ANAT - M3: S1: Types of Muscles

Skeletal muscles

help human body move, most are attached to bones via tendons.

Appearance: (striated) (multinucleated) (long cylindrical/rod)  

Location: attached to bone acts as a lever  

Regulation: voluntary  

Cardiac muscles

found in the heart, contracts rhythmically, and is modulated by neural activity and hormones.  

Appearance: (striated) (uni/binucleated) (branching) 

Location: heart  

Regulation: Involuntary 

Smooth muscles

controlled by the nervous system or hormones, may be either generally inactive and then respond to stimulation or could be rhythmic.  

Appearance: (Smooth) (uninucleated) (Fusiform) 

Location: walls of hollow organ and blood vessels 

Regulation: Involuntary 

Morphological Characterization

Striated & Smooth

Striated

marked by both light and dark bands (striations). It can be found in the heart and skeletal muscles. Contains long muscle fibres (cells) with multiple nuclei which are located peripherally for skeletal muscle or centrally for cardiac muscle. 

Smooth

found in blood vessels, digestive system, and other viscera. Each smooth muscle fibre (cell) contains a single centrally located nucleus. Smooth muscle has fusiform-shaped (Spindle-like) cells without striations. 

Functional Characterization

Voluntary & Involuntary

Voluntary muscles

is muscle that is consciously controlled in order to perform a specific function. (the muscles that move the skeleton (skeletal muscles) for walking, reaching, talking, etc.)

Involuntary muscles

not consciously controlled. Involuntary muscle consists of smooth muscle and cardiac muscle. ( intestines (smooth) and the heart (cardiac)) 

How muscles function: Excitability:

The ability of muscle tissue to receive and respond to electrical signals from nerves or stimulation from hormones.  

How muscles function: Contractility

When a muscle cell is excited by a nerve or hormone, this causes the muscle to shorten, resulting in contraction. 

what kind of muscle is this?

striated

Cardiac muscle also features intercalated discs.

Intercalated discs: Unique to cardiac muscle, intercalated discs connect heart muscle cells to each other.