Body Parts And Anatomy
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Anatomy of the Back Muscles
Muscular Anatomy
The human back is the large posterior area of the human body, rising from the top of the buttocks to the back of the neck and the shoulders.
The Latissimus Dorsi muscles (also known as the Lats) are the largest muscles of the back.
Being large, fan-shaped muscles, they are able to provide force in a wide range of body positions, e.g. leaning back to straight vertical and all points in between.
The Lats are attached to the upper end of the humerus with fibers running down in a fan down the vertebral column and pelvic girdle.
The Trapezius (trap) muscle is a long, trapezoid-shaped muscle that runs down the upper section of the spinal cord, originating at the base of the skull and attaching down in the middle to lower back.
The angles of the Trapezius fibers provide pull in three different directions: up, down and in towards the centerline of the body.
The function of the Latissimus Dorsi is to pull the arm down towards the pelvis. When the arm is fixed (e.g. during a chin-up), the lats serve to bring the body up towards the arm. It is the same basic movement but with the directions reversed. The Lats also function to stabilize the torso during many movements, including the flat bench press.
The functions of the Trapezius muscle include scapular elevation (shrugging up), scapular adduction (drawing the shoulder blades together) and scapular depression (pulling the shoulder blades down).
Spinal Erectors
The Erector Spinae is a group of muscles that support the spinal column. They include the Longissimus, the Spinalis and Iliocostalis. The muscles of the Erector Spinae attach to the vertebrae, the ribs and the pelvis. The functions of the Erector Spinae group are to extend the spine as well as provide support for it.
The Teres Major muscle originates on the outer (lateral) edge of the scapula and attaches to the humerus.
The Teres Major muscles work with the Rotator Cuff muscles to stabilize the shoulder joint and works with the Latissimus Dorsi muscles to pull the humerus back.
The Rhomboids (Major and Minor) originate on the spinal column and attach to the middle (medial) surface of the scapula.
The Rhomboid muscles get their name from their shape: rhomboid. The Major and Minor designations refer to their relative size to each other.
The function of the Teres Major is to move the humerus posteriorly, meaning that it brings the arm towards the back.
The Rhomboids function to bring the scapula in towards the spinal column, essentially squeezing the shoulder blades together when the Rhomboids of both sides are used at the same time.
Anatomy and Exercises
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Back Muscles - Keeping the Body Upright
By C-S. Health System
Soft tissues around the spine also play a key role in the health of the back. A large, complex group of muscles works together to support the spine and hold the body upright. They also allow the trunk of the body to move, twist and bend in many directions.

Three types of back muscles that help spinal function are the:
• Extensor muscles. Attached to the back of the spine, these muscles allow us to stand and lift objects. They include the large muscles in the lower back (erector spinae), which help hold up the spine, and gluteal muscles.
• Flexor muscles. Attached to the front of the spine, these muscles include the abdominal muscles. They allow us to flex, bend forward, lift and arch the lower back. When the abdominal muscles are weak, the muscles that allow us to bend at the hip get tighter, increasing the curve at the lower back.
• Oblique muscles. These are attached to the sides of the spine. They help us rotate the spine and maintain proper posture.
Muscles can cause back pain when:
• The facet joints or other parts of the spine become injured and swell, which can cause the large muscles of the back to contract involuntarily (spasm)
• Chronic stress can causes the muscles to tighten up, using up energy that is needed to hold the spine upright
• Tight muscles in the back of the thighs can cause changes in the position of the pelvis, affecting spine movement

Training can modify back muscle response to sudden trunk loading
By University of Copenhagen
Sudden, unexpected loading to the trunk has been reported in the literature as a potential cause of low-back disorders. This study's aim was to investigate the effect of "readiness training" on the response to sudden back loading among untrained healthy individuals. The study included 19 participants and 19 matched controls. All were employees at the National Institute of Occupational Health. The participants received ten 45-min training sessions during a 4-week period. The training focused on reactions to a variety of expected and unexpected sudden trunk loadings, including balance and coordination exercises. Before and after the training, all subjects were tested for reaction to sudden trunk loading (SL). This entailed applying a horizontal force of 58 N to the subject's upper back. Elapsed time--measured between SL and stopping--decreased significantly in the training group (from 337 to 311 ms) compared with the control group. The improved stopping time was associated with a changed EMG signal, characterized by an increase in the early parts of the response (up to 225 ms) and a subsequent decrease. EMG onset latency was unaffected by training. This study is apparently one of the first to demonstrate that the response to sudden trunk loading can be improved in healthy subjects without an increase in pre-activation and associated trunk stiffness. In perspective, the results indicate a possibility for a training-induced reduction of the risk of low-back injuries, e.g., in nurses exposed to sudden trunk perturbations during patient handling.
Muscles Safety
Training tips
  • Maintain your ideal body weight. The more you weigh, the more stress you are putting on your joints, especially your hips, knees, back and feet.
  • Move your body. Exercise protects joints by strengthening the muscles around them. Strong muscles keep your joints from rubbing against one another, wearing down cartilage. We can help you get started on an exercise program that works for you.
  • Stand up straight. Good posture protects the joints in your neck, back, hips and knees.
  • Pace yourself. Alternate periods of heavy activity with periods of rest. Repetitive stress on joints for long periods of time can accelerate the wear and tear that causes osteoarthritis.
  • Listen to your body. If you are in pain, don't ignore it. Pain after activity or exercise can be an indication that you have overstressed your joints.
  • Don't be static. Changing positions regularly will decrease the stiffness in your muscles and joints.
  • Forget the weekend warrior. Don't engage in activities your body for which your body isn't prepared. Start new activities slowly and safely until you know how your body will react to them. This will reduce the chance of injury.
  • Wear proper safety equipment. Don't leave helmets and wrist pads at home. Make sure you get safety gear that is comfortable and fits appropriately.
  • Ask for help. Don't try to do a job that is too big for you to handle. Get another pair of hands to help out.

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