The elbow is a vital pivotal joint in the human body, comprised of multiple articulations among the three arm bones in the area. The elbow facilitates a wide range of arm movements, enabling us to carry out our daily tasks.
Elbow Bones and Basic Anatomy
The elbow joint involves 3 bones:
- Humerus: The bone extending from the shoulder to the elbow
- Radius: The bone extending from the elbow to the thumb-side of the forearm
- Ulna: The second bone in the forearm, running from the elbow to the side of the little finger
Elbow Joints and Articulations
The elbow joint capsule comprises these three synovial joints:
- Humeroulnar (Trochlear) Joint: Between the humeral trochlea and the ulna’s trochlear notch
- Humeroradial Joint: Between the capitulum of the humerus and the radial head
- Proximal Radioulnar Joint: Between the head of the radius and the radial notch of the ulna
Only the first two articulations are part of the elbow joint. The proximal radioulnar joint forms a separate articulation within the elbow joint capsule.
Bony Projections and Prominence
- Olecranon: The pointed bony structure at the posterior side of the elbow; it is the prominence at the upper end of the ulna
- Lateral epicondyle: The elevation above the elbow on the outer side of the arm; it is part of the distal end of the humerus.
- Medial epicondyle: The second elevation that can be felt on the inner side, just above the elbow; it is also part of the humerus.
- Coronoid process: A triangular projection at the proximal end of the ulna; can’t be felt from outside
These bony landmarks serve as attachment points for all the crucial ligaments and tendons responsible for the elbow’s functioning.
Ligaments
- Ulnar/Medial collateral ligament: Connects the humerus and ulna
- Radial/Lateral collateral ligament: Links the humerus and radius
- Annular ligament: Holds the radius tightly against the ulna through a strong band of fibers around the radius’ head
- Quadrate ligament: Another connection between the radius and ulna
Muscles and Tendons
- Biceps
- Triceps
- Brachialis
- Wrist extensors
- Wrist flexors
The biceps and triceps tendons are the most crucial tendons in the elbow. Besides these, the muscles responsible for straightening the wrist and fingers converge at the lateral epicondyle into a single tendon that attaches to the humerus.
Similarly, the muscles responsible for bending the wrist and fingers converge at the medial epicondyle, forming one tendon that attaches to the humerus.
Nerves
- Median nerve
- Musculocutaneous nerve
- Radial nerve
- Ulnar nerve
Functions of the Elbow Joints
The elbow can undergo three different movements, the first being the most obvious, where the bones and ligaments aid in flexing and extending the forearm at the elbow joint (hinge action). This movement allows us to reach for objects, pick up heavy objects, and perform exercises like bicep curls.
The other two movements are less noticeable but equally crucial. The bony protrusions in the elbow bones serve as the attachment points for multiple important tendons involved in the movement of the wrist and fingers.
FAQs
Q. What is the funny bone in the elbow?
Ans. The term ‘funny bone’ refers to the ulnar nerve rather than a specific bone. The ulnar nerve crosses the elbow as it travels from the neck to the fingers.
References
- The Anatomy of the Elbow – Ortho.wustl.edu
- Elbow Bones Anatomy, Diagram, and Functions – Healthline.com
- Elbow Anatomy – Arthritis.org
- The Elbow Joint – Teachmeanatomy.info
- Elbow Joint – Kenhub.com
