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Introduction to Muscle Anatomy
Types of Muscle 1. Skeletal
– Elongated Cells – Multi nucleated – Striated – striped
appearance – Voluntary – Produces powerful
contractions – Tires easily, needs rest
(fatigue). – Covers bony skeleton
(motility) Cross Section
Notice nuclei around outside of cell.
Longitudinal View
Notice striations and nuclei around outside of cell.
Skeletal Muscle Composite Sketch
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2. Smooth – Spindle-shaped Cell – Single nucleus in each
cell – No Striations – Involuntary – Slow, sustained
contractions – In hollow visceral
organs (stomach, bladder, respiratory passages)
Cross Section Nucleus is in center of cell. Cells much smaller.
Smooth Muscle Composite Sketch
3. Cardiac (Heart) – Branched cell – Contain intercalated
discs – Single nucleus in each
cell – Striations – Involuntary – Steady, constant
contractions – Never tires
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Cardiac Muscle Composite Sketch
Muscle Functions • Produce movement
– locomotion & manipulation – Help blood move through veins & food
thru small intestines • Maintain posture • Stabilize joints • Body temp homeostasis
– Shivering: movement produces heat energy
Muscle Requirements
• Demands continuous oxygen/nutrient supply. – Lots of arteries/capillaries to muscle.
• Each muscle cell w/ its own nerve ending controlling its activity.
• Produce much metabolic waste due to constant activity.
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Muscle Requirements
• Demands continuous oxygen/nutrient supply. – Lots of arteries/capillaries to muscle.
• Each muscle cell w/ its own nerve ending controlling its activity.
• Produce much metabolic waste due to constant activity.
Motor end plate (terminus)
Axon of neuron
Muscle Attachments • Most muscles span joints • Attaches to bone in two places: (video)
1. Insertion: the moveable bone • Bicep insertion is the radius
2. Origin: the stationary bone • bicep originates in two different places in scapula
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Muscle Attachments • Attachment types
1. Direct: attaches right onto bone - ex. intercostal muscles of ribs
Muscle Attachments • Attachment types
1. 2. Indirect: via tendon or aponeurosis (sheet-like
tendon) to connect to bone - leaves bone markings such as tubercle
Agonist vs. Antagonist
• If you do a bicep curl, how do you re-straighten your arm?
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