.Mascular system types muscles charactersitics function of muscle classification of muscles sarcoplasmic organelles structure of msucles how to name muscle neck muscle intrinsic back muscle extrinsic back muscles anterior compartment of thih muscle hamstring group muscles IM injection common sites muscular tension

1. Muscular System

2. Objectives
At the end of this session, the students will be able to:
• Define the following terms as
• Endomysium, Fascia, epimysium perimysium, tendons
• Describe the location and function of major muscles of:
Neck, face, back, arms, legs

3. Introduction to muscles
• The muscular system consists of about 600
skeletal muscles excluding cardiac and smooth
muscles.
• Myology is the study of muscles.
• A skeletal muscle is composed of both
muscular tissue and connective tissue.

4. Functions of Muscles
• Movement
• Stability
• Communication—facial expression, body
language
• Control of body openings and passages
• Heat production (thermogenesis)

5. Properties of Muscular Tissue
Four properties that enable it to function.
1. Electrical excitability
2. Contractility
3. Extensibility
4. Elasticity

6. Classification of Muscles
• Striation based
• Action based
• Situation based

7. Features of Muscles
Features Skeletal Cardiac Smooth
Shape Cylindrical , unbranched Branched Spindle, unbranched
Length 1—4 cm 80—100  50—200 
Nucleus More than one one one
Striations present present absent
Myofibrils present present Absent
Sarcomere present present absent
Troponin present present Absent
Depolarization Upon stimulation Spontaneous Spontaneous
Tetanus Possible Not possible Not Possible
RMP Stable Stable Unstable
Ca++ binds with Troponin Troponin Calmodulin
Nerve supply Somatic Autonomic Autonomic
Control Neurogenic Myogenic Neurogenic and
Myogenic

8. Sarcoplasmic Organelles
• 1. Nuclei
• 2. Myofibrils
• 3. Golgi apparatus
• 4. Mitochondria
• 5. Sarcoplasmic reticulum
• 6. Ribosomes
• 7. Glycogen droplets
• 8. Occasional lipid droplets.

9. Microscopic Structure of a Myofibril
• Myofibrils are fine parallel filaments in sarcoplasm.
• Run through the entire length of the muscle fiber.
• Each myofibril consists of a number of two alternating
bands which are also called the sections, segments or
disks. These bands are formed by muscle proteins.
• The two bands are:
1. Light band or ‘I’ band (isotropic to polarized light)
2. Dark band or ‘A’ band (Anisotropic to polarized light)

10. Microscopic Structure of a Myofibril Cont...
• ‘I’ band is divided by ‘Z’ line or ‘Z’ disk
• The ‘Z’ line is formed by a protein disk, which does
not permit the passage of light.
• The portion of myofibril between two ‘Z’ lines is
called sarcomere.
• Sarcomere is structural and functional unit of a
skeletal muscle. It is also called the basic contractile
unit of the muscle.
• Sarcomere consists of many threadlike structures
called myofilaments.
• Myofilaments are of two types:
• 1. Actin filaments
• 2. Myosin filaments.

11. Sarcomere
Myocyte

12. Troponin
• Troponin is formed by three subunits:
• 1. Troponin I, which is attached to F-actin
• 2. Troponin T, which is attached to tropomyosin
• 3. Troponin C, which is attached to calcium ions.

13. Key Terms
• Endomysium: An areolar connective tissue membrane that
surrounds a single skeletal muscle cell (muscle fiber).
• Fascicle (fasc= bundle+ icle= little): The muscle fibers that are
grouped in a bundle. It is also called fasciculus.
• Perimysium: A connective tissue sheath which separates one
fascicle from neighboring ones.
• Epimysium: A connective tissue sheet that surrounds a
muscle as a whole. It is the outermost layer.
• Fascia: A connective tissue sheet that wraps around groups
of muscles.
• Aponeurosis: a white fibrous sheet of tissue by which certain
muscles are attached to bones. It is actually tendon which is
thin and flat but tough.

15. How to Name Muscles
Name Meaning Example
1. Location Pectoralis (of the chest)
Brachii (of the arm)
Pectoralis major
Biceps brachii
2. Size
Maximus
Minimus
Longus
Brevis
Latissimus
Longissimus
Magnus
Major
Minor
Vastus
Largest
Smallest
Long
Short
Widest
Longest
Larger
Larger
Smaller
Huge
Gluteus maximus
Gluteus minimus
Adductor longus
Abductor brevis
Latissimus dorsi
Longissimus capitis
Adductor magnus
Pectoralis major
Pectoralis minor
Vastus lateralis

16. Names of selected muscles
 Face Muscles
 Orbicularis Occuli
• Closes eyelid and compresses
lacrimal glands
 Levator palpebrae (opens eye &
raises upper lid
 Masseter (chewing)
 Orbicularis oris (closes &
protrudes lips)
 Buccinator (compresses cheeks,
blowing, suction)
 Zygomaticus minor and major
• Draws corners of mouth laterally
and upward as in smiling and
laughing
 Platysma
• Depresses mandible, opens and
widens mouth
 Neck Muscles
 Sternocleidomastoid
• Flexes neck and draws head down
 Scalenes
• Flex neck laterally and elevate ribs 1
&2 in inspiration
 Trapezius
• Abducts and extends neck
 Splenius capitis
• Rotate head and extend neck
 Digastric
• Opens mouth by lowering mandible
• Raises hyoid bone
 Sternohyoid
• Depresses hyoid bone after
swallowing
 Thyrohyoid
• Raises larynx

17. Neck Muscles

18. Back Muscles
• Muscles in the back are classified as extrinsic and
intrinsic.
• Extrinsic muscles consist of superficial and
intermediate group of muscles.
• Superficial muscles are involved with the
movements of upper limbs while the
intermediate muscles are associated with the
thoracic wall.
• Extrinsic muscles are innervated by the anterior
rami of spinal nerves.
• Intrinsic muscles lying deep in the back are
innervated by posterior rami of spinal nerves.

19. Extrinsic Back Muscles
 Superficial Group
 Trapezius
• Superior fibers elevate
scapula; middle fibers
retract it; inferior fibers
depress it.
 Levator scapulae
• Elevates scapula
• Rhomboid minor & major
• Retracts(adducts) and
elevates scapula
 Latissimus dorsi (swimming)
• Extends, adducts, and
medially rotates humerus
 Intermediate Group
(Respiratory muscles)
 Serratus posterior superior
• Elevates ribs II to V
 Serratus posterior inferior
• Depresses ribs IX to XII

20. Intrinsic Back Muscles
Splenius Capitis
• Together—draw head
backward, extending
neck
• Individually—draw and
rotate head to one side
Splenius Cervicis
• Together—extend neck
• Individually—draw and
rotate head to one side
Erector spinae
(erecting back)
Illiocostalis cervicis
• extend and laterally flex
vertebral column
Illiocostalis thoracis
and lumborum
• Rotate ribs during
forceful inspiration

22.  Arm Muscles
 Deltoid (abduct humerus)
 Teres major (adduct and
medially rotate humerus)
 Teres minor (abduct and
laterally rotate humerus)
 Biceps brachii (flexes
elbow)
 Brachialis (flexes elbow)
 Triceps brachii (extends
elbow)
 Pronator ( teres, quadratus)
 pronates forearm
 Supinator (teres, quadratus)
 supinates forearm
 Flexor carpi radialis
• Flexes wrist
 Palmaris longus
• Flexes wrist
 Flexor carpi ulnaris
• Flexes wrist
 Extensor carpi radialis
 Extensor carpi ulnaris
 Flexor pollicis (longus, brevis)
• Flexes thumb
 Extensor pollicis (longus, brevis)
• Extends thumb
 Flexor digitorum (superfi, profun)
• Flexes fingers II—V
 Extensor digitorum

23. Anterior Compartment Thigh Muscles
• Psoas major
• Flexes thigh at hip joint
• Iliacus
• Flexes thigh at hip joint
• Vastus
• Extends the leg at knee joint
• Rectus femoris
• Extends leg at knee and flexes the thigh at hip
• Sartorius
• Flexes thigh at hip and leg at knee

24. Hamstring Group Muscles
• Biceps femoris
• Flexes knee, extends hip, laterally rotates leg
• Semitendinous
• Flexes knee, extends hip, medially rotates tibia
• Semimembranous
• Flexes knee, extends hip, medially rotates
tibia

25. IM injection common sites
• Deltoid muscle of the arm. The deltoid
muscle is the site most typically used for
vaccines. ...
• Vastus lateralis muscle of the thigh. ... On the
front of the thigh
• Ventrogluteal muscle of the hip. At the outer
upper thigh...
• Dorsogluteal at the upper outer quadrant of
buttock

26. Muscular tension
• Isotonic
• Isometric
• Starling’s law