1. Muscular System Functions

2. Muscle Tissue Refers to all the contractile tissues of the body. Refers to all the contractile tissues of the body. Skeletal=attached to skeleton. Skeletal=attached to skeleton. Cardiac= heart muscles Cardiac= heart muscles Smooth= muscles of organs Smooth= muscles of organs

3. Smooth Muscle Cells are small spindle shaped Cells are small spindle shaped Non-striated (striations are dark lines of tissue ) Non-striated (striations are dark lines of tissue ) Involuntary muscle Involuntary muscle Found in organ groups..Example: intestinal, bladder, blood vessels. Found in organ groups..Example: intestinal, bladder, blood vessels. Muscle contractions are rhythmic and slow. Muscle contractions are rhythmic and slow.

4. Cardiac Muscle Requires continuous O2 Requires continuous O2 Only in the heart Only in the heart Striated Striated Involuntary Involuntary Muscle contractions are rhythmic & automatic Muscle contractions are rhythmic & automatic

5. Skeletal Muscle Attached to the bones of skeleton Attached to the bones of skeleton Voluntary muscle…contains nerves under voluntary control Voluntary muscle…contains nerves under voluntary control Composed of bundles of muscle cells Composed of bundles of muscle cells –Each cell is Multinucleated. –Each cell is a muscle fiber –Cell membrane=SARCOLEMMA –Cytoplasm=SARCOPLASM

6. Characteristics…. Contractibility: muscles shorten and tighten…which in turn, brings the two ends of the bone closer together..which is movement.. Contractibility: muscles shorten and tighten…which in turn, brings the two ends of the bone closer together..which is movement..

7. Characteristics…cont’ Excitability: or irritability.. The ability to respond to certain stimuli..producing signals called action potentials= impulses..(nerve impulses) Excitability: or irritability.. The ability to respond to certain stimuli..producing signals called action potentials= impulses..(nerve impulses) Extensibility: The ability of the muscle to be stretched. Extensibility: The ability of the muscle to be stretched.

8. Characteristics…cont’ Elasticity: The ability for a muscle to return to its original shape when relaxing. Elasticity: The ability for a muscle to return to its original shape when relaxing.

9. Attachments….. –Origin: point where muscle is attached to bone that moves very little –Insertion: point where muscle is attached to bone that moves. –Belly: central part of the muscle

10. Contraction of Skeletal Muscle Movement occurs as a result of 2 major events: Movement occurs as a result of 2 major events: Nerve stimulation : message sent thru nerves to the muscle.. Nerve stimulation : message sent thru nerves to the muscle.. Action potential: the muscle receives the stimuli, and contracts as a result. Action potential: the muscle receives the stimuli, and contracts as a result.

11. Muscle Groups Head and Neck Head and Neck Upper Extremities Upper Extremities Trunk Trunk –Thorax & Abdomen –Posterior & Anterior Lower extremities Lower extremities

12. Major Muscles of the Head & Neck….. Temporalis: at the temple Temporalis: at the temple Frontalis: forehead Frontalis: forehead Masseter: cheek Masseter: cheek Orbicularis oculi: around the eye Orbicularis oculi: around the eye Sternocleidomastoid: Behind the ear to the clavicle Sternocleidomastoid: Behind the ear to the clavicle Trapezius: Back of the head (occipital) to the shoulder. Trapezius: Back of the head (occipital) to the shoulder. Orbicularis oris: around the mouth Orbicularis oris: around the mouth Zygomaticus major: cheekbone to orbicularis oris Zygomaticus major: cheekbone to orbicularis oris Nasalis: muscles of the nose Nasalis: muscles of the nose

13. Intercostals

14. More to come…..