L5: Hand

Question 1

How many Bones are in the hand?
(fuck it name them all)

Answer 1

27 bones arranged into the carpals, metacarpals, and phalanges
(29 if you include the 2 sesamoid bones)

Question 2

Examine the following skeletal components. Note any major markings on each of the structures (i.e. muscle
attachment points, joint connections).

Answer 2

i) Carpal bones – (lateral to medial)
a) scaphoid
b) lunate
c) triquetrium
d) pisiform
e) trapezium
f) trapezoid
g) capitate
h) hamate (hook of hamate)
ii) Metacarpals – first, second, third, fourth, and fifth
iii) Phalanges – proximal to distal phalanges (thumb, and 2nd to 5th digits)

Question 3

Your hand is partially contracted even when relaxed. Why?

Answer 3

Your hand is partially contracted even when relaxed. The muscles that extend your hand are not as strong as the muscles that flex it.

Question 4

How many muscles are in the hand?

Answer 4

The muscles of the hand (total = 18).

Question 5

What are the hypothenars?

3

Answer 5

The hypothenar muscles are a group of muscles located on the palmar aspect (palm side) of the hand, specifically at the base of the little finger (pinky finger) side
i) Abductor Digiti Minimi.
ii) Flexor Digiti Minimi Brevis.
iii) Opponens Digiti Minimi

Question 6

Abductor Digiti Minimi

Answer 6

Abductor Digiti Minimi:

• Origin: Pisiform bone, the pisohamate ligament, and the flexor retinaculum.
• Insertion: Ulnar side of the base of the proximal phalanx of the little finger.
• Function: Abducts (moves away from the midline) the little finger at the metacarpophalangeal joint.
• Innervation: Ulnar nerve (C8, T1).

Question 7

Flexor Digiti Minimi Brevis.

Answer 7

Origin: Hook of hamate bone and the flexor retinaculum.
Insertion: Ulnar side of the base of the proximal phalanx of the little finger.
Function: Flexes the little finger at the metacarpophalangeal joint.
Innervation:ulnar nerve (C8, T1).

Question 8

Opponens Digiti Minimi

Answer 8

Attachment:
Originates from the hook of the hamate and the flexor retinaculum, inserting into the fifth metacarpal bone.

Function:
opposes the little finger (digitus minimus), allowing it to touch the thumb and aiding in fine motor movements.

Nerve Supply:
ulnar nerve (C8-T1).

Blood Supply:
Supplied by branches of the ulnar artery.

Question 9

What are the Thenars?

4

Answer 9

The thenar muscles are a group of muscles located on the palmar aspect (palm side) of the hand, specifically at the base of the thumb.
i) Abductor Pollicis Brevis.
ii) Flexor Pollicis Brevis.
iii) Opponens Pollicis.
iv) Adductor Pollicis

Question 10

Abductor Pollicis Brevis

Answer 10

Attachment:
Originates from the flexor retinaculum, the tubercles of the trapezium, and the scaphoid bone, inserting into the radial side of the proximal phalanx of the thumb.

Function:
abducting the thumb, moving it away from the palm.

Nerve Supply:
median nerve (C8-T1).

Question 11

Flexor Pollicis Brevis

Answer 11

Attachment:
Originates from the trapezium and the flexor retinaculum, inserting into the base of the proximal phalanx of the thumb.

Function:
flexing the thumb at the metacarpophalangeal joint.

Nerve Supply:
median nerve (C8-T1).

Question 12

Opponens Pollicis

Answer 12

Attachment:
Originates from the flexor retinaculum and the tubercles of the trapezium, inserting into the first metacarpal bone.

Function:
opposes the thumb, allowing it to move toward and touch the other fingers, aiding in fine motor movements and precision grip.

Nerve Supply:
median nerve (C8-T1).

Question 13

Adductor Pollicis

Answer 13

Origin:
Transverse head: From the third metacarpal bone.
Oblique head: From the bases of the second and third metacarpal bones and the capitate bone.

Insertion:
Into the base of the proximal phalanx of the thumb and the ulnar sesamoid bone.

Function:
Adducts the thumb, bringing it toward the palm and allowing opposition (bringing the thumb in contact with the other fingers).
Assists in the flexion and extension of the thumb.

Nerve Supply:
ulnar nerve (C8, T1).

Question 14

What are the Dorsal and Palmar Interossei?

Answer 14

The Dorsal and Palmar Interossei are muscles in the hand, and they are part of the intrinsic muscles that control movement of the fingers.

There are 4 Dorsal and 3 Palmar
All Innervated by the Ulnar Nerve

Question 15

Dorsal Interossei:

Answer 15

Number: There are four dorsal interossei muscles.

Location: Situated on the dorsal (back) surface of the hand between the metacarpal bones.

Function:
Abduction: Spread the fingers apart from each other.
Assist in flexion at the metacarpophalangeal (MCP) joints

Question 16

Palmar Interossei:

Answer 16

Number: There are three palmar interossei muscles.

Location: Located on the palmar (palm) surface of the hand between the metacarpal bones.

Function:
Adduction: Bring the fingers together.
Assist in flexion at the MCP joints.
Each palmar interosseous muscle is associated with a specific finger and helps in adduction toward the midline of the hand

Question 17

What are the Lumbricals?

Answer 17

There are four lumbrical muscles in each hand.

Situated between the tendons of the flexor digitorum profundus (FDP) and the extensor digitorum tendons on the radial and ulnar sides of the hand.

Function:
They flex the metacarpophalangeal (MCP) joints
They extend the interphalangeal joints of the fingers.

Question 18

What are the Nerve Supplys of the Lumbricals?

Answer 18

The lumbricals are innervated by the median nerve for the first and second lumbricals and by the ulnar nerve for the third and fourth lumbricals

Question 19

Name the bones in the proximal row of the carpus. Which of these bones articulate with the radius?

Answer 19

Scaphoid, Lunate, Triquetrum, Pisiform

The Scaphoid and Lunate articulate with the radius, forming part of the radiocarpal joint.

Question 20

Where are the styloid processes of the wrist area? What are their functions?

Answer 20

Radial Styloid Process: This is a bony prominence located at the distal end of the radius on the lateral (thumb) side of the forearm. It provides attachment points for ligaments and serves as a stabilizing structure for the wrist joint. The radial styloid process plays a crucial role in transmitting forces from the forearm to the hand.

Ulnar Styloid Process: Situated at the distal end of the ulna on the medial (pinky) side of the forearm, the ulnar styloid process also serves as an attachment site for ligaments. It contributes to the stability of the wrist joint and helps limit excessive movements.

Question 21

Which metacarpal is proximal to the little finger (i.e. what number)?
Which metacarpals articulate with the hamate carpal?

Answer 21

The metacarpal proximal to the little finger is the fifth metacarpal.

The metacarpals that articulate with the hamate carpal bone are the fourth (IV) and fifth (V) metacarpals.

Question 22

What muscle do you use to give a thumbs up?

Answer 22

Flexor pollicis longus
Opponens pollicis
Flexor pollicis brevis

Flexor digitorum superficialis
Flexor digitorum profundus
Lumbricals
Interossei muscles

Question 23

What muscles do the following actions:
i) abduction of the digits ii) adduction of the digits iii) opposition of the thumb iv) flexion of fingers v) extension of fingers

Question 24

i) Abduction of the digits:

Answer 24

Abductor digiti minimi
Dorsal interossei
Abductor Pollicis Longus
Abductor Pollicis Brevis

Question 25

ii) Adduction of the digits:

Answer 25

Adductor pollicis
Palmar interossei

Question 26

iii) Opposition of the thumb:

Answer 26

Opponens pollicis

Question 27

iv) Flexion of fingers:

Answer 27

Flexor digitorum superficialis
Flexor digitorum profundus

Question 28

v) Extension of fingers:

Answer 28

Extensor digitorum
Extensor indicis
Extensor digiti minimi

Question 29

What goes through the carpal tunnel?

6

Answer 29

Median Nerve
Flexor Digitorum Superficialis (FDS) Tendons
Flexor Digitorum Profundus (FDP) Tendons
Flexor Pollicis Longus Tendon
Flexor Carpi Radialis Tendon
Flexor Carpi Ulnaris Tendon