The intrinsic muscles of the hand serve the function of adjusting the hand during gripping and also for carrying out fined skilled movements. There are twenty muscles in the hand, they are as follow:
Thenar eminence:
There are three muscles that form the thenar eminence with a common origin from the flexor retinaculum. The fourth muscle that is related to the thenar muscles is the adductor pollicis which have a different origin. The thenar muscles include:
ABDUCTOR POLLICI BREVIS
Origin: Flexor retinaculum, tubercle of scaphoid and tubercle of trapezium.
Insertion: Is inserted into the radial side of the base of the proximal phalanx of the thumb. Some fibers are inserted into the dorsal digital expansion.
Nerve Supply: Median nerve
Action: Abduction and medial rotation of the thumb at the metacarpophalangeal joint and carpometacarpal joint.
FLEXOR POLLICIS BREVIS:
It is related to the ulnar side of abductor pollicis brevis.
Origin: It arises by a superficial head from the flexor retinaculum and the tubercle of trapezium and by a deep head from the trapezoid and capitate, sometimes this head is absent in some individuals.
Insertion: It is inserted in to the radial sesamoid of the thumb and on the radial side of the base of proximal phalanx.
Nerve Supply: Superficial head is supplied by the median nerve and the deep head by the deep branch of ulnar nerve.
Action: Flexion of the thumb at the proximal phalanx.
OPPONENS POLLICIS:
It lies deep to the flexor pollicis brevis and abductor pollicis brevis muscles.
Origin: It arises from the tubercle of trapezium and flexion retinaculum.
Insertion: Lateral half of the palmar surface of the 1st metacarpal bone.
Nerve Supply: Median nerve
Action: Opposition of the thumb.
ADDUCTION POLLICIS:
Origin: It arises by means of two heads, an oblique head which arises from the capitate bone and the base of the 2nd and 3rd metacarpal bones and a transverse head which arises from the palmar aspect of the 3rd metacarpal bone.
Insertion: Medial side of the base of the proximal phalanx of the thumb and some fibres are inserted into the dorsal digital expansion.
Nerve Supply: Deep branch of the ulnar nerve (C8T1)
Action: The muscle adducts the thumb from the flexed or abducted position. The movement is forceful in gripping.
HYPOTHENAR EMINENCE
It is the muscles that lie on the ulnar side of the palm similar to the thenar muscle. They are four in number and include:
ABDUCTOR DIGITI MINIMI
This is the most medial of the group.
Origin: It arises from the pisiform bone and the tendon of flexor carpi ulnaris proximally and from the pisohamate ligament distally.
Insertion: Ulnar side of the base of the proximal phalanx o f the little finger.
Nerve Supply: Deep branch of ulnar nerve.
Action: Abduction of little finger at the metacarpophalangeal joint.
FLEXOR DIGITI MINIMI BREVIS
Origin: Arises from the hook of hamate bone and flexor retinaculum.
Insertion: Ulnar side of the base of the proximal phalanx of the little finger.
Nerve Supply: Deep branch of ulnar nerve (C8 T1).
Action: Flexion of the little finger at the metacarpophalangeal joint.
OPPONENS DIGITI MINIMI
Origin: It arises from the flexor retinaculum and hook of hamate.
Insertion: Medial surface of the shaft of the 5th metacarpal bone.
Nerve Supply: Deep branch of ulnar nerve (C8 T1).
Action: Flexes of 5th metacarpal and rotate it laterally.
LUMBRICAL MUSCLES
These are four small muscles that take origin from the tendon of flexor digitorum profundus and passes along the radial side of the corresponding metacarpophalangeal joint on the palmar surface of the deep transverse metacarpal ligament to be inserted by a tendon into the extensor expansion of the dorsum of the medial four digits.
Origin: The 1st lumbrical arises from the radial side of the tendon for the index finger. The 2nd lumbrical arises from the radial side of the tendon for the middle finger. The 3rd lumbrical arises from the contiguous sides of the tendon of the middle and ring finger. The 4th lumbrical arises from the contiguous side of the tendon for the ring and little finger.
Insertion: The tendons of the 1st, 2nd, 3rd, and 4th lumbrical pass backward on the radial side of the 2nd, 3rd, 4th, and 5th metacarpophalangeal joints respectively. They are inserted into the dorsal expansion of the corresponding digits.
Nerve Supply:
1. The 1st and 2nd lumbrical muscles by the median nerve (C8, T1).
2. The 3rd and 4th lumbrical muscles by the deep branch of ulnar nerve.
Action: The lumbrical muscles flex the metacarpophalangeal joints and extend the interphalangeal joints of the digit into which they are inserted.
INTEROSSEOUS MUSCLE
They are of two groups, the palmar and dorsal interossei. The former are small and arises from only one metacarpal bone while the latter are large and arise from the adjacent metacarpal bone of the space in which they lie. It is easy to recall the action of the interosseous by a appreciating their format “PAD and DAB”.
PALMAR INTEROSSEI
They are numbered from lateral to medial side.
Origin:
· The 1st palmar interosseous muscle arises from the medial side of the base of the 1st metacarpal bone.
· The 2nd palmar interosseous arises from the medial half of the palmar aspect of the shaft of the 2nd metacarpal.
· The 3rd palmar interosseous arises from the lateral part of the palmar surface of the shaft of the 4th metacarpal bone.
· The 4th palmar interosseous from the lateral part of the palmar aspect of the shaft of the 5th metacarpal bone.
Insertion: Each muscle is inserted into the dorsal digital expansion of its own digit. It may also be attached to the base of the proximal phalanx of the same digit.
1. 1st palmar interosseous muscle inserts into the medial side of the thumb.
2. 2nd palmar interosseous muscle inserts into the medial side of the index finger.
3. 3rd palmar interosseous muscle inserts into the lateral side of the fourth digit.
4. 4th palmar interosseous muscle inserts into the lateral side of the 5th digit.
The middle finger does not receive the insertion of the palmar interossei.
Nerve Supply: They are all supplied by the deep branch of the ulnar nerve.
Action: They adduct (PAD) the digit to which they are attached toward the middle finger. In addition they flex the digit at the metacarpophalangeal joints and extend it at the interphalangeal joints.
THE DORSAL INTEROSSEI
They are also four in number and placed between the metacarpal bones and are numbered from lateral to medial.
Origin:
i. 1st dorsal interosseous muscle arises from the shaft of the 1st and 2nd metacarpal.
ii. 2nd dorsal interosseous muscle arises from the shaft of the 2nd and 3rd metacarpal.
iii. 3rd dorsal interosseous muscle arises from the shaft of the 3rd and 4th metacarpal.
iv. 4th dorsal interosseous muscle arises from the shaft of the 4th and 5th metacarpal.
Insertion: Each muscle is inserted in to the dorsal digital exp of the digits and into the base of the proximal phalanx of the digit.
1stdorsal interosseous muscle inserts into the lateral side of index finger
2nd dorsal interosseous muscle inserts into the lateral side of middle finger
3rd dorsal interosseous muscle inserts into the medial side of middle finger
4th dorsal interosseous muscle inserts into the medial side of 4th digit
It should be noted that the middle finger receives two dorsal interossei muscles on either side and that the 1st and 5th digit do not receive any insertion.
Action: All dorsal interossei abduct the digit away from the line of the middle finger.
Nerve supply: By the deep branch of the ulnar nerve.
APPLIED ANATOMY
Paralysis of the intrinsic muscle of the hand produces claw hand in which there is hyperextension at the metacarpophalangeal joint and flexion at the interphalangeal joint. The effect is opposite to the action of the lumbricals and interossei.
HAND
The hand is designed purposely, normally universal digit formula 3>4>2>5>1 (for man and apes)
Another digit formula for the whites
3>4=2>5>1 19% Caucasians
3>2>4>5>1> 33% Caucasians
axial line: Pass through the capitate through the metacarpal the 3rd digit.
PALM
Furrows and ridges increase the surface area and increase the force of gripping. Sebaceous gland is absent but sweat glands are present. Furrow and ridges are arranged into arches whorls.
Palmar aponeurosis it is found in the central part of the palm and is a triangular deep fascia formed due to degeneration of the palmaris longus muscle tendon. It has an apex which is attached to the flexor retinaculum, its base divides into
F our slips.
The intrinsic muscles of the hand serve the function of adjusting the hand during gripping and also for carrying out fined skilled movements. There are twenty muscles in the hand, they are as follow:
Thenar eminence:
There are three muscles that form the thenar eminence with a common origin from the flexor retinaculum. The fourth muscle that is related to the thenar muscles is the adductor pollicis which have a different origin. The thenar muscles include:
ABDUCTOR POLLICI BREVIS
Origin: Flexor retinaculum, tubercle of scaphoid and tubercle of trapezium.
Insertion: Is inserted into the radial side of the base of the proximal phalanx of the thumb. Some fibers are inserted into the dorsal digital expansion.
Nerve Supply: Median nerve
Action: Abduction and medial rotation of the thumb at the metacarpophalangeal joint and carpometacarpal joint.
FLEXOR POLLICIS BREVIS:
It is related to the ulnar side of abductor pollicis brevis.
Origin: It arises by a superficial head from the flexor retinaculum and the tubercle of trapezium and by a deep head from the trapezoid and capitate, sometimes this head is absent in some individuals.
Insertion: It is inserted in to the radial sesamoid of the thumb and on the radial side of the base of proximal phalanx.
Nerve Supply: Superficial head is supplied by the median nerve and the deep head by the deep branch of ulnar nerve.
Action: Flexion of the thumb at the proximal phalanx.
OPPONENS POLLICIS:
It lies deep to the flexor pollicis brevis and abductor pollicis brevis muscles.
Origin: It arises from the tubercle of trapezium and flexion retinaculum.
Insertion: Lateral half of the palmar surface of the 1st metacarpal bone.
Nerve Supply: Median nerve
Action: Opposition of the thumb.
ADDUCTION POLLICIS:
Origin: It arises by means of two heads, an oblique head which arises from the capitate bone and the base of the 2nd and 3rd metacarpal bones and a transverse head which arises from the palmar aspect of the 3rd metacarpal bone.
Insertion: Medial side of the base of the proximal phalanx of the thumb and some fibres are inserted into the dorsal digital expansion.
Nerve Supply: Deep branch of the ulnar nerve (C8T1)
Action: The muscle adducts the thumb from the flexed or abducted position. The movement is forceful in gripping.
HYPOTHENAR EMINENCE
It is the muscles that lie on the ulnar side of the palm similar to the thenar muscle. They are four in number and include:
ABDUCTOR DIGITI MINIMI
This is the most medial of the group.
Origin: It arises from the pisiform bone and the tendon of flexor carpi ulnaris proximally and from the pisohamate ligament distally.
Insertion: Ulnar side of the base of the proximal phalanx o f the little finger.
Nerve Supply: Deep branch of ulnar nerve.
Action: Abduction of little finger at the metacarpophalangeal joint.
FLEXOR DIGITI MINIMI BREVIS
Origin: Arises from the hook of hamate bone and flexor retinaculum.
Insertion: Ulnar side of the base of the proximal phalanx of the little finger.
Nerve Supply: Deep branch of ulnar nerve (C8 T1).
Action: Flexion of the little finger at the metacarpophalangeal joint.
OPPONENS DIGITI MINIMI
Origin: It arises from the flexor retinaculum and hook of hamate.
Insertion: Medial surface of the shaft of the 5th metacarpal bone.
Nerve Supply: Deep branch of ulnar nerve (C8 T1).
Action: Flexes of 5th metacarpal and rotate it laterally.
LUMBRICAL MUSCLES
These are four small muscles that take origin from the tendon of flexor digitorum profundus and passes along the radial side of the corresponding metacarpophalangeal joint on the palmar surface of the deep transverse metacarpal ligament to be inserted by a tendon into the extensor expansion of the dorsum of the medial four digits.
Origin: The 1st lumbrical arises from the radial side of the tendon for the index finger. The 2nd lumbrical arises from the radial side of the tendon for the middle finger. The 3rd lumbrical arises from the contiguous sides of the tendon of the middle and ring finger. The 4th lumbrical arises from the contiguous side of the tendon for the ring and little finger.
Insertion: The tendons of the 1st, 2nd, 3rd, and 4th lumbrical pass backward on the radial side of the 2nd, 3rd, 4th, and 5th metacarpophalangeal joints respectively. They are inserted into the dorsal expansion of the corresponding digits.
Nerve Supply:
1. The 1st and 2nd lumbrical muscles by the median nerve (C8, T1).
2. The 3rd and 4th lumbrical muscles by the deep branch of ulnar nerve.
Action: The lumbrical muscles flex the metacarpophalangeal joints and extend the interphalangeal joints of the digit into which they are inserted.
INTEROSSEOUS MUSCLE
They are of two groups, the palmar and dorsal interossei. The former are small and arises from only one metacarpal bone while the latter are large and arise from the adjacent metacarpal bone of the space in which they lie. It is easy to recall the action of the interosseous by a appreciating their format “PAD and DAB”.
PALMAR INTEROSSEI
They are numbered from lateral to medial side.
Origin:
· The 1st palmar interosseous muscle arises from the medial side of the base of the 1st metacarpal bone.
· The 2nd palmar interosseous arises from the medial half of the palmar aspect of the shaft of the 2nd metacarpal.
· The 3rd palmar interosseous arises from the lateral part of the palmar surface of the shaft of the 4th metacarpal bone.
· The 4th palmar interosseous from the lateral part of the palmar aspect of the shaft of the 5th metacarpal bone.
Insertion: Each muscle is inserted into the dorsal digital expansion of its own digit. It may also be attached to the base of the proximal phalanx of the same digit.
1. 1st palmar interosseous muscle inserts into the medial side of the thumb.
2. 2nd palmar interosseous muscle inserts into the medial side of the index finger.
3. 3rd palmar interosseous muscle inserts into the lateral side of the fourth digit.
4. 4th palmar interosseous muscle inserts into the lateral side of the 5th digit.
The middle finger does not receive the insertion of the palmar interossei.
Nerve Supply: They are all supplied by the deep branch of the ulnar nerve.
Action: They adduct (PAD) the digit to which they are attached toward the middle finger. In addition they flex the digit at the metacarpophalangeal joints and extend it at the interphalangeal joints.
THE DORSAL INTEROSSEI
They are also four in number and placed between the metacarpal bones and are numbered from lateral to medial.
Origin:
i. 1st dorsal interosseous muscle arises from the shaft of the 1st and 2nd metacarpal.
ii. 2nd dorsal interosseous muscle arises from the shaft of the 2nd and 3rd metacarpal.
iii. 3rd dorsal interosseous muscle arises from the shaft of the 3rd and 4th metacarpal.
iv. 4th dorsal interosseous muscle arises from the shaft of the 4th and 5th metacarpal.
Insertion: Each muscle is inserted in to the dorsal digital exp of the digits and into the base of the proximal phalanx of the digit.
1stdorsal interosseous muscle inserts into the lateral side of index finger
2nd dorsal interosseous muscle inserts into the lateral side of middle finger
3rd dorsal interosseous muscle inserts into the medial side of middle finger
4th dorsal interosseous muscle inserts into the medial side of 4th digit
It should be noted that the middle finger receives two dorsal interossei muscles on either side and that the 1st and 5th digit do not receive any insertion.
Action: All dorsal interossei abduct the digit away from the line of the middle finger.
Nerve supply: By the deep branch of the ulnar nerve.
APPLIED ANATOMY
Paralysis of the intrinsic muscle of the hand produces claw hand in which there is hyperextension at the metacarpophalangeal joint and flexion at the interphalangeal joint. The effect is opposite to the action of the lumbricals and interossei.
HAND
The hand is designed purposely, normally universal digit formula 3>4>2>5>1 (for man and apes)
Another digit formula for the whites
3>4=2>5>1 19% Caucasians
3>2>4>5>1> 33% Caucasians
axial line: Pass through the capitate through the metacarpal the 3rd digit.
PALM
Furrows and ridges increase the surface area and increase the force of gripping. Sebaceous gland is absent but sweat glands are present. Furrow and ridges are arranged into arches whorls.
Palmar aponeurosis it is found in the central part of the palm and is a triangular deep fascia formed due to degeneration of the palmaris longus muscle tendon. It has an apex which is attached to the flexor retinaculum, its base divides into
F our slips.
The intrinsic muscles of the hand serve the function of adjusting the hand during gripping and also for carrying out fined skilled movements. There are twenty muscles in the hand, they are as follow:
Thenar eminence:
There are three muscles that form the thenar eminence with a common origin from the flexor retinaculum. The fourth muscle that is related to the thenar muscles is the adductor pollicis which have a different origin. The thenar muscles include:
ABDUCTOR POLLICI BREVIS
Origin: Flexor retinaculum, tubercle of scaphoid and tubercle of trapezium.
Insertion: Is inserted into the radial side of the base of the proximal phalanx of the thumb. Some fibers are inserted into the dorsal digital expansion.
Nerve Supply: Median nerve
Action: Abduction and medial rotation of the thumb at the metacarpophalangeal joint and carpometacarpal joint.
FLEXOR POLLICIS BREVIS:
It is related to the ulnar side of abductor pollicis brevis.
Origin: It arises by a superficial head from the flexor retinaculum and the tubercle of trapezium and by a deep head from the trapezoid and capitate, sometimes this head is absent in some individuals.
Insertion: It is inserted in to the radial sesamoid of the thumb and on the radial side of the base of proximal phalanx.
Nerve Supply: Superficial head is supplied by the median nerve and the deep head by the deep branch of ulnar nerve.
Action: Flexion of the thumb at the proximal phalanx.
OPPONENS POLLICIS:
It lies deep to the flexor pollicis brevis and abductor pollicis brevis muscles.
Origin: It arises from the tubercle of trapezium and flexion retinaculum.
Insertion: Lateral half of the palmar surface of the 1st metacarpal bone.
Nerve Supply: Median nerve
Action: Opposition of the thumb.
ADDUCTION POLLICIS:
Origin: It arises by means of two heads, an oblique head which arises from the capitate bone and the base of the 2nd and 3rd metacarpal bones and a transverse head which arises from the palmar aspect of the 3rd metacarpal bone.
Insertion: Medial side of the base of the proximal phalanx of the thumb and some fibres are inserted into the dorsal digital expansion.
Nerve Supply: Deep branch of the ulnar nerve (C8T1)
Action: The muscle adducts the thumb from the flexed or abducted position. The movement is forceful in gripping.
HYPOTHENAR EMINENCE
It is the muscles that lie on the ulnar side of the palm similar to the thenar muscle. They are four in number and include:
ABDUCTOR DIGITI MINIMI
This is the most medial of the group.
Origin: It arises from the pisiform bone and the tendon of flexor carpi ulnaris proximally and from the pisohamate ligament distally.
Insertion: Ulnar side of the base of the proximal phalanx o f the little finger.
Nerve Supply: Deep branch of ulnar nerve.
Action: Abduction of little finger at the metacarpophalangeal joint.
FLEXOR DIGITI MINIMI BREVIS
Origin: Arises from the hook of hamate bone and flexor retinaculum.
Insertion: Ulnar side of the base of the proximal phalanx of the little finger.
Nerve Supply: Deep branch of ulnar nerve (C8 T1).
Action: Flexion of the little finger at the metacarpophalangeal joint.
OPPONENS DIGITI MINIMI
Origin: It arises from the flexor retinaculum and hook of hamate.
Insertion: Medial surface of the shaft of the 5th metacarpal bone.
Nerve Supply: Deep branch of ulnar nerve (C8 T1).
Action: Flexes of 5th metacarpal and rotate it laterally.
LUMBRICAL MUSCLES
These are four small muscles that take origin from the tendon of flexor digitorum profundus and passes along the radial side of the corresponding metacarpophalangeal joint on the palmar surface of the deep transverse metacarpal ligament to be inserted by a tendon into the extensor expansion of the dorsum of the medial four digits.
Origin: The 1st lumbrical arises from the radial side of the tendon for the index finger. The 2nd lumbrical arises from the radial side of the tendon for the middle finger. The 3rd lumbrical arises from the contiguous sides of the tendon of the middle and ring finger. The 4th lumbrical arises from the contiguous side of the tendon for the ring and little finger.
Insertion: The tendons of the 1st, 2nd, 3rd, and 4th lumbrical pass backward on the radial side of the 2nd, 3rd, 4th, and 5th metacarpophalangeal joints respectively. They are inserted into the dorsal expansion of the corresponding digits.
Nerve Supply:
1. The 1st and 2nd lumbrical muscles by the median nerve (C8, T1).
2. The 3rd and 4th lumbrical muscles by the deep branch of ulnar nerve.
Action: The lumbrical muscles flex the metacarpophalangeal joints and extend the interphalangeal joints of the digit into which they are inserted.
INTEROSSEOUS MUSCLE
They are of two groups, the palmar and dorsal interossei. The former are small and arises from only one metacarpal bone while the latter are large and arise from the adjacent metacarpal bone of the space in which they lie. It is easy to recall the action of the interosseous by a appreciating their format “PAD and DAB”.
PALMAR INTEROSSEI
They are numbered from lateral to medial side.
Origin:
· The 1st palmar interosseous muscle arises from the medial side of the base of the 1st metacarpal bone.
· The 2nd palmar interosseous arises from the medial half of the palmar aspect of the shaft of the 2nd metacarpal.
· The 3rd palmar interosseous arises from the lateral part of the palmar surface of the shaft of the 4th metacarpal bone.
· The 4th palmar interosseous from the lateral part of the palmar aspect of the shaft of the 5th metacarpal bone.
Insertion: Each muscle is inserted into the dorsal digital expansion of its own digit. It may also be attached to the base of the proximal phalanx of the same digit.
1. 1st palmar interosseous muscle inserts into the medial side of the thumb.
2. 2nd palmar interosseous muscle inserts into the medial side of the index finger.
3. 3rd palmar interosseous muscle inserts into the lateral side of the fourth digit.
4. 4th palmar interosseous muscle inserts into the lateral side of the 5th digit.
The middle finger does not receive the insertion of the palmar interossei.
Nerve Supply: They are all supplied by the deep branch of the ulnar nerve.
Action: They adduct (PAD) the digit to which they are attached toward the middle finger. In addition they flex the digit at the metacarpophalangeal joints and extend it at the interphalangeal joints.
THE DORSAL INTEROSSEI
They are also four in number and placed between the metacarpal bones and are numbered from lateral to medial.
Origin:
i. 1st dorsal interosseous muscle arises from the shaft of the 1st and 2nd metacarpal.
ii. 2nd dorsal interosseous muscle arises from the shaft of the 2nd and 3rd metacarpal.
iii. 3rd dorsal interosseous muscle arises from the shaft of the 3rd and 4th metacarpal.
iv. 4th dorsal interosseous muscle arises from the shaft of the 4th and 5th metacarpal.
Insertion: Each muscle is inserted in to the dorsal digital exp of the digits and into the base of the proximal phalanx of the digit.
1stdorsal interosseous muscle inserts into the lateral side of index finger
2nd dorsal interosseous muscle inserts into the lateral side of middle finger
3rd dorsal interosseous muscle inserts into the medial side of middle finger
4th dorsal interosseous muscle inserts into the medial side of 4th digit
It should be noted that the middle finger receives two dorsal interossei muscles on either side and that the 1st and 5th digit do not receive any insertion.
Action: All dorsal interossei abduct the digit away from the line of the middle finger.
Nerve supply: By the deep branch of the ulnar nerve.
APPLIED ANATOMY
Paralysis of the intrinsic muscle of the hand produces claw hand in which there is hyperextension at the metacarpophalangeal joint and flexion at the interphalangeal joint. The effect is opposite to the action of the lumbricals and interossei.
HAND
The hand is designed purposely, normally universal digit formula 3>4>2>5>1 (for man and apes)
Another digit formula for the whites
3>4=2>5>1 19% Caucasians
3>2>4>5>1> 33% Caucasians
axial line: Pass through the capitate through the metacarpal the 3rd digit.
PALM
Furrows and ridges increase the surface area and increase the force of gripping. Sebaceous gland is absent but sweat glands are present. Furrow and ridges are arranged into arches whorls.
Palmar aponeurosis it is found in the central part of the palm and is a triangular deep fascia formed due to degeneration of the palmaris longus muscle tendon. It has an apex which is attached to the flexor retinaculum, its base divides into
F our slips.
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