Movements of the Fingers:

Flexion and Extension of Fingers: Uses the fingernails as a fan.

Abduction and Adduction of Fingers: Uses the fingernails to slice through the air, centered around the middle finger.

THUMB: Same goes for thumb -- flexion, extension, abduction, and adduction are based on the position of the thumb-nail.

Circumduction: The combination action of flexion, extension, abduction, and adduction. Moving around in a circle, as you can do with your fingers, wrist, and

shoulder.

Force Transduction through the Hand and Arm:

Weight-bearing on the hand can be transmitted as follows:

SCAPHOID ------> RadioCarpal joints ------> RADIUS ------> Interosseus Membrane ------> ULNA ------> Olecranon ------> HUMERUS

------> Glenohumeral Joint ------> SCAPULA ------> Coracoclavicular Ligaments ------> CLAVICLE

The clavicle is the only bony articulation between the upper limb and trunk.

Most common points of fracture in a fall:

The surgical neck of the humerus

The middle of the clavicle

Common Wrist Fractures:

Colles Fracture: Fracture of the distal radius.

Scaphoid Fractures: Fracture of the scaphoid bone.

Extrinsic Muscles of the Hands: Mostly concerned with grip.

Intrinsic Muscles of the Hands: Concerned with manipulation of the digits. All of them are basically innervated by T1.

PALMAR APONEUROSIS: Deep to the skin and fascia. It holds it down, so that the skin on the palm is tight and hairless.

CLINICAL -- DUPUYTREN'S CONTRACTURE: Flexion of the 4th and 5th digits, resulting from progressive shortening of the palmar aponeuroses, from

hypertrophy and hyperplasia. Unknown cause.

FIBROUS FLEXOR SHEATHS (N435): Strong sheath covering the long tendons going into the hand, distal to the flexor retinaculum.

The fibrous sheaths of the fingers contain two tendons: The tendons of the Flexor Digitorum Superficialis and the Flexor Digitorum Profundus.

The fibrous sheath of the thumb contains one tendon: The Flexor Pollicis Longus.

SYNOVIAL FLEXOR SHEATHS (N435): The fibrous sheaths are enclosed in synovial sheaths in areas where there is friction. Primarily:

Deep to the flexor retinaculum.

Within the digits.

There are NO SYNOVIAL SHEATHS in the central palm of the hand.

RADIAL BURSA (N435, N436):

Contains the Pollicis Longus tendon.

Communicates with Ulnar Bursa in 50% of people.

ULNAR BURSA (N435, N436):

Contains the Flexor Digitorum Superficialis and Profundus tendons.

Communicates with Radial Bursa in 50% of people.

CLINICAL -- HORSESHOE INFECTION: Infection spreading from little finger to thumb or vice versa, as a consequence of the communication between the

radial and ulnar bursae.

CLINICAL: DORSAL SUBCUTANEOUS SPACE will receive lymph from the palmar aspect of the hand. Thus a hand-infection can easily result in swelling on

posterior aspect of the hand, in which case it would be lymph -- not pus -- so don't incise it.

SUPERFICIAL PALMAR ARCH (N439a): Main arterial supply to the hand.

Literally it is formed by a continuation of the artery, and it anastomoses with the Superficial Palmar Branch of the Radial Artery.

It gives off Common Palmar Digital Arteries ------> Proper Palmar Digital Arteries

DEEP PALMAR ARCH (N439b): Lies deep to the flexor retinaculum.

This is formed by the radial artery, and it anastomoses with the terminal ulnar artery.

It gives off the Palmar Metacarpal Arteries ------> Proper Palmar Digital Arteries

DORSAL CARPAL ARCH: From the dorsal carpal branches of the Radial and Ulnar arteries.

It gives off the Dorsal Metacarpal Arteries ------> Dorsal Digital Arteries.

THENAR SPACE: The area deep to the 1st lumbrical muscle and the 2st flexor tendon, in the palm of the hand.

MIDPALMAR SPACE: The medial part of the deep palm of the hand, deep to the rest of the flexor tendons. It is next to the Thenar Space.

A SEPTUM separates the Thenar from MidPalmar spaces.

CUTANEOUS INNERVATION OF HAND, FOREARM, ARM (N454, N445):

Axillary N:

Shoulder and Deltoid regions

Musculocutaneous N / Lateral Antebrachial Cutaneous N:

Lateral forearm (both posterior and anterior)

Medial Antebrachial Cutaneous N:

Medial Forearm (both posterior and anterior)

Radial N:

Central posterior arm and forearm

Lateral 2/3 of posterior hand (up to middle of 4th digit or so) -- EXCEPT the finger tips!!

Lateral part of the thumb

Median N:

Lateral two thirds of anterior hand

Fingertips of lateral 2/3 of posterior hand

Ulnar N:

Medial third of the hand, both anterior and posterior.

LUMBRICALS: They provide stability to the digits.

They are anterior to the Metacarpophalangeal (MCP) joints (knuckles).

So they flex the knuckles.

They are posterior to the proximal and distal interphalangeal (PIP and DIP) joints.

So they extend the distal phalanges.

They originate from the tendon of the flexor digitorum Profundus.

FUNCTION OF LUMBRICALS: They are rich in neuromuscular spindle organs, and they are thought to give you proprioception (spatial orientation)

and kinesthesia (sense of motion) of the digits, due to the tension placed on them by the digital tendons.

In other words, they allow you to know where your finger is and where it is going.