Podcast
Questions and Answers
What distinguishes skeletal muscle from cardiac and smooth muscle?
What distinguishes skeletal muscle from cardiac and smooth muscle?
Which naming convention would you most likely find in skeletal muscles named after their location?
Which naming convention would you most likely find in skeletal muscles named after their location?
Which of the following best describes the function of the abdominal skeletal muscles?
Which of the following best describes the function of the abdominal skeletal muscles?
What is a characteristic feature of cardiac muscle tissue?
What is a characteristic feature of cardiac muscle tissue?
Signup and view all the answers
Which type of muscle is classified as multi-unit smooth muscle?
Which type of muscle is classified as multi-unit smooth muscle?
Signup and view all the answers
What is the primary function of skeletal muscles during movement?
What is the primary function of skeletal muscles during movement?
Signup and view all the answers
Which of the following is NOT a characteristic of cardiac muscle?
Which of the following is NOT a characteristic of cardiac muscle?
Signup and view all the answers
What distinguishes multi-unit smooth muscle from visceral smooth muscle?
What distinguishes multi-unit smooth muscle from visceral smooth muscle?
Signup and view all the answers
Which of the following skeletal muscles is primarily involved in respiratory actions?
Which of the following skeletal muscles is primarily involved in respiratory actions?
Signup and view all the answers
Which muscle-naming convention is based on the muscle’s shape?
Which muscle-naming convention is based on the muscle’s shape?
Signup and view all the answers
Study Notes
Skeletal Muscle
- Moves the bones of the skeleton, which moves the animal.
- Voluntary, striated muscle.
- Under conscious control.
- Responsible for maintaining balance and posture.
- Governed by sensory structures, the central nervous system, and nerve fibers.
- Enables actions like breathing, swallowing, and standing without conscious thought.
- Uses a "cruise control" mechanism.
Skeletal Muscle Attachments
- Attached to bones by tough, fibrous connective tissue bands called tendons.
- Continuation of the epimysium (muscle sheath).
- Aponeuroses: broad sheets of fibrous connective tissue.
- Linea alba: prominent aponeurosis that connects muscles.
- Connects muscles from both sides together.
Skeletal Muscle Attachments (continued)
- Origin of the muscle: the less movable attachment site.
- Insertion of the muscle: the more movable attachment site.
Skeletal Muscle Actions
- Skeletal muscle's only action is to contract (shorten).
- Stimulated by nerve impulses.
- Skeletal muscles typically work in groups.
- Some muscles produce the desired movement while others stabilize nearby joints.
- Provides control over body movements.
- Agonist: muscle or muscle group directly producing a desired movement.
- Antagonist: muscle or muscle group that opposes the action of the agonist.
Actions (continued)
- Antagonists perform partial contractions to smooth out agonist movements.
- Can contract forcefully at the same time as an agonist, which results in rigidity or lack of motion.
- Synergist: skeletal muscle that contracts alongside the agonist to assist with the action.
- Fixator: muscle that stabilizes joints to allow other movements.
Muscle-Naming Conventions
- Action: part of a muscle's name, related to its function.
- Flexors: muscles that flex a joint.
- Extensors: muscles that extend a joint.
- Shape: muscle's name can reflect its shape, such as deltoid (triangular).
- Location: muscle's name can indicate its location in the body, such as biceps brachii.
Muscle-Naming (continued)
- Direction of fibers: Rectus means straight.
- Number of heads or divisions: number of attachments to the origin.
- Attachment sites: origin and insertion sites are used to name some muscles (e.g., sternocephalicus).
Selected Skeletal Muscles
- Animals have numerous muscles, focusing on clinically important/landmark muscles.
Cutaneous Muscles
- Connective tissue under the skin.
- Little or no attachment to bones.
- Thin, broad, superficial.
- Twitch the skin.
Head & Neck Skeletal Muscles
- Control facial expressions, enable chewing, and move sensory structures (eyes, ears).
- Masseter muscle: main chewing muscle; closes the jaw.
Head & Neck Muscles (continued)
- Muscles that raise the head (e.g., splenius, trapezius).
- Brachiocephalicus: large, strap-like muscle running from proximal humerus to base of skull.
- Neck flexor muscles (e.g., sternocephalicus).
Abdominal Skeletal Muscles
- Support abdominal organs.
- Help with flexing the back and various straining actions.
- Play a role in respiration (discussed elsewhere).
- Arranged in layers.
Abdominal – Outside In
- Abdominal obliques: left and right parts; come together on ventral midline.
- Linea alba: connective tissue midline.
- Fibers run in an oblique direction.
- Rectus abdominis: strap-like muscles on each side of linea alba, run from ribs to pubis.
- Transversus abdominis: deepest abdominal muscle, fibers run vertically.
Thoracic Limb Skeletal Muscles
- Function in locomotion.
- Superficial shoulder muscles (e.g., latissimus dorsi, flexes shoulder, helps propel body).
- Pectoral muscles (located on each side of sternum).
- Adductor muscle: keeps front legs under the body.
- Deltoid muscle: abducts and flexes the shoulder.
Thoracic Limb- Continued
- Biceps brachii and triceps brachii: reveal their general location and appearance, have opposite actions on the elbow joint.
- Biceps brachii: has two proximal head attachments.
- Triceps brachii: has three proximal head attachments, extends elbow joint.
- Extensor Carpi Radialis: extends carpus and is over the radius.
- Digital flexor muscles: flexes the digit and is located beneath the other digits.
Pelvic Limb Skeletal Muscles
- Involved in locomotion.
- Gluteal muscles and hamstring muscles: extensor muscles of hip joint.
- Help propel body forward and pull leg backward.
- Gluteal muscles extend to trochanters of femur.
- Hamstring group: extend hip and flex stifle joint.
Pelvic Limb Continued
- Quadriceps femoris: main extensor of stifle joint, located in the cranial thigh.
- Composed of four heads
- Flexors and extensors of tarsus and digits are similar to those in the thoracic limb.
- Gastrocnemius muscle: extends from caudal portion of femur, inserts on calcaneal tuberosity, powerful extensor of hock.
Skeletal Muscles of Respiration
- Muscles increase and decrease thoracic cavity size for breathing.
- Diaphragm: thin, dome-shaped muscle separating thoracic and abdominal cavities.
- External intercostals: increase thoracic cavity size.
Skeletal Muscles of Respiration Continued
- Two sets of intercostal muscles.
- External intercostals go in an oblique direction when contracted to rotate ribs up and forward, increasing the thoracic cavity. Internal intercostals go at right angles to external, when contracted rotate ribs back, decreasing size of thoracic cavity.
Cardiac Muscle
- Involuntary, striated muscle.
- Contractions are not under conscious control.
- Found in the heart, making up the majority of its wall.
- Cells have similar striated appearance under microscope.
Microscopic Anatomy of Cardiac Muscle
- Contains organelles typical to muscle cells, smaller than skeletal, and have one nucleus per cell.
- Cells are branched and interconnected end-to-end in an intricate network.
- Visible attachment sites are called intercalated discs
Visceral Smooth Muscle
- Found in the walls of internal organs (viscera).
- Cells are linked to form sheets of muscle.
- Characterized by rhythmic contraction waves and fine movements aren't possible.
- Stomach, intestine, uterus, and urinary bladder
Multi-unit Smooth Muscle
- Small, delicate; made of individual smooth muscle cells/small groups.
- Found where precise, small contractions are needed (e.g., iris, blood vessels).
- Require specific impulses from autonomic nerves to contract.
- Control blood flow and airflow according to body's needs.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
This quiz covers the structure and functions of skeletal muscles, including their movements and attachments to the skeleton. It also explains the roles of tendons and nerve impulses in muscle contraction, as well as the concepts of origin and insertion. Test your understanding of these fundamental aspects of muscular anatomy!
