2. Did you know that ?
- more than 50% of body weight
is muscle !
- And muscle is made up of
proteins and water
3.
4. The Muscular System
• Muscles are responsible for all movement
of the body
• There are three basic types of muscle
– Skeletal
– Cardiac
– Smooth
5. Info About Muscles
• Only body tissue able
to contract
• create movement by
flexing and extending
joints
• Body energy
converters (many
muscle cells contain
many mitochondria)
8. Classification of Muscle
Skeletal-
found in limbs
Cardiac-
found in heart
Smooth-
Found in
viscera
Striated, multi-
nucleated
Striated, 1
nucleus
Not striated, 1
nucleus
voluntary involuntary involuntary
9. Characteristics of Muscle
• Skeletal and smooth muscle are elongated
• Muscle cell = muscle fiber
• Contraction of a muscle is due to movement
of microfilaments (protein fibers)
• All muscles share some terminology
– Prefixes myo and mys refer to muscle
– Prefix sarco refers to flesh
10. Shapes of Muscles
• Triangular- shoulder, neck
• Spindle- arms, legs
• Flat- diaphragm, forehead
• Circular- mouth, anus
12. Skeletal Muscle
• Most are attached by tendons to bones
• Cells have more than one nucleus
(multinucleated)
• Striated- have stripes, banding
• Voluntary- subject to conscious control
• Tendons are mostly made of collagen fibers
• Found in the limbs
• Produce movement, maintain posture,
generate heat, stabilize joints
13. Structure of skeletal muscle
• Each cell (fibre) is long and cylindrical
• Muscle fibres are multi-nucleated
• Typically 50-60mm in diameter, and up
to 10cm long
• The contractile elements of
skeletal muscle cells are
myofibrils
14. Skeletal muscle - Summary
• Voluntary movement
of skeletal parts
• Spans joints and
attached to skeleton
• Multi-nucleated,
striated, cylindrical
fibres
15. Smooth Muscle
• No striations
• Spindle shaped
• Single nucleus
• Involuntary- no conscious control
• Found mainly in the walls of hollow organs
16. Smooth muscle
• Lines walls of viscera
• Found in longitudinal or
circular arrangement
• Alternate contraction of
circular & longitudinal
muscle in the intestine
leads to peristalsis
18. Structure of smooth muscle
• Spindle shaped uni-nucleated cells
• Striations not observed
• Actin and myosin filaments are present(
protein fibers)
19. Smooth muscle - Summary
• Found in walls of
hollow internal
organs
• Involuntary
movement of
internal organs
• Elongated, spindle
shaped fibre with
single nucleus
20. Cardiac Muscle
• Striations
• Branching cells
• Involuntary
• Found only in the heart
• Usually has a single nucleus, but can have
more than one
21. Cardiac muscle
• Main muscle of heart
• Pumping mass of heart
• Critical in humans
• Heart muscle cells
behave as one unit
• Heart always contracts
to it’s full extent
22. Structure of cardiac muscle
• Cardiac muscle cells (fibres) are
short, branched and
interconnected
• Cells are striated & usually have 1
nucleus
• Adjacent cardiac cells are joined
via electrical synapses (gap
junctions)
• These gap junctions appear as
dark lines and are called
23. Cardiac muscle - Summary
• Found in the heart
• Involuntary rhythmic
contraction
• Branched, striated
fibre with single
nucleus and
intercalated discs
24. Muscle Control
Type of
muscle
Nervous
control
Type of
control
Example
SkeletalSkeletal Controlled
by CNS
Voluntary Lifting a
glass
Cardiac Regulated
by ANS
Involuntary Heart
beating
Smooth Controlled
by ANS
Involuntary Peristalsis
25. Types of Responses
• Twitch-
– A single brief contraction
– Not a normal muscle function
• Tetanus
– One contraction immediately followed by
another
– Muscle never completely returns to a relaxed
state
– Effects are compounded
26. Where Does the Energy Come
From?
• Energy is stored in the muscles in the form
of ATP
• ATP comes from the breakdown of glucose
during Cellular Respiration
• This all happens in the Mitochondria of the
cell
• When a muscle is fatigued (tired) it is
unable to contract because of lack of
Oxygen
27. Fast Twitch and Slow Twitch
Fibers
Fast Twitch vs Slow Twitch
28. Exercise and Muscles
• Isotonic- muscles shorten and movement
occurs ( most normal exercise)
• Isometric- tension in muscles increases, no
movement occurs (pushing one hand
against the other)
29. How are Muscles Attached to
Bone?
• Origin- attachment to immovable bone
• Insertion- attachment to a movable bone
• Muscles are always attached to at least 2
points
• Movement is attained due to a muscle
moving an attached bone
31. Muscle Attachments
• The origin is on the clavicle and sternum.
• The insertion is on the skull.
• When the muscle contracts it will shorten
the distance between the origin and
insertion.
• The head will move when this muscle
contracts.
37. More Types of Movement……
• Inversion- turn sole of foot medially
• Eversion- turn sole of foot laterally
• Pronation- palm facing down
• Supination- palm facing up
• Opposition- thumb touches tips of fingers
on the same hand
38. The Skeletal Muscles
There are about 650 muscles in the
human body. They enable us to
move, maintain posture and generate
heat. In this section we will only
study a sample of the major muscles.
40. Sternocleidomastoideus
• Sometimes called the sternocleitomastoid.
• It is the same neck muscle shown on the previous
slide.
• This muscle has two origins.
– The first origin is on the sternum manubrium.
– The second origin is on the clavicle.
• The insertion is on the mastoid process of the skull.
• Contraction of both sternocleidomastoideus muscles
will flex the head. If just one of the muscles contracts,
the head will rotate.
42. Masseter
• The masseter is one of major chewing
muscles.
• The origin of the masseter is on the
zygomatic arch.
• The insertion is on the mandible.
• Contraction of the masseter will elevate the
jaw.
44. Temporalis
• The temporalis is another chewing muscle.
– Note how it attaches on the side of skull.
• It also elevates the mandible.
• You do not need to know the insertions and
origins for this muscle
46. Trapezius
• The trapezius is a large muscle in the upper back.
• It attaches to the skull, shoulder and vertebrae of
the back.
• When this muscle contracts it will cause the head
to extend.
• It will also move the scapula.
• The direction the scapula moves depends on
which part of the trapezius contracts.
• The trapezius may elevate or depress the scapula.
48. Latissimus Dorsi
• The latissimus dorsi is a large muscle in the back.
– It is often referred to as a lat.
• It has origins on the vertebrae, ilium ribs and
scapula.
• The insertion is on the humerus.
– When it contracts it moves the humerus.
• It can extend, adduct and rotate the arm medially.
• This is the main muscle used in movement such as
pounding a nail with a hammer.
50. Deltoid
• The deltoid covers the shoulder and has the shape
of a delta.
• It has origins on the scapula and clavicle.
– The deltoid inserts on the deltoid tuberosity of
the humerus.
• Contraction of the deltoid will adduct the arm.
• If only the anterior fibers of the muscle contract it
will flex the arm.
• Contraction of the posterior fibers will extend the
arm.
52. Pectoralis Major
• The pectoralis major is a large muscle in the
pectoral region of the body.
• It has origins on the clavicle and sternum.
– The insertion is on the greater tubercle of the
humerus.
• Contraction of the pectoralis major will flex the
arm.
• It will also adduct and rotate the arm medially.
• The pectoralis major is used in movements such a
climbing, throwing and doing pushups.
54. Biceps Brachii
• The biceps brachii is located on the anterior side of the
upper arm.
• It is often just called the biceps.
– There is a biceps femoris in the leg we will study
shortly.
• The biceps has two origins. One origin is on the
corocoid process and the other on the Glenoid cavity of
the scapula.
• The “bi” in biceps refers to the two origins.
– It inserts on the radial tuberosity.
• Contraction of the biceps will cause flexing at the elbow
joint.
56. Triceps Brachii
• The triceps is on the back of the upper arm.
• It has three origins.
• Two origins are on the back of the humerus
and one on the scapula.
• The triceps inserts on the olecranon.
• Movement of the triceps will extend the
elbow joint.
58. Rectus Abdominus
• Rectus abdominus is a long muscle in the
abdomen.
• The muscle originates on the pubis.
• It inserts on the xiphoid process of the
sternum and also on cartilage of the ribs.
• When rectus abdominus contracts it will
flex the abdomen.
60. External Oblique
• Another muscle in the abdomen is the
external oblique.
• It has muscle fibers that run in an oblique
direction across the abdomen.
• Contraction of the external oblique will
compress the abdomen.
62. External Intercostals
• There are two groups of muscles that run
between the ribs.
• The first are the external intercostals.
• They will elevate the ribs.
66. Diaphragm
• This is an inferior view of the diaphragm.
• This muscle separates the abdominal cavity
from the thoracic cavity.
• When it contracts it will cause inspiration.
70. Gluteus Maximus
• The large muscle on the posterior side of
the body at the top of each leg is the gluteus
maximus.
• The gluteus maximus originates on the
ilium, sacrum and coccyx.
• It inserts on the gluteal tuberosity of the
femur.
• This muscle will extend and rotate the thigh
laterally.
72. Rectus Femoris
• Rectus femoris is located on the anterior
side of the thigh.
• It originates on the ilium.
• The insertion is on the patella and the tibial
tuberosity.
• When rectus femoris contracts it will flex
the thigh and extend the lower leg.
76. Sartorius
• Sartorius is a long, strap like muscle.
• It originates on the anterior superior iliac
spine of the ilium.
• The insertion is on the medial side of the
tibia.
• Contraction of the sartorius flexes the thigh
and rotates the thigh laterally.
• This is the muscle used when crossing the
legs to sit on the floor.
78. Biceps Femoris
• Biceps femoris is one of the hamstring
muscles.
• The origin is on the ischial tuberosity.
• Biceps femoris inserts on the tibia and
fibula.
• This muscle extends the thigh and flexes the
lower leg.
80. Gastrocnemius
• Gastrocnemius is commonly called the calf
muscle.
• It originates on the distal end of the femur.
• The insertion is on the calcaneus bone of
the foot.
• It will cause plantar flexion of the foot and
also flex the lower leg.
82. Tibialis Anterior
• Tibialis anterior is located on the anterior
side of the tibia.
• It will dorsiflex and invert the foot.
Notas del editor
Muscles attach in at least two places in the body. *The origin is the attachment that moves the least. *The insertion is the attachment that moves the most. This diagram illustrates the origin and insertion of one of the neck muscles. Note the origin is on the clavicle and sternum. The insertion is on the skull. When the muscle contracts it will shorten the distance between the origin and insertion. The head will move when this muscle contracts. Remember the insertion is the end of the muscle that moves the most. Since the head moves the attachment on the head is called the insertion. The origin is generally on a larger body part will move the least. The chest does not move when this muscle contract. The bones in the chest are therefore the origin.
You will need to know the action or movement performed for each of the muscles we study. The first type of movement is called flexion. Note the lower leg is being flexed in this diagram. During flexion the angle of joint is decreased. As the knee is flexed, the angle between the lower leg and the thigh is decreased. Flexion of the upper arm is also illustrated in this diagram. Here the angle between the arm and the frontal plane is decreased.
Extension is the opposite of flexion. In extension the angle of a joint is increased. Extension of the lower leg causes an increased angle between the lower leg and the thigh.
Flexion and extension also apply to the neck. When a joint is extended past the anatomical position the movement is called hyperextension.
Abduction refers to moving away from the median plane of the body. Adduction is the opposite movement to abduction. It is moving toward the medial plane. Circumduction refers to inscribing a circle while moving a limb.
Rotation is turning a bone on its own axis. Moving the head back and forth to indicate “no” is an example of rotation. Note the difference between medial and lateral rotation. In lateral rotation the limb is rotated the lateral side of the body. Medial rotation rotates the limb toward the medial side of the body.
There are about 650 muscles in the human body. They enable us to move, maintain posture and generate heat. In this unit will only study a sample of the major muscles.
The first muscle we will learn is the sternocleidomastoideus. It is sometime called the sternocleitomastoid. It is the same neck muscle shown on the previous slide. * This muscle has two origins. The first origin is on the sternum manubrium. The second origin is on the clavicle. *The insertion is on the mastoid process of the skull. *Contraction of both sternocleidomastoideus muscles will flex the head. If just on of the muscles contracts, the head will rotate.
The masseter is one of major chewing muscles. *The origin of the masseter is on the zygomatic arch. *The insertion is on the mandible. *Contraction of the masseter will elevate the jaw.
The temporalis is another chewing muscle. Note how it attaches on the side of skull. *It also elevates the mandible. Also note I did not give the origin and insertion of this muscle. You will only need to know the origin and insertion of a few of the muscles in this unit.
The trapezius is a large muscle in the upper back. It attaches to the skull, shoulder and vertebrae of the back. *When this muscle contracts it will cause the head to extend. It will also move the scapula. The direction the scapula moves depends on which part of the trapezius contracts. The trapezius may adduct elevate or depress the scapula.
The latissimus dorsi is a large muscle in the back. It is often referred to as a lat. *It has origins on the vertebrae, ilium ribs and scapula. *The insertion is on the humerus. When it contracts it moves the humerus. *It can extend, adduct and rotate the arm medially. This is the main muscle used in movement such as pounding a nail with a hammer.
The deltoid covers the shoulder and has the shape of a delta. *It has origins on the scapula and clavicle. *The deltoid inserts on the deltoid tuberosity of the humerus. *Contraction of the deltoid will adduct the arm. If only the anterior fibers of the muscle contract it will flex the arm. Contraction of the posterior fibers will extend the arm.
The pectoralis major is a large muscle in the pectoral region of the body. *It has origins on the clavicle and sternum. *The insertion is on the greater tubercle of the humerus. *Contraction of the pectoralis major will flex the arm. It will also adduct and rotate the arm medially. The pectoralis major is used in movements such a climbing, throwing and doing pushups.
The biceps brachii is located on the anterior side of the upper arm. It is often just called the biceps. There is a biceps femoris in the leg we will study shortly. *The biceps has two origins. One origin is on the corocoid process and the other on the Glenoid cavity of the scapula. The “bi” in biceps refers to the two origins. *It inserts on the radial tuberosity. *Contraction of the biceps will cause flexing at the elbow joint.
The triceps is on the back of the upper arm. *It has three origins. Two origins are on the back of the humerus and one on the scapula. *The triceps inserts on the olecranon. *Movement of the triceps will extend the elbow joint.
Rectus abdominus is a long muscle in the abdomen. *The muscle originates on the pubis. *It inserts on the xiphoid process of the sternum and also on cartilage of the ribs. *When rectus abdominus contracts it will flex the abdomen.
Another muscle in the abdomen is the external oblique. It has muscle fibers that run in an oblique direction across the abdomen. *Contraction of the external oblique will compress the abdomen.
There are two groups of muscles that run between the ribs. The first are the external intercostals. *They will elevate the ribs.
The internal intercostals are also located between the ribs. *They will depress the ribs.
This is an inferior view of the diaphragm. This muscle separates the abdominal cavity from the thoracic cavity. *When it contracts it will cause inspiration.
There are several muscles in the forearm that have important movements. *The flexor carpi are used to flex the wrist. *Extensor carpi extend the wrist. *Flexor digitorum flexes the fingers. *Extensor digitorum extends the fingers. *The pronator pronates. *A supinator muscle will supinate.
The large muscle on the posterior side of the body at the top of each leg is the gluteus maximus. *The gluteus maximus originates on the ilium, sacrum and coccyx. *It inserts on the gluteal tuberosity of the femur. *This muscle will extend and rotate the thigh laterally.
Rectus femoris is located on the anterior side of the thigh. *It originates on the ilium. *The insertion is on the patella and the tibial tuberosity. *When rectus femoris contracts it will flex the thigh and extend the lower leg.
The gracilis is on the medial side of the thigh. *It adducts and flexes the thigh.
Sartorius is a long, strap like muscle. *It originates on the anterior superior iliac spine of the ilium. *The insertion is on the medial side of the tibia. * Contraction of the sartorius flexes the thigh and rotates the thigh laterally. This is the muscle used when crossing the legs to sit on the floor.
Biceps femoris is one of the hamstring muscles. *The origin is on the ischial tuberosity. *Biceps femoris inserts on the tibia and fibula. This muscle extends the thigh and flexes the lower leg.
Gastrocnemius is commonly called the calf muscle. *It originates on the distal end of the femur. *The insertion is on the calcaneus bone of the foot. *It will cause plantar flexion of the foot and also flex the lower leg.
Tibialis anterior is located on the anterior side of the tibia. *It will dorsiflex and invert the foot.