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CBL CUBITAL FOSSA, FOREARM AND HAND

BY DR. ABDUL WAHEED ANSARI

CHAIRPERSON & PROFESSOR OF ANATOMY, RAKCOMS.RAKMHSU.

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A clinical case of dislocation of head of radius from the annular ligament at elbow joint

• One evening while playing in the yard, a father picked up his four-year-old daughter by her hand and started swinging her around in a circle.

• At first the girl giggled, but all of a sudden, she cried out in pain. • When her father put her down, he noticed that she was holding her elbow. • Her arm was partially flexed and pronated, and she was unable to supinate her

hand without considerable pain, so her parents took her to the emergency room.

• When the physician palpated her elbow, she found that the joint was tender, especially on the lateral side, but all of the bony landmarks were in their normal locations, leading the physician to suspect that the head of the radius had slipped out of the annular ligament.

• The physician attempted to reposition the head of the radius by supinating the forearm fully and then flexing the elbow.

• She felt a small pop on the lateral side of the cubital fossa as the head of the radius slipped back into position and within a few moments the girl's elbow was as good as new.

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The gross anatomy of elbow joint

• The elbow is a hinge joint and consists of the humero-ulnar, humero-radial and proximal radio-ulnar articulations.

• The radial head articulates with the humeral capitellum whilst the trochlear notch of the ulna articulates with the humeral trochlea.

• Posteriorly the ulna forms the olecranon, which contacts the olecranon fossa of the humerus at full elbow extension.

• When fully extended the elbow joint forms a valgus angle, this is commonly referred to as the carrying angle and is generally greater in women.

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Normal and abnormal carrying angles

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Radiological anatomy of elbow joint

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The ligaments of elbow joints• The lateral and medial collateral ligaments

provide joint stability. The nearby annular ligament attaches to the anterior and posterior margins of the radial notch on the ulna and forms a collar around the radial head.

• The annular ligament is a circular ligament which forms a collar around the head of the radius, holding it firmly in place without directly attaching to the radius.

• This allows relatively free rotary movement of the radius at its proximal articulation with the capitulum of the humerus.

• The annular ligament is attached to the anterior and posterior margins of the radial notch on the ulna.

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Movements at elbow joint

• Elbow flexion results from the actions of the biceps brachii, brachialis, brachioradialis and pronator teres muscles, which cross the joint anteriorly.

• The triceps tendon inserts into the olecranon process posteriorly and together with the anconeus muscle is responsible for elbow extension.

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The muscles surrounding the elbow joint

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The cubital fossa boundaries are laterally brachioradialis, medially pronator teres, floor by brachialis and supinator.

• The cubital fossa is a triangular depression found anterior to the elbow joint and contains the median nerve, biceps tendon, brachial artery, and radial nerve (deep and superficial branches).

• The ulnar nerve crosses the elbow joint posteriorly, running behind the medial epicondyle in a groove adjacent to the olecranon.

• The olecranon bursa is located over the posterior aspect of the olecranon.

• Several muscles responsible for wrist and finger flexion have a common insertion into the medial epicondyle (flexor carpi radialis, palmaris longus, flexor carpi ulnaris and flexor digitorum superficialis).

• Similarly, several extensor muscles insert into the lateral epicondyle (extensor carpi radialis brevis, extensor digitorum, extensor digiti minimi and extensor carpi ulnaris).

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Nerves and vessels around the elbow joint

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The normal radiocapitellar line= there is no dislocation of head of radius

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The radiocapitellar line is not passing through the capitellum=there is dislocation of head of radius

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Clinical case of Colle’s fracture

• A 28-year-old volleyball player fell on her right outstretched arm during a game.

• She felt an immediate pain in her wrist, and the orthopedic surgeon at the emergency room described the deformity in her right wrist as similar to a "dinner fork."

• All wrist movements were painful. • A plain radiograph revealed a transverse fracture of the

distal end of the radius, which was tilted backwards and radially.

• The patient was diagnosed with a typical Colles' fracture.

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The dinner fork deformity after fall on an out stretched hand(FOOH)

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A Colles' fracture, is a fracture of the distal radius in the forearm with dorsal (posterior) and radial displacement of the wrist and hand.The fracture is sometimes referred to as a "dinner fork" or "bayonet" deformity due to the shape of the resultant forearm.

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The flexor group of muscles of forearm

• The anterior forearm muscles are flexors of wrist, flexor of thumb,flexors of fingers and pronators of forearm.

• The arteries of flexor region are radial, ulnar and anterior interosseous arteries.

• The nerve supply is anterior interosseous branch of median and ulnar nerves.

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The extensor group of muscles of forearm

• The brachioradialis, long and short extensors of wrist,extensors of digits, abductors of thumb, long extensor of thumb, extensor of elbow and supinator.

• The nerve of extensor compartment is deep branch of radial nerve(posterior interosseous nerve).

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Injury to median nerve• An injury above the elbow may result

in difficulty or even inability to turn the hand over or flex the wrist down.

• Injuries below this may cause tingling or numbness in the forearm, thumb and the three adjacent fingers.

• Weakness with gripping and inability to move the thumb across the palm may also be experienced along with wasting of the muscles at the base of the thumb.

• The median nerve can be torn partially or fully or compressed at the elbow.

• This can be from a fracture or other traumatic injury, or compression from excess fluid build up following an injury.

• Injuries such as a supracondylar fracture, elbow dislocation or any form of fracture should be examined for damage to the median nerve.

• The most common injury involving the median nerve is Carpal Tunnel Syndrome.

• However this is caused by a decrease in space at the carpal tunnel in the wrist and so would not occur as a result of an elbow injury.

• Pronator Teres Syndrome is another entrapment neuropathy of the median nerve, this time as it passes between the two heads of the pronator teres muscle.

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Clinical case of Carpal tunnel syndrome

• A 28-year-old dentist consults her physician, complaining that she feels tingling and slight pain in her right hand.

• The symptoms are localized to her thumb, index, middle and lateral side of her ring finger.

• The sensations are more intense at night or if she overworks. • Recently, she has experienced some weakness in her grasp and finds

it more difficult to hold her instruments. • Also, movements of her right thumb are not as strong as before.• On examination, there is loss of power on certain movements of the

thumb. She has impaired appreciation of light touch and pin pricks to the thumb, index, middle and lateral side of her ring finger, but sensation to her palm is not affected.

• Pressure and tapping over the flexor retinaculum causes tingling. • After a complete examination, the patient is diagnosed with carpal

tunnel syndrome.

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The gross anatomy of hand

• The ventral aspect of hand is having thenar and hypothenar muscles.

• There are short flexors, abductors and opponens for thumb and little finger.

• There are long and short flexor tendons along with lumbricals and interossei for the remaining fingers.

• The median and ulnar nerves supply the muscles of thenar and hypothenar regions.

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The dorsum of hand

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The dermatomes on the palm

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References

• http://www.rcemlearning.co.uk/references/elbow-injuries/

• http://www.med.umich.edu/lrc/coursepages/m1/anatomy2010/html/musculoskeletal_system/joints_case.html

• http://www.med.umich.edu/lrc/coursepages/m1/anatomy2010/html/musculoskeletal_system/hand_case.html

• https://en.wikipedia.org/wiki/Adductor_pollicis_muscle

• https://nervesurgery.wustl.edu/ev/upperextremity/median/digitalcutaneousnerves/Pages/ProperPalmarDigitalNerves.aspx

• http://www.unmc.edu/dissection/idg05forearm.cfm

• http://teachmeanatomy.info/upper-limb/muscles/posterior-forearm

• http://droualb.faculty.mjc.edu/Lecture%20Notes/Unit%203/muscles%20with%20figures.htm

• http://www.sportsinjuryclinic.net/sport-injuries/elbow-pain/median-nerve-injury