The Farm Hand:Anatomy, Function, Trauma, and

Injury PreventionCarla Wilhite, OT

Oklahoma State University-AgrAbility Specialist

Millee Jorge, PTLangston University-Dean of Physical

Therapy

Session Description

The session will introduce participants to the structure of the hand, its functions, and to mechanisms and types of injuries in farm work environments.

Participants will learn strategies for prevention of primary and secondary injury, and apply problem-solving skills to case examples

Objectives

• Identify basic anatomy of the hand

• Demonstrate understanding of hand function

• List prevalent mechanisms of injury on farms

• Injury prevention strategies

What is a hand?

• A paired organ dominantly controlled by the opposing brain hemisphere

• Our chief way for physically manipulating the environment

• Richest source of tactile feedback(From the Wikipedia)

Photo from: www.radiologyinfo.org

Anatomy

• Structures– Shoulder– Upper arm– Forearm– Wrist– Hand– Fingers

Shoulder

• Shoulder provides stability and dynamic movement to position hand for function

• Main components– Scapula– Clavicle

• Movement derives from:– Upper back– Rotator cuff

Source: Netter’s

Upper arm and forearm

• Bony structure– Humerus– Radius– Ulna

• Movements derive from:– Flexors– Extensors– Supinators– Pronators

Source: Netter’s Anatomy

Wrist

• Carpal bones• Movements

– Deviation– Flexion– Extension

Source: www.assh.org

Hand

• Metacarpals• Phalanges• Movements

– Flex– Extend– Abduction– Adduction– Isolated movement

vs. mass movement

Source: www.radiologyinfo.org

Vascular Anatomy

• Brachial artery• Radial artery• Ulnar artery• Palmar arch• Digital arteries• Anastamosis

Source: Top: Netter’s anatomy, Bottom: www.assh.org

Neuroanatomy

• Median Nerve• Ulnar Nerve

Source: Netter’s anatomy

Neuroanatomy

• Radial nerve

Source: Netter’s anatomy

Connective tissues

• Muscles– Move bony segments of the body

• Tendons– Termination of a muscle into bone

• Cartilage– Lines the articular joint surfaces

• Ligaments– Connect across joints

• Joint lubrication and bursa

Hand Functions

• Grasping patterns– Hook, spheres, cylinders

• Pinches– Key, tripod, inferior/superior

• Fine motor manipulation• Sensation

– Pain, touch, discrimination, object identification, vibration

Common hand injuries in farm work

• Contributing factors– Farmer state of mind

• i.e. attention, attitude toward safety

– Musculoskeletal forces

• i.e. wear and tear

– Removal of safety shields or other protective equipment

– Lack of training or skill

Source: American Farm Bureau Photo Gallery

Mechanisms of farm hand injuries

• Bites from farm animals

• Wounds– Punctures

• Canines

– Crushing/tearing wounds

• livestock

– Risk of infection– Disease

Source: www.assh.org

Mechanisms of farm hand injuries

• Chemicals– Plants– Vaccines– Fertilizers– Herbicides– Pesticides

• Wounds– Contact dermatitis– Lesions

Source: www.dermnet.com

Mechanisms of farm hand injuries

• Falls– Ladders– Stairs– Objects– Slippery hazards

• Injuries– Colles (radial wrist)

fracture– Scaphoid Non-union– Hand fracturesSource:Copyright by Jonathan Cluett, 2001

Mechanisms of farm hand injuries

• Machinery– Augers– Belts– Chains– Saws– Hitches– Hydraulic leaks– Mufflers/engines

• Wounds– Amputations– Fractures– Avulsions– Crushing– Lacerations– Contusions– Burns

Mechanisms of farm hand injuries

• Wounds– Tendon lacerations

• Flexion• Extension

http://www.davidlnelson.md/Tendon_Surgery.htm

Mechanisms of farm hand injuries

• Musculoskeletal forces– Cumulative trauma– Repetitive use

• Injuries– Sprains/strains– Tendonitis– Carpal tunnel– Bursitis– Cysts– Vascular compromise– Arthritis

Source: http://orthoinfo.aaos.org

Mechanisms of farm hand injuries

• Arthritis and Joint involvement– Pain– Joint enlargement– Joint erosion– Nodes– Deformities

Mechanisms of farm hand injuries

• Vibration • Cold and heat

– Vascular compromise– Nerve damage– Thermal injury– Raynaud’s syndrome

(sympathetic)

Source:http://www.assh.org

Mechanisms of farm hand injuries

• Related injuries that affect hand function– Brachial plexus injury– Cubital tunnel– Rotator cuff trauma– Nerve injuries proximal to

the hand

• Mechanism– Pulling/pushing– Overuse– Dislocations– Lacerations/crushing

Source: http:www.assh.org

Prevention of Hand Injuries

• Design to fit body size– No such thing as “average size”– Provide adjustability in work station

• Design to fit body posture– Three work positions: lying, sitting, and

standing– But, transient postures of every kind

between these postures (asymmetry):– Stooping, squatting, kneeling

Prevention of Hand Injuries

• Designing for Hand Use– Hand tasks fall into five major groups

• Fine manipulation (writing, assembling small parts)

• Fast movements to an object (hitting a switch)• Frequent movements between targets (larger

parts from bins to assembly)• Forceful activities with little displacement (turning

a wrench)• Forceful activities with large displacements

(hammering)

Prevention of Hand Injuries

• Hand tools– Purpose of tool handle is to maintain secure control– Tool should fit contours of hands– Tool for right or left (or both)– Does tool require precision grip or power grip?– Consider energy between tool handle and hand,

and tool to object– Manual tools or power?– See Therese Willkomm’s AgrAbility article!!!

Prevention of Hand Injuries by Agricultural Workers

• Most effective control is to “engineer out” the risk of injury

• When risk cannot be designed out: then use safety procedures and use of personal protective equipment

Source: Nordin, Andersson, & Pope (1997)

Prevention of Hand Injuries by Agricultural Workers

• Be familiar with personal protective equipment• Use correct gloves and safety equipment• Remove rings, watches, jewelry when working with

power tools or on equipment• Do not wear gloves near machine gears or other

devices• Replace gloves that are stretched, ragged, or torn• Keep machine guards in place• Use push sticks with table saws• When using sharp blades or needles keep point away

from the body, cut away from the body, use retractable blades

Prevention of Hand Injuries by Agricultural Workers

• Pay special attention to round or cylindrical parts that are unstable when placing them on a floor or bench. Use a roll stopper.

• Use extra caution around “pinch points”• Check high pressure hoses for pinpoint leaks • Wash hands often to prevent spread of disease

and infection

• (Source: Maine Municipal Association Risk Management Services)

Prevention of Hand Injuries by Agricultural Workers

• Take a break every hour or switch to another activity to prevent overuse of repetitive hand movements

• Break tasks into short sessions• Store tools to prevent accidents• Choose the right tool for the job• Avoid sustained/constant gripping and

awkward motions• Plan ahead, arrange work space• (Source: adapted from American Society of Hand Therapists, www.asht.org)

Prevention of Hand Injuries by Agricultural Workers

• Upper extremity warm-up exercises– Fold your hands together, turn palms away from

body, extend arms, hold 10 seconds and repeat 8 times (upper back and shoulder)

– Then do it over head– Hold arm across chest, use opposite hand to push

elbow gently toward chest, alternate with other arm (upper back and shoulder)

– Extend arm, palm down, take opposite hand and bend wrist gently downward. Then do palm up, and stretch wrist back gently.

– Gently open/close fists– “Play the piano”(Source: Adapted from ASHT)

Case studies