Fascial Spaces of the Palm-Fascial Spaces of the Palm and Infection -Pulp Space of the Fingers--Pulp-Space Infection (Felon)

Fascial Spaces of the Palm

Normally, the fascial spaces of the palm are potential spaces filled with loose connective tissue. Their boundaries are important clinically because they may limit the spread of infection in the palm.

The triangular palmar aponeurosis fans out from the lower border of the flexor retinaculum. From its medial border, a fibrous septum passes backward and is attached to the anterior border of the 5th metacarpal bone. Medial to this septum is a fascial compartment containing the three hypothenar muscles; this compartment is unimportant clinically. From the lateral border of the palmar aponeurosis, a second fibrous septum passes obliquely backward to the anterior border of the third metacarpal bone. Usually, the septum passes between the long flexor tendons of the index and middle fingers. This second septum divides the palm into the thenar space, which lies lateral to the septum (and must not be confused with the fascial compartment containing the thenar muscles), and the midpalmar space, which lies medial to the septum. Proximally, the thenar and midpalmar spaces are closed off from the forearm by the walls of the carpal tunnel. Distally, the two spaces are continuous with the appropriate lumbrical canals .

The thenar space contains the first lumbrical muscle and lies posterior to the long flexor tendons to the index finger and in front of the adductor pollicis muscle

The midpalmar space contains the 2nd, 3rd, and 4th lumbrical muscles and lies posterior to the long flexor tendons to the middle, ring, and little fingers. It lies in front of the interossei and the third, fourth, and fifth metacarpal bones.

The lumbrical canal is a potential space surrounding the tendon of each lumbrical muscle and is normally filled with connective tissue. Proximally, it is continuous with one of the palmar spaces

Fascial Spaces of the Palm and Infection

The fascial spaces of the palm are clinically important because they can become infected and distended with pus as a result of the spread of infection in acute suppurative tenosynovitis; rarely, they can become infected after penetrating wounds such as falling on a dirty nail.

Pulp Space of the Fingers

The deep fascia of the pulp of each finger fuses with the periosteum of the terminal phalanx just distal to the insertion of the long flexor tendons and closes off a fascial compartment known as the pulp space . Each pulp space is subdivided by the presence of numerous septa, which pass from the deep fascia to the periosteum. Through the pulp space, which is filled with fat, runs the terminal branch of the digital artery that supplie the diaphysis of the terminal phalanx. The epiphysis of the distal phalanx receives its blood supply proximal to the pulp space.

Pulp-Space Infection (Felon)

The pulp space of the fingers is a closed fascial compartment situated in front of the terminal phalanx of each finger. Infection of such a space is common and serious, occurring most often in the thumb and index finger. Bacteria are usually introduced into the space by pinpricks or sewing needles.

Because each space is subdivided into numerous smaller compartments by fibrous septa, it is easily understood that the accumulation of inflammatory exudate within these compartments causes the pressure in the pulp space to quickly rise. If the infection is left without decompression, infection of the terminal phalanx can occur. In children, the blood supply to the diaphysis of the phalanx passes through the pulp space, and pressure on the blood vessels could result in necrosis of the diaphysis. The proximally located epiphysis of this bone is saved because it receives its arterial supply just proximal to the pulp space.

The close relationship of the proximal end of the pulp space to the digital synovial sheath accounts for the involvement of the sheath in the infectious process when the pulpspace infection has been neglected.