Anatomy- Elbow and Forearm Flashcards
What type of joint is the elbow joint?
-Hinge synovial joint
What 3 joints share the same synovial cavity and make up the elbow joint?
- Humeroulnar joint
- Humeroradial joint
- Proximal radioulnar joint
What movements can the elbow joint do?
- Flexion/extension
- Proximal radioulnar joint also allows movement of hand through supination and pronation of the forearm.
What provides main stability of elbow joint?
-Main stability from bony articulations of the trochlea (humerus) and olecranon (ulna).
What does the humerus articulate with?
- 2 forearm bones
- Laterally: radius: rounded at capitulum
- Medially: ulna: trochlea
Where are the medial and lateral epicondyles of the humerus and what are they there for?
- Proximal to trochlea and capitulum
- Also sites of muscle attatchment
Is the ulna medial or lateral and is it smaller or larger than the radius?
- Medial
- Larger than the radius
What is found proximally on the ulna?
- Trochlear notch
- 2 processes:
- larger; olecranon; posterior; elbow prominence
- smaller; coronoid process; anterior
Where does the humerus articulate with the ulna and how is this area created?
- Trochlear notch
- The 2 processes (olecranon and coronoid) form the trochlear notch to articulate with the trochlea of the humerus.
What is found distally on the ulna?
- Head; anterior, articulates with radius
- Styloid processes; posterior/medial, wrist ligaments
Is the ulna part of the wrist joint?
Not strictly:
- articulates with radius at distal radioulnar joint
- prevented from articulating with the carpal bones by a fibrocartilaginous ligament = articular disc
Is the radius medial or lateral?
Lateral
What can be found proximally on the radius?
- Head; articulates with capitulum of humerus and radial notch of ulna
- Radial tuberosity; medially, biceps attatch here
What can be found distally on the radius?
- broad
- articulates with ulna and proximal carpal bones
- Styloid processes alterally; wrist ligaments attatch
- Ulnar notch; medially
What forms the humeroulnar joint?
- Trochlea of humerus AND
- Trochlear notch of ulna
Where is humeroulnar joint ?
Medially
What is the main joint of the elbow?
-Humeroulnar joint
What reinforces the humeroulnar joint?
Ulnar collateral ligament
What movements does the humeroulnar joint allow?
- Flexion and extension
- Ulnar processes limit range of movement
- No pronation or supination
What makes up the humeroradial joint?
- Capitulum of humerus AND
- Head of radius
Where is humeroradial joint located?
-Lateral
What reinforces humeroradial joint?
-Reinforced by radial collateral ligament.
What movements does the humeroradial joint allow?
-Supination and pronation
What does the annular ligament do?
-Stabilises both humeroradial and humeroulnar joint
What are the flexors of the arm?
- Biceps brachii
- Coracobrachialis
- Brachialis
What are the extensors of the arm?
Triceps
Anconeus
Which areas move to allow forearm rotation?
- Movements between forearm bones at radioulnar joints.
- Around radius head to ulna styloid process.
- Radius rotates, proximal ulna stays in place
Where does forearm rotation occur?
- Occurs below and independant of shoulder and elbow.
- Even though superior radioulnar joint cavity continous with elbow.
Is supination or pronation more powerful?
Supination
What gives forearm rotation the apparent range of 360 degrees?
- Rotation of humerus
- Pectoral girdle movements
What happens in pronation and where are the radius and ulna located in pronation?
- Palm turned posteriorly
- Proximal radius lateral to ulna
- Distal radius medial to ulna
What happens in supination and where are the radius and ulna located in pronation?
- Palm turned anteriorly
- Movement reversed
- Radius lateral and paralell with ulna.
What type of joint is the superior radioulnar joint and what is it a joint between?
- Pivot joint
- Between head of radius and osseofibrous ring (radial notch of ulna and annular ligament).
What does the radial annular ligament do?
-Consists of string fibres, encircles head of radius.
What type of joint is inferior radioulnar joint and what make it up?
- Pivot synovial joint
- Between head of ulna AND
- ulnar notch of radius
What holds the inferior radioulnar joint together?
- Articular disc
- Interosseous membrane
What is the interosseous membrane?
- Is a broad thin fibrous tissue separating bones.
- Fibrous sheet connecting radius and ulna to form radio ulnar syndesmosis (fibrous joint between radius and ulna).
- Divides forearm into anterior and posterior.
- Site of attatchment for muscles of forearm.
What happens to the interosseous membrane fibres going from pronation to supination?
-Fibres change from relaxed to tense in the neutral position, relax again as forearm supinates.
What may cause disloaction/subluxation of radial head and what group of people are at high risk?
- Pre school kids
- If jerked by UL while forearm pronated
- Tears distal attatchment of annular ligament
- Radial head moves distally out.
What is the treatment for disloaction/subluxation of radial head?
-Manipulating forearm into supination whilst elbow flexed-radial head back in place.
What are the supinator muscles?
- Biceps brachii
- Supinator
What are the pronator muscles?
- Pronator teres
- Pronator quadratus
What is the cubital fossa important for?
-Important transition between arm and forearm.
What is the triangular depression of the cubital fossa bound by?
- Brachioradialis laterally
- Pronator teres medially
What artery enters cubital fossa and what does it leave as?
- Brachial artery
- Leaves as radial and ulnar arteries
What nerves found in the cubital fossa?
- Median nerve runs through
- Radial nerve laterally if brachioradialis retracted.
How can the muscles of the forearm be categorised?
- 2 layers:
- Superficial: long muscles; humerus to hands (act on elbow and wrist), humerus to digits (act on elbow, wrist, digits)
- Deep: arise from forearm bones and pass to digits. Crossing and acting on wrist joints and digit joints.
