NASM: Chapter 5 - The Nervous, Skeletal, and Muscular Systems Part 1

The combination and interrelation of the nervous, muscular, and skeletal systems. It includes functional anatomy, functional biomechanics, and motor behavior.

1. Sensory Function

2. Integrative Function

3. Motor Function

A conglomeration of billions of cells specifically designed to provide a communication network within the human body.

The ability of the nervous system to sense changes in either the internal or external environment.

The ability of the nervous system to analyze and interpret sensory information to allow for proper decision making, which produces the appropriate response.

The neuromuscular response to the sensory information.

The cumulative sensory input to the central nervous system from all mechanoreceptors that sense body position and limb movement.

The neuron cell body contains the nucleus and other organelles, including lysosomes, mitchondia, and a Golgi complex.

Dendrites gather information from other structures and transmit it back into the neuron.

• A cylindrical projection from the cell body that transmits nervous impulses to other neurons or effector sites (muscles, organs).
  (Passes messages away from the cell body to the other neurons, muscles or glands.)

• It is the part of the neuron that provides communication from the brain and spinal cord to other parts of the body.

A specialized cell that processes and transmits information through both electrical and chemical signals.

It is the functional unit of the nervous system and is divided into 3 main parts: the cell body, axon, and dendrites.

Sensory neurons transmit nerve impulses from effector sites (such as muscles and organs) via receptors to the brain and spinal cord.

They respond to touch, sound, light, and other stimuli and transmit nerve impulses from effector sites.

Interneurons are neurons that transmit nerve impulses from one neutron to another.

Motor neurons transmit nerve impulses from the brain and spinal cord to effector sites such as muscles or glands.

Example: brain tells hand muscles to let go of a hot coffee cup (after interpreted it was hot from sensory neurons and communicated through Interneurons).

1. Providing a connection for the nervous system to activate different effector sites, such as muscles (motor function).

2. Relaying information from effector sites back to the brain via sensory receptors (sensory function).

Overall peripheral nerves/nervous system provide a constant update on the relation between the body and the environment.

The PNS consists of 12 cranial nerves, 31 pairs of spinal nerves (which branch out from the brain and spinal cord), and sensory receptors that spread throughout the body.

1. Somatic nervous system: nerves that serve the outer areas of the body and skeletal muscle, and are largely responsible for the voluntary control of movement.

2. Autonomic nervous system: supplies neural input to the involuntary systems of the body (heart, digestive systems, and endocrine glands).

1. Sympathetic - increase levels of activation in preparation for activity

2. Parasympathetic - decrease levels of activation during rest and recovery.

Sensory receptors are specialized structures located throughout the body that convert environmental stimuli (heat, light, sound, taste, and motion) into sensory information that the brain and spinal cord use to produce a response.

1. mechanoreceptors (touch and pressure)

2. nociceptors (pain receptors)

3. chemoreceptors (chemical interaction / smell and taste)

4. photo receptors (light / vision)

Mechanoreceptors are sensory receptors responsible for sensing distortion in body tissues / respond to mechanical pressure and outside forces (touch, pressure, stretching, sound waves, and motion) within tissues and then transmit signals through sensory nerves.

They are located in muscles, tendons, ligaments, joint capsules, and include muscle spindles, Golgi tendon organs, and joint receptors.

Muscle spindles are receptors that run parallel to muscle fibers that are sensitive to change in length of the muscle and the rate of that change.

Muscle spindles help regulate the contraction of muscles via the stretch reflex mechanism (when stretching.

The spindle sends an impulse to the brain, the brain then sends info to contract muscle within 1 to 2 milliseconds to prevent overstretching and potential muscle damage.

GTOs are receptors sensitive to change in tension of the muscle and the rate of that change.

They are located where skeletal muscle fibers insert the tendons of skeletal muscle.

Activation of the Golgi tendon organ will cause the muscle to relax, which prevents the muscle from excessive stress or possibility of injury.

• Receptors surrounding a joint that respond to pressure, acceleration, and deceleration of the joint, and act to signal extreme joint positions in order to prevent injury.

• Located in and around the joint capsule.

• Can initiate a reflexive inhibitory response in the surrounding muscles if there is too much stress placed on that joint.

• Examples: Ruffini endings and Pacinian corpuscles

The kinetic chain is the linked system of nerves, muscles, and joints that work together to produce movements.

The kinetic chain integrates these systems to produce efficient movement.

To produce motion/force

• The body's framework, composed of bones and joints. It provides the shape and form for our bodies in addition to supporting, protecting, allowing body movement, producing blood for the body, and storing minerals.

• Composed of 206 bones (approx. 177 are used in voluntary movement)

Note: the growth, maturation, and functionality of the skeletal system are greatly affected by posture, physical activity, and nutrition status.

The portion of the nervous system that consists of the brain and spinal cord.

The portion of the skeletal system that consists of the skull, rib age, and vertebral column.

Contains approximately 80 bones.

Joints are the junctions of bones, muscles, and connective tissue at which movement occurs.

The portion of the skeletal system that includes the upper and lower extremities as well as shoulders and pelvic girdles.

Contains approximately 126 bones.

The pelvic girdle is often considered a component of either the axial or appendicular system and is actually a link between the two systems.

1. Act and perform as levers when acted on by muscles.

2. Provide Support, which translates into posture and is necessary for the efficient distribution of forces acting on the body.

Bones are hard structures that provide a resting ground for muscles and protection of vital organs.

The process of resorption and formation of bone.

1. Long Bones

2. Short Bones

3. Flat Bones

4. Irregular Bones

5. Sesamoid Bones

A type of cell that is responsible for bone formation

Osteoblasts lay down new bone tissue to replace the old during remodeling.

A type of bone cell that removes bone tissue during resorption.

Osteoclasts break down during resorption, removed by osteoclasts.

• Bones with a long, cylindrical body (shaft), with irregular or widened bony ends with slight curvature that is necessary for efficient force distribution.

• Composed predominately of compact bone tissue to ensure strength and stiffness.

• Contains considerable amounts of spongy bone tissue for shock absorption.

• Upper Body Long Bones: clavicle, humerus, radius, ulna, metacarpals, and phalanges.

• Lower Body Long Bones: femur, tibia, fibula, metatarsals, and phalanges.

• The end of long bones, which is mainly composed of cancellous bone, and houses much of the red marrow involved in red blood cell production.

• They are also one of the primary sites for bone growth.

Note: during growth periods, the area can be vulnerable to injury.

The shaft portion of the long bone, predominately consisting of compact bone with a hollow inside shaft.

• The region of long bone connecting the diaphysis to the epiphysis.

• It is a layer of subdividing cartilaginous cells in which growth in length of the diaphysis occurs.

Note: damage to the epiphyseal plate before the end of growth in puberty could result in shorter bone

• A dense, tough membrane composed of fibrous connective tissue that closely wraps (invests) all bone, except that of the articulating surfaces in joints, which are covered by a synovial membrane.

• It contains nerves, blood vessels, and bone-producing cells

• Inner surface provides the materials for nutrition repair and facilitates growth in the diameter of the bone.

• Fundamental Role in movement by providing the point of attachment for tendons.

The space that runs down through the center of the diaphysis and contains fatty yellow marrow that is predominately composed of adipose tissue and serves as a useful energy reserve.

• Cartilage that covers the articular surfaces of bones.

• Hard, white, shiny tissue that, along with synovial fluid, helps reduce friction in freely moveable (synovial joints).

• Fundamental for smooth joint action.

• Similar in length and width and appear somewhat cubical in shape.

• Consist predominately of spongy bone tissue to maximize shock absorption.

• Examples: carpals of hands and tarsals of feet

• Thin bones comprising two layers of compact bone tissues surrounding a layer of spongy bone tissue.

• Involved in protection of internal structures.

• Provide broad attachments for muscles.

• Examples: sternum, scapulae, ribs, ilium, and cranial bones.

• Unique shape and function

• Do not fit characteristics of other bone categories.

• Examples: vertebrae, pelvic bones, and certain facial bones.

• Small bones embedded in a joint capsule or found in locations where a tendon passes over a joint.

• Develop within particular tendons at a site of considerable friction or tension.

• Serve to improve leverage and protect the joints from damage.

• Example: the patella in the knee

• Projections protruding from the bone where muscles, tendons, and ligaments can attach.

• More common processes:

• Process

• Condyle

• Epicondyle

• Tubercle

• Trochanter

• Projections protruding from the bone where muscles, tendons, and ligaments can attach.

• More common processes:

1. Spinous

2. Coracoid

3. Condyle

4. Epicondyle

5. Tubercle

6. Trochanter

1. Cervical vertebrae (C1-C7): first 7 vertebrae starting at the top of the spinal column that form a flexible framework and provide support and motion for the head.

2. Thoracic vertebrae (T1-T12): next 12 vertebrae located in the upper and middle back behind the ribs. Move with the ribs to form rear anchor to the rib cage. Larger than cervical vertebrae and increase in size from top to bottom.

3. Lumbar vertebrae (L1-L5): 5 vertebrae of the low back below the thoracic spine. Support most of the body's weight and are attached to many of the back muscles. Often a location of pain since these vertebrae carry the most amount of weight and are subject to the largest forces and stresses along the spine.

4. Sacrum: triangular bone located below the lumbar spine. Consists of 4 or 5 sacral vertebrae in a child, which become fused into a single bone during adulthood.

5. Coccyx: located below the sacrum, more commonly known as the tailbone. Consists of 3 to 5 bones that are fused together in an adult. Many muscles connect to the coccyx.

• Optimal arrangement of curves in which the vertebrae and associated structures are under the least amount of load.

1. Posterior cervical curvature: a posterior concavity of the cervical spine.

2. Anterior thoracic curvature: a posterior convexity of the thoracic spine.

3. Posterior lumbar curvature: a posterior concavity of the lumbar spine.

By two bones that articulate with one another.

Joint motion

1. Roll

2. Slide

3. Spin

One joint rolls across the surface of another like a bike tire rolls on the street.

Body example: femoral condyles moving (rolling) over the tibial condyles in a squat.

One joint's surface slides across another like bike tires skidding on the street.

Body example: the tibial condyles moving (sliding) across the femoral condyles during a knee extension.

One joint's surface rotates on another like twisting a lid of a jar.

Example: the head of the radius (a bone of the forearm) rotating on the end of the humerus during pronation and supination of the forearm.

Joints that are held together by a joint capsule and ligaments and are most associated with movement in the body.
These are the most common joint types - 80% of all joints in the body are synovial.

To increase mobility.

1. Synovial capsule: collagenous structure surrounding the entire joint

2. Synovial membrane: inner layer of the capsule

3. Hyaline cartilage: pads the ends of the articulating bones

A fluid that resembles egg whites and works like engine oil.
It is secreted within joint capsule from synovial membrane to lubricate joint surfaces to reduce excessive wear and to nourish the cartilage cells that line the joint.