber (contraction). Acetylcholine is the neurotransmitter responsible for skeletal muscle contraction. This needs ATP and high [Ca++] This is called the Sliding Filament Theory.

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18 Aerobic respiration: requires oxygen and produces ATP, which is used by muscles. Creatine phosphate: provides phosphate to ADP to make ATP, which is then used by muscles. Lactic acid fermentation: this is anaerobic respiration (no oxygen used). Lactic acid is produced (and a small amount of ATP).

19 Energy goes into cycle (to make ATP) Energy to do work

20 Active muscles tend to become O 2 deficient. An accumulation of lactic acid in muscles causes fatigue, cramping and pain. Repaying an oxygen debt (after strenuous exercise) may take several hours. Even at rest, muscle tone exists. This is the sustained contraction of muscles. This is important in maintaining posture.

21 Muscles move according to their location & position. The immovable end of a muscle is called the origin (head) while the movable end is called its insertion. Insertion is pulled towards its origin. Some muscles have more than 1 origin or insertion. Ex: biceps brachii (in arm) has 2 origins (biceps=2 heads)

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23 Flexion means decreasing an angle Extension means increasing an angle Muscle name usually indicates info about it: its location, size, # of attachments, shape or action. Examples: deltoid (shaped like a delta or triangle) biceps brachii (2 heads in the brachium, or arm) pectoralis major (large in size, located in pectoral, or chest, region)

24 Look up labeled diagram of muscle system in text or online. Know this diagram!

25 Chewing Muscles Frontalis Occipitalis Orbicularis Oculi Orbicularis Oris Buccinator Zygomaticus Masseter Temporalis Neck Muscles Platysma Sternocleidomastoid Facial muscles

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27 Pectoralis Major: covers chest Intercostal Muscles: between ribs Rectus Abdominis: from pubis to rib cage External oblique Internal oblique Transversus abdominus

28 Trapezius: kiteshaped muscle over neck & shoulder Latissimus Dorsi Erector Spinae (deep back) Quadratus Lumborum Deltoid (triangularshaped muscle of shoulder)

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30 Biceps brachii Brachialis Brachioradialis Triceps Brachii

31 Hip Joint Muscles: Gluteus Maximus (buttocks) Gluteus Medius Iliopsoas (p is silent; iliac crest to vertebrate) Adductor Muscles Knee Joint Muscles: Hamstrings (includes biceps femoris) Sartorius Quadriceps (includes rectus femoris): intramuscular injections usually occur here.

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33 Ankle & Foot: Extensor Digitorum Longus Fibularis Muscles (fibula to metatarsals) Gastrocnemius (calf) Soleus

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37 Look up in text or online! Know the following: Atrophy, rotation, abduction, adduction, circumduction, dorsiflexion, plantar flexion, inversion, eversion, supination, pronation, opposition, prime mover, antagonists, synergists, fixators, muscular dystrophy, Duchene s muscular dystrophy, and mysthenia gravis

38 This slide show was developed by Dana Halloran, Cardinal Mooney High School, Sarasota, FL. Used with her personal permission, adapted and amended by Rosa Whiting, Manatee School for the Arts, Palmetto, FL.