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a.
Finger Joint Bones
1. Phalanges
Except
for first digits (thumbs), five digits have three bones; proximal
phalanges, middle phalanges and distal phalanges. First digits
do not have middle phalanges.
b. Finger
Joint Kinesiological Actions
Fingers
bend, straighten, move closer together and move apart. Kinesiologists
do not usually analyze finger movements.
1. Abductions occur when finger joint muscles contract to
move fingers' lateral surfaces apart.
2. Adductions occur when finger joint muscles contract to
move fingers' lateral surfaces closer together.
3. Extensions occur when finger joint muscles contract to
straighen fingers.
4. Flexions occur when finger joint muscles contract to bend
fingers.
c. Finger
Joint Muscle
While
all forearm, wrist and finger muscles contribute to pitching,
I include only the one finger muscle that attaches to the humerus.
1. Flexor
Digitorum Superficialis I
Flexor
digitorum superficialis I muscles attach to middle phalanges
II-Vs' lateral surfaces and to humeral medial epicondyles. When
flexor digitorum superficialis I muscles contract, digits two
through fives' middle phalanges and humerus' medial epicondyles
move closer together. Flexor digitorum superficialis I muscles
indirectly flex, medially flex and medially extend ulnas. Flexor
digitorum superficialis muscles flex metacarpals. Flexor digitorum
superficialis muscles flex middle phalanges. During forearm accelerations,
flexor digitorum superficialis I muscles medially extend elbow
joints, flex wrist joints and flex finger joints.
Flexor
digitorum superficialis I muscles are only slips of large and
more powerful flexor digitorum superficialis II muscles. Flexor
digitorum superficialis II muscles attach to forearms' anterior
surfaces. Flexor digitorum superficialis I muscles are inferior-most
of five flexor epicondyle muscles.
Middle
phalanges II and III drive pitches to releases and distal phalanges
II and III impart distinguishing spins. When finger joint flexion
muscles fatigue, pitchers cannot match baseballs' acceleration
resistance and pitches sail high. Adult pitchers injure fatigued
flexor digitorum superficialis I muscles. Adolescent pitchers
injure skeletally immature medial epicondyle ossification centers,
'Little League Elbow.' Adults cannot suffer 'Little League Elbow.'
In
conclusion, finger joint muscles drive to release and impart
spins. When finger joint flexion muscles fatigue, pitchers lose
control and spin velocities.
d. Pitching
Finger Joint Actions
1. Transition
During
transitions, finger joint muscles mioanglosly flex phalanges.
2. Upper Arm
Acceleration
During
upper arm accelerations, finger joint muscles isoanglosly flex
proximal phalanges II and III and distal phalanges II and III.
3. Forearm
Acceleration
During
forearm accelerations, finger joint muscles mioanglosly flex
proximal phalanges II and III through release and strongly flex
distal phalanges II and III.
4. Deceleration
During
decelerations, finger joint muscles plioanglosly extend phalanges
II and III. |
