Muscle Muscle tissuetissue vs. Muscle as an vs. Muscle as an organorgan
One of the 4 primary tissue types
How many subtypes?
Made up of 4 tissue types.
> 700 skeletal muscles
Word roots:sarco mys
Overview of Muscle TissueOverview of Muscle Tissue
• Functions of muscle tissue
– Movement
– Maintenance of posture – enables the body to remain sitting or standing
– Joint stabilization
– Heat generation – muscle contractions produce heat
•Helps maintain normal body temperature
Types of Muscle TissueTypes of Muscle Tissue
• Three types • Skeletal muscle tissue – packaged into
skeletal muscles, Cells are striated, voluntary
•Makes up 40% of body weight
• Cardiac muscle tissue – occurs only in the walls of the heart, striated, involuntary
• Smooth muscle tissue – occupies the walls of hollow organs. Visceral, no striations, involuntary
Similarities of Muscle TissueSimilarities of Muscle Tissue
• Cells of skeletal and smooth muscles are known as fibers
• Muscle contraction depends on two types of myofilaments
• One type contains actin
• Another type contains myosin
•These two proteins generate contractile force
• Plasma membrane is called a sarcolemma
• Cytoplasm is called sarcoplasm
Basic Features of a Skeletal Muscle
• Connective tissue sheaths bind a skeletal muscle and its fibers together
•Epimysium –(overcoat) dense regular connective tissue surrounding entire muscle
•Perimysium – surrounds each fascicle (group of muscle fibers)
•Endomysium – a fine sheath of connective tissue wrapping each muscle cell
• Connective tissue sheaths are continuous with tendons
Gross AnatomyGross Anatomy
Each skeletal muscle is wrapped by 3 concentric layers of connective tissue.
Epi-, Peri-, and Endomysium
Are interwoven - Go over into tendon
Distinguish between:TendonAponeurosisLigament
Basic Features of a Skeletal Muscle
• Muscle attachments
– Most skeletal muscles run from one bone to another
– One bone will move – other bone remains fixed
– Origin – immovable or less movable bone that muscle moves toward when a muscle contracts
– Insertion – Movable bone when a muscle contracts, moves towards origin
Basic Features of a Skeletal Muscle
• Muscle attachments • Muscles attach to origins and insertions
by connective tissue
•Direct (fleshy) attachments – connective tissue fibers are short, epimysium of muscle is fused to the periosteum of a bone of perichondrium of a cartilage
•Indirect attachments – connective tissue forms a tendon or aponeurosis
• Bone markings present where tendons meet bones
•Tubercles, trochanters, and crests
Arrangement of FasciclesArrangement of Fascicles
• Parallel/Fusiform-long axis of fascicles run parallel to long axis of the muscle
• Pennate – fascicles short and attach obliquely
• Convergent – has broad origin and fascicles converge toward a single tendon
• Circular-fascicles arranged in concentric rings
Pennate Muscles: UnipennatePennate Muscles: Unipennate
One or more tendons run though muscle body
Fascicles in oblique angle to tendon
Can generate more tension
Circular Muscles Circular Muscles
= Sphincters
Concentric fibers adjust opening
Examples: orbicularis occuli and oris
Types of ActionsTypes of Actions
flexion, extension adduction, abduction elevation, depression rotation pronation, supination
Grouping of Muscles according to Grouping of Muscles according to Primary ActionPrimary Action
Agonist = Prime Mover
Antagonist (action opposes agonist)
Synergists = Assistants of prime mover
Naming the Skeletal MusclesNaming the Skeletal Muscles
• Location –most often with regard to bone
• Shape– the deltoid is triangular
• Relative size - Maximus (largest), minimus (smallest), longus (long), and brevis (short), indicate size
• Direction of fascicles and muscle fibers -Name tells direction in which fibers run
– Example – rectus (straight) abdominis and transversus or oblique abdominis
• Location of attachments – name reveals point of origin and insertion. Origin always named first! Example – brachioradialis,