The Farm Hand:
Anatomy, Function, Trauma, and
Injury Prevention
Carla Wilhite, OT
Oklahoma State University-AgrAbility Specialist
Millee Jorge, PT
Langston 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
–
–
–
–
–
Source: www.radiologyinfo.org
Flex
Extend
Abduction
Adduction
Isolated movement
vs. mass movement
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
Source: American Farm Bureau Photo Gallery
– Removal of safety
shields or other
protective equipment
– Lack of training or
skill
Mechanisms of farm hand
injuries
• Bites from farm
animals
• Wounds
– Punctures
• Canines
– Crushing/tearing
wounds
• livestock
Source: www.assh.org
– Risk of infection
– Disease
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
Source:Copyright by Jonathan Cluett, 2001
– Colles (radial wrist)
fracture
– Scaphoid Non-union
– Hand fractures
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
Source: http://orthoinfo.aaos.org
–
–
–
–
–
–
–
Sprains/strains
Tendonitis
Carpal tunnel
Bursitis
Cysts
Vascular compromise
Arthritis
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
–
–
–
–
Source: http:www.assh.org
Pulling/pushing
Overuse
Dislocations
Lacerations/crushing
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