Lecture 19 - Muscles Of The Hand

Question 1

What is the Thenar group?

Answer 1

• Fleshly prominence on the radial side of the palm proximal to the thumb
• Comprised of 4 muscles that act of the thumb ONLY

Question 2

What is the flexor retinaculum?

Answer 2

• Also called the transverse carpal ligament
• Runs between the outer carpals on the palmar side of the hand
• Has a similar twin structure on the back of the hand
• Creates the Carpal Tunnel for the Median nerve, Flexor tendons & Blood vessels supplying the hand

Question 3

What is carpal tunnel syndrome ?

Answer 3

• Compression of the median nerve can be due to overuse of the flexor tendons of the fingers (ie. keyboarding)
• Can also be caused by pregnancy & other medical conditions

Question 4

What are the 4 muscles of the Thenar group?

Answer 4

• flexor pollicis brevis
• abductor/adductor pollicis brevis
• Opponens brevis

Question 5

What are the origins of the adductor pollicis brevis?

Answer 5

• Oblique Head - capitate & base of 2nd & 3rd metacarpals
• Transverse Head - palmer aponeurosis

Question 6

What is the insertion/innervation/main action of the adductor pollicis brevis?

Answer 6

• I: Ulnar side of the proximal phalanx of the thumb
• Inn: Branch of ulnar nerve
• MA: Adducts thumb

Question 7

What is the hypothenar group ?

Answer 7

• The fleshly prominence proximal to the 5th digit on the hand ONLY
• Comprised of 3 muscles

Question 8

What are the 3 muscles of the hypothenar group?

Answer 8

• abductor Digiti Minimi
• flexor Digiti Minimi brevis
• Opponens Digiti Minimi

Question 9

What is the origin/insertion/innervation/main action of the abductor Digiti Minimi brevis?

Answer 9

• O: Pisiform
• I: Base of 5th proximal phalanx
• Inn: Branch of ulnar nerve
• MA: Abduction of 5th digit (at 5th MCP joint)

Question 10

What is the origin/insertion/innervation/main action of the flexor Digiti Minimi brevis?

Answer 10

• O: Hamate
• I: Base of the 5th proximal phalanx
• Inn: Branch of ulnar nerve
• MA: Flexion of 5th digit (at 5th MCP joint)

Question 11

What is the origin/insertion/innervation/main action of the Opponens digiti minimi?

Answer 11

• O: Hamate
• I: Ulnar border of 5th metacarpal
• Inn: Branch of ulnar nerve
• MA: Opposition of 5th digit to the thumb

Question 12

What are the short muscles of the hand?

Answer 12

• lumbricals (4)
• interossei: dorsal (4) & palmer (3)

Question 13

What is the origin/insertion/innervation/main action of the lumbricals ?

Answer 13

• O: Tendons of flexor digitorum profundus
• I: Expansions of extensor digitorum
• Inn: Median nerve & Ulnar nerve depending on location, 1 & 2 = 2 Median, 3 & 4 = Ulnar
• MA: Flexion at the metacarpophalangeal joint while also extending the interphalangeal joints

Question 14

What is the origin/insertion/innervation/main action of the dorsal interossei?

Answer 14

• O: The two metacarpals between which it inserts, I.e., 1st dorsal interossei originates between the 1st & 2ndmetacarpals
• I: Base of respective proximal phalanx
• Inn: Branch of Ulnar nerve
• MA: Abduction of digits 2-4

Question 15

What is the origin/insertion/innervation/main action of the palmer interossei?

Answer 15

• O: Palmar surfaces of metacarpals 2, 4 & 5
• I: Extensor expansion of the same digit
• Inn: Branch of Ulnar nerve
• MA: Adduction of digits 2, 4 & 5

Question 16

What is the extensor hood?

Answer 16

• Also called the “Dorsal Digital Expansion” or “Extensor Expansion”
• Made up of aponeurotic tendons of Extensor Digitorum & Extensor Pollicis Longus
• Expands over the metacarpal heads & the proximal phalanges - dorsal & lateral aspects

Question 17

What is the extensor hood?

Answer 17

• Also called the “Dorsal Digital Expansion” or “Extensor Expansion”
• Made up of aponeurotic tendons of Extensor Digitorum & Extensor Pollicis Longus
• Expands over the metacarpal heads & the proximal phalanges - dorsal & lateral aspects