Total no of intrinsic hand muscles

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Here is a complete, textbook-confirmed answer on intrinsic hand muscles:

Intrinsic Muscles of the Hand - Total: 20

The intrinsic muscles of the hand have both their origin and insertion within the hand itself. They are divided into four groups:

1. Thenar Muscles (4)

#	Muscle	Nerve
1	Abductor pollicis brevis	Median (recurrent branch)
2	Flexor pollicis brevis	Median (recurrent branch)
3	Opponens pollicis	Median (recurrent branch)
4	Adductor pollicis	Ulnar (deep branch)

Note: Adductor pollicis is often grouped separately or with thenar muscles - Gray's Anatomy includes it with intrinsic muscles of the hand.

2. Hypothenar Muscles (4)

#	Muscle	Nerve
5	Abductor digiti minimi	Ulnar (deep branch)
6	Flexor digiti minimi brevis	Ulnar (deep branch)
7	Opponens digiti minimi	Ulnar (deep branch)
8	Palmaris brevis	Ulnar (superficial branch)

3. Lumbricals (4)

#	Muscle	Nerve
9	1st lumbrical	Median
10	2nd lumbrical	Median
11	3rd lumbrical	Ulnar (deep branch)
12	4th lumbrical	Ulnar (deep branch)

4. Interossei (8 = 4 dorsal + 4 palmar*)

#	Muscle	Action	Nerve
13	1st dorsal interosseous	Abducts index finger	Ulnar
14	2nd dorsal interosseous	Abducts middle finger (radial)	Ulnar
15	3rd dorsal interosseous	Abducts middle finger (ulnar)	Ulnar
16	4th dorsal interosseous	Abducts ring finger	Ulnar
17	1st palmar interosseous	Adducts index finger	Ulnar
18	2nd palmar interosseous	Adducts ring finger	Ulnar
19	3rd palmar interosseous	Adducts little finger	Ulnar

*Important note on palmar interossei count: Gray's Anatomy for Students notes that the 1st palmar interosseous is rudimentary and "when present is often considered part of either adductor pollicis or flexor pollicis brevis." This is why different textbooks give either 3 or 4 palmar interossei.

Summary Table

Group	Count
Thenar	4
Hypothenar	4
Lumbricals	4
Dorsal interossei	4
Palmar interossei	3 or 4*
Total	19 or 20

The standard accepted answer for most anatomy exams is 20 (4 thenar + 4 hypothenar + 4 lumbricals + 4 dorsal interossei + 4 palmar interossei).

Innervation rule (easy to remember):

Median nerve - lateral 2 lumbricals + 3 thenar muscles (all except adductor pollicis) = LOAF muscles (Lumbricals 1&2, Opponens pollicis, Abductor pollicis brevis, Flexor pollicis brevis)
Ulnar nerve (deep branch) - all remaining intrinsic muscles (all interossei + medial 2 lumbricals + hypothenar + adductor pollicis)

(Source: Gray's Anatomy for Students, 4th Ed., pp. 924-929)

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