The muscular system consists of a large number of muscles concerned with movements of the body

Voluntary muscles are attached to

Bone

Cartilages

Ligaments,

Skin or to other muscles in order to stimulate movements

Types of Muscle Tissue

Skeletal muscle (also called striated muscle)

Cardiac muscle (the muscle of the heart)

Visceral muscle (also called smooth muscle)

Is the most abundant type of muscle

It attaches to bone and so is important in producing movements in our joints and maintaining our posture.

Under the microscope, skeletal muscle cells look like long fibres and have a striped (striated) appearance.

We generally think of skeletal muscle as being under voluntary control.

Cardiac Muscle

Is the muscle of the heart

Under the microscope, cardiac muscle cells also appear striated; however the striations are not as well organized as in skeletal muscle.

The activity of cardiac muscle is controlled to a large degree by the autonomic nervous system.

We generally think of cardiac muscle as being involuntary.

Is the muscle which lines our blood vessels and internal organs

Under the microscope, visceral muscle cells do not have the obvious striations of skeletal or cardiac muscle hence called smooth muscle

Visceral muscle cells are often relatively short, and usually they each have only one nucleus

We generally think of visceral muscle as being involuntary

The ability of muscle to contract depends on the presence of two protein molecules: actin and myosin

Bundles of actin and myosin molecules are arranged end to end in muscle cells

It is these bundles that give skeletal and cardiac muscle their striated appearance

When a muscle is properly stimulated, the actin and myosin bundles slide together and so the muscle cell gets shorter

This process requires calcium and ATP for energy

Muscles, especially skeletal muscle, may be stimulated to contract by motor nerves.

Depolarization from a motor nerve causes calcium to move from the sarcoplasmic reticulum into the sarcoplasm

This release of calcium causes actin and myosin to slide together and shorten the muscle

Muscles of the Head

The muscle of the head are divided into two groups: Muscles of expression and muscles of mastication

Name

Position

Origin

Insertion

Action

Muscle of expression

Orbiculis oculi (circular muscles)

Obicularis oris

Skin

Eye

Mouth

Closes eye

Screws up the eye

Closes lip

Shapes mouth

Muscles of mastication

Masseter (broad muscles)

Temporalis muscle

Zygomatic

arch to the right angle of jaw

Temporal bone

Draws mandible and maxilla

Closes jaw

Draws mandible

Name

Position

Origin

Insertion

Action

Sternocleidomastoid

Trapezius

Side of the neck

Back of the neck and shoulder

Sternum and clavicle

Occiput

Spines of thoracic vertebra

Mastoid process

Clavicle

Spine of scapula

Turns head to the side

Tilts to same shoulder

Flex of the neck

Draws scapula back

Raises and lowering of shoulder

Extending neck

Muscle moving shoulder

They are powerful muscles

They also connect the upper limb and the trunk

Name

Position

Origin

Insertion

Action

Pectoralis major

Lattissimus dorsi

Serratus anterior

Front of chest

Crosses the back from lumbar region to shoulder

Over the side of the thorax

Under scapula

Sternum

and clavicle

Cartilages of true ribs

Lower thoracic, lumbar and sacral vertebrae Iliac crest

Front of the eight upper ribs

Humerus (bicipital groove)

Medial border of scapula

Adducts shoulder

Draws the arm across front chest

Rotates shoulder internallis

Adducts the shoulder

Draws arm back wards and downs in bell pulling

Internal rotation of shoulder

Draws scapula forwards; antagonistic to the trapezius

Name

Position

Origin

Insertion

Action

Diaphragm (dome shaped sheet)

Between thoracic and abdominal cavity

Tip of sternum, lower ribs

Thee lumber vertebrae

Central aponeurosis

Involved in the mechanism of respiration

External intercostals muscle

Between the ribs

Lower border of rib above

Upper

border of the rib below

Draw ribs upwards and downwards during slow inhaltion

Internal intercostals muscle

Between the ribs

Lower border of the rib above

Upper

border of the rib below

Draw ribs downwards and inwards to

decrease the size of the thorax in force expiration

Antagonistic external intercostal muscle

Name

Position

Origin

Insertion

Action

Rectus abdominis (Resctus = straight)

Anterior abdominal wall

Pubis, sternum and costal cartilage

Abdominal wall

Forms the anterior wall of abdominal wall

External oblique

Lateral abdominal wall

Lower ribs

Iliac crest and inguinal ligament

Attaches muscle

Forms lateral wall of the abdominal wall

Internal oblique

Lateral abdominal wall

Lower ribs

Iliac crest and inguinal ligament

Form firm wall of abdomen

Give attachment to muscle

Name

Position

Origin

Insertion

Action

Transversus abdominis

Under the internal oblique

Illiac crest and lumber fascia

Aponeurosis across the front wall of abdomen

Forms the lateral wall of the abdominal wall

Quadratus lumborum

Lateral and posterior wall

Iliac crest

to 12th rib

Upper lumbar vertebrae

Iliac crest and inguinal canal

Forms the posterior wall of the abdominal wall

Holds the 12th rib during breathing

Name

Position

Origin

Insertion

Action

Psoas major

Crosses the region behind inguinal ligament

Transverse processes of lumber vertebrae

Lesser trochanter of femur

Flexes the hip

Iliucus

Crosses the groin behind the inguinal ligament with psoa

Front surface of the iliac bone

Lesser trochanter of femur

Flexes the hip

Gluteal muscles

Cross the back of the hip

Posterior surface of ilium and sacrum

Greater trochanter and gluteal line of femur

Extends, abducts hip laterally

Rotates hip

The pelvic diaphragm consists of muscles forming the support of the pelvic organs

Runs from the pubis in front back to sacrum and coccyx

The pelvic diaphragm is composed of the levator ani and coccygeus muscles

In the female it is pierced in the middle by three openings for the urethra, vagina and rectum. In the male there are two openings, for the urethra and the recturm respectively

Name

Position

Origin

Insertion

Action

Biceps

Front of the arm

Coracoid process

Above glenoid cavity of scapula

Radial tuberosity

Flexes elbow, shoulder

Supinates the hand

Triceps (three heads)

Back of the arm

One head the axillary border of scapula

Olecramon of ulna

Extends elbow and shoulder

Deltoid

Over the shoulder

Acromion and spine of scapula, the clavicle

Detoid tuberosity of humerus

Abducts the shoulder to a right angle

Brachialis

Crosses the front elbow

Humerus

Anterior surface of coronoid process of ulna

Flexes the elbow

The muscles for the forearm are numerous powerful muscles for movement of the wrist and digits

These muscle are

Pronator teres

Flexor carpiulnalis

Flexar carpi radialis

Pronator quadratus

Flexor renaculum

Thenar eminence

Hypothenar eminence

Muscles of the Lower Limb

Muscles of the lower limb are much larger and more powerful than those of the upper limb

Name

Position

Origin

Insertion

Action

Quadriceps femoris

Front of thigh

Ilium

Femur

Patella

Extension of knee

Flexes hip

Harm strings

Back of thigh

Ischial tuberosity

Femur

Tibia

Fibula

Flexion of the knee

Extension of the hip

Sartorius

Crosses front of thigh

Anterior superior iliac spine

Tibia at inner side

Assist in flexion of hip, knee

Abduction and external rotation of hip

Abductor of the hip

Inner side of thigh

Pubis and ischium

Linea aspera

Medial condyle of femur

Abducts the hip

Name

Position

Origin

Insertion

Action

Gastrocnemius

The calf

Condyles of the femus

Calcaneum

Plantar flexion of the ankle

Soleus

The calf

Tibia

Fibula

Calcaneum

Plantar flexion of the ankle

Tibialis anterior

Side of the leg

Tibia

Tarsals

Metatarsals

Dorsiflexion of the ankle

raising the toe

inversion of foot

Interosseous muscles

Foot

Tibia

Between the metatarsals

Abducts and adducts digits