Muscle Functions and Naming Criteria

Study Notes

Muscle Functions

Muscles can only contract, they cannot expand.
Prime movers (agonists): muscles primarily responsible for a particular motion.
Antagonists: muscles opposing a movement, providing resistance and delicate motion.
Synergists: muscles assisting prime movers, contributing force or reducing undesirable movements.
Fixators: synergists that immobilize bones, maintaining posture.

Muscle Naming Criteria

Location: example, temporalis muscle is located near the temporal bone.
Shape: example, the trapezius muscles are shaped like a trapezoid
Size: examples, maximus (large), minimus (small), longus (long), brevis (short)
Direction of muscle fibers:
- Rectus: muscle fibers run parallel to a line (e.g., rectus femoris parallel to femur).
- Transversus: muscle fibers run perpendicular to a line.
- Oblique: muscle fibers run at an angle.
Number of origins: biceps (2), triceps (3), quadriceps (4).
Attachment points: describes origins and insertions (example: sternocleidomastoid muscle originates at sternum and clavicle, inserts at mastoid process).
Motion produced: flexor, extensor, adductor.

Muscle Shapes

Circular: fascicles in concentric rings, like muscles around eyes and mouth.
Convergent: fascicles spread out and converge towards a tendon, like the pectorals.
Fusiform: tapered at both ends with a tendon at each, like the biceps.
Parallel: fascicles run parallel to the long axis, like the sartorius muscle.
Pennate: short fascicles at oblique angles.
- Unipennate: fascicles on one side of a tendon.
- Bipennate: fascicles on both sides of a tendon.
- Multipennate: multiple feathers inserted into the same tendon.

Major Muscles

While hundreds of muscles exist, the text suggests focusing on a few major ones.
Use screenshots for reference.
More detailed study will come later for those entering the medical field.

Muscle Functions

Muscles can only contract, they cannot expand.
Prime movers (agonists) are the muscles primarily responsible for a particular motion.
Antagonists oppose a movement, providing resistance and delicate motion.
Synergists assist prime movers, contributing force or reducing undesirable movements.
Fixators immobilize bones and maintain posture.

Muscle Naming Criteria

Location: Muscle names often indicate their location, such as temporalis (near the temporal bone).
Shape: The shape of a muscle can be reflected in its name, like trapezius muscles which are shaped like a trapezoid.
Size: Terms like maximus (large), minimus (small), longus (long), and brevis (short) indicate muscle size.
Direction of muscle fibers:
- Rectus: Muscle fibers run parallel to a line, like rectus femoris being parallel with the femur.
- Transversus: Muscle fibers run perpendicular to a line.
- Oblique: Muscle fibers run at an angle.
Number of origins: Muscle names often specify the number of origins, like biceps (2), triceps (3), and quadriceps (4).
Attachment points: This includes the points of origin and insertion, like sternocleidomastoid originates at sternum and clavicle and inserts at mastoid process.
Motion produced: The motion a muscle produces is often part of the name, like flexor, extensor, and adductor.

Muscle Shapes

Circular: These muscles have fascicles arranged in concentric rings, seen around the eyes and mouth.
Convergent: Fascicles spread out and converge towards a tendon, like the pectoralis muscles.
Fusiform: These muscles are tapered at both ends with a tendon at each, like the biceps.
Parallel: Parallel muscles have fascicles running parallel to the long axis, like the sartorius muscle.
Pennate: Pennate muscles have short fascicles at oblique angles.
- Unipennate: Fascicles are on one side of a tendon.
- Bipennate: Fascicles are on both sides of a tendon.
- Multipennate: Multiple feathers are inserted into the same tendon.

Major Muscles

Hundreds of muscles exist, but the text focuses on a few major ones.
Refer to screenshots for a visual representation of major muscles.
More detailed study of muscles will be covered later for those entering the medical field.

Description

Explore the essential functions of muscles, including prime movers, antagonists, synergists, and fixators. Learn the criteria used in naming muscles, such as location, shape, size, and the direction of muscle fibers. Test your knowledge with relevant questions that cover these fundamental concepts.