Muscle Overview Quiz

Muscle Overview

• Muscles are one of the four basic tissues in the body
• Characteristics include: excitability (responding to nerve impulses), contractility (shortening in length), extensibility (stretching), and elasticity (returning to original shape)
• Three primary functions: providing motion, maintaining posture, and generating heat
• Skeletal muscles: controlled by the conscious mind, move bones of the skeleton, are voluntary and striated muscles, with a well-defined sheath (epimysium)
• Tendons: fibrous tissue bands connecting muscles to bones
• Aponeurosis: broad sheets of fibrous tissue connecting muscles
• Origin: more stable site of a muscle that does not move during contraction
• Insertion: site of a muscle that moves the most during contraction
• Agonist: prime mover, directly produces the desired movement
• Antagonist: directly opposes the agonist's action
• Synergist: contracts simultaneously with the agonist to assist its action
• Fixator: stabilizes joints to allow other movements
• Cardiac muscle: found only in the heart; involuntary
• Smooth muscle: carries out internal body movements; found throughout the body; involuntary

Muscle Naming Conventions

• Action: e.g., superficial digital flexion
• Shape: e.g., deltoid
• Location: e.g., biceps brachii
• Direction of fibers: e.g., rectus abdominis

Skeletal Muscle

• Number of heads: Some muscles, like biceps brachii, have multiple heads
• Attachment sites: Muscles attach to bones
• Cutaneous muscles: thin, superficial muscles, often under the skin

Abdominal Skeletal Muscles

• Functions: support abdominal organs, aid in back flexion, and participate in various processes like defecation, urination, parturition, vomiting, and respiration
• Help maintain posture
• Also involved in breathing
• Layers: External and internal abdominal oblique muscles, rectus abdominis muscle, transverse abdominis muscle

Thoracic Limbs Muscles

• Functions: locomotion
• Superficial muscles of the brachium (upper arm) include: adductors, latissimus dorsi, pectorals, abductors, and deltoid
• Brachial muscles: flexor and extensor muscles
• Carpal and digital muscles

Pelvic Limbs Muscles

• Function: locomotion and support
• Groups of muscles for thighs: Gluteal muscles, hamstrings, etc.
• Stifle joint muscles
• Tarsus and digital extensor muscles, such as extensor gastrocnemius and achilles tendon

Muscles of Respiration

• Functions to increase and decrease the size of the thorax cavity
• Examples: diaphragm and external intercostal muscles

Skeletal Muscle Cell (Fiber)

• Very large and thin
• Multinucleated (many nuclei)

Myofibril

• Fiber-like structures within the cytoplasm of the muscle cell
• Responsible for the contraction
• Made of filaments (actin and myosin)

Sarcomere

• Contractile units within a myofibril
• Composed of thick and thin filaments

Neuromuscular Junctions

• Where motor nerve fibers connect to muscle fibers
• Synaptic vesicles release acetylcholine onto sarcolemma

Muscle Contraction

• Requires ATP
• Includes depolarization and repolarization
• Includes several phases of contractions and relaxation

Muscle Metabolism

• Aerobic metabolism: adequate oxygen supply for energy needs; glucose is the primary source
• Anaerobic metabolism (no oxygen): glucose is broken down; lactic acid production

Clinical Relevance

• Muscle problems, such as hypocalcemia, can lead to severe pain, tremors, and even death.
• Muscle injuries can affect the ability of the body to execute daily functions.
• Muscle function is important to maintenance of daily functions in an animal.

Nervous System Part 1

• Nervous system structure: central nervous system (CNS), composed of brain and spinal cord; and peripheral Nerves
• The nervous system uses neurotransmitters through synapses to allow communication between cells for coordinated body response
• Parts of the nervous system include : sensory, integrating, and motor functions
• Neurons (nerve cells) conduct electrical signals (impulses)

Nervous System Part 2

• Saltatory conduction: rapid transmission of action potentials across myelinated nerves; a form of transmission where electrical signals do not travel the entire length of the axon at the same time, but instead jump between spaces along the axon called nodes of Ravier.
• Excitatory and inhibitory neurotransmitters: influence the postsynaptic cell either toward or away to their threshold

Cranial Nerves

• List of Cranial nerves with names/function
• 12 pairs of cranial nerves
• Numbered I through XII
• Sensory, motor, or mixed function

Autonomic Nervous System

• Responsible for automatic bodily functions
• Consist of sympathetic and parasympathetic nervous Systems
• Sympathetic: "fight-or-flight" response (e.g., increased heart rate)
• Parasympathetic: "rest-and-digest" response (e.g., slowing heart rate)

Muscle Contraction Mechanisms

• Depolarization and repolarization: rapid changes in electrical charge across the cell membrane that form an nerve impulse; necessary for contraction
• Action potentials: rapid changes in electrical charge that spread along the nerve fiber
• Neurotransmitters: chemicals that transmit signals from one neuron to another, (or muscle cell)
• Reflex arcs: simple pathways that allow for rapid responses to stimuli
• Also called reflexes; for instance, the stretch reflex and withdrawal reflex

Brain Structures

• Cerebrum
• Cerebellum

Feline Cerebellar Hypoplasia

• Cause: Feline panleukopenia in utero, malnutrition, severe trauma, or inflammation
• Symptoms: Hypermetria, intention tremors
• Diagnosis: often determined by clinical observation
• Treatment: No specific treatment, mainly supportive care

Diencephalon

• Passageway between brainstem and cerebrum

Brain Stem

• Connection between the spinal cord and rest of the brain
• Responsible for vital functions

Meninges

• Protective membranes surrounding the brain and spinal cord

Cerebrospinal Fluid

• Fluid between the layers of meninges

Blood-Brain Barrier

• Structure that separates brain capillaries from nervous tissue
• Protects brain cells from harmful substances

Spinal Cord

• Continues from brainstem, involved in transmitting impulses
• Components: medulla, cortex, and dorsal/ventral nerve roots
• Grey matter contains neuron cell bodies
• White matter contains nerve fibers

Cranial Nerves

• Afferent and efferent (motor)nerve fibers are apart of the cranial nerve system, and their functions
• 12 Pairs of sensory/motor/mixed cranial nerves

Reflexes

• Rapid, autonomic response
• Types: Stretch, withdrawal, crossed extensor reflexes

Test your understanding of muscle tissue characteristics and functions in this engaging quiz. Explore concepts such as muscle types, action roles, and the anatomy of muscle attachments. Perfect for anyone studying human anatomy and physiology.