The Skeletal and Muscular Systems

The Skeletal System The bones of the body make up the skeletal system (206 bones in adults) FUNCTION: Bones provide protection for internal organs and work with muscles to enable movement

Label the Skeleton…

Structure of Bones There are two layers of bone –1st LAYER: The outer compact bone- dense connective tissue with a calcium salt matrix (hard) Bone cells release calcium in rings forming tubes called Haversian canals –2nd LAYER: The inner layer of spongy bone with many cavities… (bone marrow makes blood cells and platelets some bone marrow stores fats for energy) –Covering-tough exterior membrane called the periosteum

Joints The place where two bones meet are called joints A tough connective tissue called cartilage cushions the bones at the joints Bands of connective tissue called ligaments hold bones together anterior cruciate ligament cartilage

Types of Joints Ball-and-socket joints: allow the widest range of motion – backward, forward, sideways, and in a circle –Hips and shoulders Pivot joints: allow a rotation movement –Vertebrae in the neck Hinge joints: allow bending and straightening –Knees and knuckles

Ball-and-socket joints

Pivot Joints

Hinge Joints

More Joint Types Gliding joints: allow a sliding motion –Wrists and ankles Saddle joint: allows rotation and bending –At the base of the thumb

Gliding Joints

Hinge Joints Saddle Joint

Muscular System Although bones allow for movement, they couldn’t do so without the muscular system Your body has over 600 muscles All muscles are specialized for contraction "It eats meat. We're meat!” -From Zathura

Types of Muscles Smooth muscle – found in organs and blood vessels…under involuntary control Cardiac muscle – found only in the heart…under involuntary control Skeletal muscle – attached to bones by strips of connective tissue called tendons

Skeletal muscle Smooth muscle Cardiac muscle

How they work… Muscles receive a nerve impulse with causes them to contract… They are attached to bones in opposing pairs –Flexor muscles cause a joint to bend –Extensor muscles cause a joint to straighten Connective tissues called tendons connect the muscles to the bones

Relationships… The muscular and skeletal systems work together to allow movement. The circulatory system brings oxygen (respiratory) and nutrients (digestive) to the muscles and removes wastes (excretory). The nervous system tells the muscles to move (voluntarily and involuntarily).