DR. Carlos slide#11 class pre exam review 11/6/25

Overview of Axial and Appendicular Skeleton

• Discussion on functional aspects of the skeleton and muscle coordination.

  • Focuses on pectoral and pelvic girdles.

Appendicular Skeleton

• Definition: The parts of the skeleton that support the appendages.

• Two main divisions:

  • Muscles of the shoulder and upper limbs

  • Muscles of the pelvis and lower limbs

Function of the Appendicular Skeleton

• Position and stabilization of pelvic and pectoral girdles.

  • Allows for movement of upper and lower limbs.

Muscle Groups in the Upper Limbs

• The upper limb muscles can be categorized into four groups:

  • Muscles that position the pectoral girdle

  • Muscles that move the arm

  • Muscles that move the forearm and hand

  • Muscles that move the fingers

Important Muscle Actions

• Flexors vs. Extensors:

  • Anterior Muscles: Typically act as flexors (e.g., Biceps Brachii).

  • Posterior Muscles: Typically act as extensors (e.g., Triceps Brachii).

• The anterior and posterior muscles act as agonists and antagonists:

  • Example: Biceps (flexor) vs. Triceps (extensor).

Muscle and Tendon Characteristics

• Tendon Behavior: Muscles of the forearm do not cross into the hand; they pass through tendons.

  • This is important for repair and understanding of injuries: Tendons can be reattached which aids functionality.

• Similarities in Upper Limbs and Lower Limbs

  • The musculature of hands and feet has similar structural dynamics but inverts the function of flexors and extensors:

  • Upper Limbs:

    • Anterior is flexor

    • Posterior is extensor

  • Lower Limbs:

    • Anterior is extensor

    • Posterior is flexor

Key Muscle Groups and Examples

• Psoas Major: Known for strength; critical for maintaining posture.

  • In animal models (e.g., cows), it is softer due to lack of load-bearing.

  • Example: Its relation to the filet mignon in cuisine.

• Quadriceps: Largest muscle group in the body.

  • Composed of:

    • Rectus Femoris

    • Vastus Medialis

    • Vastus Lateralis

  • Functions include extension of the knee.

• Gastrocnemius: Important for locomotion and its name derives from its relation to digestive treatment in some cultures.

  • Calcaneus Tendon: Important attachment to heel bone, critical for walking mechanics.

Muscle Physiology

• Muscle Contraction:

  • Involves interactions between actin and myosin filaments.

  • Mechanism described as the sliding filament theory.

Muscle Fiber Types

• Identification of muscle types based on function, location, and control:

  • Voluntary muscles: Skeletal muscles controlled by conscious thought.

  • Involuntary muscles: Smooth and cardiac muscles unconsciously controlled.

Questions & Review

• Concept checks were included in teaching:

  • e.g., Muscle types, functions of different muscle groups, and specific muscle anatomy.

Questions from the Assessment

1. True/False: Wrapping muscle as a type of parallel muscle (True).

2. Multiple Choice: Circular muscles include sphincters and open/close body entrances (All answers correct).

3. Identify Action: Biceps Brachii for elbow flexion and shoulder stabilization is true.

4. Muscle Isolation: Agonist-antagonist muscle relationships in arm movement discussed, emphasizing flexor and extensor roles.

5. Skeletal Muscle Structure:

   • Questions regarding muscle fibers and their connective tissue layers such as epimysium, perimysium, and endomysium.

Changes with Aging in Musculature

• Skeletal muscle fibers decrease in diameter, elasticity, and exercise tolerance with age.

Miscellaneous Remarks

• Cultural implications of musculature discussed, such as in cases of severe injury affecting mobility in certain cultures.

  • Emphasis on understanding muscle functions in a practical context through anecdotal evidence.

Conclusion

• Study the interactive role of muscles and tendons in relation to movements, injuries, and anatomical structure to better understand their functionalities during physical activity.

• Preparation for future assessments includes careful review of functional anatomy and muscular systems, ensuring a robust understanding of both theoretical and applied kinesiology principles.

Overview of Axial and Appendicular Skeleton

• The human skeleton is divided into two major functional parts: the axial skeleton and the appendicular skeleton.

• This section will focus on the appendicular skeleton, its functional aspects, and muscle coordination.

  • Special emphasis is placed on the pectoral and pelvic girdles, which serve as critical connections for the limbs to the axial skeleton.

Appendicular Skeleton

• Definition: The appendicular skeleton comprises the parts of the skeleton that support the body's appendages, including the upper and lower limbs.

• It is primarily concerned with locomotion and the manipulation of objects.

• Two main divisions:

  • Muscles of the shoulder and upper limbs: These muscles facilitate a wide range of movements, from fine motor skills of the fingers to powerful movements of the arm.

  • Muscles of the pelvis and lower limbs: These muscles are essential for bearing weight, maintaining posture, and enabling locomotion.

Function of the Appendicular Skeleton

• The primary function involves the precise positioning and stabilization of the pelvic and pectoral girdles.

  • The pectoral girdle (clavicle and scapula) provides a highly mobile but less stable attachment for the upper limbs.

  • The pelvic girdle (hip bones, sacrum, and coccyx) offers a strong, stable base for the lower limbs, crucial for transmitting weight to the legs.

• This structural arrangement allows for extensive movement of the upper and lower limbs, enabling complex actions such as grasping, walking, and running.

Muscle Groups in the Upper Limbs

• The upper limb muscles can be categorized into four functional groups:

  • Muscles that position the pectoral girdle: Such as the trapezius and serratus anterior, which elevate, depress, protract, and retract the scapula, thereby affecting the shoulder's position.

  • Muscles that move the arm: Including the deltoid, pectoralis major, and latissimus dorsi, responsible for flexion, extension, abduction, and adduction of the humerus.

  • Muscles that move the forearm and hand: Examples include the biceps brachii and triceps brachii for elbow movement, and muscles in the forearm that control wrist and finger movements.

  • Muscles that move the fingers: Located primarily in the forearm (extrinsic) and within the hand (intrinsic), allowing for precise manipulation and grasping.

Important Muscle Actions

• Flexors* vs. *Extensors: These terms refer to opposing muscle actions around a joint.

  • Flexion generally decreases the angle between two body parts.

  • Extension generally increases the angle between two body parts.

  • Anterior Muscles: In the upper limbs, muscles located on the anterior (front) side of a limb typically act as flexors.

    • Example: The Biceps Brachii muscle, located on the anterior arm, is a primary elbow flexor.

  • Posterior Muscles: In the upper limbs, muscles located on the posterior (back) side of a limb typically act as extensors.

    • Example: The Triceps Brachii muscle, located on the posterior arm, is a primary elbow extensor.

• The anterior and posterior muscles often act as agonists and antagonists in opposing pairs:

  • Agonist (Prime Mover): The muscle primarily responsible for a specific movement.

  • Antagonist: The muscle that opposes the action of the agonist, often relaxing to allow the movement or providing controlled resistance.

  • Example: During elbow flexion, the Biceps Brachii acts as the agonist, while the Triceps Brachii acts as the antagonist.

Muscle and Tendon Characteristics

• Tendon Behavior: A crucial anatomical feature is that many muscles of the forearm, which control hand and finger movements, do not cross directly into the hand as muscle belly; instead, their force is transmitted via long, strong tendons.

  • These tendons extend through the wrist and into the hand and fingers.

  • This arrangement allows for smaller muscle bellies in the hand, facilitating dexterity, and more powerful muscles in the forearm.

  • This is important for repair and understanding of injuries: Tendons, being fibrous connective tissue, can be reattached surgically, which aids in restoring functionality after severance or damage.

• Similarities in Upper Limbs and Lower Limbs:

  • While structurally similar, the arrangement of flexors and extensors is inverted between the upper and lower limbs, reflecting their different primary functions (manipulation vs. locomotion and weight-bearing).

  • Upper Limbs (e.g., arm):

    • Anterior compartment muscles are primarily flexors (e.g., Biceps Brachii for elbow flexion).

    • Posterior compartment muscles are primarily extensors (e.g., Triceps Brachii for elbow extension).

  • Lower Limbs (e.g., thigh):

    • Anterior compartment muscles are primarily extensors (e.g., Quadriceps Femoris for knee extension).

    • Posterior compartment muscles are primarily flexors (e.g., Hamstrings for knee flexion).

Key Muscle Groups and Examples

• Psoas Major: Part of the iliopsoas group, it originates from the lumbar vertebrae and inserts into the lesser trochanter of the femur.

  • Known for its strength and deep location; it is critical for maintaining posture, flexing the trunk, and hip flexion.

  • In animal models (e.g., cows), the psoas major, being largely non-weight-bearing in a quadrupedal stance compared to its human equivalent, tends to be softer and more tender.

  • Example: Its relation to the filet mignon in cuisine, which comes from the tenderloin, a cut directly corresponding to the psoas major due to its relatively low workload.

• Quadriceps Femoris: The largest and most powerful muscle group in the body, forming the bulk of the anterior thigh.

  • Composed of four distinct muscles:

    • Rectus Femoris: Originates from the ilium; unique among the quadriceps for crossing both the hip and knee joints, allowing it to flex the hip in addition to extending the knee.

    • Vastus Medialis: Originates from the medial aspect of the femur.

    • Vastus Lateralis: Originates from the lateral aspect of the femur.

    • Vastus Intermedius: Lies deep to the rectus femoris, originating from the anterior aspect of the femur.

  • Functions: Primarily responsible for powerful extension of the knee, essential for walking, running, jumping, and stability.

• Gastrocnemius: A superficial, two-headed muscle of the posterior leg, forming part of the triceps surae group.

  • Originates from the femoral condyles and inserts via the calcaneal tendon into the calcaneus (heel bone).

  • Important for powerful locomotion, primarily plantarflexion of the foot (pointing toes down) and also assists in knee flexion.

  • Its name derives from the Greek for