Muscular System Notes
Types of Muscles
Skeletal: Found on bones.
Cardiac: Found only in the heart.
Smooth: Found in internal organs and blood vessels.
Sphincter: Special circular muscles that open and close to allow the passage of substances.
Muscle Control
Voluntary Muscles: Contract when you actively think about using them.
Involuntary Muscles: Work without actively thinking about using them.
Challenge: Which muscles may be both voluntary and involuntary?
Characteristics of Muscles
Contractibility: Allows muscle tissue to pull or shorten.
Excitability: Able to respond to a stimulus.
Extensibility: Ability to stretch or extend.
Elasticity: Able to return to its original state.
Muscle Tone: Amount of tension or resistance a muscle generates during movement.
Tendons
Definition: Fibrous tissue that extends off a muscle or muscle group and allows a muscle to attach and connect to bone.
Challenge: What is the name of the tendon that connects the muscle to the calcaneous bone of the heel?
Muscles - Anterior and Posterior
Anterior Muscles:
Deltoid
Rotator Cuff
Pectoralis Major
Rectus Abdominis
Abdominal External Oblique
Iliopsoas
Biceps Brachii
Brachialis
Brachioradialis
Pronator Teres
Brachioradialis
Latissimus Dorsi
Quadriceps Femoris
Adductor Muscles
Peroneus Longus
Tibialis Anterior
Peroneus Brevis
Posterior Muscles:
Trapezius
Deltoid
Levator Scapulae
Rhomboids
Rotator Cuff
Triceps Brachii
Biceps Femoris
Semitendinosus
Gluteus Maximus
Tibialis Posterior
Semimembranosus
Gastrocnemius
Peroneus Longus
Peroneus Brevis
Soleus
Muscles of the Head and Neck
Frontalis: Moves eyebrows up and wrinkles the forehead.
Masseter: Chewing muscle of the jaw.
Orbicular Oculi: Closes the eyelids.
Orbicular Oris: Encircles the mouth.
Temporalis: Chewing muscle of the upper jaw that covers the temporal bone.
Zygomaticus Major: Smiling muscle.
Sternocleidomastoid: Rotates the head and flexes the neck.
Muscles of the Torso/Trunk
External Intercostals: Located between the ribs. Assist the lungs by raising the ribcage.
Diaphragm: Thin muscle that separates the thoracic and abdominal cavities. Contracts when you inhale, relaxes when you exhale.
Rectus Abdominus: Long, thin muscle. The "six pack" abs. Helps flex the waist abdomen.
External Oblique: Located on each side of the waist. Contracts to flex your trunk to the side.
Internal Oblique: Located on each side of the waist, below the external obliques. Assists with twisting the trunk and respiration.
Latissimus Dorsi: Lower back muscle. Largest muscle in the upper body. Works opposite of the rectus abdominus to stabilize the core and extend the waist.
Muscles of the Upper Extremities
Trapezius: Upper back - supports the arm and scapula stabilization. Helps to adduct the shoulder.
Deltoid: Helps lift (abduct) the upper arm.
Pectoralis Major: Chest muscles, assist with arm movements and motion (horizontal shoulder flexion when doing a push-up).
Biceps Brachi: Anterior upper arm, flexes the elbow toward the forearm.
Triceps Brachi: Posterior upper arm. Extends the elbow.
Brachioradialis: Anterior lower arm, flexes the wrist toward the forearm.
Muscles of the Anterior Lower Extremities
Quadriceps: Major muscle group on the anterior femur. Crosses 2 joints, enabling both hip flexion and knee extension.
Rectus Femoris: Long thin muscle on the femur. Part of the quads. Helps with knee extension and hip flexion.
Sartorius: Longest muscle in the human body. Runs from the hip, across the thigh to the medial knee. Crossing your legs (hip adduction) is one function.
Tibialis Anterior: On the (anterior) front side of the tibia. Dorsiflexes the ankle. When contracted allows the toes to come up towards the shin.
Quadriceps Components
The quads are made up of the rectus femoris, the vastus lateralis, the vastus intermedius, and the vastus medialis.
Muscles of the Posterior Lower Extremities
Vastus Medialis: Medial hamstring muscle that helps to adduct the hip. When contracted, the thigh moves closer to the body’s midline.
Biceps Femoris: Major middle hamstring muscle that is on the posterior femur. Crosses 2 joints, enabling both knee flexion and hip extension.
Vastus Lateralis: Hamstring muscle on the outer side of the thigh. Helps to extend the knee and abducts the hip. When contracted, the thigh will move away from the midline of the body.
Gluteus Maximus: Buttocks. Helps with several hip movements, especially hip extension.
Gastrocnemius: Commonly referred to as the calf muscle. Works with the soleus to plantarflex the ankle when you raise up on your toes.
Soleus: Lies just below the gastrocnemius. Both the gastrocnemius and soleus insert on the heel bone and contract whenever the foot plants during running or walking.
Muscle Conditions
Atrophy: Wasting away of muscle, usually due to not being used.
Hypertrophy: Growth and development of muscle.
Muscle Fatigue: Inability to generate force, muscle exhaustion.
Functions of the Muscular System
Connects to the skeletal system to generate movement.
Maintain proper posture, trunk/core stability.
Muscle movement helps the body to generate body heat.
Smooth muscle aids the digestive system to help churn and push food along the digestive tract.
Cardiac muscle of the heart contracts to allow the heart to pump blood throughout the body.
Disorders of Muscular System
Fibromyalgia:
Muscle pain
Fatigue
Sleep disorders
Memory loss
Mood swings
Mostly affects women.
May be triggered after trauma, surgery, infection, or stress.
No cure, treat the symptoms.
Hernia:
Intestinal organ pushes through an opening in the muscle lining.
Many occur in abdomen or in groin area.
Most are not life-threatening but may need surgical repair.
Symptoms: bulge or lump in the affected area that disappears when lying down.
Muscle Spasms:
Sudden involuntary contraction of a muscle.
May be caused by overuse of the muscle, dehydration, or electrolyte imbalance.
Symptoms: Pain.
Treatment: Usually resolves on its own. Stretching and massaging the muscle. Apply ice to ease pain. Rehydrate.
Muscular Dystrophy:
A group of diseases that cause progressive weakness and loss of muscle mass. Many different kinds. Mostly affects boys.
Symptoms: Frequent falls, difficulty rising from a sitting position, muscle pain and stiffness.
No cure. Treat the symptoms with medications and therapy.
Muscle Strain:
Tear to the muscle fibers or tendon.
Symptoms: Swelling, bruising, pain, weakness of muscle, or inability to use it at all.
Treatment: RICE (Rest, Ice, Compression, Elevation), Nonsteroidal anti-inflammatory drugs (NSAIDs), e.g., Ibuprofen.
Tendonitis:
Inflammation of the tendons.
Caused by overuse or overload of tendon. Shoulder is most common, followed by elbow.
Symptoms: Dull aching pain that may worsen at night in the affected area.
Treatment: Rest, Ice, NSAIDs, splints, or braces to restrict overuse movement.
Tetanus:
Commonly known as “Lockjaw”.
Can interfere with breathing.
Serious illness caused by Clostridium bacteria. Bacteria can enter the body through a deep cut.
Symptoms: Painful tightening of the muscles, usually all over the body.
Treatment: Managing the complications.
Prevention: Tetanus vaccine with booster shot every 10 years.