Muscle Anatomy and Physiology Quiz

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the primary role of muscles that cross few joints?

Enhance muscle fiber contraction efficiency

Increase the range of joint motion

Prevent undesired movement at an intermediate joint (correct)

Facilitate multi-directional movement

Which term describes a muscle that has a triangular shape?

Trapezius

Rhomboid

Latissimus

Deltoid (correct)

What does the term 'minimus' indicate when naming a muscle?

A muscle that is small (correct)

A muscle that is short

A muscle located in the chest

A muscle that is long

Which muscle classification is based on its function to extend a structure?

Extensor Signup and view all the answers

The term 'brachioradialis' refers to a muscle that originates in which part of the body?

The arm Signup and view all the answers

What characterizes skeletal muscle tissue?

Long cylindrical fibers with prominent transverse striations Signup and view all the answers

Which of the following statements about smooth muscle is true?

It is located in the walls of hollow viscera and is non-striated. Signup and view all the answers

What is the primary function of connective tissue associated with muscle fibers?

To transmit force of contraction and provide pathways for blood vessels and nerves Signup and view all the answers

How can skeletal muscles be classified?

According to their location, shape, and fiber arrangement Signup and view all the answers

Which of the following is true about cardiac muscle?

It exhibits rhythmic contraction controlled by autonomic nerves. Signup and view all the answers

What component of muscle fibers is responsible for contraction?

Myofibrils Signup and view all the answers

Which type of muscle is characterized by non-striated fibers?

Smooth muscle Signup and view all the answers

Which of the following statements correctly describes myocytes?

They form muscle fibers, which are elongated in one direction. Signup and view all the answers

Which component is responsible for connecting other fibers in skeletal muscle?

Basement membrane Signup and view all the answers

What type of muscle fibers have a rapid contraction but develop fatigue early?

White muscle Signup and view all the answers

What is the primary function of muscle spindles?

Serve as stretch receptors Signup and view all the answers

Which band within a myofibril contains no actin filaments?

H band Signup and view all the answers

What is the characteristic arrangement of parallel muscle fibers?

Parallel to the line of pull Signup and view all the answers

The striated appearance of skeletal muscle arises from which structural feature?

Myofibrils Signup and view all the answers

Which type of muscle contraction is served by motor end plates?

Phasic contractions Signup and view all the answers

Which of the following proteins is not part of actin within a myofibril?

Myomesin Signup and view all the answers

In skeletal muscle, where are organelles predominantly located?

Near the nucleus Signup and view all the answers

What is the main characteristic of fusiform muscles?

Spindle-shaped with a central belly Signup and view all the answers

What structure surrounds individual muscle fibers?

Endomysium Signup and view all the answers

Which type of bursa is characterized as a closed sac filled with lubricant?

Articular Signup and view all the answers

Which statement is true regarding smooth muscle cells?

They are non-striated and have tapering ends. Signup and view all the answers

What is the innervation type of smooth muscle?

Autonomic Nervous System Signup and view all the answers

What characterizes pennate muscles regarding their fibers?

Fibers are short and plenty, sloping obliquely. Signup and view all the answers

In the gut, the arrangement of smooth muscle consists of which layers?

Inner circular and outer longitudinal Signup and view all the answers

Which type of pennate muscle has fibers that only slope onto one side of a tendon?

Unipennate Signup and view all the answers

Which of the following muscles is an example of a spurt muscle?

Brachialis Signup and view all the answers

What role do nerves play in unitary smooth muscle?

They synchronize the contraction of numerous myocytes. Signup and view all the answers

What is the primary function of antagonistic muscles?

To oppose the desired movement. Signup and view all the answers

Which of the following structures does NOT contain smooth muscles?

Tendons Signup and view all the answers

What characterizes a tendon synovial sheath?

It is a bilaminar tubular structure. Signup and view all the answers

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

Bipennate Signup and view all the answers

What distinguishes cruciate muscles in their fiber arrangement?

Fibers arrange in an 'X' formation. Signup and view all the answers

Which of the following is a role of fixation muscles?

To stabilize the proximal joint. Signup and view all the answers

Which muscle would be classified as a shunt muscle?

Brachio-radialis Signup and view all the answers

What is a characteristic feature of cardiac muscle fibers?

Presence of intercalated discs Signup and view all the answers

Which structure is less prominent in cardiac muscle compared to skeletal muscle?

Sarcoplasmic reticulum Signup and view all the answers

Which of the following is true about smooth muscle cells?

Have a fusiform shape Signup and view all the answers

Which type of muscle is involuntary and can contract spontaneously?

Cardiac muscle Signup and view all the answers

What distinguishes cardiac muscle fibers from skeletal muscle fibers?

They have branching structures Signup and view all the answers

What type of connective tissue surrounds the sarcolemma of smooth muscle?

External lamina Signup and view all the answers

What could be a common misconception about skeletal muscle compared to smooth muscle?

Both have transverse striations Signup and view all the answers

In terms of cell organization, how do cardiac muscle fibers differ from smooth muscle fibers?

Cardiac fibers have a branched structure Signup and view all the answers

Study Notes

Muscle Tissue Overview

Muscle tissue is specialized for shortening, enabling movement
Composed of myocytes, elongated in one direction
Muscle fibers are groups of myocytes
Connective tissue invests muscle fibers, transmitting contraction force and supporting blood vessels/nerves

Learning Outcomes

Differentiate skeletal, cardiac, and smooth muscles based on structure and function
Identify muscle fiber components (myofibrils, sarcomeres, filaments)
Understand the hierarchical structure of muscle tissue (tissue → fibers → fascicles → myofibrils)
Classify skeletal muscles based on action, location, shape, fiber arrangement, and lever system roles (e.g., agonists, antagonists)

General Features of Muscle Tissue

Muscle cells are specialized for shortening and generating movement
Primarily composed of myocytes/muscle cells
Connective tissue envelopes muscle fibers and facilitates force transmission to other structures
Connective tissue provides pathways for blood vessels and nerves

Muscles - 3 Types

Skeletal Muscle:
- Attached to bones, responsible for voluntary movement
- Characterized by visible striations
- Controlled by somatic motor nerves
Smooth Muscle:
- Found in internal organs, involuntary movements
- No visible striations
- Controlled by autonomic nerves
Cardiac Muscle:
- Exclusively in the heart, involuntary and rhythmic
- Striated
- Controlled by autonomic nerves

Skeletal Muscle

Composed of long, cylindrical fibers
High variability in length and diameter
Possesses transverse striations
Multiple nuclei per fiber, placed peripherally
Encased by a cell membrane (sarcolemma)

Skeletal Muscle - Cellular Components

Cytoplasm (sarcoplasm) contains numerous myofibrils
Organelles (mitochondria, glycogen) located near the nuclei
Nucleus positioned peripherally beneath the cell membrane

Structural Components of Muscle

Muscle fibers are composed of myofibrils
Myofibrils contain repeating units called sarcomeres
Sarcomeres consist of thick (myosin) and thin (actin) filaments
Arrangement of filaments creates striations
Supporting structures within include tendons, epimysium, perimysium and endomysium

Ultrastructure of Skeletal Muscle

The cell membrane (sarcolemma) is covered by a basement membrane (external lamina)
Cytoplasm (sarcoplasm) exhibits transverse (T) tubules for signaling
Sarcoplasmic reticulum (SR) manipulates calcium for contraction
Cell organelles (e.g., mitochondria) are aligned near the nuclei
Cell contains large amounts of glycogen

Bands - Striations

Skeletal muscle displays distinct, repeating dark and light bands (striations)
Bands are associated with the arrangement of contractile proteins like actin and myosin
I band (isotropic) reflects equally in all directions
A band (anisotropic) cannot reflect light equally

Structure of a Myofibril

Myofibrils are composed of actin and myosin filaments
Actin filaments are thin and are found in the I band and part of the A band
Myosin filaments are thick and occupy the A band
Other proteins (e.g., titin, nebulin) provide structural support and elasticity

Structure of a Myofibril - Detailed

I band – actin filaments
A band – myosin filaments
H band – has no actin filaments
Z band – where actin filaments of adjoining sarcomeres meet
M band – myosin filaments of adjacent myosin filaments

Neuro-Muscular Junction

Motor end plates allow for fast phasic contraction
Trail endings enable tonic contractions
Neurotransmission involves neurotransmitters stored in vesicles
Neurotransmitters are released into the synaptic cleft, initiating muscle contraction

Muscle Spindles

Sensory receptor organs found between muscle fascicles
Play role in stretch reflexes

Organization of Muscle Fibres

Muscle fibers are organized into fascicles
Different fiber arrangements result in varying strength and range of motion
Examples are strap-like, fusiform, or pennate type

Classification of Muscles - Based on Colour

Red muscles (deep) experience slower, sustained contractions with more myoglobin
White muscles (superficial) experience faster, less sustained contractions with reduced myoglobin content

Classification of Muscles – Based on Arrangement of Muscle Fibres

Muscle fiber arrangements influence their functions
Parallel, Pennate, Unipennate, Bipennate, Multipennate, Circular or Convergent fibers exist

Classification of Muscles- Based on Action of Muscles

Muscles produce actions by working together in groups (Spurt muscles or Shunt muscles)
Prime movers, agonists, antagonists, and synergists are examples of muscle action classifications

Classification – Based on Action of Muscles - Detailed

Prime movers generate intended movement
Antagonists oppose intended movement
Fixation muscles stabilize proximal joints
Synergists coordinate actions to prevent undesired movements
Skeletal muscle contraction involves individual muscle fibers where a portion shortens 50-55% during contraction

Nomenclature of Muscles

Muscles are named based on various criteria (size, shape, location, and actions)

Connective Tissue Framework

Endomysium surrounds individual muscle fibers
Perimysium surrounds muscle bundles (fascicles)
Epimysium surrounds the entire muscle

Bursa

Small fluid-filled sacs, reducing friction between tendons and bones

Tendon Synovial Sheath

Double-layered bursa encasing tendons in areas of high friction

Smooth Muscle

Non-striated
Spindle-shaped myocytes
Central nucleus
Endomysium invests smooth muscle cells
Involuntary contractions
Walls of hollow organs

Smooth Muscle - Innervation

Controlled by the autonomic nervous system
Multi-unit smooth muscle receives direct nerve input
Unitary smooth muscle exhibits intrinsic rhythmic contractions

Smooth Muscle - Ultrastructure

Composed of actin and myosin filaments
Encased by a basement membrane (external lamina)
Sarcoplasmic reticulum (SR) facilitates calcium management for contraction
Other organelles, such as mitochondria, are also present

Cardiac Muscle

Involuntary
Specialized, branching myocytes with interconnected junctions (intercalated discs)
Spontaneously contracts rhythmically (pacemaker function)
Autonomic innervation (though not essential for contraction)

Individual Cardiac Muscle Fibers

Branched, anastomosing (connecting) arrangement
Uninucleated (one nucleus per cell)
Central location of nucleus within cell
Contains abundant sarcoplasm and mitochondria
Intercalated discs

Similarities Between Cardiac and Smooth Muscle

Elongated myocytes, with myofilaments and transverse striations (in cardiac)
Similar connective tissue and capillary network
Similar presence of organelles (sarcoplasmic reticulum, mitochondria, T-system)

Differences Cardiac vs Skeletal Muscle

Skeletal: parallel fibers, no branching, no intercalated discs, voluntary control, somatic nerves
Cardiac: branched fibers, intercalated discs, involuntary control, autonomic nerves

Differences Smooth vs Skeletal Muscle

Smooth: no striations, spindle-shaped fibers, central nucleus, involuntary control, autonomic nerves
Skeletal: striated, cylindrical fibers, peripheral nucleus, voluntary control, somatic nerves

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Test your knowledge on muscle anatomy and physiology with this quiz. You'll explore various muscle classifications, their functions, and unique terminologies related to muscular structures. Perfect for students interested in biology or anatomy.