MUSCULAR SYSTEM for nursing students .pptx

Anatomy of the muscular system

1. MUSCULAR SYSTEM MR. WUYEH HYDARA

2. MUSCULAR SYSTEM When most of us hear the word “muscle,” we think of the muscles that move the skeleton. These muscles are considered organs because they are composed not only of muscle tissue, but also of epithelial, connective, and nervous tissue. Over 700 skeletal muscles have been named and together they form the MUSCULAR SYSTEM. However, skeletal muscles are not the only places where muscle tissue is found.

3. PROPERTIES OF MUSCLE TISSUES Excitability. Excitability is equated with responsiveness. In other words, muscle cells are very responsive to input from stimuli. When a muscle cell is stimulated by the nervous system, by stretching, or by other stimuli in the environment, it responds by initiating electrical changes that sweep across its entire plasma membrane and spark internal events leading to muscle contraction. Contractility. Stimulation of muscle cells generates tension within the cell (contraction), which may cause the cell to shorten. This shortening results in either a pull on bones of the skeleton or the movement of specific body parts.

4. Elasticity. A contracted muscle cell recoils to its resting length when the applied tension is removed. Thus, elasticity is not the muscle’s ability to stretch, but its ability to return to its original length when tension is released. Extensibility. A muscle cell must be capable of extending in length in response to the contraction of opposing muscle cells. For example, when you flex your elbow joint, you are contracting the biceps brachii on the anterior side of your arm and extending the triceps brachii on the posterior side of your arm .

5. FUNCTIONS OF SKELETAL MUSCLES Body movement . Bones of the skeleton move when muscles contract and pull on the tendons which attach the muscles to the bones Maintenance of posture . Contraction of specific skeletal muscles stabilizes joints and helps maintain the body’s posture or position. Postural muscles contract continuously when a person is awake to prevent collapse. Temperature regulation. Energy is required for muscle tissue contraction, and heat is always produced as a waste product of this energy usage. Most of this heat maintains our normal body temperature. Note that when you exercise, you feel warmer; the heat you feel is produced by your working muscles. Likewise, you shiver when you are cold because your muscles are contracting and relaxing to produce heat.

6. Storage and movement of materials . Circular muscle bands, called sphincters , contract at the openings, or orifices , of the gastrointestinal and urinary tracts. These sphincters may be voluntarily closed (to store the material within an organ) or opened (to facilitate movement of materials). Support . Skeletal muscle is sometimes arranged in flat sheets or layers, such as along the walls of the abdominal cavity and the floor of the pelvic cavity. These sheets of muscle protect the organs and support their weight within the abdominopelvic cavity. In fact, one of the primary functions of your abdominal muscles is to hold your abdominal organs in place

7. TERMS USE IN STUDYING MUSCLES FUNCTIONS FLEXION:- a bending movement that decreases the angle between two parts. E.g. bending the elbow or clinching a hand into a fist. EXTENSION:- a straightening movement that increases the angle between body parts. E.g :- stretching a hand to shake someone’s own. ABDUCTION :- movement of the limbs in the coronal plane away from the body. E.g :- spreading the fingers or toes away from the centerline of the hand or foot.

8. ADDUCTION:- a return of the part of the body to anatomical position after abduction . Opposite of abduction. ROTATION:- circular movement of a part of the body. SUPINATION:- lateral rotation of the hand. E.g :- the hands are supinated when the body is in anatomic position. PRONATION:- is the medial rotation of the hands from anterior-facing to posterior-facing. E.g - returning your hands to its anatomic position after supination .

9. CIRCUMDUCTION:- movement of the muscles in a conical shape with the point of the cone being at the origin . Is the orderly combination shoulder movement so that the hand traces a circle and the arm traces a cone. ELEVATION:- moving in a superior position. DEPRESSION:- moving in an inferior position . PROTRACTION:- a horizontal movement in the anterior as in jutting the chin forward. RETRACTION:- the reverse of protraction. REVERSION:- movement of the soles of the feet away from the median plane. INVERSION:- movement of the feet by turning the soles of the feet so that they face each other

10. NAMING OF MUSCLES Muscles are named according to the following:- LOCATION: - in relation to the bone, the following terms are used- Lateral, Medial, Internal, external. SIZE: - Maximus , Major, Minor, Longus , etc SHAPE:- Circular, Triangular, etc. NUMBER OF ATTACHMENTS:- Biceps, Triceps, Quadriceps, etc ACTION:- Flexor, extensor, adductor, etc

11. Muscle attachments . Many muscle names identify their origins, insertions, or other prominent attachments. In this case, the first part of the name indicates the origin and the second part the insertion. For example, the sternocleidomastoid has origins on the sternum and clavicle ( cleido ) and an insertion on the mastoid process of the temporal bone.

12. Orientation of muscle fibers . The rectus abdominis muscle is named for its lengthwise-running muscle fibers; rectus means “straight.” Similarly, names such as oblique or obliquus indicate muscles with fibers extending at an oblique angle to the longitudinal axis of the body.

13. Muscle shape and size . Examples of shape in muscle names include: deltoid, shaped like a triangle; orbicularis, a circle; rhomboid, a rhombus; and trapezius, a trapezoid Short muscles are called brevis; long muscles are called longus or longissimus ( longest). Teres muscles are both long and round. Large muscles are called magnus , major or bigger, or maximus ( biggest). Small muscles are called minor ( smaller) or ́ minimus ( smallest).

14. Pattern of skeletal muscle organization Circular : Fibers arranged concentrically around an opening Functions as a sphincter to close a passageway or opening (e.g., orbits, mouth, anus. Parallel: Fascicles are parallel to the long axis of the muscle Body of muscle increases in diameter with contraction High endurance, not very strong eg : rectus abdominis

15. Convergent: Triangular muscle with common attachment site Direction of pull of muscle can be changed Does not pull as hard as equal-sized parallel muscle. Eg pectoralis major Pennate : Muscle body has one or more tendons Fascicles at oblique angle to tendon Pulls harder than a parallel muscle of equal size. Unipennate : All muscle fi bers on the same side of the tendon. Eg extensor digitorium Bipennate : Muscle fi bers on both sides of the tendon. Eg rectus femoris Multipennate : Tendon branches within the muscle. Eg deltoid

16. CLASSIFICATION OF MUSCLES ACCORDING TO MOVEMENT. AGONIST: - These are often referred to as Prime Movers. They enable positive movements. ANTAGONIST:- This type oppose or make negative movements. SYNERGISTS:- They help the prime movers by either producing the same movement or by reducing undesirable or unnecessary movement. FIXATORS:- They are specialized synergists. They act by holding a bone still or to stabilize the origin of a prime mover.

17. CLASSIFICATION OF MUSCLEACCORDING TO LOCATION & FUNCTION 1. MUSCLES OF THE HEAD 2. MUSCLES OF THE NECK 3. MUSCLES OF THE BACK & VERTEBRAL COLUMN. 4. MUSCLES OF THE RIBS 5. MUSCLES OF THE ANTERIOR THORAX 6. MUSCLES OF THE POSTERIOR THORAX 7. MUSCLES OF THE ABDOMEN 8. THE DIAPHRAGM 9. MUSCLES OF THE UPPER LIMBS 10. MUSCLES OF THE LOWER LIBMS .

18. NAMING ACCORDING TO MUSCLE ACTIONS. Adductor (adducts body part) Abductor (abducts body part) Flexor (flexes a joint) Extensor (extends a joint) Adductor magnus Abductor pollicis longus Flexor carpi radialis Extensor hallucis longus

19. NAMES ACCORDING TO SPECIFIC BODY REGIONS Oris (mouth) Cervicis (neck) Brachial (arm) Carpi (wrist) Pollicis (thumb) Gluteal (buttocks) Femoris (thigh) Hallucis (great toe) Anterior (toward the front of the body) Posterior or dorsal/ dorsi (toward the back of the body) Orbicularis oris Semispinalis cervicis Biceps brachii Flexor carpi ulnaris Opponens pollicis Gluteus medius Quadratus femoris Extensor hallucis longus Tibialis anterior Tibialis posterior Latissimus dorsi

20. Superior Inferior Superficialis (superficial) Profundus (deep) Serratus posterior superior Serratus posterior inferior Flexor digitorum superficialis Flexor digitorum profundus

21. Name according to muscle attachements . Sternum and clavicle ( cleido ) Between the ribs Subscapular fossa Fibula Zygomatic bone Sternocleidomastoid Intercostal Subscapularis Fibularis longus Zygomaticus major

22. Names according to orientation of muscle fiber Rectus (straight) Oblique (angled) Orbicularis (circular) Rectus abdominis External oblique Orbicularis oculi

23. Name according to muscle shape and size Deltoid (triangular) Quadratus (rectangular) Trapezius (trapezoidal) Longus (long) Brevis (short) Major (larger of two muscles) Minor (smaller of two muscles) Maximus (largest) Medius (medium sized) Minimus (smallest) Deltoid Pronator quadratus Trapezius Abductor pollicis longus Abductor pollicis brevis Pectoralis major Pectoralis minor Gluteus maximus Gluteus medius Gluteus minimus

24. Name according to muscle heads/ tendons of origin. Biceps (two heads) Triceps (three heads) Quadriceps (four heads) Biceps femoris Triceps brachii Quadriceps femoris