L5: Hand Flashcards
How many Bones are in the hand?
(fuck it name them all)
27 bones arranged into the carpals, metacarpals, and phalanges
(29 if you include the 2 sesamoid bones)
Examine the following skeletal components. Note any major markings on each of the structures (i.e. muscle
attachment points, joint connections).
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)
Your hand is partially contracted even when relaxed. Why?
Your hand is partially contracted even when relaxed. The muscles that extend your hand are not as strong as the muscles that flex it.
How many muscles are in the hand?
The muscles of the hand (total = 18).
What are the hypothenars?
3
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
Abductor Digiti Minimi
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).
Flexor Digiti Minimi Brevis.
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).
Opponens Digiti Minimi
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.
What are the Thenars?
4
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
Abductor Pollicis Brevis
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).
Flexor Pollicis Brevis
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).
Opponens Pollicis
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).
Adductor Pollicis
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).
What are the Dorsal and Palmar Interossei?
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
Dorsal Interossei:
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
Palmar Interossei:
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
What are the Lumbricals?
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.
What are the Nerve Supplys of the Lumbricals?
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
Name the bones in the proximal row of the carpus. Which of these bones articulate with the radius?
Scaphoid, Lunate, Triquetrum, Pisiform
The Scaphoid and Lunate articulate with the radius, forming part of the radiocarpal joint.
Where are the styloid processes of the wrist area? What are their functions?
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.
Which metacarpal is proximal to the little finger (i.e. what number)?
Which metacarpals articulate with the hamate carpal?
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.
What muscle do you use to give a thumbs up?
Flexor pollicis longus
Opponens pollicis
Flexor pollicis brevis
Flexor digitorum superficialis
Flexor digitorum profundus
Lumbricals
Interossei muscles
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
i) Abduction of the digits:
Abductor digiti minimi
Dorsal interossei
Abductor Pollicis Longus
Abductor Pollicis Brevis
ii) Adduction of the digits:
Adductor pollicis
Palmar interossei
iii) Opposition of the thumb:
Opponens pollicis
iv) Flexion of fingers:
Flexor digitorum superficialis
Flexor digitorum profundus
v) Extension of fingers:
Extensor digitorum
Extensor indicis
Extensor digiti minimi
What goes through the carpal tunnel?
6
Median Nerve
Flexor Digitorum Superficialis (FDS) Tendons
Flexor Digitorum Profundus (FDP) Tendons
Flexor Pollicis Longus Tendon
Flexor Carpi Radialis Tendon
Flexor Carpi Ulnaris Tendon
