Dr. Mike Marshall's Pitching Book; Chapter Thirteen

Coaching Baseball Pitchers By Michael G. Marshall, Ph.D. Copyright 2007
Section IV:   Applied Anatomy
    For baseball pitchers to perform at their best, all muscle that contribute to the baseball pitching motion throughout the entire body must function properly. However, to discuss all muscles requires too much space and reader’s time. Therefore, I will discuss only thirty-six muscles that attach on one end to pitching arm’s clavicle, scapula or humerus bones.

     Because the muscles that contract during the Transition Phase muscles operate at controlled uniform velocities and, thereby, baseball pitchers cannot injure them, I will not include those muscles in this discussion. Also, because, the muscles that contract during the Deceleration Phase muscles are the same muscles that contract during the Recovery Phase, I will not repeat the names of those muscles. Therefore, for the kinesiological analysis of my baseball pitching motion, I will discuss only the muscles that contract during the Acceleration and Deceleration Phases.

Chapter Thirteen: The Shoulder Girdle
1. Shoulder Girdle Bones

     The Scapula bone is the shoulder girdle bone of interest. Because the Clavicle bone solidly joins the Scapula bone, the Clavicle bone is also a shoulder girdle bone of interest. Actually, because they operate together, we should consider the two bones as one bone.

     The Sternoclavicular Ligament secures the Clavical to the Manubrium of the Sternum in the middle of the chest. And, the Costoclavicular ligament secures the Clavicle to the costal cartilage of the first rib. The Clavicle/Sternal joint has an articular disc. This means that, at its medial end, the Clavicle has some range of motion.

     Laterally, the Clavicle attaches to Acromion process of the Scapula. The two-part Coracoclavicular and Acromioclavicular Ligaments secure the Clavicle to the Scapula. This means that the Clavicle/Scapula joint does not have articular discs. Therefore, the Clavicle does NOT have any range of motion at its lateral end.

     The Clavicle maintains the Scapula at fixed distances from the Sternum. Therefore, the Scapula cannot move closer to or farther away from the Sternum. However, the Scapula can move up and down backs and around sides of rib cages. Consequently, shoulder girdles enjoy a tremendous range of motion.

     Without question, the extreme range of motion of the Scapula bone contributes greatly to baseball pitching. Pitchers with longer Clavicles have a leverage advantage. Therefore, after surgery where doctors removed the lateral one-third of the Clavicle, such as they did with Washington Redskin quarterback Billy Kilmer, because without complete Clavical bones, the contractions of muscles would have to stabilize the medial/lateral movement of the Scapula bone, I did not know how well his shoulder girdle would respond. Therefore, I taught Mr. Kilmer how to eliminate the medial/lateral movement of his passing arm.

     In his next season’s first game, Mr. Kilmer passed the Redskins to victory. Without the lateral one-third of his Clavicle, he passed the football powerfully and accurately. Unfortunately, his battered legs could not keep pace with his passing arm and indomitable spirit for the whole season.

2. Other Shoulder Girdle Bones

     Shoulder girdle muscles attach at one end to either the Clavicle or the Scapula. The other end of shoulder girdle muscles attach to the vertebral column, rib or hip bones.

     The vertebral column has three sections; cervical, thoracic and lumbar. Seven cervical vertebrae make up the neck. Twelve ribs attach to the twelve thoracic vertebrae. Five lumbar vertebrae complete the distal end of the vertebral column.

     The Manubrium, Body and Xiphoid process make up the Sternum. The first rib attaches to the Manubrium of the Sternum. Ribs’ two through seven attach to the Body of the Sternum. The Xiphoid process is a cartilaginous tip that hangs from the Body of the Sternum. Ribs’ one through seven attach to the Sternum. Costal cartilages attach to ribs seven. Ribs’ eight, nine and ten attach to costal cartilages. Ribs’ eleven and twelve float freely.

     The Sacrum, two Ilium bones, two Ischium bones and two Pubis bones form circular hip structures. Below the lumbar vertebrae, five fused sacral vertebrae make up the Sacrum. Bi-lateral sacroiliac ligaments stabilize the Sacrum with the two Ilium bones. Ilium bones are the largest of three bones that make up the two halves of the hips. Three bones fuse into the Acetabulum. The Acetabulum is the joint sockets that receive heads of the Femur bones. The Iliac Crest forms the superior limits of the hip. Two Ischium bones form the posterior/inferior limits of the hip. Humans sit on their Ischial tuberosities. Pubic ligaments attach the two pubis bones together.

3. Shoulder Girdle Kinesiological Actions

     The movement of the Scapula bone defines the kinesiological actions of the shoulder girdle. The Scapula moves up and down, tilts toward front and back, rotates upward and downward and moves away from and toward the vertebral column.

     a. Shoulder Girdle Abduction: When muscles contract that move the Scapula away from the vertebral column.
     b. Shoulder Girdle Adduction: When muscles contract that move the Scapula closer to the vertebral column.
     c. Shoulder Girdle Backward Tilt: When muscles contract that tilt the Scapula backward.
     d. Shoulder Girdle Forward Tilt: When muscles contract that tilt the Scapula forward.
     e. Shoulder Girdle Depression: When muscles contract that move the Scapula downward.
     f. Shoulder Girdle Elevation: When muscles contract that move the Scapula upward.
     g. Shoulder Girdle Downward Rotation: When muscles contract that downwardly rotate the acromion process of the Scapula.
     h. Shoulder Girdle Upward Rotation: When muscles contract that upwardly rotate the acromion process of the Scapula.

4. Shoulder Girdle Muscles

     At one end, the shoulder girdle muscles attach to the Scapula or Clavicle bones, but not to the Humerus, Ulna or Radius bones.

     a. Latissimus Dorsi II

     The Latissimus Dorsi II muscle attaches to the inferior angle of the Scapula bone, to the spinous processes of the seventh through twelfth thoracic vertebraes, to the posterior/superior surfaces of the ninth through twelfth ribs (R9-R12) and to the superior surface of the iliac crest of the Hip bone. Therefore, when the Latissimus Dorsi II muscle contracts, these structures move closer together. This means that the Latissimus Dorsi II muscle depresses the Shoulder Girdle.

     At rest, the inferior angle of the Scapula bone hangs at the level of the eighth thoracic vertebrae (T8). Because, during the deceleration phase of the baseball pitching motion, baseball pitchers must safely return the Scapula bone to its normal resting position, the Latissimus Dorsi II muscle powerfully depresses the Scapula bone.

     Eight percent of the population does not have the Latissimus Dorsi II muscle. To determine whether baseball pitchers have the Latissimus Dorsi II muscle, coaches should have their baseball pitchers place the back of their hands on their hips and move both elbows forward. If the inferior angles of the both Scapula bones dramatically protrude backward, such that coaches can put their fingers under the inferior tip of the Scapula, then these baseball pitchers do not have the Latissimus Dorsi II muscle.

     b. Levator Scapulae

     The Levator Scapulae muscle attaches to the transverse processes of the first through fourth cervical vertebrae (C1-C4) and to the vertebral border of the Scapula bone from the medial angle to root of the spine of the Scapula bone. Therefore, when the Levator Scapulae muscle contracts, these structures move closer together. This means that the Levator Scapulae muscle elevates the Shoulder Girdle.

     At rest, the medial angle of the Scapula bone hangs at the level of the second thoracic vertebrae (T2). Because, during the acceleration phase of the baseball pitching motion, baseball pitchers must have a solid, stable Scapula bone from which to apply their force to their pitches, the Levator Scapulae muscle forwardly solidifies the Scapula bone.

     c. Pectoralis Minor

     The Pectoralis Minor muscle attaches to the coracoid process of the Scapula bone and to the anterior, superior surfaces of the third through fifth ribs (R3-R5). Therefore, when the Pectoralis Minor muscle contracts, these structures move closer together. This means that the Pectoralis Minor muscle forwardly tilts the Shoulder Girdle.

     Because, during the upper arm acceleration phase of the baseball pitching motion, baseball pitchers must have a solid, stable Scapula bone from which to apply their force to their pitches, the Pectoralis Minor muscle forwardly solidifies the coracoid process of the pitching arm side Scapula bone.

     d. Rhomboid Major and Minor

     The Rhomboid Major and Minor muscles attach to the vertebral border of the Scapula bone from the root of its spine to its inferior angle and to the spinous processes of the seventh cervical vertebrae (C7) and first through fifth thoracic vertebrae (T1-T5). Therefore, when the Rhomboid Major and Minor muscles contract, these structures move closer together. This means that the Rhomboid Major and Minor muscles adduct the Shoulder Girdle.

     At rest, the spine of the Scapula bone hangs at the level of the fourth thoracic vertebrae (T4). Because, during the deceleration phase of the baseball pitching motion, baseball pitchers must safely return the Scapula bone to its normal resting position, the Rhomboid Major and Minor muscles powerfully adduct the Scapula bone.

     e. Serratus Anterior

     The Serratus Anterior muscle attaches to a groove along entire vertebral borders of the internal surface of the Scapula bone and to lateral surfaces of the first through ninth ribs (R1-R9). Therefore, when the Serratus Anterior muscle contracts, these structures move closer together. This means that the Serratus Anterior muscle abducts the Shoulder Girdle.

     Because, during the acceleration phase of the baseball pitching motion, baseball pitchers must have a solid, stable Scapula bone from which to apply their force to their pitches, the Serratus Anterior muscles laterally solidifies the vertebral border of the Scapula bone.

     f. Subclavius

     The Subclavius muscle attaches to the inferior surface of the Clavicle and to the anterior aspects of the superior border of the first rib (R1). Therefore, when the Subclavius muscle contracts, these structures move closer together. This means that the Subclavius muscle indirectly forwardly tilts the Shoulder Girdle.

     Because, during the acceleration phase of the baseball pitching motion, baseball pitchers must have a solid, stable Scapula bone from which to apply their force to their pitches, the Subclavius muscle forwardly solidifies the Scapula bone.

     g(1). Trapezius I

     The Trapezius I muscle attaches to lateral one-third of the superior surface of the Clavicle bone, the occipital protuberance of the Skull, the superior nuchal lines and the first three cervical vertebraes (C1-C3). Therefore, when the Trapezius I muscle contracts, these structures move closer together. This means that the Trapezius I muscle elevates and adducts the Shoulder Girdle.

     Because, during the accceleration phase of the baseball pitching motion, baseball pitchers must upwardly rotate the Scapula bone on their pitching side, the Trapezius I muscle elevates the Clavicle bone on their pitching side.

     g(2). Trapezius II

     The Trapezius II muscle attaches to the superior surface of the acromion process of the Scapula bone and to the transverse processes of the seven cervical vertebrae (C1-C7). Therefore, when the Trapezius II muscle contracts, these structures move closer together. This means that the Trapezius II muscle upwardly rotates, elevates and adducts the Shoulder Girdle.

     Because, during the acceleration phase of the baseball pitching motion, to raise their pitching upper arm to as near vertical as possible, baseball pitchers must upwardly rotate the Scapula bone on their pitching side, the Trapezius II muscle upwardly rotates the Scapula bone.

     g(3). Trapezius III

     The Trapezius III muscle attaches to the superior surfaces of the spine of the Scapula bone and to the transverse processes of the first five thoracic vertebraes (T1-T5). Therefore, when the Trapezius III muscle contracts, these structures move closer together. This means that the Trapezius III muscle adducts and upwardly rotates the Shoulder Girdle.

     Because, during the acceleration phase of the baseball pitching motion, baseball pitchers must upwardly rotate the Scapula bone on their pitching side, the Trapezius III muscle adducts and upwardly rotates the Scapula bone.

     g(4). Trapezius IV

     The Trapezius IV muscle attaches to the root of the spine of the Scapula bone and to the transverse processes of the sixth through twelfth thoracic vertebraes (T6-T12). Therefore, when the Trapezius IV muscle contracts, these structures move closer together. This means that the Trapezius IV muscle adducts and upwardly rotates the Shoulder Girdle.

     Because, during the acceleration phase of the baseball pitching motion, baseball pitchers must upwardly rotate the Scapula bone on their pitching side, the Trapezius IV muscle upwardly rotates the Scapula bone.

5. The Kinesiological Actions of the Shoulder Girdle During the Marshall Baseball Pitching Motion

     During the acceleration phase of the Marshall baseball pitching motion, to have a solid base from which to apply their force, baseball pitchers need to powerfully mioanglosly abduct and forwardly tilt the Scapula bone on the pitching side of their body. To enable my baseball pitchers to raise their pitching upper arm to as vertical as possible, they also need to upwardly rotate this Scapula bone.

     During the deceleration phase of the Marshall baseball pitching motion, to safely recover the Scapula bone on the pitching arm side of their body, baseball pitchers need to powerfully plioanglosly adduct, backwardly tilt and downwardly rotate this Scapula bone.

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