What are the intrinsic muscles of the hand?

The intrinsic muscles of the hand are a group of 20 muscles located entirely within the hand. They are essential for fine motor control and grip precision, and are classified into five groups: thenar muscles, adductor pollicis, hypothenar muscles, lumbricals, and interossei (palmar and dorsal).

What is the function of the thenar muscles?

The thenar muscles form the thenar eminence on the lateral palm and primarily enable thumb opposition. They include the abductor pollicis brevis, flexor pollicis brevis, and opponens pollicis, which work together for fine motor control of the thumb.

How are the lumbrical muscles innervated?

The innervation of the lumbrical muscles varies: the first and second lumbricals are innervated by the median nerve, while the third and fourth lumbricals are innervated by the deep branch of the ulnar nerve.

What is the difference between palmar and dorsal interossei muscles?

The interossei muscles are divided into two groups: palmar interossei (4 muscles), which adduct the digits, and dorsal interossei (4 muscles), which abduct the digits. Both groups assist in hand movements like extending IP joints and flexing MP joints.

What is Froment's sign used to test?

Froment's sign is a clinical test used to assess the function of the adductor pollicis muscle. It helps detect ulnar nerve palsy by observing thumb flexion at the IP joint when a patient grips a paper between the thumb and index finger.

Which nerves innervate the intrinsic hand muscles?

The intrinsic hand muscles are primarily innervated by two nerves: the median nerve innervates the thenar muscles and the first two lumbricals, while the ulnar nerve innervates the hypothenar muscles, adductor pollicis, interossei, and the last two lumbricals.

What is the role of the adductor pollicis muscle?

The adductor pollicis is a deep, fan-shaped muscle that plays a key role in thumb grip strength. Its main action is adduction of the thumb, pulling it toward the palm to enhance grip and precision movements.

Intrinsic Hand Muscles – Thenar, Hypothenar & Interossei

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