Contrahens

Contrahens

The contrahentes (singular contrahens) are muscles widely present in the hands of mammals, including monkeys and gorillas.[1] They are on the palmar/plantar side. There is one each for digits I II IV V but not III. They pull the fingers/toes down and together.

Contents

Human anatomy

In humans, the adductor pollicis muscle (and the adductor hallucis in the foot) is a well-developed remnant of the first contrahens though it has lost the insertion on the distal phalanx of the thumb. [1] The other contrahentes only appear as rare atavistic abnormalities. [2] In other mammals, the contrahentes may have their origin either on the carpus or the metacarpus, which suggests that the palmar interossei muscles also contain elements of the contrahentes. [1] They appear in the human fetus as a layer of flesh which mostly disappears.

In other animals

The contrahentes of the fourth digit is absent in dogs but present in cats and rabbits. [1]

In primates, the contrahentes vary in number between zero and four. By their insertion onto the proximal phalanges they facilitate convergence of the digits. [3]

In tarsiers, they facilitate the grip by increasing the pressure between the large distal pads and the gripped surface by simultaneously flexing the metacarpophalangeal joints and the proximal interphalangeal joints and extending the distal interphalangeal joints. [3]

Notes

  1. ^ a b c d Yamamoto, Murakami & Ohtsuka 1988
  2. ^ Stark et al. 1979
  3. ^ a b Wright, Simons & Gursky 2003, p. 100

References

v · d · eList of muscles of upper limbs (TA A04.6, GA 4.432)
Shoulder

deltoid · rotator cuff (supraspinatus, infraspinatus, teres minor, subscapularis) · teres major

fascia: Deltoid fascia · Supraspinous fascia · Infraspinous fascia
Arm
(compartments)
Axillary sheath · Axillary fascia · Brachial fascia · intermuscular septa (Lateral, Medial)
Other
Forearm
Other
Hand
Lateral volar
Medial volar
Intermediate
lumbrical · interossei (dorsal, palmar)

M: MUS, DF+DRCT

anat (h/n, u, t/d, a/p, l)/phys/devp/hist

noco(m, s, c)/cong(d)/tumr, sysi/epon, injr

proc, drug (M1A/3)
v · d · eList of muscles of lower limbs (TA A04.7, GA 4.465)
ILIAC Region
/ ILIOPSOAS
BUTTOCKS
THIGH /
compartments
LEG/
Crus/
compartments
fibularis muscles (longus, brevis)
FOOT
Dorsal
Plantar

M: MUS, DF+DRCT

anat (h/n, u, t/d, a/p, l)/phys/devp/hist

noco(m, s, c)/cong(d)/tumr, sysi/epon, injr

proc, drug (M1A/3)


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