Lecture 23 - Forearm and Hand Flashcards
Forearm is
between elbow joint and wrist joint
Hand is
from wrist joint onwards
Elbow joint is a
synovial hinge joint
Function of elbow
forearm flexion and extension (i.e. the movements involved in a bicep curl)
Elbow joint is made of 3 different bones…
Humerus
Ulna
Radius
Coronoid process
on the ulna for brachialis
Radial tuberosity
on radius for biceps brachii
Anatomical postion - order of the forearm bones
Radius, Ulna, Middle (RUM)
Proximal radio-ulnar joint is a
synovial pivot joint
Pivot joint
Uniaxial
A rounded process of bone fits into a bony ligamentour socket, permitting rotation
Nerve behind medial epicondyle of humerus =
ulnar nerve
Capitulum
more rounded structure
on the lateral side of the humerus
Trochlear notch
of ulna pulley more 'w' in shape medial fits the trochlea of the humerus
Radial notch
of ulnar
part of the ulnar
bit concave to accomodate for radius
Radio-ulnar joints are between
radius and ulnar
Proximal radioulnar joint and ligaments
Ligaments aid stability
Anular ligament • Laxity in childhood • Yanking movements can dislocate the radius • Potential damage to ligament • aka Nursemaid’s elbow
Anular ligament
Anular ligament
• Laxity in childhood - so need to take care and be careful with childrens arms and pulling on them with a large amount of force
• Yanking movements can dislocate the radius - head of radius comes off ligament
• Potential damage to ligament
• aka Nursemaid’s elbow
distal radioulnar joint is a
synovial pivot joint
Distal radioulnar joint
- For pronation and supination
* Has an articular disc to allow twisting of joint capsule during pronation
Pronation in terms of radius
only the radius moves in pronation, croses over the ulna
Supination in terms of radius
radius and ulna parallel to one another
Pronation and supination happens
at the radiuolnar joints (have proximal and distal ones)
distal radioulnar joint has a disc to attach to ulna (articular disc is made up of fibrocartilage)
Cubital fossa is a triangular space bordered by…
Pronator teres
Brachioradialis
Epicondyles
^ think of triangle opposite to this i.e. with base up
base is lateral epicondyle ——medial epicondyle
Left border is brachioradialis (more lateral)
RIght border is pronator teres (more medial)
Nearby structures to cubital fossa
Brachialis Biceps brachii Median cubital vein Brachial artery Median nerve
Median cubital veins connects
the cephalic vein and the basilic vein
Forearm muscles - pronators for pronation
pronator teres
pronator quadratus
Forearm muscles - supinators for supination
Biceps brachii
Supinator (on lateral side)
pronator teres
quite superficial
pronator
part of cubital fossa
anterior
pronator quadratus
deep
pronator
anterior
Forearm muscles - anterior compartment movement
Flexors are in the anterior compartment
Forearm muscles - posterior compartment movement
Extensors are in the posterior compartment
Forearm muscles useful for
Useful for control and forceful movements of the wrist and hand. e.g., grip, lifting, writing, grabbing, etc
extension of hand =
pointing hand up towards face
flexion of hand =
pointing hand down away from face
Forearm muscles and tendons
muscle bellies are in the forearm and the tendons extend to the digits
Flexor retinaculum
Median nerve under here
anterior
compression of median nerve = carpal tunnel syndrome
Extensor retinaculum
posterior
Forearm arteries
- Brachial artery divides into radial and ulnary arteries
- As the names suggest, radial artery runs along the radius, and ulnar artery runs along the ulna
- Pulse can easily be palpated in distal radial artery
radial and ulna artery empty into the superior and deep palmar arch
Innervation of anterior forearm muscles
median nerve supplies most of the forearm muscles, ulnar nerve supplies some of the forearm muscles
Innervation of posterior forearm muscles
radial nerve
Innervation of posterior hand muscles
none as there are non muscles on the posterior hand
Anterior hand and nerves
Most muscles =ulnar
some muscles= median
Anterior forearm and nerves
Most muscles = median
some muscles = ulnar
Location of the biceps tendon
Biceps tendon in groove between the greater and lesser tubercle of the humerus
Wrist =
radiocarpal joint
What does the articular disc do ?
Articular disc does not allow the ulna to come in contact with the carpal
Wrist joint is an
ellipsoid (condyloid) synovial joint
Wrist joint is between
between radius and proximal carpals
Movements of wrist
flexion extension adduction abduction circumduction
Carpometacarpal joint =
between carpal and metacarpal
Metacarpophalangeal joint =
between metacarpal and phalanges
Interphalangeal joint =
between phalanges
Intercarpal joints are
synovial plane joints
Carpal tunnel
The carpal tunnel is a narrow passageway surrounded by bones and ligaments on the palm side of your hand. When the median nerve is compressed, the symptoms can include numbness, tingling and weakness in the hand and arm.
The flexor retinaculum is a fibrous connective tissue band that forms the anterior roof of the carpal tunnel.
Narrow space so not a lot of movement
there are ten different tendons that go through here as well as the median nerve
Hand bony features
metacarpals
phalanges
Function of the hand
- Manipulation
- Sensation
- Interaction with environment
- Joints within hands are synovial joints
Movement of interphalangeal joints
flexion and extension
Movement of metacarpo-phalangeal joints
flexion, extension
abduction, adduction
circumduction
abduction in hands =
spreading fingers
carpometacarpal joint 1 movement
joint at thumb, more flexible
important for opposition (and subsequent reposition which is going back to a flat hand)
flexion and extension of thumb (extension is moving out in coronal plane, flexion is bring in like when you show four fingers on your hand)
abduction and adduction of thumb (abd = moving out in sagittal plane)
Carpometacarpal joints 2-5 movement
minimal movement possible
Arterial supply to hand
Radial and ulnar arteries form superficial and deep palmar arches in the hand
superficial = digits deep = thumb
Venous supply to hand
the dorsal side of the hand has the dorsal venous network/arch
cephalic vein originates on the lateral side
basilic vein originates from the medial side
Innervation of anterior muscles of the hand
median nerve supplies some hand muscles
ulnar nerve supplies most hand muscles
innervation of the posterior muscles of the hand
no posterior hand muscles so no need for innervation by nerves
Intrinsic hand muscles functions
small so do not generate as much force
for fine motor movements such as writing and clay making
Intrinsic hand muscles
Thenar and hypothenar
Interossei
Thenar and hypothenar muscles are for
thumb and digit 5 movements
used in grips, precise movement and control of the digits
intrinsic hand muscles
Thenar and median nerve
supplied by median nerve so carpel tunnel sundrome affects thumb movement
thenar movement of
thumb
hypothenar movement of
digit 5 (pinky finger)
Interossei muscles are for
digits abduction and adduction
intrinsic hand muscles
located between the metacarpals
palmar interossei = attaches more on medial side, PADduciton
Dorsal interossei = attaches more on lateral side, DABduction
palmar interossei
palmar interossei = attaches more on medial side, PADduciton
dorsal interossei
Dorsal interossei = attaches more on lateral side, DABduction
