Hand - Anatomy

How many rows of carpal bones are there and how many bones in each row?

2 rows of 4 bones each (total of 8 carpal bones)

What's the mnemonic for remembering the carpal bones in order (proximal then distal row)?

"Some Loves Try Positions That They Can't Handle"

S - Scaphoid
L - Lunate
T - Triquetral
P - Pisiform
T - Trapezium
T - Trapezoid
C - Capitate
H - Hamate

How many metacarpal bones are there in the hand?

5

How are metacarpals numbered?

From lateral (thumb) to medial (pinky)

What are the three parts of a metacarpal bone?

Base, body, and head

How many total phalanges are in the hand?

14

How many phalanges are in each finger?

3 (proximal, middle, and distal phalanx)

How many phalanges are in the thumb?

2 (proximal and distal only - no middle phalanx)

What are the three parts of a phalanx?

Base, body, and head

Which finger is numbered as metacarpal 1?

The thumb (most lateral)

Which finger is numbered as metacarpal 5?

The little finger/pinky (most medial)

What is joint #1 in the image? (carpal joints)

Distal radioulnar joint (between radius and ulna)

What is joint #2 in the image? (carpal joints)

Radiocarpal joint (between radius and scaphoid/lunate)

What is joint #3 in the image? (carpal joints)

Articular disk between ulna and triquetral (helps form condyloid joint)

What is joint #4 in the image? (carpal joints)

Midcarpal joint (between proximal and distal carpal rows)

What is joint #5 in the image? (carpal joints)

Carpometacarpal joint (between distal carpal row and metacarpals)

Name the three types of ligaments in the wrist

Radial and ulnar collateral ligaments

Dorsal and palmar radiocarpal

Intercarpal ligaments

What is structure #8?

Flexor retinaculum (transverse carpal ligament)

What are the two retinaculums of the wrist?

Extensor retinaculum

Flexor retinaculum

What is the carpal tunnel?

Space beneath the flexor retinaculum where tendons and nerves pass through

What are the two main types of joints in the fingers? (metacarpal and phalangeal joints)

Metacarpophalangeal (MCP) joints

Interphalangeal (IP) joints

What movements occur at the metacarpophalangeal joint around the transverse axis?

Flexion and extension

What movements occur at the metacarpophalangeal joint around the palmar dorsal axis?

Abduction and adduction

What additional movement is possible at the metacarpophalangeal joint?

Circumduction

What movements are possible at the interphalangeal joints?

Only flexion and extension (around transverse axis)

What ligaments stabilize the interphalangeal joints?

Palmar and collateral ligaments

What is the key difference in movement between MCP and IP joints?

MCP joints allow flexion/extension, abduction/adduction, and circumduction

IP joints only allow flexion/extension

What muscles are found in the thenar compartment? (musculature of hand)

1. Abductor pollicis brevis

2. Flexor pollicis brevis

3. Opponens pollicis

What is structure #1 in the images?

Abductor pollicis brevis muscle

What is structure #2 in the images?

Flexor pollicis brevis muscle

What is structure #3 in the images?

Opponens pollicis muscle

What is structure #4 in the images?

Recurrent branch of median nerve

What nerve innervates the thenar compartment muscles?

Recurrent branch of the median nerve

Where are the thenar muscles located?

In the thenar eminence (thumb pad) of the hand

What two flexor tendon groups are found in the central compartment?

Flexor digitorum superficialis

Flexor digitorum profundus

How do the superficialis and profundus tendons interact?

Superficialis tendon splits to allow profundus tendon to reach distal phalanx

What are the vincula?

Vincula longa and brevia - small mesenteric folds that carry blood vessels to the tendons

How many lumbrical muscles are there?

4 lumbrical muscles
*#2

Which nerve innervates the lateral (radial) two lumbricals?

Median nerve

Which nerve innervates the medial (ulnar) two lumbricals?

Ulnar nerve

Where are the lumbrical muscles located in the hand?

In the central compartment, associated with the flexor digitorum profundus tendons

What is the more superficial of the two flexor digitorum tendons?

Flexor digitorum superficialis

What is the deeper of the two flexor digitorum tendons?

Flexor digitorum profundus

What does "vl" indicate in the image?

Vincula longa

What does "vb" indicate in the image?

Vincula brevia

What is the function of vincula?

They are small mesenteric folds that carry blood vessels to the tendons

What is #2 in the image?

Lumbrical muscle

How many lumbrical muscles are found in the hand?

4

What are the two heads of the adductor pollicis muscle (#3 in image)?

Transverse head

Oblique head

Which nerve innervates the adductor pollicis?

Deep branch of ulnar nerve

How many palmar interosseous muscles are there and what do they do?

3 muscles - Adductors (PAD)
*Sometimes one of pollex but often absent

How many dorsal interosseous muscles are there and what do they do?

4 muscles - Abductors (DAB)

What's the mnemonic for remembering interosseous muscle actions?

"PAD and DAB":

PAD = Palmar ADduct
DAB = Dorsal ABduct

Which nerve innervates the interosseous muscles?

Deep branch of ulnar nerve

What does #4 indicate in the image?

Interosseous muscles

Muscles of the central compartment of the hand:

Adductor pollicis muscle

Interosseous muscles

"PAD and DAB" Mnemonic - What does this stand for?

Palmar Adduct and Dorsal ABduct
*A key memory device for remembering the actions of the interosseous muscles

Palmar Interosseous Muscles - Number and Action

Number: 3 muscles

Action: ADduct digits toward 3rd digit (PAD)

Innervation: Deep branch of ulnar nerve

Dorsal Interosseous Muscles - Number and Action

Number: 4 muscles

Action: ABduct 2nd, 3rd, and 4th digits from midline (DAB)

Innervation: Deep branch of ulnar nerve

Which three muscles make up the hypothenar compartment?

Abductor digiti minimi

Flexor digiti minimi (brevis)

Opponens digiti minimi

What nerve innervates all hypothenar muscles?

Ulnar nerve
*#4

What is structure #1?

Aductor digiti minimi muscle

What is structure #2?

Flexor digiti minimi muscle (brevis)

What is structure #4?

Ulnar nerve

What is structure #1?

Abductor digiti minimi muscle

What is structure #2?

Flexor digiti minimi muscle (brevis)

What is structure #3?

Opponens digiti minimi muscle

What is structure #4?

Ulnar nerve

What is the cutaneous innervation pattern of the median nerve in the palm?

Radial half of palm to radial side of 4th digit

Where does the median nerve provide cutaneous innervation on the dorsal hand?

Overlaps digits to nailbeds on dorsal hand

What area does the palmar cutaneous branch of the median nerve innervate?

Thenar eminence

How many lumbrical muscles does the median nerve innervate?

2 (the lateral lumbrical muscles)

What is the "1/2 LOAF" mnemonic referencing?

Mnemonic used to remember the muscles in the hand that are innervated by the median nerve

1/2: Refers to the lateral two lumbricals (those on the thumb side of the hand).

L: Lateral part of the lumbricals

O: Opponens pollicis

A: Abductor pollicis brevis

F: Flexor pollicis brevis (specifically, the superficial head)

Which three thenar muscles are innervated by the median nerve?

Abductor pollicis brevis

Flexor pollicis brevis

Opponens pollicis

What digits receive cutaneous innervation from the ulnar nerve?

All of 5th digit

Medial half of 4th digit

Where does the ulnar nerve provide cutaneous innervation on the hand?

On both palmar and dorsal surfaces

Which lumbrical muscles does ulnar nerve innervate?

Medial lumbrical muscles (2)

How many hypothenar muscles does ulnar nerve innervate?

3

Name the 3 hypothenar muscles innervated by ulnar nerve:

Abductor digiti minimi

Flexor digiti minimi brevis

Opponens digiti minimi

What thumb muscle does ulnar nerve innervate?

Adductor pollicis muscle

How many interosseous muscles does ulnar nerve innervate?

7:

• 3 palmar

• 4 dorsal

What are the first branches of the ulnar artery (structure A) at the wrist?

Palmar and dorsal carpal branches

What is structure A?

Ulnar artery

What is branch #2 of the ulnar artery in the hand?

Deep palmar branch

What is the name of structure #3 in the image?

Superficial palmar arch

What arteries are labeled #4 in the image?

Common palmar digital arteries

What are the terminal branches (#5) of the common palmar digital arteries?

Proper palmar digital arteries

List the 5 major components of ulnar artery distribution in order:

Carpal branches (palmar & dorsal)

Deep palmar branch

Superficial palmar arch

Common palmar digital arteries

Proper palmar digital arteries

What is the first branch of the radial artery (structure B) at the wrist?

Palmar carpal branch

What is structure B?

Radial artery

What is labeled as #2 in the image?

Superficial palmar branch

What is labeled as #3 in the image?

Deep palmar arch
*Hard to see

What arteries are labeled as #4?

Palmar metacarpal arteries

What artery supplies the thumb (#5)?

Princeps pollicis artery

What artery supplies the index finger (#6)?

Radialis indicis artery

What structures are the white, cord-like structures running longitudinally down each digit?

Flexor tendons (flexor digitorum superficialis and profundus)
*Left image

What structure forms the horizontal band across the palm?

Flexor retinaculum (transverse carpal ligament)
*Left image

What is the difference in appearance between the right and left images?

Right image shows deeper dissection with muscles and neurovascular structures

Left image shows more superficial dissection focusing on tendons

What structures are the yellowish bundles visible in the palm?

Neurovascular bundles (digital nerves and vessels)
*Right image

What compartment of the hand is most visible in these dissections?

Central compartment (containing flexor tendons and neurovascular structures)