Cubital fossa
Table of content
- Definition
- Structure and Function
- Blood Supply and Lymphatics
- Nerves
- Muscles
- Anatomy of anti-cubital fossa
- Physiologic Variants
- Surgical Considerations
- Clinical Significance
- Conclusion
Definition
The cubital fossa is a small triangular area located on the anterior surface of the elbow, with the apex of the triangle pointing distally. It contains some important structures, on their passage from the arm to the forearm. It is homologous to the popliteal fossa of the lower limb.
Structure and Function:
Being triangular, the cubital fossa has three borders:
• Superior (base) - an imaginary line between the medial and lateral epicondyles of the humerus
• Medial - the lateral boundary of the pronator teres
• Lateral - the medial border of the brachioradialis
The apex is directed distally and forms from the joining of the two borders.
The floor of the fossa is formed by the brachialis muscle proximally, and the supinator muscle distally — the roof (from superficial to deep) forms from the skin, fascia, and the bicipital aponeurosis.
The cubital fossa is a very narrow space, and the boundaries have to be retracted to see the contents within it. The fossa possesses several vital structures, vital to the function of the forearm and hand. From lateral to medial, these structures are:
• Radial nerve - originating from the posterior cord of the brachial plexus, with contributions from C5-T1 roots. In the cubital fossa, it runs close to the brachioradialis muscle and splits into its deep and superficial branches within.
• Biceps tendon - perhaps the most prominent structure of the cubital fossa, the biceps tendon runs through attaching to the radial tuberosity of the radius.
• Brachial artery - the brachial artery runs through the fossa, just medial to the biceps tendon, branching at the apex into the radial and ulnar arteries.
• Median nerve - originating from the lateral and medial cords of the brachial plexus, with contributions from C6-T1 roots. It can be found most medially within the cubital fossa, running between the two heads of pronator teres in the majority of the population. While not in the cubital fossa itself, found within the roof is the median cubital vein - forming a communication between the cephalic and basilic superficial veins of the arm. Also seen in the superficial fascia of the roof are the medial and lateral cutaneous nerves of the forearm.
Blood Supply and Lymphatics:
As stated above, the brachial artery passes through the cubital fossa, bifurcating into the radial and ulnar arteries at the distal apex of the fossa. These arteries then continue down into the forearm to supply the anterior and posterior aspects of the lower arm, ending with the deep and superficial arches of the hand.
The two primary superficial veins of the arm have an essential communication in the roof of the cubital fossa - the median cubital vein. The cephalic vein commences on the anterolateral surface of the wrist, and the basilic vein begins on the anteromedial aspect of the wrist. They continue up the forearm into the arm, connecting with the median cubital vein on the way. The basilic vein joins with the brachial vein to form the axillary vein (at the lower border of teres major), with the cephalic vein draining into the axillary vein within the axilla region.
Nerves:
As mentioned above, two of the primary nerves of the arm run through the cubital fossa - the median and radial nerves.
The median nerve, with C6-T1 roots, innervates the majority of the muscles of the anterior forearm (barring the ulna nerve innervated flexor carpi ulnaris and ulnar half of flexor digitorum profundus), the muscles of the thenar eminence of the hand, and the medial two lumbricals. As such, it plays a vital role in the flexion of the wrist, pronation of the forearm, and movements of the fingers. It supplies sensory innervation to the lateral palm and volar surface of the lateral three-and-one-half digits.
The radial nerve, with C5-T1 roots, innervates all of the muscles in the posterior compartment of the forearm, thus having a key role in wrist extension and movements of the fingers. It supplies sensory innervation to the lateral aspect of the dorsum of the hand and the dorsal surface of the lateral three-and-one-half digits.
Muscles:
There are four muscles involved in the boundaries of the cubital fossa.
Pronator teres form the medial border of the fossa. It receives nerve supply from the median nerve, and its main action is the pronation of the forearm. The pronator teres has two heads - the ulnar head originating from the coronoid process of the ulna and the humeral head originating from the medial epicondyle, the heads come together to attach to the midshaft of the radius. The median nerve passes through the two heads in 75 to 80% of the population.
Brachioradialis forms the lateral border of the cubital fossa. It receives nerve supply from the radial nerve, and despite originating from the posterior compartment of the forearm, it acts to flex the forearm. It originates from the distal humerus at the lateral supracondylar ridge and attaches to the distal radius.
Brachialis forms the proximal aspect of the floor. It receives nerve supply from the musculocutaneous nerve, and it is a weak flexor of the forearm. It originates from the shaft of the humerus and inserts into the ulna tuberosity of the ulna.
The supinator forms the distal aspect of the floor. Its nerve supply is from the posterior interosseus branch of the radial nerve, and its function is the supination of the forearm. It has two heads, with one from the lateral humeral epicondyle, and the other originating from the posterior ulna. They come together and insert into the posterior radius.
Anatomy of anti-cubital fossa
The cubital fossa is a triangular-shaped depression located on the anterior (front) aspect of the elbow joint. It is also commonly referred to as the antecubital fossa or elbow pit.
The boundaries of the cubital fossa are formed by three muscles: the brachioradialis muscle laterally, the pronator teres muscle medially, and the base of the triangle is formed by an imaginary line between the two epicondyles of the humerus bone (the medial and lateral epicondyles).
The floor of the cubital fossa is made up of three structures: the brachialis muscle, the supinator muscle, and the radial nerve. The roof of the fossa is formed by the skin and subcutaneous tissue.
Within the cubital fossa, several important structures can be found, including the brachial artery, the median nerve, and the biceps tendon. These structures are often used for medical procedures such as taking blood pressure measurements, drawing blood, or administering injections.
The cubital fossa also contains the radial and ulnar arteries, which provide blood supply to the forearm and hand, as well as several veins, including the median cubital vein, which is often used for venipuncture.
Physiologic Variants:
Research has reported variations in the anatomy of the structures of the cubital fossa:
• Radial nerve - the main variations occur at its site of bifurcation. This most commonly occurs within the cubital fossa but may occur proximal or distal to the fossa.
• Biceps tendon - the distal tendon may appear bifurcated if there has been continuing separation of the short and long heads.
• Brachial artery - similarly to the radial nerve, the main variations occur relative to its bifurcation. While most commonly occurring at the apex of the cubital fossa, this can occur more distally down the arm. There have even been reports of an absent brachial artery, with the ulnar and radial arteries coming directly from the axillary artery.
• Median nerve - the anatomy is relatively constant at the cubital fossa, with the majority of variations occurring further down the arm at the level of the carpal tunnel.
• Median cubital vein - there are several variations of the vein, with previous criteria developed as:
1. A dominant median antebrachial vein of the forearm joins the basilic and cephalic veins in the fossa.
2. The median cubital vein connecting the basilic and cephalic veins (the most common, and as described above).
3. Median cubital vein present, but absent development of the cephalic artery in the upper arm.
4. No communication is present between the cephalic and basilic veins.
Surgical Considerations:
Due to the key structures lying within the cubital fossa, damage secondary to trauma can lead to significant long-term effects, most commonly occurring following supracondylar fractures. Supracondylar fractures can be described by the Modified Gartland classification:
• Type I - undisplaced
• Type II - displaced, posterior cortex remains intact
• Type III - completely displaced
• Type IV - completely displaced, instability during flexion or extension
Gartland II, III, and IV fractures, in particular, are at risk of causing damage to the radial nerve, median nerve, or brachial artery. Early reduction and/or fixation of these fractures, alongside close monitoring following this, are crucial to management to attempt avoidance of long-term complications.
Clinical Significance:
i. Venipuncture
The area superficial to the cubital fossa is a common site used for the collection of venous blood specimens and blood transfusion. The basilic vein, median cubital vein, and cephalic vein are superficial veins that are frequently selected for venipuncture at the cubital fossa. The median cubital vein connects the basilic and cephalic veins, and it lies directly on the deep fascia, running diagonally from the cephalic vein of the forearm to the basilic vein of the arm.
It crosses the bicipital aponeurosis, which separates it from the underlying brachial artery and median nerve, and it provides protection to the latter. Because of its characteristics and visibility, it is easily accessible for the collection of venous blood specimens. It may also be used for the insertion of a peripherally inserted central catheter.
ii. Brachial pulse and blood pressure
The brachial pulse can be palpated immediately medial to the biceps tendon in the cubital fossa. Also, when measuring blood pressure manually, a stethoscope is placed over the cubital fossa to auscultate the brachial artery for Korotkoff sounds.
• An important pathology to note is cubital tunnel syndrome. While not directly involving the cubital fossa itself, it is an ulnar neuropathy that occurs at the level of the cubital fossa. The ulnar nerve runs posteriorly to the medial epicondyle of the humerus, within a structure named the cubital tunnel. The ulnar nerve can become compressed within this tunnel, either acutely or chronically. The syndrome typically presents with sensory paraesthesia in the ulnar distribution of the hand (the medial aspect of the hand and medial one-and-a-half digits) and can present with motor symptoms, such as clumsiness with intrinsic hand movements. Treatment of the condition can be conservative, including education and elbow splinting or surgical decompression.
Conclusion
The cubital fossa is a triangular area on the anterior surface of the elbow joint, with its apex pointing downwards. It is delimited by three borders: the medial border formed by the lateral border of the pronator teres, the lateral border formed by the medial border of the brachioradialis, and the superior border formed by an imaginary line between the medial and lateral epicondyles of the humerus.
The floor of the fossa is made up of the brachialis muscle proximally and the supinator muscle distally, while the roof is formed by the skin, fascia, and bicipital aponeurosis. The cubital fossa contains important structures such as the radial nerve, biceps tendon, brachial artery, median nerve, and median cubital vein.
The brachial artery passes through the fossa, dividing into the radial and ulnar arteries. The median nerve runs medially within the fossa, while the radial nerve runs laterally. The median cubital vein is a communication between the cephalic and basilic superficial veins of the arm, and it lies within the roof of the cubital fossa. Four muscles form the boundaries of the cubital fossa, including the pronator teres, brachioradialis, brachialis, and supinator muscles.
FAQS
What Are The 3 Main Veins In The Antecubital Fossa?
The antecubital fossa is located on the anterior surface of the elbow and is a common site for venipuncture or drawing blood. The three main veins in the antecubital fossa are:
Median cubital vein: This vein is often the first choice for venipuncture because it is usually large and easily accessible.
Cephalic vein: This vein runs along the lateral side (thumb side) of the arm and may be used if the median cubital vein is not available.
Basilic vein: This vein runs along the medial side (pinky finger side) of the arm and may be used if the other two veins are not available or difficult to access.
It is important to note that individual variations in anatomy can result in the absence, variation or other differences in the veins present in the antecubital fossa, and in some cases, it may be necessary to choose an alternate site for venipuncture.
Where Is The Antecubital Fossa Of The Arm?
The antecubital fossa is located at the bend of the elbow on the anterior (front) surface of the arm. It is a triangular-shaped depression that is bounded by the pronator teres and brachioradialis muscles laterally, the biceps brachii muscle medially, and the base of the triangle is formed by an imaginary line connecting the medial and lateral epicondyles of the humerus bone. The antecubital fossa is a common site for venipuncture and is used for drawing blood or administering intravenous therapy.
What Is The Difference Between Cubital And Antecubital Fossa?
The cubital fossa and the antecubital fossa are both located in the arm, but they are slightly different anatomical regions.
The cubital fossa is a triangular depression in the front of the elbow joint. It is located on the anterior (front) aspect of the forearm and is bounded by the brachioradialis muscle on the lateral side, the pronator teres muscle on the medial side, and the brachialis muscle superiorly. The cubital fossa contains several important structures such as the median nerve, the brachial artery, and the biceps tendon.
The antecubital fossa is a larger region that encompasses the cubital fossa. It is the triangular area on the front of the elbow that extends from the crease of the elbow to the wrist. The boundaries of the antecubital fossa are the brachioradialis muscle laterally, the pronator teres muscle medially, and the imaginary line connecting the epicondyles of the humerus bone superiorly. The antecubital fossa also contains several important structures, including the brachial artery, the median nerve, and the basilic and cephalic veins.
In summary, the cubital fossa is a small triangular depression within the antecubital fossa, which is a larger triangular region on the front of the elbow.
What Is The Longest Vein In The Body?
The longest vein in the body is the great saphenous vein, which runs from the top of the foot, up the inside of the leg, and into the groin. It is also one of the most superficial veins in the body, meaning it is located near the surface of the skin. The great saphenous vein plays an important role in venous circulation and can be used for various medical procedures, such as vein harvesting for bypass surgery or for treating varicose veins.
What Are The 5 Sites For Venipuncture?
There are several sites for venipuncture, but some of the most common ones include:
Median cubital vein: This vein is located in the antecubital fossa and is the first choice for most blood draws. It is usually easy to access and relatively large, making it ideal for venipuncture.
Cephalic vein: This vein runs along the outer side of the upper arm and can be accessed easily in most patients. It is often used when the median cubital vein is not accessible.
Basilic vein: This vein is located on the inner side of the upper arm and can be more difficult to access, especially in patients with small or deep veins. It is often used when other sites are not available.
Brachial vein: This vein is located in the upper arm and is less commonly used for venipuncture than the other sites mentioned above. It is often used in emergency situations when other sites are not accessible.
Dorsal hand veins: These veins are located on the back of the hand and can be used when other sites are not accessible or have been exhausted. They are generally smaller and more difficult to access, so they are not preferred sites for routine blood draws.
What Is The Largest Vein In Antecubital Fossa?
The largest vein in the antecubital fossa is the median cubital vein. It is a superficial vein that connects the cephalic vein and basilic vein, and it is often used for venipuncture or drawing blood. The median cubital vein is located in the center of the antecubital fossa and is relatively easy to access due to its size and superficial location.
What Major Nerve Is In The Antecubital Area?
The major nerve in the antecubital area is the median nerve, which runs through the center of the elbow and down the forearm. It is responsible for providing sensation to the palm of the hand and the fingers, as well as controlling some of the muscles in the forearm and hand. The median nerve can be accessed in the antecubital area for certain medical procedures, such as nerve conduction studies or blood draws.
What Is Inner Elbow Called?
The inner part of the elbow is called the antecubital fossa. It is a triangular-shaped depression located on the front of the elbow, between the biceps and triceps muscles.
What Major Artery Is In The Antecubital Area?
The major artery in the antecubital area is the brachial artery. It is the main artery of the upper arm and one of the major blood vessels that supply blood to the arm. The brachial artery runs from the shoulder to the elbow in the upper arm, and it is located deep beneath the skin and muscle. In the antecubital fossa, the brachial artery divides into two branches, the radial artery, and the ulnar artery, which supply blood to the forearm and hand.
0 Comments