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Questions and Answers
What type of muscle fiber arrangement is best described as resembling a feather?
What type of muscle fiber arrangement is best described as resembling a feather?
Which of the following muscles is an example of a strap-like muscle?
Which of the following muscles is an example of a strap-like muscle?
What is the role of the length of muscle fibers in muscle action?
What is the role of the length of muscle fibers in muscle action?
What kind of muscle attachment involves an intermediate tendon with fleshy bellies on each side?
What kind of muscle attachment involves an intermediate tendon with fleshy bellies on each side?
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Which of the following fibers are attached all around the tendon and classified as circumferential?
Which of the following fibers are attached all around the tendon and classified as circumferential?
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Which type of muscle fiber is characterized by rapid contraction and rapid fatigue?
Which type of muscle fiber is characterized by rapid contraction and rapid fatigue?
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What is the main characteristic of cardiac muscle fibers?
What is the main characteristic of cardiac muscle fibers?
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What type of muscle attachment involves a band of fibrous tissue through which two muscles fuse together?
What type of muscle attachment involves a band of fibrous tissue through which two muscles fuse together?
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Which statement correctly describes skeletal muscles?
Which statement correctly describes skeletal muscles?
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Where are high myoglobin content red fibers predominantly found?
Where are high myoglobin content red fibers predominantly found?
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Which type of muscle is primarily involved in moving the skin?
Which type of muscle is primarily involved in moving the skin?
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What is a characteristic function of smooth muscles?
What is a characteristic function of smooth muscles?
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What is true regarding muscle contractions and their attachments?
What is true regarding muscle contractions and their attachments?
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Study Notes
Muscle Types and Structure
- Muscles comprise about half of body weight
- Muscles have contractile ability
- Classified into three types: smooth, cardiac, and skeletal
Smooth Muscles
- Shape: Plane and spindle-shaped
- Nerve supply: Involuntary autonomic fibers
- Location: Walls of blood vessels and visceral organs
Cardiac Muscles
- Shape: Striated and branched
- Location: Heart
- Nerve supply: Involuntary autonomic fibers
Skeletal Muscles
- Shape: Striated, non-branching
- Nerve supply: Voluntary, supplied by at least one somatic nerve
- Attachment: Bony attachments, origin, and insertion
- Blood supply: Receive blood supply from surrounding blood vessels
Types of Striated Muscles
- Pale fibers: Rapid contraction and fatigue
- Location: Prime mover muscles initiating movement
- Red fibers: Sustained slow contraction, less prone to fatigue
- Location: Anti-gravity muscles, maintain posture
- Examples: Gastrocnemius (pale), Soleus (red)
Muscle Attachments
- Muscles attach at both ends, with one end fixed (origin), the other approximating (insertion)
- Origin tends to be proximal, insertion distal
- Attachments can be to bone, fibrous raphe, deep fascia, aponeurosis, skin, cartilage, and intermediate tendons
Types of Muscle Attachments
- Attachment to bone: Direct or via tendon
- Attachment to fibrous raphe: Fused muscles (e.g., mylohyoid)
- Attachment to deep fascia: E.g., tensor fascia lata
- Attachment to aponeurosis: Flat tendon (e.g., external oblique)
- Attachment to skin: Facial muscles
- Attachment to intermediate tendon: Muscles with multiple bellies (e.g., digastric)
- Attachment to cartilage: Muscles in the larynx (e.g., cricothyroid)
Skeletal Muscle Forms
-
Parallel fibers: Fibers run parallel to the line of pull
- Strap-like: Sartorius
- Quadrate: Quadratus femoris
- Fusiform: Palmaris longus
- Tendinous intersections: Rectus abdominis
-
Oblique fibers: Fibers run obliquely to the line of pull
- Unipennate: One side of tendon, flexor pollicis longus
- Bipennate: Two sides of tendon, rectus femoris
- Multipennate: Multiple bipennate, deltoid
- Circumpennate: Fibers around tendon, tibialis anterior
-
Non-pennate oblique fibers: Triangular (temporalis), Spiral (latissimus dorsi), Cruciate (masseter), Circular (orbicularis oculi).
Muscle Action
- Factors impacting muscle action:
- Fiber length
- Number of fibers
- Fiber direction
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Description
Explore the three main types of muscles: smooth, cardiac, and skeletal. Learn about their unique characteristics, locations, and nerve supplies. This quiz will test your knowledge on muscle structure and function.
