Chapter 8The Muscular System

• Muscle tissue is made of a collection of similar muscle cells (or fibers). There are three types of muscle found in the human body:– Skeletal Muscle– Cardiac Muscle– Smooth Muscle

• Some muscle tissues in the body are “voluntary” muscles– This means that you can control the actions of

these muscles with your mind• Ex. Skeletal muscle

• Other muscle tissues are “involuntary” muscles– This means that we normally do not have control

over their contractions• Ex. Smooth muscle

• The primary function of muscle tissue is movement through contractions. – Skeletal muscle contractions allow us to move– Cardiac muscle contraction pump blood

throughout our body– Smooth muscle contraction perform many

vital functions, including moving food through our digestive tract.

• Most skeletal muscle attach to two bones that have a moveable joint between them. – The muscle’s attachment to the bone that is

most stationary is called the origin.– The muscle’s attachment to the bone that is

more moveable is called the insertion.

Tendons anchor muscles firmly to bones (this is a type of connective tissue)

• Skeletal muscle tend to work in coordinated teams:– Prime mover – the muscle mainly

responsible for producing a movement– Synergist – muscle that help produce the

movement along with the prime mover– Antagonist – muscle that produce an

opposite movement to the prime mover

• The secondary function of muscle tissue is posture or muscle tone.– Our body is constantly held in proper position

by tonic contractions• The whole muscle does not contract, but enough

fibers contract to maintain the muscle shape and position.

• An addition function of muscle tissue is heat production.– The contraction of muscle fibers produces

heat which is used to help maintain a proper body temperature (98.6º)

• There are several terms that are commonly used to describe muscle movements:– Flexion– Extension– Abduction– Adduction– Rotation and Circumduction– Supination and Pronation– Dorsiflexion and Plantar Flexion

• Flexion – a movement that makes the angle between two bones at their joint smaller than at the beginning of the movement

• Extension – a movement that makes the angle between two bones at their joint larger that at the beginning of the movement

• Abduction – means to move a body part away from the midline of the body

• Adduction – means to move a body part towards to midline of the body

• Rotation – movement around a longitudinal axis

• Circumduction – movement where the distal end of a part moves in a circle

• Supination – a hand position where the palm is turning to face forward or up

• Pronation – a hand position where the palm is turning to face backward or down

• Dorsiflexion – a movement where the top of the foot and toes point upward

• Plantar flexion – a movement where the bottom of the foot and toes are pointed downward

Muscle on your Maniken®

• Temporalis– Origin: Temporal region of the skul– Insertion: Mandible

Function – closes the jaw

• Oribicularis Oculi– Origin: Maxilla and Frontal bone (encircles

eys)– Insertion: Maxilla and Frontal bone

Function – Closes the eye

• Orbicularis oris– Origin: Encircles the lips– Insertion: Encircles the lips

Function – draws lips together

(kissing)

• Intercostals– Origin: inferior border of the ribs– Insertion: superior border of the ribs

Function – to raise the ribs

and expand the chest cavity

to aid in inhalation (breathing)

• Serratus Anterior– Origin: lateral surface of the ribs (1-8)– Insertion: medial border of the scapula

Function – to move the

shoulder forward

• Pectoralis Minor– Origin: anterior surface of the ribs (3-5)– Insertion: coracoid process of the scapula

Function – to rotate the

shoulder forward

• Pectoralis Major – Origin:

• tendon of the external oblique (abdominal portion)• Sternum and upper ribs (sternal portion)• Clavicle (clavicular portion)

– Insertion: lateral edge of the most proximal part of the humerus

Function – adduction and medial rotation of the humerus

• Brachialis– Origin: halfway down the humerus– Insertion: proximal ulna

Function – elbow flexion

• Triceps medial head– Origin: proximal half of the dorsal humerus– Insertion: distal end of elbow on the ulna

Function – extension of

the elbow