1. THE MUSCULAR SYSTEM
Dr Idara

2. Muscular System Muscles are responsible for all types of body movement
3 basic muscle types are found in the body. They are:
Skeletal muscle
Cardiac muscle
Smooth muscle

3. Characteristics of Muscles
Muscle cells are elongated (muscle cell = muscle fiber)
Contraction of muscles is due to the movement of microfilaments
All muscles share some terminology
Prefix myo refers to muscle
Prefix mys refers to muscle
Prefix sarco refers to flesh

4. Muscle histology (cont.)
Scaterred throughout the sarcoplasm is the sarcoplasmic reticulum
It stores Calcium ions
The sarcoplasm contains myoglobin
Red pigmented protein related to Hemoglobin that carries oxygen
Along entire length are myofibrils
Myofibrils made of protein filaments
Come in thick and thin filaments

5. Comparison of Types of Muscle

6. Types of Muscle, cont

7. Skeletal Muscle Characteristics
Most attach to bones by tendon
Cells are multinucleate
Striated—have visible binding
Voluntary
Cells surrounded & bundled by connective tissue

8. Smooth Muscle Characteristics
Picture sub A
Has no striations
Spindle-shaped cells
Single Nucleus
Involuntary—no conscious control
Found mainly in the walls of hollow organs

9. Characteristics of Cardiac Muscle
Picture sub B
Has striations
Usually has a single nucleus
Joined to another cardiac muscle cell
Involuntary
Found only in the heart

10. Functions of Skeletal Muscle Produce Movement Maintain posture
Stabilize joints
Generate Heat
Sites of Muscle Attachment
Bones
Cartilage
Connective tissue coverings
Muscle Fibers blend into a connective tissue attachment
Tendon—cordlike structure
Aponeurosis—sheet-like structure
Properties of Muscle
Irritability – ability to receive and respond to a stimulus
Contractibility – ability to shorten when an adequate stimulus is received
Extensibility – ability to lengthen when an adequate stimulus is received
Elasticity – ability to return to normal shape

11. To Note: A muscle cell is also called a muscle Fiber
A discrete bundle of muscle cells is called a Fascicle
The thin connective tissue that surrounds each muscle cell is called Endomysium
The connective tissue that surrounds each Fascicle is called Perimysium
The connective tissue surrounding the entire muscle is called Epimysium

12. Anatomy of a Muscle Cell

13. Naming Skeletal Muscles

14. Direction of Muscle Fibers

15. Location Structure near which muscle is found
FRONTALIS = near FRONTAL bone
OCCIPITALIS = near OCCIPITAL bone

16. Size Relative Size of Muscle and location MAXIMUS = largest
Gluteus Maximus
MEDIUS = middle
Gluteus Medius
MINIMUS = smallest
Gluteus Minimus
LONGUS = longest
Fibularis Longus
BREVIS = short
Fibularis Brevis
TERTIUS = shortest
Fibularis Tertius

17. Number of Origins Number of tendons of origin BICEPS = Two
Biceps Brachii
Biceps Femoris
TRICEPS = Three
Triceps Brachii
QUADRICEPS = Four
Quadriceps Femoris

18. Shape Relative Shape of the Muscle DELTOID = triangular shape Δ
TRAPEZIUS = trapezoid shape 
SERRATUS = saw-toothed ♒
RHOMBOIDEUS = rhomboid shape 
TERES = round ○

21. Origin & Insertion Origin – attachment to an immoveable bone
Insertion – attachment to a movable bone
ILIO COSTALIS= attaches to the ilium & ribs (costal = ribs)

22. Types of Muscle--Actions
Prime mover (Agonist) – muscle with the major responsibility for a certain movement
Antagonist – muscle that opposes or reverses a prime mover
Synergist – muscle that aids a prime mover in a movement and helps prevent rotation
Fixator – stabilizes the origin of a prime mover

23. Head & Neck Muscles

24. Key Muscles of Facial Expression
Smiling Muscles
Orbicularis Oculi
Nasalis
Levator Labii Superioris
Levator Anguli Superioris
Zygomaticus
Risorius
Frowning Muscles
Frontalis
Orbicularis Oris
Depressor Anguli Oris
Depressor Labii Inferioris
Mentalis
Platysma

26. Frontalis - Used in frowning Orbicularis Oculi – Surrounds the eye, eyelid and orbit. Used to close the eyes Zygomaticus - Used in smiling Buccinator- A flat muscle of the cheek, draws in the cheek and puffs up the cheeks. Called the Trumpeter’s Muscle.
Orbicularis Oris- surrounds the mouth, closes the lips when contracted and used for whistling and kissing. Masseter- Is the Prime mover for jaw closure. Also used for chewing. Temporalis - is the synergist for jaw closure and assists with chewing.

27. Muscles of the Axial Skeleton

28. Muscles of the Axial Skeleton
Intrinsic Muscles
Erector Spinae: maintain posture of back/extension
Spinalis
Longissimus
Iliocostalis
Oblique Muscles: rotation of the vertebrae
Semispinalis
Multifidus
Rotatores
Muscles of Quiet Respiration
Diaphragm
External Intercostals
Internal Intercostals—deep breaths
Abdominal Muscles
External Obliques
Internal Obliques
Transverse Abdominus
Rectus Abdominus
Quadratus Lumborum – Fixes the lower rib during respiration and cause lateral flexion of the vertebral column.

30. Diseases and Disorders of the Muscular System
Cerebral Palsy: This disorder is characterized by paralysis and or weakened muscles due to loss of muscle tone.
It can be caused due to lack of oxygen to the region of the motor region of the cerebrum of the brain which controls conscious control of muscles.
This is often attributed to complication during birth.

31. Others
Myalgia: Muscle pain due to strain, tearing of muscle fibers. It also is a symptom of an immune response along with a fever.
Myositis: Inflammation of muscle tissue due to injury or disease.
Charley Horse (fibromyositis): Inflamation of muscle tissue and the tendons associated with that muscle due to injury (tear or severe bruising- contusion).
Cramps: Painful, involuntary muscle contraction, typically caused by fatigue or strain.

32. Muscular Dystrophy
A Series of genetic disorders characterized by the atrophy or wasting away of skeletal muscle.
Duchenne Muscular Dystrophy is the most common and affects primarily males.
X- linked recessive mutation i.e. mother’s transmit disease to their sons.
Onset before 5 years of age.
Deletion of the dystrophin gene

35. Becker’s Muscular Dystrophy
Onset in adolesence or early adulthood. Mutated dystrophin gene