Dr. Mike Marshall's Pitching Book; Chapter Fourteen

Coaching Baseball Pitchers By Michael G. Marshall, Ph.D. Copyright 2007
Chapter Fourteen: The Shoulder Joint
1. Shoulder Joint Bones

     The Humerus bone is the bone of interest in the Shoulder Joint. The head of the Humerus bone articulates with the Glenoid Fossa of the Scapula bone. The Glenoid Fossa has a very shallow fossa. While the shallowness of the Glenoid Fossa decreases the stability of the Shoulder Joint, it also increases the range of motion of the Shoulder Joints. This means that the Humerus bone has a three hundred and sixty degree full circle range of motion.

     Anteriorly, the Gleno-Humeral ligaments stabilize the head of he Humerus bone in the Glenoid Fossa. Superiorly, the Coraco-Humeral ligament suspends the head of the Humerus bone.

     A circular band of connective tissue called, the ‘Labrum,’ attaches to the rim of the Glenoid Fossa. Its purpose is to stabilize the head of the Humerus bone in the Glenoid Fossa. The long head of the Biceps Brachii muscle attaches to the Labrum on its superior border and the posterior head of the Triceps Brachii muscle attaches to the Labrum on it inferior border.

     a. Humerus

         1) Anterior Surface

     The anterior surface of the proximal (shoulder) end of the Humerus bone has four bony landmarks; the head of the Humerus bone, the bicipital groove, the lesser tuberosity and the greater tuberosity.

01. From the shaft of the Humerus bone, the head of the Humerus bone angles inward and, with a smooth, round surface articulates with the Glenoid Fossa of the Scapula bone.
02. The Bicipital Groove divides the lateral greater tuberosity from the medial lesser tuberosity and extends one-quarter down the shaft of the Humerus bone.
03. The Lesser Tuberosity protrudes from the medial aspect of the head of the Humerus bone.
04. The Greater Tuberosity protrudes from the lateral, superior aspect of the Humerus bone.

     The tendons of five Shoulder Joint muscles attach to the anterior surface of the proximal end of the Humerus bone.

01. The tendon of the Pectoralis Major muscle attaches to the lateral lip of the bicipital groove.
02. The tendon of the Latissimus Dorsi muscle attaches to the medial lip of the bicipital groove.
03. The tendon of the Teres Major muscle also attaches to the medial lip of the bicipital groove just next to the tendon of the Latissimus Dorsi muscle.
04. The tendon of the Subscapularis muscle attaches to the lesser tuberosity of the head of the Humerus bone.
05. The tendon of the Supraspinatus muscle attaches to the superior surface of the greater tuberosity on the head of the Humerus bone.

     The lateral surface of the mid-shaft of the Humerus bone has one bony landmark; the Deltoid Tuberosity.

     Two tendons attach to the lateral and medial surfaces of the mid-shaft of the Humerus bone.

01. The tendons of the Anterior, Middle and Posterior Deltoid muscles attach to the Deltoid Tuberosity, which is on the lateral surface of the mid-shaft of the Humerus bone.
02. The tendon of the Coracobrachialis muscle attaches to the medial surface of the mid-shaft of the Humerus bone.

     The anterior surface of the distal (elbow) end of the Humerus bone has seven bony landmarks.

01. The Medial Supracondylar Ridge lies immediately above the Medial Epicondyle on the medial side of the anterior surface of the distal end of the Humerus bone.
02. The Lateral Supracondylar Ridge lies immediately above the Lateral Epicondyle on the lateral side of the anterior surface of the distal end of the Humerus bone.
03. The Medial Epicondyle protrudes medially off the side of the distal end of the Humerus bone.
04. The Lateral Epicondyle protrudes laterally off the side of the distal end of the Humerus bone.
05. The Trochlea lies on the medial side of the distal end of the Humerus bone and articulates with the Ulna bone of the forearm.
06. The Capitulum lies on the lateral side of the distal end of the Humerus bone and articulates with the head of the Radius bone of the forearm.
07. The Coronoid Fossa lies between the Medial and Lateral Epicondyles on the anterior surface of the distal end of the Humerus bone.

     Nine elbow and forearm joint muscles arise from the anterior surface of the distal end of the Humerus bone.

01. The Brachialis muscle arises from entire distal one-half of the anterior surface of the Humerus bone.
02. The Pronator Teres muscle arises from the medial supracondylar ridge.
03. The Flexor Carpi Radialis muscle arises from the medial epicondyle of the anterior surface of the distal Humerus bone.
04. The Palmaris Longus muscle arises from the medial epicondyle of the anterior surface of the distal Humerus bone.
05. The Flexor Carpi Ulnaris muscle arises from the medial epicondyle of the anterior surface of the distal Humerus bone.
06. A small portion of the Flexor Digitorum Superficialis muscle arises from the medial epicondyle of the anterior surface of the distal Humerus bone.
07. The Brachioradialis muscle arises from the lateral supracondylar ridge of the anterior surface of the distal Humerus bone.
08. The Extensor Carpi Radialis Longus muscle arises from the lateral epicondyle of the anterior surface of the distal Humerus bone.
09. The Extensor carpi radialis brevis muscle arises from the lateral epicondyle of the anterior surface of the distal Humerus bone.

         2) Posterior Surface

     The posterior surface of the Humerus bone has one bony landmark, the Olecranon Fossa, which lies at the distal end of the Humerus bone between the medial and lateral epicondyles.

     The tendons of two Shoulder Joint muscles attach to the posterior surface of the Humerus bone.

01. The tendon of the Infraspinatus muscle attaches to the posterior surface of the head of the Humerus bone immediately below the attachment of the Supraspinatus muscle.
02. The tendon of the Teres Minor muscle attaches to the posterior surface of the Humerus bone immediately below the attachment of the Infraspinatus muscle.

     Three elbow and forearm joint muscles arise from the posterior surface of the Humerus bone.

01. The lateral head of the Triceps Brachii muscle arises from the lateral side of the posterior surface of the proximal one-third of the Humerus bone.
02. The medial head of the Triceps Brachii muscle arises from the posterior surface of the distal one-half of the Humerus bone.
03. The Anconeus muscle arises from the Capitulim on the posterior surface of the distal end of the Humerus bone.

2. Other Shoulder Joint Bones

     While most Shoulder Joint muscles attach between the Scapula and the Humerus bones, some Shoulder Joint muscles attach to the Sternum, the vertebral column and the bones of the hip.

      a. Sternum

     The Manubrium, Body and Xiphoid Process makes up the Sternum. The first rib attaches to the Manubrium of the Sternum. The second through seventh ribs attach to the Body of the Sternum. The Xiphoid Process is the cartilaginous tip that hangs from the Body of the Sternum.

3. Shoulder Joint Kinesiological Actions

     The movements of the Humerus bone define the kinesiological actions of the Shoulder Joint. The Humerus bone moves forward and backward, up from and down to sides, forward and backward from shoulder high positions and rotate inwardly and outwardly.

1. Shoulder Joint Abduction: When muscles contract that move the Humerus bone upward from the sides of the body.
2. Shoulder Joint Adduction: When muscles contract that move the Humerus bone down to the sides of the body.
3. Shoulder Joint Extension: When muscles contract that move the Humerus bone backward from the sides of the body.
4. Shoulder Joint Flexion: When muscles contract that move the Humerus bone forward from the sides of the body.
5. Shoulder Joint Horizontal Extension: When muscles contract that move the shoulder high abducted Humerus bone backward.
6. Shoulder Joint Horizontal Flexion: When muscles contract the move the shoulder high abducted Humerus bone forward.
7. Shoulder Joint Inward Rotation: When muscles contract that inwardly rotate the Humerus bone.
8. Shoulder Joint Outward Rotation: When muscles contract that outwardly rotate the Humerus bone.

4. Shoulder Joint Muscles

     Shoulder Joint muscles attach at one end to the Humerus bone.

     a. Coracobrachialis

     The Coracobrachialis muscle attaches to the middle of the medial side of the mid-shaft of the Humerus bone and to the Coracoid Process of the Scapula bone. Therefore, when the Coracobrachialis muscle contracts, these structures move closer together. This means that the Coracobrachialis muscle adducts and flexes the Shoulder Joint.

     Because, during the acceleration phase of the baseball pitching motion, baseball pitchers must have a solid platform from which to forwardly accelerate their pitching forearm through release, the Coracobrachialis muscle forwardly ‘locks’ their Humerus bone of their pitching upper arm with their Scapula bone.

     b(1). Deltoid, Anterior

     The Anterior deltoid muscle attaches to the deltoid tuberosity on the lateral side of the mid-shaft of the Humerus bone and to the lateral one-third of anterior surface of the Clavicle. Therefore, when the Anterior Deltoid muscle contracts, these structures move closer together. This means that the Anterior Deltoid muscle abducts and flexes the Shoulder Joint.

     Because, during the acceleration phase of the baseball pitching motion, baseball pitchers must have a solid platform from which to forwardly accelerate their pitching forearm through release, the Anterior Deltoid muscle forwardly ‘locks’ their Humerus bone of their pitching upper arm with their Scapula bone.

     b(2). Deltoid, Middle

     The Middle Deltoid muscle attaches to the middle portion of the deltoid tuberosity of the Humerus bone and to the superior surface of the acromion process of the Scapula bone. Therefore, when the Middle Deltoid muscle contracts, these structures move closer together. This means that the Middle Deltoid muscle abducts the Shoulder Joint.

     Because, during the deceleration phase of the baseball pitching motion, baseball pitchers must safely return the Humerus bone to its normal resting position, the Middle Deltoid muscle outwardly rotates the Humerus bone.

     b(3). Deltoid, Posterior

     The Posterior Deltoid muscle attaches to lateral portion of the deltoid tuberosity of the Humerus bone and to the superior surface of the spine of the Scapula bone. Therefore, when the Posterior Deltoid muscle contracts, these structures move closer together. This means that the Posterior Deltoid muscle abducts and extends the Shoulder Joint.

     Because, during the deceleration phase of the baseball pitching motion, baseball pitchers must safely return the Humerus bone to its normal resting position, the Posterior Deltoid muscle extends and outwardly rotates the Humerus bone.

     c. Infraspinatus

     The Infraspinatus muscle attaches to the posterior surface of the head of the Humerus bone immediately below the attachment of the Supraspinatus muscle and to the infraspinatus fossa on the posterior surface of the Scapula bone below its spine. Therefore, when the Infraspinatus muscle contracts, these structures move closer together. This means that the Infraspinatus muscle extends the Shoulder Joint. The Infraspinatus muscle is the third anterior-most of the four rotator cuff muscles.

     Because, during the deceleration phase of the baseball pitching motion, baseball pitchers must safely return the Humerus bone to its normal resting position, the Infraspinatus muscle extends and outwardly rotates the Humerus bone.

     d. Latissimus Dorsi I

     The Latissimus Dorsi I muscle attaches to the medial lip of the bicipital groove on the anterior surface of the proximal end of the Humerus bone and to the spinous processes of the seven through ninth thoracic vertebrae (T7-T9), to the posterior/superior surfaces of the nine through twelfth ribs (R9-R12) and to the superior surfaces of the Iliac Crest. Therefore, when the Latissimus Dorsi I muscle contracts, these structures move closer together. This means that the Latlissimus Dorsi I muscle extends, horizontally extends and inwardly rotates the Shoulder Joint.

     Because, during the deceleration phase of the baseball pitching motion, baseball pitchers must safely return the Humerus bone to its normal resting position, the Latissimus Dorsi I muscle horizontally extends the Humerus bone.

     Because, during the acceleration phase of the baseball pitching motion, baseball pitchers must powerfully inwardly rotate their Humerus bone through release, after horizontally extending the Humerus bone of the pitching upper arm to a stop, the Latissimus Dorsi I muscle powerfully inwardly rotates the Humerus bone.

     e. Pectoralis Major

     The Pectoralis Major muscle attaches to the lateral lip of the bicipital groove and to the medial one-third of the anterior surface of the Clavicle, the Sternum and the anterior surfaces of the first through seventh ribs (R1-R7). Therefore, when the Pectoralis Major muscle contracts, these structures move closer together. This means that the Pectoralis Major muscle flexes and inwardly rotates the Shoulder Joint.

     Because, during the acceleration phase of the baseball pitching motion, baseball pitchers must have a solid platform from which to forwardly accelerate their pitching forearm through release, the Pectoralis Major muscle forwardly ‘locks’ the Humerus bone of their pitching upper arm with their Scapula bone.

     f. Subscapularis

     The Subscapularis muscle attaches to the lesser tuberosity of the head of the Humerus bone and to the entire internal surfaces of subscapular fossa of the Scapula bone. Therefore, when the Subscapularis muscle contracts, these structures move closer together. This means that the Subscapularis muscle adducts and inwardly rotates the Shoulder Joint. The Subscapularis muscle is the anterior-most of the four rotator cuff muscles.

     Because, during the acceleration phase of the baseball pitching motion, baseball pitchers must have a solid platform from which to forwardly accelerate their pitching forearm through release, the Subscapularis muscle forwardly ‘locks’ the Humerus bone of their pitching upper arm with their Scapula bone.

     g. Supraspinatus

     The Supraspinatus muscle attaches to the top of the head of the Humerus bone and to the supraspinatus fossa on the posterior surface of the Scapula bone above its spine. Therefore, when the Supraspinatus muscle contracts, these structures move closer together. This means the the Supraspinatus muscle abducts the Shoulder Joint. The Supraspinatus muscle is the second anterior-most of the four rotator cuff muscles.

     Because, during the acceleration phase of the baseball pitching motion, baseball pitchers must powerfully inwardly rotate their Humerus bone through release. After decelerating the Humerus bone of the pitching upper arm to a stop, the Supraspinatus muscle powerfully inwardly rotates the Humerus bone.

     Because, during the deceleration phase of the baseball pitching motion, baseball pitchers must safely return the Humerus bone to its normal resting position, the Supraspinatus muscle outwardly rotates the Humerus bone.

     h. Teres Major

     The Teres Major muscle attaches to the medial lip of the bicipital groove of the Scapula bone immediately outside of the attachment of the Latissimus Dorsi I muscle and to the inferior one-thirds of posterior surfaces of the axillary border of the Scapula. Therefore, when thhe Teres Major muscle contracts, these structures move closer together. This means that the Teres Major muscle extends, horizontally extends and inwardly rotates the Shoulder Joint.

     Because, during the deceleration phase of the baseball pitching motion, baseball pitchers must safely return the Humerus bone to its normal resting position, the Teres Major muscle horizontally extends the Humerus bone.

     Because, during the acceleration phase of the baseball pitching motion, baseball pitchers must powerfully inwardly rotate their Humerus bone through release. After decelerating the Humerus bone of the pitching upper arm to a stop, the Teres Major muscle powerfully inwardly rotates the Humerus bone.

     i. Teres Minor

     The Teres Minor muscle attaches to the posterior surface of the head of the Humerus bone immediately below the attachment of the Infraspinatus muscle and to the middle one-thirds of posterior surfaces of axillary border of the Scapula bone. Therefore, when the Teres Minor muscle contracts, these structures move closer together. This means that the Teres Minor muscle extends the Shoulder Joint. The Teres Minor muscle is the fourth anterior-most muscle of the rotator cuff muscles.

     Because, during the deceleration phase of the baseball pitching motion, baseball pitchers must safely return the Humerus bone to its normal resting position, the Teres Minor muscle extends, horizontally extends and outwardly rotates the Humerus bone.

5. The Kinesiological Actions of the Shoulder Joint 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 extend the Humereus bone in their pitching upper arm. To enable my baseball pitchers to raise their pitching upper arm to as vertical as possible, at the same time that they maximally upwardly rotate the Scapula bone on their pitching arm side, they need to maximally mioanglosly abduct their Humerus bone in their pitching upper arm.

     During the deceleration phase of the Marshall baseball pitching motion, to safely recover the Humereus bone in the pitching upper arm, baseball pitchers need to continue to powerfully plioanglosly abduct and outwardly rotate this Humerus bone.

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