1.2.2 to 1.2.6 bones and joints

describe the proximal ends of the radius

- at the end is the head of the radius and the neck - the end of the head articulates with the capitulum of the humerus - the curved side of the head articulates partly with the radial notch of the ulna and partly with the ligament that surrounds it - distal to the neck is the radial tuberosity which is the insertion for the biceps tendon

describe the distal end of the humerus

- flattened from front to back - complicated articular surface - it is in two parts; the pulley like trochlea articulates with the ulna and the rounded capitulum articulates with the radius - two prominent lumps; medial epicondyle and lateral epicondyle which are major muscle origins - above each epicondyle is an epicondylar ridge - the olecranon fossa is a big hollow on the back of the humerus

how stable is the elbow joint, why

- it is stable, meaning it stays together - partly because of the strength of the ligaments - partly because of the shape of the bones; the humerus and ulna interlock closely and deeply. - their surfaces are curved in two planes, from front to back and from side to side

Where is pisiform bone located?

- lies on the palmar surface of the triquetrum

describe the proximal radio-ulnar joint

- the anular ligament and radial notch of the ulna provides a perfecting fitting socket for the head of the radius to rotate in - the anular ligament forms a ring shape and it attached to the edges of the radial notch of the ulna and is shaped like a shallow cup, wider and the end closest to the joint to fit the radial head at the most proximal section and nearer to the neck

describe the articulations of the metacarpals with the carpals

- the bases of the five metacarpals articulate with the distal row of carpal bones - the first (thumb) articulates by itself with the trapezium - the other 4 articulate in a row with the trapezoid, capitate and hamarte

how the the radius move round the ulna

as the distal end of the radius rides around the head of the ulna, the ulnar styloid provides the pivot point

how are the radius and ulna joined

by two radio-ulnar joints, the proximal and distal - forearm rotation happens simultaneously at both these joints - the two bones are also held together along most of their length by a strong flexible interosseous membrane which prevents the two bones moving lengthwise relative to each other

what is the route of the ulnar collateral ligament

goes from the ulnar styloid to the triquetral and pisiform bones

what movements can the radial head make

it is free to rotate but is otherwise completely trapped

watch 1.2.6 for review

okay!

are the elbow joint and proximal radio-ulnarjoint considered to be one or two separate joints

one because they are enclosed in one continuous space

describe the arrangement of the proximal row of carpal bones

- the bones in each row are attached closely to one another - the 4 bones of the proximal row are the scaphoid, lunate, triquetral and pisiform ( which sits by itself on the triquetral) - the scaphoid, lunate and part of the triquetral articulate with part of the distal end of the radius to form the radiocarpal joint - the distal surface of the proximal row forms a deeply concave notch which the bones of the distal row fit into and articulate with to form the midcarpal joint

describe the arrangement of the distal row of carpal bones

- the bones in each row are attached closely to one another - the distal surface of the proximal row forms a deeply concave notch which the bones of the distal row fit into and articulate with to form the midcarpal joint - the bones of the distal row are the trapezium, trapezoid, capitate and hamate - the capitate and part of the hamate project proximally - the projecting capitate and hamate fit into the notch in the proximal row - the bases of the five metacarpals articulate with the distal row of carpal bones

describe the articular surfaces of the distal end of the radius

- the broad end has 2 articular surfaces - the larger surface articulates with the proximal row of carpal bones - the smallersurface articulates with the ulna

what happens at the elbow region in terms of bones

- the humerus articulates with the forearm bones to form the elbow joint - the two forearm bones articulate with each other to form the proximal radio-ulnar joint

describe the elbow joint key ligament structure for the radius

- the ligament that holds the radial side of the of the elbow togheter and holds the rotating head of the radius in place against the ulna - it has two parts, the radial collateral ligament and the anular ligament - the radial collateral ligaments arises from the lateral epicondyle and fans out to become continuous with the annular ligaments - these two parts hold the humerus and radial head together - the jagged edge we see is not the ligament, it is the cut edge of the tendon of origin of the supinator muscle which arise from the ligament

describe the proximal end of the ulna

- the main feature is a curved surface which forms a curve called the trochlear notch - this notch articulated with the trochlear of the humerus - at the most proximal end of the ulna is the olecranon; which attached to the triceps tendon - there is also a coronoid process - distal to the process is a rough area called the ulnar tuberosity which marks the insertion of the brachialis tendon - there is a small curved surface called the radial notch where the head of the radius articulates

describe the differences in the radius and ulna

- the ulna is bigger proximally and the radius is bigger distally - the radius rotates but the ulna doesn't

describe the elbow joint key ligament structure for the ulna

- the ulnar collateral ligament arise from the medial epicondyle and fans out in a triangle - it is attached to the ulna all along the medial side of the trochlear notch

breifly describe the bones in the wrist and palm region of the hand

8 small carpal bones form the carpus - distal to the carpus are the metacarpal bones, numbered 1-5, 1 is the thumb - the carpal bones are in two rows, proximal and distal - the bones in each row are attached closely to one another

what is an epicondyle

Raised area on or above a condyle (the round prominence at the end of a bone, most often part of a joint - an articulation with another bone)

describe how the wrist joint is held together

entirely by the strength of its ligaments - the two collateral ligaments hold the bones together in radial and ulnar abduction - the radio-carpal ligaments holds the bones together in flexion and exntension - the strength of the radio-carpal ligaments ensures that when the radius rotates the hand goes with it

what is the carpus

equivalent to our wrist

what are the two forearm bones

radius and ulna

how is the ulna accomdated in full extension by the humerus

the big hollow at the back of the humerus called the olecranon fossa accomodates the end of the ulna (the olecranon) in full extension

what is the capsule of the elbow joint like

the capsule is thin and baggy in front and also behind to allow a full range of movement - there is also a very flexible sleeve of joint capsule between the annular ligament and the neck of the radius

what are the flexor and extensor aspects

the extensor surface is the area of skin on the outside of a joint. The muscle that causes a joint to open and extend is aptly called the extensor muscle. Examples of an extensor surface include the front of the knee or the back of the elbow or forearm. By contrast, the flexor surface is the skin on the side of a joint that folds. Directed by a flexor muscle, the flexor surface can be described as areas where folded skin can touch, such as the inside of the elbow or the back of the knee.

describe the joint capsule of the wrist joint

the joint capsule is thick and strong all the way round the joint - on the extensor aspect, the capsule forms the broad dorsal radiocarpal ligament - on the flexor aspect it forms the palamar radiocarpal ligament

what is the route of the radial collateral ligaments

the radial collateral ligament goes from radial styloid to the scaphoid and its neighbour, the trapezium

what is the pointon the distal end of the radius

the radial styloid

what is the pointed tip at the distal end of the ulnar

the ulnar styloid

what structuresholds the distal radio-ulnar joint together

triangular fibrocartilage also know as the articular disk it is attaches to the radius and the ulnar styloid

how many joints are at the wrist

two joints very close together called the radio-carpal joint and the mid-carpal joint

are the distal radio-ulnar joint and the wrist joint considered to be one or two joints

two separate joints, even though they are close together

describe the difference between the way that the wrist adn elbowjoints are held together and made stable

unlike the elbow joint which is held together partly by the interlocking shape of the bones, the wrist joint is held together entirely by the strength of its ligaments

which joints are involved in movement of the wrist

when flexion and extension occur at the wrist, the movement happens partly at the radiocarpal joint and partly at the midcarpal joint - when radial and ulnar deviation occur e.g waving hand side to side, the action ahppens mainly at the radio-carpal joint