Part 3 - Cubital Fossa & Forearm

• Cubital Fossa


  • Shape- upside down triangle
  • Superficially- a depression on the anterior aspect of the elbow region
  • Deeply- space filled with fat anterior to the most distal part of the humerus and elbow joint

  
• Boundaries of Cubital Fossa

  • Superior (base)- imaginary line between medial and lateral epicondyles of humerus
  • Medially- pronator teres
  • Laterally- brachioradialis
  • Inferiorly (apex)- meeting of brachioradialis and pronator teres
  • Posteriorly (floor)- brachialis superiorly and supinator muscle inferiorly
  • Anteriorly (roof)- skin, superficial and deep fasciae and bicipital aponeurosis

  
• Contents of Cubital Fossa

  • Superficial: Median cubital vein, Medial cutaneous nerve of forearm, Upper lateral cutaneous nerve of forearm
  • Deep: Median nerve, Biceps brachii tendon, Radial nerve deep to brachialis, Terminal end of brachial artery, Radial and ulnar arteries, Radial recurrent artery

  
• Median cubital vein


  Used for IV and venipuncture injections, fixed by a communicating perforating vein, runs diagonally from cephalic vein of forearm to basilic vein of arm
• Bicipital aponeurosis separates superficial and deep structures of the cubital fossa

  
• Radius


  • Articulates proximally with the humerus at the capitulum and medially with the ulna on both proximal and distal ends, Articulates with 2 carpal bones of the wrist: lunate medially and scaphoid laterally

  
• Landmarks of Radius


  • Radial head, Radial neck, Radial (bicipital) tuberosity, Shaft, Interosseus border, Anterior oblique line, Ulnar notch, Styloid process, Suprastyloid crest

  
• Radial head


  Round articular structure on the proximal end of the radius, Cupped proximal surface (articular fovea or facet) articulates with the capitulum of the humerus, The articular circumference articulates with the ulna

  
• Radial neck


  Slender segment of the radius between the head and the radial tuberosity
• Radial (bicipital) tuberosity


  Blunt variably shaped structure on the anteromedial side of the proximal radius, Marks the insertion of the biceps brachii

  
• Shaft of Radius


  Long, thin section between the radial tuberosity and the expanded distal end, Divided into 3 surfaces- anterior, posterior and lateral
• Interosseus border of Radius

  Sharp medial edge of the radial shaft, Serves as attachment site for interosseus membrane which divides forearm into anterior and posterior compartments
• Anterior oblique line of Radius


  Gives origin to the extrinsic muscles of the hand

  
• Ulnar notch of Radius


  Concave articular hollow surface on the medial corner of the distal radius, articulating with distal ulna

  
• Styloid process of Radius

  Sharp projection on the lateral side of the distal radius
• Suprastyloid crest of Radius


  Runs obliquely over the styloid process on the anterior surface, Serves as attachment for brachioradialis

  
• Ulna


  • Longest, thinnest bone in the forearm, Articulates proximally with the trochlea of the humerus and with the head of the radius, Articulates distally with the ulnar notch of the radius and with the articular disc that separates it from the carpal bones

  
• Landmarks of Ulna


  • Olecranon, Trochlear notch, Coronoid process, Ulnar (brachial) tuberosity, Radial notch, Shaft, Interosseus border, Ulnar head, Ulnar styloid process, Articular circumference

  
• Olecranon of Ulna


  Most proximal part of the bone, Massive blunt process, Triceps brachii inserts onto the tuberosity of this process

  
• Trochlear notch of Ulna

  Articulates with the trochlea of the distal humerus, Rotary motion is restricted at the ulnar part of the elbow which limits its ability to rotate along its long axis

  
• Coronoid process of Ulna

  Anterior beak-shaped projection at the base of the trochlear notch

  
• Ulnar (brachial) tuberosity of Ulna


  Roughened depression immediately inferior to the coronoid process, Marks the insertion of the brachialis muscle

  
• Radial notch of Ulna


  Small articular surface for the radius, Located along the lateral margin of the coronoid process

  
• Shaft of Ulna


  Long segment between the brachial tuberosity and the distal end of the ulna, Divided into 3 surfaces by the 3 borders- interosseus, anterior (medial), posterior

  
• Interosseus border of Ulna


  Sharpest border of the ulna, Lies opposite to radius, Between the anterior and posterior surfaces

  
• Ulnar head


  Enlarged distal end of the bone

  
• Ulnar styloid process


  Sharp distalmost projection of the ulna, On the posteromedial aspect of the bone, Provides attachment to the ulnar collateral ligament of the wrist, Separated from the remainder of the head by a deep groove, the fovea

  
• Articular circumference of Ulna


  Distal, lateral, round articulation that conforms to the ulnar notch of the radius (in the same way that the radial head conforms to the radial notch of the proximal ulna)

  
• Elbow Joint


  • Hinge type synovial joint, Movements limited to: Flexion by brachialis and biceps brachii, Extension by triceps brachii assisted by anconeus, Articulation: Humeroulnar- trochlear of humerus and trochlear notch of ulna, Humeroradial- capitulum of humerus and head of radius

  
• Ligaments of Elbow Joint

  • Radial collateral ligament, Anular ligament (part of proximal radio-ulnar joint), Ulnar collateral ligament

  
• Radial collateral ligament


  Fan-like, Extends from lateral epicondyle of humerus and blends distally with the anular ligament of the radius

  
• Anular ligament


  Encircles and holds the head of the radius in the radial notch of the ulna, Forms the proximal radio-ulnar joint which allows the pronation and supination of the forearm

  
• Ulnar collateral ligament


  Triangular, Extends from the medial epicondyle of the humerus to the coronoid process and olecranon of the ulna, Consists of 3 bands: The strongest anterior cord-like band, The weakest posterior fan-like band, The slender oblique band deepens the socket for the trochlear of the humerus

  
• Elbow Joint Capsule


  • Fibrous layer surrounds the elbow joint, Attached to the humerus at the lateral and medial ends of the articular surfaces of capitulum and trochlea, Carried superiorly, proximal to coronoid and olecranon fossae, Synovial membrane lines the internal surface of the capsule, Continuous inferiorly with the synovial membrane of the proximal radio-ulnar joint, Weak anteriorly and posteriorly but strengthened by collateral ligaments

  
• Blood supply to Elbow Joint

  • Inferior ulnar collateral artery anastomoses with anterior ulnar recurrent artery, Superior ulnar collateral artery anastomoses with posterior ulnar recurrent artery, Middle collateral branch of profunda brachii a. anastomoses with recurrent interosseus a., Radial collateral branch of profunda brachii artery anastomoses with radial recurrent artery

  
• Innervation of Elbow Joint

  Musculocutaneous, radial and ulnar nerves

  
• Bursae around Elbow Joint


  • Intratendinous olecranon bursa, Subtendinous olecranon bursa, Subcutaneous olecranon bursa, Bicipitoradial bursa

  
• Proximal Radio-Ulnar Joint


  • Pivot type synovial joint, Articulation: head of radius and radial notch of ulna, Joint capsule: Fibrous layer encloses the joint and is continuous with the elbow joint, Synovial membrane lines deep surface of the fibrous layer and nonarticulating aspects of the bone, Synovial membrane is an inferior prolongation of the synovial membrane of the elbow joint

  
• Anular Ligament


  Attached to ulna anterior and posterior to radial notch, Creates a ring that completely encircles the head of the radius, Synovial membrane continues distally as sacciform recess of proximal radio-ulnar joint on the neck of the radius

  
• Blood supply to Proximal Radio-Ulnar Joint

  Radial portion of the peri-articular arterial anastomosis of elbow joint, Radial and middle collateral arteries anastomose with the radial and recurrent interosseus arteries