Last Updated on June 20, 2025
The anatomy of the hand includes several well-defined spaces formed by layers of fascia and interconnecting fascial septa. These spaces of hand are clinically significant because they can act as potential sites for infection.
When pus accumulates, these compartments can become distended, often requiring surgical drainage. Understanding their structure and relationships is essential for recognizing patterns of spread and selecting appropriate treatment.
Important spaces of the hand are, pulp space of fingers, the web spaces. palmar spaces, dorsal spaces, and the space of Porona in the forearm. The palmar and dorsal spaces further have divisions. [1]
The following spaces of the hand are included in the palmar spaces
- Thenar Space
- Midpalmar space
- Hypthenar Space
- Thenar space
These spaces are described below one by one
Pulp Space of The Fingers
The pulp spaces are located at the tips of the fingers and thumb. These regions contain subcutaneous fat organized into small compartments by vertical fibrous septa.
These septa extend from the skin to the periosteum of the terminal phalanx.
Due to the limited capacity of the space, infections can rapidly lead to severe throbbing pain. [1]
If left untreated, the pressure buildup may lead to osteomyelitis of the terminal phalanx.
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.
But the proximally located epiphysis of this bone is saved as the blood supply to it is just proximal to the pulp space.
The pulp space is in close relation to the digital synovial sheath, which may become secondarily involved in neglected infections.
Infection of the pulp space is called Whitlow [2]. Drainage of a pulp space infection is best performed through a lateral incision. This approach allows access to all compartments while preserving the tactile tissue on the volar aspect of the finger.
Interdigital (Web) Spaces of Hand
The web spaces of the hand form narrow channels between adjacent digits, bounded by skin and fibrous septa. Infections in these areas can lead to collar-button abscesses, where pus collects both on the palmar and dorsal sides of the web.
Drainage Principle
Requires dual incisions, one on the palmar and one on the dorsal aspect of the affected web to avoid incomplete drainage.
Midpalmar Space
The midpalmar space is a triangular fascial compartment located beneath the medial half of the palm.
Proximally, it extends up to the distal border of the flexor retinaculum and communicates with the forearm space of Parona.
Distally, it reaches the distal palmar crease and connects with the fascial sheaths of the third and fourth lumbrical muscles.
Boundaries
- Anteriorly: Palmar aponeurosis
- Posteriorly: Third, fourth, and fifth metacarpals; fascia over the interossei of the third and fourth spaces; medial part of the transverse head of the adductor pollicis
- Medially: Medial palmar septum
- Laterally: Intermediate palmar septum
Contents
- Flexor tendons of the third, fourth, and fifth fingers
- Second, third, and fourth lumbrical muscles
- Superficial palmar arch
- Digital nerves and vessels to the medial three and a half fingers
Clinical Relevance
Infection of the midpalmar space may result from flexor tenosynovitis of the middle or ring finger, or from web space infections that track proximally through the lumbrical canals. [3]
This space can expand significantly in infection, with swelling sometimes extending onto the dorsum of the hand.
Drainage is typically performed through the third or fourth web space, depending on where pus collection is evident.
Thenar Space
The thenar space is a triangular fascial compartment located in the thenar region of the palm.
Proximally, it extends to the distal border of the flexor retinaculum. Distally, it reaches the proximal transverse palmar crease.
It communicates with the forearm space of Parona, the subcutaneous web of the thumb, and potentially the second lumbrical canal through the fascial sheath of the first lumbrical muscle. [4]
Boundaries [4]
- Anteriorly: Palmar aponeurosis
- Posteriorly: Fascia covering the transverse head of the adductor pollicis and the first dorsal interosseous muscle
- Medially: Intermediate palmar septum
- Laterally: Lateral palmar septum
Contents
- Flexor pollicis longus tendon with its synovial sheath
- Flexor tendons of the index finger
- First lumbrical muscle
- Palmar digital nerves and vessels to the thumb and radial side of the index finger
Clinical Relevance
Infection in the thenar space often arises from the thumb or index finger. It leads to swelling in the thenar region and the web of the thumb. The thumb is typically held in an abducted position due to pain and muscle involvement.[3]
Drainage is usually performed through an incision in the first web space dorsally, or where the pus is pointing.
Hypothenar Space
The hypothenar space lies beneath the hypothenar muscles on the ulnar side of the palm, lateral to the midpalmar septum.[3]
Boundaries
- Anterior: Palmar skin and subcutaneous tissue
- Posterior: Fifth metacarpal and fascia over interosseous muscles
- Medially: Medial palmar septum
- Laterally: Continuity with the midpalmar space
Contents
- Hypothenar muscle group (abductor digiti minimi, flexor digiti minimi brevis, opponens digiti minimi)
- Branches of the ulnar nerve and artery
Clinical Relevance
Infections in the hypothenar space are uncommon but may result from direct trauma or spread from adjacent midpalmar infections. Swelling is localized over the ulnar aspect of the palm.
Drainage is typically via a longitudinal incision along the ulnar border of the palm, avoiding the sensory branches of the ulnar nerve.
Dorsal spaces of Hand
The dorsum contains two main fascial spaces of the hand, the dorsal subcutaneous space and the dorsal subaponeurotic space.
Dorsal Subcutaneous Space
This space lies just beneath the loose skin on the dorsum of the hand. It is relatively superficial and can easily become involved in infections or edema secondary to involvement of the palmar space.
Dorsal Subaponeurotic Space
This deeper space is located between the extensor tendons and the dorsal surfaces of the metacarpal bones.
Infections in the dorsal subaponeurotic space may result in diffuse dorsal hand swelling. Pus typically collects and points either at the web spaces or along the margins of the hand, providing potential sites for drainage.
Because the dorsal fascia is more compliant than the palmar fascia, swelling tends to be more obvious dorsally, even when the primary infection is palmar.
Forearm Space of Parona
This space is located in the distal forearm, just above the wrist. It lies deep to the long flexor tendons and anterior to the pronator quadratus muscle. [1]
Superiorly, the space extends up to the oblique origin of the flexor digitorum superficialis.
Inferiorly, it reaches the flexor retinaculum.
This space communicates with the midpalmar space, and possibly with the thenar space, through extensions of the flexor synovial sheaths — particularly the ulnar bursa, which may protrude into it.
Clinical Relevance
Infection can spread into Parona’s space from the flexor tendon sheaths, especially through the ulnar bursa.[3]
Clinically, this may present as swelling in the distal forearm with pain and stiffness of the fingers. Because the space lies deep, signs of infection may be subtle initially but can progress rapidly.
Drainage typically requires a volar forearm approach, especially if the source is tenosynovitis extending proximally.
Clinical Points in Infections of the Spaces of Hand
- MRI is the gold standard for identifying deep space involvement and guiding surgical planning, though ultrasound can help detect fluid collections in the superficial pulp space.
- Staphylococcus aureus is the most frequent pathogen, with MRSA strains becoming increasingly prevalent [2]
- Streptococcus and mixed flora may occur in bite wounds or in immunocompromised patients
- Special points
- Pulp space infections present with intense pain and risk of osteomyelitis, especially in children.
- Midpalmar and thenar space infections can result from flexor tenosynovitis or web space infections and often require drainage through specific web spaces.[2]
- Dorsal swelling may reflect deeper palmar involvement due to the more compliant nature of dorsal tissues.
- Parona’s space serves as a proximal extension for palmar infections, particularly via the ulnar bursa, and may lead to forearm involvement.
Early recognition and proper drainage of spaces of hand are essential to prevent complications such as tendon necrosis, osteomyelitis, and permanent loss of function.
References
- Drake, R. L., Vogl, A. W., & Mitchell, A. W. M. (2020). Gray’s Anatomy for Students (4th ed.). Elsevier Health Sciences.
- Rerucha CM, Ewing JT, Oppenlander KE, Cowan WC. Acute Hand Infections. Am Fam Physician. 2019 Feb 15;99(4):228-236. [Link]
- Jebson PJ. Deep subfascial space infections. Hand Clin. 1998 Nov;14(4):557-66, viii. [PubMed]
- Crosswell S, Vanat Q, Jose R. The anatomy of deep hand space infections: the deep thenar space. J Hand Surg Am. 2014 Dec;39(12):2550. [PubMed]
