Lecture 9: The Forearm flexor compartment and Wrist Flashcards
What is the ‘head’ of the bone and at what end is the head of the radius and ulna
The head is the smaller end of the bone. The head of the radius is at the proximal end of the forearm (sup R/U joint) whereas the head of the ulna is at the distal end of the forearm (inf R/U joint)
How does the position of the flex/pro comp of the forearm and ext/ sup comp change from the superior to inferior Radio-ulnar joint
There are 4 segments at the sup joint, with a line from post to ant going through the Radius and ulna forming a boundary, with the two middle squares containing the flex and ext compartment of the arm.
The outer semicircles contain forearm compartments, with the Medial semicircle = the flex/pro comp of forearm and Lateral semicircle= ext sup comp.
Eventually the forearm at the distal R/U joint has only a horizontal line with Anterior compartment : Flex and pro and Posterior compartment : Extend and Sup compartment
Describe the articulation at the distal radio-ulnar joint
The head of the ulna articulates with the tail of the radius by fitting into the ulnar notch. In between them is the sacciform recess which extends a little higher and underneath the ulnar but in the layer above the fibrous articular disc (excludes ulnar from proper wrist joint).
What is the lateral pointy part of the bone sticking out from the radius or the ulnar
Styloid process
What is the interosseous membrane and its function
Interosseous membrane is investing fascia that joins the medial border of the radius to the lateral border of the ulna. Its function is to act as a hinge for radial rotation, a place for muscle attachement and a medium for transmission of force from radius to ulnar to prevent excessive force on the head of the radius
What bones articulate at the wrist joint proper?
The radius with the the fibrous articular disc proximally and then the scaphoid, lunate and triquetrum distally.
What are the other 2 joints in the wrist (apart from wrist joint proper) and what bones articulate there
The mid carpal/ transverse intercarpal joint which is a n shape between the two rows of 4 carpal bones. AND
The carpo-metacarpal joint: between the distal row of carpal bones and the medial 4 digits (metacarpal bones)
Compare the range of movement available in the 3 joints of the wrist (from distal to proximal)
At Carpal- metacarpal joint there is very little movement
At midcarpal joint there is some flexion/ extenion
At Wrist joint proper there is flexion/ extension + abduction/adduction + a little rotation.
What are the 8 carpal bones of the wrist: proximal then distal row, from lateral to medial both rows
Scaphoid, Lunate, Triquetrum, Pisiform
Trapezium, Trapezoid, Capitate, Hamate
Some lovers try positions that they can’t handle
What is the carpal tunnel made out of and what does it do
It is the space enclosed by the carpal bones and covered by the flexor retinaculum which is a thickening of the fascia which holds the flexor tendons of the elbow and stops them from bow stringing. It attaches to the pisiform and hamate bones medially and the scaphoid and trapezium laterally.
What are the 3 types of bones that make up the hand (from proximal to distal )
The carpals which make up the wrist. The metacarpals which make up the palm and the phalanges that make up the digits/ fingers.
The phalanges have a proximal, middle and distal for the 4 fingers and no middle for the thumb.
What are the 4 superficial forearm muscles, 1 intermediate forearm muscle and 3 deep forearm muscles
Superficial: Pronator Teres, Flexor carpi radialis, Palmaris longus, Flexor carpi ulnaris
Intermediate: Flexor digitorum superficialis
Deep: Flexor pollicis longus, Flexor digitorum profundus and Pronator quadratus
What is the origin and insertion of the superficial forearm muscles
Origin: at the common flexor tendon except for pronator teres on the supracondylar ridge
Insertion;
Pronator Teres - middle lateral surface of the radius
Flexor carpi radialis - the base of 2nd metacarpal
Palmaris longus - palmar aponeurosis
Flexor carpi ulnaris- pisiform carpal bone
What is the action of the 4 superficial forearm muscles
PT: pronates the forearm
FCR and FCU ( and PL) flexes the forearm
What is the origin and insertion and movement of the intermediate forearm muscle-
Flexor digitorum superficialis O; radial and humero ulnar heads,
Insertion: 4 tendons that insert on the base of the middle phalanx of the 4 digits. Insertion is slit in two
What is the action of the intermediate forearm muscle
It flexes the fingers, giving more control on individual flexion
What is the origin and insertion and movement of the deep forearm muscles
O: interosseous membrane: FDP+ PQ is ulnar, FPL is radius
Insertion;
FPL: base of the distal phalanx of the thumb
FDP: splits into 4 tendons to base of distal phalanx of digits
PQ: last inner part of the radius.
What is the action of the deep forearm muscles
FPL and FDP : flex and PQ pronates
What tendons of forearm muscles pass under flexor retinaculum and through the common synovial sheath of the palm
Long tendons of Flexor digitorum superficialis, Flexor digitorum profundus and Flexor pollicis longus (which may have its own sheath
What tendons of forearm muscles pass on top of the flexor retinaculum
Palmaris Longus and Flexor carpi ulnaris
How does the median nerve travel down the forearm and what muscles does it innervate along the way (including branches) for motor and cutaneous
Motor:
- Main branch : PT, FCRadialis, PalmL, FDSup,
- Anterior interosseous (smaller deeper branch) : PQ, FpollicisL, Lateral half of FDprofundus,
- Recurrent branch after retinaculum which does Thenar, 1st and 3rd lumbricals
Cutaneous: 3.5 digits including thumb
- Palmar cutaneous branch for skin on the palm
- Proper palmar digital nerve
How does the ulnar nerve travel down the forearm and what muscles does it innervate along the way (including branches) for motor and cutaneous
Cutaneous: medial 1.5 digits
- palmar cutaneous branch
- proper palmar digital nerves
Motor:
- FCUlnaris and Medial half of FDProfundus
- Deep branch of ulnar nerve does most intrinsic muscles of the hand
Describe the arterial supply to the forearm from the cubital fossa
At the cubital fossa the brachial artery splits into Radial and Ulnar arteries which go down the side of their bones. There is a branch of the ulnar artery which is the common interosseous branch towards the midline of the arm which splits into the anterior and posterior interosseous artery.
There are recurrents for radial and interosseous , two for ulnar.
The superficial and deep branches of the ulnar and radial arteries form arches.
