Lecture 13 - Hand

Question 1

What nerves innervate the dorsal hand and what portions of the hand do they innervate?

Answer 1

Radial:

• dorsolateral hand
• dorsal thumb
• dorsal proximal second and third digits

Median:

• distal dorsal second and third digits (exclusive)
• distal dorsal fourth digit

Ulnar:

• dorsomedial hand
• dorsal proximal third digit
• dorsal fourth digit
• dorsal fifth finger (exclusive)

Question 2

What nerves innervate the palmar hand and what portions of the hand do they innervate?

Answer 2

Median:
-central palm

Ulnar:
-medial palm

Question 3

What are the joints in the hand?

Answer 3

Carpometacarpal joints

Metacarpophalangeal joints
-MCP

Interphalangeal joints

• proximal interphalangeal (PIP)
• distal interphalangeal (DIP)

Question 4

What type of joint are the carpometacarpal joints and what movements do they allow?

(slide 7)

Answer 4

Type:
-plane, synovial joint

Movement:

• digits 2-3; almost none
• digit 4; limited
• digit 5; ab/adduction, flexion/extension, circumduction

Question 5

What type of joint are the metacarpophalangeal joints and what movements do they allow?
What ligaments are present

(slide 8)

Answer 5

Type:
-condyloid, synovial

Movement:

• flexion/extension
• abduction/adduction

Ligaments:

• palmar ligaments
• collateral ligaments

Question 6

Why can you not spread your fingers while they are flexed?

Answer 6

-collateral ligaments are taut during flexion preventing it

Question 7

What type of joint are the interphalangeal joints and what movements do they allow?
What ligaments are present?

(slide 9)

Answer 7

Type:
-hinge, synovial

Movement:
-flexion/extension

Ligaments:
-collateral ligaments

Question 8

What are the superficial palmar structures?

slides 11

Answer 8

Palmar aponeurosis

Flexor retinaculum

Palmaris brevis

Question 9

Describe the palmar aponeurosis.

Answer 9

• triangular layer of deep fascia
• protects for superficial vessels, nerves, and tendons
• anchored to skin by flexor retinaculum
• spilt into 4 sheaths which blend into flexor sheaths of digits 2-4

Question 10

Describe the flexor retinaculum.

Answer 10

• laterally attaches to tubercles of scaphoid and trapezium

- medially attaches to hook of hamate and pisiform

Question 11

Describe the carpal tunnel.

Answer 11

• groove between pisiform and hook of hamate
• roof is flexor retinaculum

Contains:

• tendon of flexor digitorum superficialis
• tendon of flexor digitorum profundus
• tendon of flexor pollicis longus
• median nerve

Question 12

What passes through Guyon’s canal?

Answer 12

• ulnar nerve

- ulnar artery

Question 13

What are the intrinsic muscles of the thumb?

Answer 13

• abductor pollicis brevis
• flexor pollicis brevis
• opponens pollicis
• adductor pollicis

Question 14

Of the intrinsic muscles of the thumb, which muscles are part of the thenar eminence?
Other than this, what differentiates these muscles?

Answer 14

Thenar eminence:

• innervated by MEDIAN nerve
• abductor pollicis brevis
• flexor pollicis brevis
• opponens pollicis

Not:

• innervated by ULNAR nerve
• adductor pollicis

Question 15

What are the intrinsic muscles of the fifth digit?

What is the common innervation?

What structure do these muscles form?

Answer 15

Muscles:

• abductor digiti minimi
• flexor digiti minimi brevis
• opponens digiti minimi

Innervation:
-ulnar nerve

Hypothenar eminance

Question 16

What are the thenar and midpalmar spaces?

Answer 16

Thenar:
-area between the adductor pollicis muscle and the long flexor tendons of the index finger/thumb

Midpalmar:
-area between metacarpals 4-5 and long flexor tendons to digits 4-5

Question 17

What path does he radial artery take through the wrist and hand?

Answer 17

• lies lateral to the tendon of the flexor carpi radialis (radial pulse)
• passes across scaphoid in anatomical snuff box
• wraps around dorsum of the first metacarpus
• pierces first dorsal interosseous muscle into the palm of the hand
• forms deep palmar arch

Question 18

What vessels supply the dorsum of the hand?

Slide 35

Answer 18

Arteries:

• dorsal arterial arch (radial and ulnar arteries)
• dorsal metacarpals
• dorsal digitals

Venous:
-dorsal venous arch (medially to basilic vein and laterally to cephalic vein)

Lymphatic:
-medial through lymph nodes accompanying basilic vein (to subtrochlear and lateral axillary nodes)

Question 19

What is the arterial supply to the palmar hand?

Answer 19

• superficial palmar arch (continuation of ulnar artery)

- deep palmar arch (continuation of radial artery)

Question 20

What path does the ulnar nerve take in the hand?

Answer 20

• enters superficial to flexor retinaculum
• branches into superficial branch and deep branch

Superficial branch:

• innervates palmaris brevis
• cutaneous innervation

Deep branch:
-innervates other muscles innervated by ulnar nerve

Question 21

What path does the ulnar nerve take in the hand?

Answer 21

• enters deep to flexor retinaculum

- divides into lateral and medial branches

Question 22

What is mallet finger?

Slide 40

Answer 22

• avulsion of long extensor tendon

- results in hyper flexion of DIP

Question 23

What is Dupuytren’s contracture?

Slide 40

Answer 23

• progressive fibrosis of palmar aponeurosis

- marked flexion of fingers at MP joints

Question 24

What is Colle’s fracture?

Answer 24

-fracture of distal end of the radius

Question 25

What results from median nerve injury?

Answer 25

- loss of thumb opposition - atrophy of thenar muscles - ape hand

Question 26

What results from ulnar nerve injury?

Answer 26

- paralysis of interossei (guttering) - loss of thumb adduction - claw hand

Question 27

What are the components of the extensor mechanism and what is its function?

Answer 27

Components: - hood - lateral bands (bases of distal phalanges) - central bands (bases of middle phalanx) Function: - flexion at MCP joint - extension at PIP and DIP joints