Muscular System

MUSCULAR SYSTEM

• a biological system that is composed of skeletal, smooth, and cardiac muscle tissues.

• functions include movement of the body, maintenance of posture, and heat production.

PARTS OF MUSCULAR SYSTEM• Frontalis • In the eyebrows, its primary function

is to lift them (thus opposing the orbital portion of the orbicularis), especially when looking up. It also acts when a view is too distant or dim.

• It is located on the front of the head.• It has no bony attachments.

PARTS OF MUSCULAR SYSTEM• Trapezius • The trapezius is a large superficial muscle that

extends longitudinally from the occipital bone to the lower thoracic vertebrae and laterally to the spine of the scapula (shoulder blade).

• Its functions are to move the scapulae and support the arm.

• The trapezius has three functional regions: the superior region (descending part), which supports the weight of the arm; the intermediate region (transverse part), which retracts the scapulae; and the inferior region (ascending part), which medially rotates and depresses the scapulae.

PARTS OF MUSCULAR SYSTEM• Deltoid • The deltoid muscle is the muscle forming the

rounded contour of the shoulder.• it appears to be made up of three distinct sets of

fibers though electromyography suggests that it consists of at least seven groups that can be independently coordinated by the central nervous system.

• Controls movement in the shoulder. Allows arms to move in a rotational movement.

PARTS OF MUSCULAR SYSTEM• Pectoralis major• The pectoralis major is a thick, fan-shaped

muscle, situated at the chest (anterior) of the body. It makes up the bulk of the chest muscles in the male and lies under the breast in the female. Underneath the pectoralis major is the pectoralis minor, a thin, triangular muscle.

• The pectoralis major is responsible for movement of the shoulder joint.

• 1) It flexes and rotates the humerus.• 2) It keeps the arm attached to the trunk of the

body.

PARTS OF MUSCULAR SYSTEM• Triceps branchii• It is the large muscle on the back of

the upper limb of many vertebrates. It is the muscle principally responsible for extension of the elbow joint (straightening of the arm).

• It extends the elbow along with other muscles which extend the elbow If the arm is abducted, the long head adducts the shoulder along with other Muscles which produce shoulder Adduction.

PARTS OF MUSCULAR SYSTEM• Biceps branchii• The biceps brachii is a two-headed muscle

located on the upper arm. Both heads arise on the scapula and join to form a single muscle belly which is attached to the upper forearm. While the biceps crosses both the shoulder and elbow joints.

• Its main function is at the latter where it flexes the elbow and supinates the forearm. Both these movements are used when opening a bottle with a corkscrew: first biceps unscrews the cork (supination), then it pulls the cork out (flexion)

PARTS OF MUSCULAR SYSTEM

• Latissimus dorsi• It is the larger, flat, dorso-lateral muscle on the trunk,

posterior to the arm, and partly covered by the trapezius on its median dorsal region.

• The latissimus dorsi is responsible for extension, adduction, transverse extension also known as horizontal abduction, flexion from an extended position, and (medial) internal rotation of the shoulder joint. It also has a synergistic role in extension and lateral flexion of the lumbar spine.

PARTS OF MUSCULAR SYSTEM

• Abdominal muscles• It is the part of the body between the pelvis and

the thorax.• Functionally, the human abdomen is where

most of the alimentary tract is placed and so most of the absorption and digestion of food occurs here.

PARTS OF MUSCULAR SYSTEM• Gluteus maximus• It is the largest and most superficial of the three

gluteal muscles. It makes up a large portion of the shape and appearance of the buttocks.

• Its large size is one of the most characteristic features of the muscular system in humans.

• connected as it is with the power of maintaining the trunk in the erect posture.

• Primates have much flatter buttocks.

PARTS OF MUSCULAR SYSTEM

• Sartorius• The Sartorius muscle – the longest muscle in

the human body • is a long thin muscle that runs down the

length of the thigh. Its upper portion forms the lateral border of the femoral triangle.

• It flexes your knees and allows flexing and movement of your hips. If you pick your foot up and look at the sole of your foot then you are using all the functions of the sartorius muscle.

PARTS OF MUSCULAR SYSTEM• Rectus femoris• The rectus femoris muscle is one of the four

quadriceps muscles of the human body.• The rectus femoris is situated in the middle of

the front of the thigh; it is fusiform in shape, and its superficial fibers are arranged in a bipenniform manner, the deep fibers running straight down to the deep aponeurosis.

PARTS OF MUSCULAR SYSTEM• Biceps femoris• one of the posterior femoral muscles. It has two

heads at its origin. The biceps femoris flexes the leg and rotates it laterally and extends the thigh, rotating it laterally.

• It is one of the hamstring muscle group and lies on the posterior, lateral side of the thigh.

• It allows you to jump higher as it extends the thighs and hip movment.

• FLexion and hip extension

PARTS OF MUSCULAR SYSTEM• Gastrocnemius• is a very powerful superficial pennate muscle that

is in the back part of the lower leg. • It runs from its two heads just above the knee to

the heel, and is involved in standing, walking, running and jumping.

• Its function is plantar flexing the foot at the ankle joint and flexing the leg at the knee joint.

PARTS OF MUSCULAR SYSTEM• Achilles tendon• also known as the calcaneal tendon or the tendo

calcaneus, is a tendon of the posterior leg.• It serves to attach the plantaris, gastrocnemius (calf)

and soleus muscles to the calcaneus (heel) bone.• The Achilles tendon unites the two calf muscles to the

heel. The two calf muscles are known as the underlying soleus muscle and the thick outer gastrocnemius muscle.

• When these two muscles contract, the stress on the Achilles causes the heel to rise and the weight of the foot to move onto the toes. This movement is necessary for sprinting, jumping and climbing.

•Properties of muscular system

PROPERTIES OF MUSCULAR SYSTEM

• Muscles are described in reference to four properties: irritability, contractibility, extensibility and elasticity.

PROPERTIES OF MUSCULAR SYSTEM

• Irritability• Irritability denotes how a

muscle responds when it receives an electrical impulse or is damaged.

PROPERTIES OF MUSCULAR SYSTEM

• Contractibility• Contractibility is how

muscles move; they shorten, then relax to control the bones they are attached to.

PROPERTIES OF MUSCULAR SYSTEM

• Extensibility• When muscles are

stretched, they are demonstrating extensibility, which allows the muscles to avoid damage.

PROPERTIES OF MUSCULAR SYSTEM

• Elasticity• A muscle that returns

to its resting position after being stretched or contracted is showing elasticity.

•Types of muscles

TYPES OF MUSCLE

• There are three types of muscle: cardiac, smooth and skeletal.

• The muscles are typed based on what they look like or where they are located.

TYPES OF MUSCLE

• Cardiac muscle is a striated (or banded) fiber located only in the heart.

• Smooth muscle is found within internal organs, blood vessels and glands and is the only non-striated muscle fiber.

• Cardiac and smooth muscle fibers are involuntary, meaning you do not actively control those muscles (such as in your heart beating or your breathing).

• Skeletal muscles are the voluntary muscles and striated muscles that work in pairs to move your body parts.

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