Myology and Muscle Classification

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Questions and Answers

What is the primary function of a muscle's origin?

To provide a moving point for muscle attachment

To serve as the most distal point of attachment

To connect muscles to bones via tendons

To remain fixed during muscle contraction (correct)

Which type of muscle attachment is characterized by a cord-like band of fibrous tissue?

Connector tissue

Raphae

Tendon (correct)

Aponeurosis

What are sesamoid bones primarily associated with?

Providing additional flexibility to joints

Serving as a leverage point for tendons (correct)

Protection of the muscle fibers

Connection between ligaments and muscles

What distinguishes aponeuroses from other muscle attachments?

They are thin but strong flat sheets. Signup and view all the answers

Which term describes a feature formed by the interdigitation of aponeurosis of flat muscles?

Raphae Signup and view all the answers

What is the primary function of skeletal muscles?

Produce voluntary movements Signup and view all the answers

Which layer of connective tissue encases individual muscle fibers?

Endomysium Signup and view all the answers

Which type of muscle is characterized by striated fibers and voluntary control?

Skeletal muscle Signup and view all the answers

What type of muscle tissue is responsible for involuntary contractions and is found in the heart?

Cardiac muscle Signup and view all the answers

What is the function of smooth muscle within the body?

Regulate involuntary actions Signup and view all the answers

Which of the following is NOT a form of skeletal muscle?

Cardiac muscles Signup and view all the answers

What structure supports the synchronized contraction of cardiac muscle tissue?

Intercalated discs Signup and view all the answers

Which connective tissue layer is found surrounding the entire muscle?

Epimysium Signup and view all the answers

Which of the following describes a type of parallel muscle?

Rectus abdominis Signup and view all the answers

What is the primary characteristic of convergent muscles?

A broad area converges to a single attachment site Signup and view all the answers

Which type of pennate muscle has fibers on both sides of a tendon?

Bipennate Signup and view all the answers

What is the role of an antagonist muscle?

Opposes the movement of the agonist Signup and view all the answers

Which of the following best describes circular muscles?

Open and close to guard entrances of the body Signup and view all the answers

Which terms describe the functional roles within a muscle group?

Agonist, antagonist, synergist Signup and view all the answers

Which of the following correctly defines 'sarcoplasm'?

The cytoplasm within a muscle fiber Signup and view all the answers

What makes up the majority of total protein in skeletal muscle?

Actin and myosin Signup and view all the answers

What term describes the specific orientation of muscle fibers in a muscle?

Fascicle organization Signup and view all the answers

Which of the following describes a muscle that is primarily visible at the body surface?

Externus (superficialis) Signup and view all the answers

What is the significance of the prefix 'bi' in muscle naming?

Indicates two tendons present Signup and view all the answers

What best describes smooth muscle?

No striations and single nuclei Signup and view all the answers

Which of these names is used to describe muscles that are created based on their action?

Extensor Signup and view all the answers

Which type of fascia is characterized by being formed of dense fibrous tissue and spreading over muscles?

Deep fascia Signup and view all the answers

What is the role of annular ligaments in relation to tendons?

Convert grooves into canals Signup and view all the answers

Which muscle type is under autonomic control?

Smooth muscle Signup and view all the answers

Study Notes

Myology

Myology studies muscles and accessory structures like fascia, tendon sheaths, and bursae.
Muscles are contractile tissues made of muscle fiber bundles, responsible for movement.

Muscle Functions

Movement production
Heat generation in warm-blooded animals
Body stabilization
Substance transport within the body

Muscle Classification

Skeletal muscle: Striated, voluntary control
Smooth muscle: Non-striated, involuntary control
Cardiac muscle: Striated, involuntary control

Skeletal Muscle

Striated fibers
Multinucleated
Voluntary control
Epimysium: Outermost connective tissue layer surrounding the muscle
Perimysium: Middle layer, encases fascicles (bundles of muscle fibers)
Endomysium: Innermost layer, surrounds individual muscle fibers

Skeletal Muscle Forms

Long muscles: Found in limbs
Flat muscles: Found in abdomen and chest
Short muscles: Various locations
Sphincter muscles: Ring-like muscles closing orifices, examples include:
- Sphincter ani: Around the anus
- Orbicularis oris: Around the mouth
- Orbicularis oculi: Around the eye

Skeletal Muscle Attachment

Origin: Fixed point of attachment, usually proximal
Insertion: Movable point of attachment, usually distal
Tendon: Cord-like, fibrous tissue connecting muscle to bone
Aponeurosis: Thin, strong sheet of fibrous tissue, found in flat muscle attachments
Raphae: Interdigitation of aponeuroses, examples:
- Pharyngeal raphe: Short aponeurosis
- Linea alba: Wide and long aponeurosis between abdominal muscles

Skeletal Muscle Fiber Organization

Parallel: Fibers parallel to the long axis of the muscle, example: biceps brachii
Convergent: Muscle fibers converge on a single attachment point, example: pectoralis muscles
Pennate: Muscle fibers are obliquely arranged, with different subtypes:
- Unipennate: Fibers on one side of the tendon, example: extensor digitorum
- Bipennate: Fibers on both sides of the tendon, example: rectus femoris
- Multipennate: Series of bipennate arrangements, example: deltoid
Circular: Also called sphincters, guard body entrances, example: obicularis oris

Muscle Actions

Movements generated by muscle contraction, classified as:
- Flexors
- Extensors
- Adductors
- Abductors
- Cutaneous

Muscle Terminology

Agonist (prime mover): Muscle responsible for the primary movement
Antagonist: Muscle opposing the agonist's movement
Synergist: Smaller muscle assisting the agonist, may help start motion or stabilize the origin
Fixator: Synergist muscle stabilizing the origin of the agonist

Sarcomere

Basic structural and functional unit of muscle

Contractile Proteins

Actin: Thin myofilament
Myosin: Thick filament
Tropomyosin: Thin filament
Troponin: Thin filament
Actin and myosin constitute approximately 55% of total protein in skeletal muscle

Muscle Description

Name:
- Action: extensor, adductor
- Shape: quadratus, triangularis
- Direction: rectus, oblique
- Position: subscapularis, iliacus
- Division: biceps, triceps
- Size: major, minor
- Attachment: sterno-cephalicus
- Structure: semitendinosus
Shape: triangular, quadrilateral, fusiform
Attachment: cartilage, bone, skin
Action: movement produced
Structure: including direction and arrangement of fibers
Relations: relationship to surrounding structures

Naming Skeletal Muscles

Location: Identifies body regions, example: temporalis muscle
Origin and insertion: First part of name indicates origin, second part indicates insertion, example: genioglossus muscle
Fascicle organization: Describes fiber orientation within the muscle, example: rectus (straight), transversus, oblique
Relative position: Describes muscle depth and location within the body, example: externus (superficialis), interus (profundus), extrinsic, intrinsic
Structural characteristics: Number of tendons, shape, size, example: bi = 2, tri = 3, trapezius, deltoid, rhomboid, major, minor
Action: Movement produced, example: flexor, extensor, retractor

Muscle Fascia

Superficial fascia: Loose connective tissue, may contain fat, also called subcutaneous fascia
Deep fascia: Dense fibrous tissue, spreads over muscles, may fuse with epimysium, tendons, bones, and ligaments, forms fibrous sheaths around muscles, forms annular ligaments to create canals for tendons

Bursa and Synovial Sheath

Bursa: Fluid-filled sac reducing friction between structures
Synovial sheath: Encloses tendons to reduce friction during movement
Peritendon: Outer layer of the synovial sheath
Mesotendon: Attaches the peritendon to tendon
Bone: Connective tissue with a rigid extracellular matrix
Periosteum: Membrane covering bone, important for growth, repair, and attachment of tendons

Smooth Muscle

Non-striated
Spindle-shaped
Single nucleus
Autonomic control

Cardiac Muscle

Striated
Uninucleated
Intercalated discs facilitate synchronized contraction
Autonomic control

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Description

Explore the fascinating field of myology, which focuses on muscle structure and function, including the various types of muscles and their roles in the body. This quiz covers muscle classifications, functions, and the intricacies of skeletal muscle anatomy.