Muscles Of The Body: Types, Groups, Anatomy & Functions

Muscles Of The Body: Types, Groups, Anatomy & Functions

What are the properties of the muscles?

Answer. The properties of muscles are as follows:

• Irritability, i.e. they are sensitive to stimuli.
• Contractility, i.e. they contract in response to stimuli.
• Extensibility, i.e. they can stretch.
• Elasticity, i.e. they can assume a desired shape after being stretched.

“Importance Of Muscles For Movement And Posture”

Compare and contrast three types of muscles – skeletal, cardiac and smooth.

Comparison and Contrast Between Skeletal, Cardiac and Smooth Muscles

Classify the various types of muscles according to their shape and direction of their muscle fibres.

• When the direction of muscle fibres is parallel to each other, i.e. in line of pull
  • Strap muscles: These muscles are like long ribbons. Examples: Sternohyoid, sternothyroid and sartorius.
  • Fusiform muscles: These muscles are spindle shaped. Examples: Biceps femoris and biceps brachii.
  • Quadrilateral/quadrate muscles: These muscles are square shaped. Examples: Pronator quadratus and thyrohyoid.
  • Flat muscles: These muscles are in the form of thin sheets of fleshy fibres. Examples: Muscles of anterior abdominal wall such as external oblique, internal oblique, and transversus abdominis.
• When the direction of muscle fibres is oblique to line of pull
  • Triangular, e.g. temporalis and adductor longus.
  • Pennate (feather-like):
    • Unipennate, e.g. extensor digitorum longus, flexor pollicis longus, palmar and plantar interossei.
    • Bipennate, e.g. rectus femoris, dorsal interossei and flexor hallucis longus.

Read And Learn More: Selective Anatomy Notes And Question And Answers

• • • Multipennate, e.g. deltoid (acromial part) and subscapularis.
    • Circumpennate, e.g. tibialis anterior.
• When the direction of muscle fibres is circular, i.e. they are arranged circularly around the orifice, e.g. orbicularis oris and orbicularis oculi.
• When the muscle fibres are arranged in a twisted manner, e.g. trapezius, pectoralis major and latissimus dorsi.
• When the muscle fibres are arranged in two planes in different directions and cross, these are called cruciate muscles, e.g. masseter, sternocleidomastoid and adductor magnus.

“Functions Of Skeletal, Smooth, And Cardiac Muscles”

Enumerate the parts of a typical skeletal muscle.

These are given in the following flowchart:

“Comprehensive Overview Of Muscle Groups And Their Significance”

Muscles Of The Body: Types, Groups, Anatomy & Functions

What are the types of muscles according to their action?
Answer. A single muscle or a group of muscles alone cannot produce a desired movement at a particular joint.

Any particular movement of a joint is brought about by a group of muscles, while the whole range of any movement is brought about by the smooth coordinated actions of different groups of muscles. These groups of muscles are as follows:

• Prime movers (agonists): These are the muscles that initiate and bring about a desired movement. They are responsible for the specific movements. Examples: Biceps brachii and brachialis are prime movers to cause flexion at elbow joint.
• Antagonists: These are the muscles that have opposite action to that of prime movers, i.e. they oppose prime movers or initiate and maintain a movement converse to that produced by agonists. Examples: Triceps brachii, which acts as antagonist during flexion of the elbow joint but helps in smooth flexion of the elbow joint by gradually relaxing itself.

“The Role Of Skeletal Muscles In Maintaining Posture”

• Fixators: These are the muscles that stabilize the proximal joint/joints of a limb to provide a fixed base for the agonist muscle (prime mover) to act on a distal joint to bring about a desired movement.
• Synergists: These muscles help the prime movers in bringing out the desired movement. They eliminate the undesired actions at proximal joint when the prime movers cross two or more joints. Examples: While making a tight fist, extensors of the wrist act as synergists to long flexor tendons.