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a. Forearm
Joint Bones
The
Radius is the forearm joint bone of interest. Radial heads articulate
with humeral capitulums. Radial collateral ligaments secure radial
heads to humerus' lateral sides. To attach ulnas' proximal/medial
ends and radial collateral ligaments, annular ligaments wrap
around radial heads' anterior surfaces. Radial tuberosities medially
protrude from radius' proximal ends. Oblique cords proximally
attach radiuses and ulnas. Interosseous membranes attach radiuses
and ulnas all along distal two-thirds of radial shafts. Radiuses
rotate toward and away from non-rotating ulnas. Therefore, forearm
joint actions refer only to radial movements.
1. Radius
a) Anterior
Surface
Radius'
anterior surfaces have two bony landmarks, two tendon attachments
and share three lateral surface tendon attachments with posterior
surfaces and one area from which a primary pitching muscle arises.
Radial proximal heads loosely articulate with humeral capitulums.
Biceps brachii muscles' two heads combine into common tendons
that attach to radial tuberosities. Supinator tendons attach
to lateral surfaces of radius' proximal one-quarters. Pronator
teres muscles attach to the lateral surfaces of radius' mid-shafts.
Pronator quadratus tendons attach to distal one-fifths. Brachioradialis
tendons attach to lateral surfaces of radius' distal ends.
b) Posterior
Surface
Radius'
posterior surfaces have no bony landmarks, share three tendon
attachments laterally with anterior surfaces and no areas from
which primary pitching muscles arise. Supinator tendons attach
to lateral surfaces of radius' proximal one-quarters. Pronator
teres muscles attach to lateral surfaces of radius' mid-shafts.
Brachioradialis tendons attach to lateral surfaces of radius'
distal ends.
b. Forearm
Joint Kinesiological Actions
Forearm
joint actions involve radial movements relative to ulnas. Ulnas
remain fixed while radiuses rotate toward and away from ulnas.
Therefore, when discussing forearm joints, examine radial movements.
1. Pronations occur when forearm joint muscles contract to
rotate radiuses toward ulnas.
2. Supinations occur when forearm joint muscles contract
to rotate radiuses away from ulnas.
c. Forearm
Joint Muscles
Forearm
joint muscles attach to radiuses from humeruses or scapulas.
These muscles position radiuses relative to ulnas. When pitchers
throw magnus fastballs, radiuses and ulnas parallelly move toward
home plates. When pitchers throw magnus curves, ulnas lead radiuses.
When pitchers throw airfoil pitches, radiuses lead ulnas.
1. Pronator
Teres
Pronator
teres muscles attach to lateral surfaces of radius' middle one-thirds
and to humeral medial epicondylar ridges. When pronator teres
muscles contract, radius' lateral surfaces and humerus' medial
epicondylar ridges move closer together. Pronator teres muscles
indirectly flex and medially flex ulnas. Pronator teres muscles
pronate radiuses. During forearm accelerations, pronator teres
muscles powerfully pronate forearm joints.
Pronator
teres muscles are superior-most of the five humeral medial epicondyle
muscles. Sports medicine personnel refer to medial epicondyles
as flexor epicondyles and injuries to flexor epicondyle muscles
as 'Little League Elbow.' During forearm accelerations, forearm
joints pronate. Pronator teres muscles directly pronate forearm
joints and indirectly medially extend elbow joints. Forearm joint
pronations continue shoulder joint inward rotations.
Forearm
joint muscles dramatically accelerate pitches through releases.
Pronator teres muscles powerfuly pronate forearm joints and medially
extend elbow joints. Therefore, pronator teres muscle fitness
indicates pitching arm fitness. Consequently, baseball coaches
should palpate pronator teres muscles at forearms' anterior/superior
surfaces. If, with moderate thumb pressures, pitchers complain,
they should not vigorously pitch those days.
During
1974, Los Angeles Dodger pitcher Tommy John suffered a severe
pitching elbow injury. To promote sweating, Tommy wore a rubber
jogging jacket. I arrived at Dodger Stadium early two weeks prior
to Tommy's injury and saw Tommy jogging in his rubber jacket.
I checked Tommy's pronator teres muscle. I found pronator teres
tauntness.
Sweat
contains higher potassium electrolytes than body fluids. Therefore,
sweating reduces potassium concentrations. Potassium/sodium pumps
balance nerve conductions and relaxations. Lower potassium concentrations
increase muscle crampings. I attributed Tommy's pronator teres
tauntness to potassium insufficiency. However, Tommy was enjoying
an outstanding season and continued his training routine.
Two
weeks later, Tommy's forearm buckled when he threw a pitch to
a Montreal Expo batter. He threw one more pitch. The pitch bounced
halfway to home plate. He walked straight to me and said, "You
were right." I walked with him to the training room and
examined his arm. His flexor epicondyle muscles had torn from
the humerus. They balled in the middle of the forearm's anterior
surface. I told Tommy that he has seriously injured his pitching
arm.
The
next day, I arrived at Dodger Stadium to find Tommy throwing
to a catcher in the home bullpen. I grabbed Tommy and took him
to the trainer. I explained Tommy's problem. Fortunately, the
team physician later confirmed my diagnosis and he had corrective
surgery.
2. Biceps
Brachii
Two
biceps brachii tendons attach to scapulas' supraglenoid fossa
and coracoid process and to radial tuberosities. Radial tuberosities
protrude from medial sides of radius' proximal ends. When biceps
brachii muscles contract, radial tuberosities and scapulas' anterior
surfaces move closer together. Biceps brachii muscles indirectly
flex and horizontally flex humeruses. When humeruses abduct overhead
beyond vertical posteriorly, biceps brachii muscles extend humeruses.
Biceps brachii muscles indirectly flex ulnas. Biceps brachii
muscles supinate radiuses. During forearm accelerations, biceps
brachii muscles extend and horizontally flex humeruses. During
decelerations, biceps brachii muscles flex elbow joints and supinate
forearm joints. As with all two-joint muscles, biceps brachii
muscles stabilize one joint before changing other joint angles.
3. Brachioradialis
Brachioradialis
muscles attach to lateral surfaces of radius' styloid processes
and to humerus' lateral supracondylar ridges. When brachioradialis
muscles contract, lateral surfaces of radius' styloid processes
and humerus' lateral supracondylar ridges move closer together.
Brachioradialis muscles indirectly flex and laterally flex ulnas.
Brachioradialis muscles supinate pronated radiuses. During decelerations,
brachioradialis muscles laterally flex elbow joints and supinate
forearm joints.
In
conclusion, forearm joints position radiuses relative to ulnas.
When pitchers throw magnus fastballs, forearm accelerations hold
radiuses parallel to ulnas. When pitchers throw curves, forearm
accelerations lead with ulnas. When pitchers throw airfoil pitches,
forearm accelerations lead with radiuses.
d. Pitching
Forearm Joint Actions
1. Transition
During
transitions, forearm joint muscles maximally mioanglosly supinate
radiuses. To promote easy forearm transitions to proper forearm
leverage positions, pitchers outwardly turn forearms' anterior
surfaces to face upward.
After
the California Angels released Tommy John following the 1986
baseball season, he visited me in Florida to rediscover his proper
pitching rhythm. Tommy's forearm transition movement inwardly
turned his forearms' anterior surface to face downward. I changed
Tommy's forearm transition movement. Tommy described my recommended
forearm transition movement as, '
holding
pie plate of water in his pitching palm and throwing it without
spilling any.' I still recommend not turning the forearm to face
downward, but I have changed the 'don't spill the water' part.
2. Upper Arm
Acceleration
During
upper arm accelerations, forearm joint muscles isoanglosly pronate
radiuses. While humeruses drive toward home plates, forearm joints
maintain forearm leverage positions.
3. Forearm
Acceleration
During
forearm accelerations, forearm joint muscles mioanglosly pronate
radiuses. After humeruses decelerate and stop, elbow and forearm
joints simultaneously drive toward home plates. However, accelerating
baseball inertia prevents radius pronation. When pitchers release
pitches, forearm joints completely pronate radiuses.
4. Deceleration
During
decelerations, forearm joint muscles plioanglosly supinate radiuses. |
