Human Anatomy (205)

[Skeletal Muscle] [Fiber Physiology] [Muscular System] [Lab Models] [Practice Tests] Muscular System Myology is the study of muscles

Three principle functions of muscle
1. Movement
2. Heat Production
3. Posture & Body support
Three muscle tissue types
1. Skeletal muscle cells have striations [alternating dark and light bands] * [Also see cross section]
2. Cardiac muscle cells
3. Smooth muscle cells
Properties of muscle tissue [irritability contractility, extensibility, elasticity]

Skeletal muscles are composed of fibers (cells) bound together by connective tissue.

Connective tissue associated with muscle [endomysium, perimysium, epimysium, fascia]
Muscle attachments
- Tendons are bands of dense connective tissue attaching muscle to bone.
- Most moveable attachment is insertion
- Least moveable attachment is origin
- Aponeurosis is a flattened sheetlike muscle attachment. See palmar aponeurosis
Four principal fiber patterns in skeletal muscle
1. Parallel fibers [rectus abdominus]
2. Convergent fibers [pectoralis major]
3. Circular fibers [orbicularis oris]
4. Pennate fibers [rectus femoris]
Muscle cells contract when stimulated by nerve impulses
- Isotonic & Isometric Contractions
- Motor Unit is a motor neuron + muscle fibers it innervates
- Myoneural Junction is the contact site between the end of the motor neuron and muscle fiber
- Motor End Plate is the portion of the sarcolemma in contact with motor neuron.

The Structure and Functions of Skeletal Muscle Fibers (Cells)

The Gross Physiology of Skeletal Muscle
Organelles of fiber [sarcolemma, sarcoplasm, myofibrils, sarcoplasmic reticulum]
Muscle fiber has striations of alternating A bands [dark] and I bands [light]
The contractile elements of muscle fibers are myofibrils. See myofibril animation
Myofibril has pattern of alternating A bands [dark] and I bands [light]
Each Myofibril is made up of an organized chain of subunits (sarcomeres)
Sarcomere is the smallest contractile unit of muscle fiber. * Review Sarcomere the functional unit
- Sarcomere length extends between Z discs of myofibril (Z disc in each I band)
- Sarcomere includes a centrally located A band with one half an I band on each end
- Each sarcomere is composed of two sets of protein myofilaments, acitn and myosin.
- Actin anchored in Z disc and extends toward center of sarcomere and overlaps part of myosin suspended in A band
Sliding filament Mechanism explains the interaction of Actin & Myosin in muscle fiber contraction
See animation of Sliding filament Mechanism
ATP and Ca⁺⁺are necessary for the Myosin/Actin reaction
Regulation of contraction of skeletal muscle fibers
- Contraction triggered by release of Ca++ into sarcomere from Sarcoplasmic reticulum
- Two proteins [troponin, tropomyosin] interact with Ca++ to allow myosin to bond to actin
Souces of ATP for muscle contraction
- Aerobic respiration in mitochondrion [requires oxygen]
- Anaerobic respiration [partial breakdown of glucose without oxygen]
- Glycogenesis is formation of glycogen from glucose. - occurs in muscle
- Some ATP converted to Creatine Phosphate

Skeletal Muscular System Naming of Muscles	Click on specific parts of the lab torso's musculature to view information and closeup of torso muscles
Organization of Muscular System Axial Muscles muscles of facial expression and mastication neck muscles muscles of vertebral column Appendicular Muscles - Pectoral appendage [Anterior View] [Posterior-lateral View] muscles that act on pectoral girdle muscles that move the humerus muscles that move the forearm Appendicular Muscles - Pelvic appendage [ Frontal View] [Posterior View] [ Lateral View of Hip] muscles of the hip and gluteus that move thigh muscles of the thigh that moves leg muscles of the anterior and posterior thigh muscles of the leg Check Camelet's Lab Muscle List! For lab exam you should know: Name of muscle {identify on Lab Torsos & models} Action or function of muscle Name of prime antagonist (muscle with opposite action) Attachment names [origin is least moveable attachment and insertion is most moveable]	[Torso muscle map]	[Torso muscle map]

The Hosford Muscle Tables: List of skeletal muscles including their origin, insertion and action.

Identify muscles on surface anatomy of male body builders or female body builders

Laboratory Torsos and Models

Anterior and posterior muscle illustration on Lab wall muscle chart
LMC Lab virtual torso Interactive torso can be rotated and includes zoom.
LMC Lab Torso [ Frontal View] [ Head and Neck] [ Muscles of Mastication] [Posterior View]
LMC Lab Torso (trunk unlabeled) [ Frontal View from left] [ Posterior View ]
LMC Lab Torso thighs and legs [ Frontal View] [Posterior View] [ Lateral View of Hip]
LMC Lab arm model [Anterior View] [Posterior-lateral View]

Quizzes, crosswords and tutorials

Crossword on Myology and on Naming muscles
Try muscular system links at Human Anatomy On Line; also Muscles Tutorial or see Getbodysmart.com
Muscular System Quizzes at Web Anatomy
The Anatomy Game(Web Anatomy II) Muscles of the: [body] [face] [trunk] [upper limb] [lower limb]
Quizzes at Getbodysmart.com

Dynamic Human
at McGraw-Hill

Human Anatomy
Online

Etymology of
Medical Terms

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