Basic of Muscles by Hetu (MSc. Medical Biochemistry)

Muscles

•  Muscles is a contractile tissue which brings about movements.
• Muscles can be regarded as motors of the body.

Derivation of Name Muscles (L. Mus = mouse) are so named because, many of them resemble a mouse, with their tendons representing the tail. 

 

Types of muscles

The muscles are of three types, skeletal, smooth and cardiac. 

(A) Striated muscles/ Skeletal muscles :-

• Striated muscles are present in the limbs, body wall, tongue, pharynx, and beginning of oesophagus.
• 
  Long and cylindrical.
• Fibres and unbranched.
• Multinucleated.
• Bounded by sarcolemma.
• Light and dark bands present.
• No intercalated disc.
• Nerve supply from cranial nervous system.
• Blood supply is abundant.
• Very rapid contraction.
• They soon get fatigued.
• Voluntary.
  

(B) Non- Striated muscles/ Smooth muscles :-

• Oesophagus (Distal part), urogenital tract, urinary bladder, blood vessels, iris of eye, arrector pilli muscles of hair.
• Spindle shaped.
• Fibre unbranched.
• Uninucleated.
• Bounded by Plasmalemma.
• Light and dark bands absent.
• No intercalated discs.
• Nerve supply from autonomic nervous system.
• Blood supply is scanty.
• Slow contraction.
• They don't get fatigued.
• Involuntary.

                            

(C) Cardiac muscles :-

• 
  Wall of heart.
• Short and cylindrical.
• Fibres branched.
• Uninucleated.
• Bounded by plasmalemma.
• Faint light and dark bands present.
• Intercalated disc present and a characteristic feature.
  
• Nerve supply from autonomic nervous system.
• Blood supply is abundant.
• Rapid contractions.
• They never get fatigued.
• Involuntary