Hand and Fascial Spaces

Question 1

What form the hypothenar and thenar eminences?

Answer 1

Thenar = bulge of tissue around thumb
hypothenar = bulge of tissue around pinky

Question 2

What is the midpalmar compartment?

Answer 2

The area between the hypothenar and thenar eminences. A compartment is defined as an area of the body enclosed by fascia or connective tissue and contains muscles, blood vessels, nerves, etc

Question 3

How many phalanges are there for each digit? What type of bone are they?

Answer 3

Metacarpals and phalanges are all miniature long bones. The thumb has two phalanges and all the other digits have 3

Question 4

Where are the digits connected most distally? How do phalanges connect?

Answer 4

The metacarpophalangeal ligaments connect as 4 digits with the transverse metacarpal ligament, which include a palmar ligament/plate for the flexor tendons to run. Ligaments also connect interphalangeal ligaments

Question 5

For finger movements, what are abduction and adduction in relation to?

Answer 5

The plane of the palm for the thumb, through the middle finger for the other digits

Question 6

What makes the carpometacarpal joint of the thumb different from the other digits?

Answer 6

Flexion, abduction, adduction, and extension can happen at that joint -> it is a moving joint. Joints of other digits cannot do that.

Question 7

What are MP and IP joints?

Answer 7

MP = metacarpophalangeal, between metacarpals and proximal phalanx
IP = interphalangeal, between proximal and intermediate; intermediate and distal phalanges

They are all synovial joints

Question 8

What are the origin, insertion, innervation, and action of the abductor pollicis brevis muscle?

Answer 8

Origin: Flexor retinaculum, scaphoid, trapezium
Insertion: Sesamoid bone of metacarpal I, proximal phalanx, and extensor expansion on posterior thumb
Innervation: Median nerve (recurrent)
Action: Abduction and flexion of proximal phalanx
Most lateral muscle of thenar compartment

Question 9

What are the origin, insertion, innervation, and action of the flexor pollicis brevis muscle?

Answer 9

Origin: Flexor retinaculum, trapezium
Insertion: Sesamoid bone of metacarpal I, proximal phalanx, and extensor expansion on posterior thumb
Innervation: Median nerve (recurrent)
Action: Flexion of proximal phalanx

Question 10

What are the origin, insertion, innervation, and action of the opponens pollicis muscle?

Answer 10

Origin: Flexor retinaculum, trapezium
Insertion: Lateral side of first metacarpal
Innervation: Median nerve (recurrent)
Action: Rotates our thumb during opposition -> lets us have opposable thumb to grasp things

Question 11

What supplies blood to the thumb and lateral first digit?

Answer 11

Branches of the radial artery, called princeps pollicis for thumb and radialis indicis for lateral digit II. The radial artery in general crosses deep to the adductor pollicis to supply the skin and subcutaneous tissue of the thumb

Question 12

What is the superficial palmar arch?

Answer 12

Blood mostly supplied by ulnar artery but partially from radial artery through anastomoses, supplies blood to digits (digital arteries), thenar eminenance, and superficial palm (palmar digitals).

Question 13

What are the origin, insertion, innervation, and action of the palmaris brevis muscle?

Answer 13

Origin: Flexor retinaculum, palmar aponeurosis
Insertion: Ulnar side of palm
Innervation: SUPERFICIAL branch of ulnar nerve
Action: Draws skin from ulnar side of palm to middle of palm, deepening hollow

Question 14

What are the origin, insertion, innervation, and action of the abductor digiti minimi muscle?

Answer 14

Origin: Pisiform
Insertion: Proximal phalanx of 5th digit
Innervation: Deep branch of ulnar nerve
Action: Abduction of digit V

Question 15

What are the origin, insertion, innervation, and action of the flexor digiti minimi muscle?

Answer 15

Origin: Hamate
Insertion: Proximal phalanx of digit 5
Innervation: Deep branch of ulnar nerve
Action: Flexion of digit 5 at proximal phalanx

Question 16

What are the origin, insertion, innervation, and action of the opponens digiti minimi muscle?

Answer 16

Origin: Hamate
Insertion: 5th metacarpal
Innervation: Deep branch of ulnar nerve
Action: Draws 5th metacarpal anteriorly to contact thumb during opposition, but cannot rotate it

Question 17

What forms the superficial palmar arch?

Answer 17

Vessels from the ulnar artery, supply the medial 3 and 1/2 digits. Also has help from the radial artery in forming the superficial arch

Question 18

What supplies blood to the hypothenar compartment?

Answer 18

Deep branches of the ulnar artery

Question 19

What are the boundaries of the mid palmar compartment?

Answer 19

palmar aponeurosis, interosseous fascia posteriorly, thenar fascia / compartment, and hypothenar fascia / compartment

Question 20

What are the lumbricals and what is their function?

Answer 20

Wormlike muscle on the radial (lateral) side of FDP tendons (digits II-V). They attach on the extensor expansions, and cause flexion at MP joints and extension at IP

Question 21

What are the innervations of the lumbricals?

Answer 21

Unipennate lumbricals of digits II and III = median nerve

Bipennate lumbricals of digits IV and V = ulnar nerve

Question 22

What are the origin, insertion, innervation, and action of the adductor pollicis?

Answer 22

Origin: Oblique head - 2nd and 3rd metacarpals and capitate
Transverse head - 3rd metacarpal
Insertion: Medial sesamoid bone, proximal phalanx, extensor expansion of thumb
Innervation: deep branch of ulnar nerve
Action: adduction of thumb, helps with opposition

Question 23

Why can you still move your thumb inward when you have CTS?

Answer 23

the adductor pollicis is innervate by the ulnar nerve

Question 24

What is the function of the palmar interossei and where do they originate and attach? What innervates them?

Answer 24

They function to adduct the fingers towards the middle finger. There is some debate as to whether the thumb one exists. They originate on the palmar side of the digits (Except middle finger) and insert on the side of the base of the proximal phalanx of each finger, as well as the extensor expansion. Innervated by deep branch of ulnar nerve

Question 25

What is the function of the dorsal interossei and where do they originate and attach? What innervates them?

Answer 25

They function to abduct the fingers. They each have two heads and arise between the metacarpal bones and pull them away from imaginary line through the middle finger. First dorsal interosseous is largest and pulls index finger towards thumb. Only the third digit has attachments on the medial and lateral side. Digit 5 has no attachment of these (that’s why is it has abductor digiti minimi). They also attach to extensor expansion and can have the same function as lumbricals. Innervated by ulnar nerve.

Question 26

What is the extensor expansion?

Answer 26

Aponeurotic or tendinous fusion of digital extensors, lumbricals, and interossei tendons on dorsal aspecct of digits. Flexion at MP joint causes extension at IP joints when the interossei and lumbrical muscles are active

Question 27

What are vincula?

Answer 27

Special folds of connective tissue which hold the long flexor tendons at each joint and protect the supplying blood vessels. They provide nutrients to the tendons?

Question 28

What is the fibrous digital sheath?

Answer 28

The sheath that encloses the tendons and extensors in the fingers, making them much stronger

Question 29

What muscles does the recurrent medial nerve supply?

Answer 29

Abductor pollicis brevis, flexor pollicis brevis, opponens pollicis, and the first and second lumbricals. It is vulnerable to cuts on the thenar eminence because it is superficial distally to flexor retinaculum.

Question 30

What does the deep branch of the ulnar nerve supply in the hand?

Answer 30

After passing laterally to the pisiform, it supplies all three muscles of the hypothenar compartment, the 3rd and 4th lumbricals, all interossei, and the adductor pollicis.

Question 31

How does the ulnar nerve supply cutaneous innervation?

Answer 31

Dorsal branch supplies medial 1 and 1/2 digits on dorsal side, superficial branch supplies medial 1 and 1/2 digits on palmar side, after splitting with deep (motor) branch of ulnar nerve

Question 32

What is the function of the superficial radial nerve in the hand?

Answer 32

Supplies dorsal surface sensation of medial 3 and 1/2 digits, except for distal phalanges (supplied by medial nerve). Remember, this courses through the anatomical snuff box

Question 33

Where does the deep palmar arch of the radial artery go?

Answer 33

Between the two heads of the 1st dorsal interosseous muscle. Eventually meets with ulnar artery deeply.

Question 34

What is the lateral fibrous septum?

Answer 34

Also called the oblique palmar septum, extends from third metacarpal to palmar aponeurosis. Definds the boarders of the medial and lateral palmar fascial spaces

Question 35

What is a fascial space?

Answer 35

Any area between fascial layers of a compartment

Question 36

Where is the lateral palmar space?

Answer 36

Also called the thenar space, it is lateral to the oblique palmar septum

Question 37

What is the medial palmar space?

Answer 37

The space medial to the oblique palmar septum.

Question 38

Why do the palmar spaces matter?

Answer 38

Because the fascia is compartmentalized, the infection can only spread proximally up the arm, but not medially or laterally since the fascia prohibits it.