e posters of 2023-24 batch- cubital fossa

 

CHAPTER 10

PALM OF HAND

          The skin of the palm is thick and the superficial fascia contains palmaris brevis muscle across the base of hypothenar eminence.

Deep fascia is thickened to form:

Flexor retinaculum

Palmar aponeurosis

Fibrous flexor sheaths of digits

Flexor retinaculum:

It covers the anterior concave surface of the carpus into an osseo fibrous carpal tunnel

Attachments:

Medially – pisiform bone and  hook of the hamate

Laterally - tubercle of scaphoid and the crest of trapezium

Structures passing superficial to flexor retinaculum:

Palmaris longus tendon

Palmar cutaneous branch of median nerve

Palmar cutaneous branch of ulnar nerve

Superficial palmar branch of radial artery

Ulnar nerve and ulnar vessels

In between superficial and deep slips on the lateral distal part, flexor carpi radialis tendon passes.

Structures passing deep to flexor retinaculum:

Median nerve

Tendons of flexor digitorum superficialis and 

Tendons of flexor digitorum profundus-these two tendons are covered by the common synovial sheath called ulnar bursa

Tendon of flexor policis longus is covered by a synovial sheath called radial bursa

APPLIED ANATOMY:

Carpal tunnel syndrome:

Compression of median nerve in the carpal tunnel by the long continued swelling of synovial sheath is called carpal tunnel syndrome. 

Manifestations are:

weakness and wasting of thenar muscles.

Loss of opposition of thumb

Loss of cutaneous sensations of the palmar surface of lateral 3 ½ digits.

Palmar aponeurosis:

It is thickened deep fascia of palm. 

It consists of three parts:

Central part – thick

Medial part and lateral parts are thin

• Central part is thick and called palmar aponeurosis proper. 
• It is triangular in shape
• Apex directed proximally and is continuous with the tendon of palmaris longus.
• Distally, the aponeurosis splits into four digital slips for the medial four fingers.
• Each slip divides into superficial and deep set of fibers
• Superficial slip is continuous with the dermis and blend with superficial transverse ligament of palm.

The deep set fibres divides into two bands which are continuous with

• deep transverse ligament of palm
• palmar ligaments of meta carpophalangeal joints
• fibrous flexor sheaths of digits

Medial and lateral palmar septa extend dorsally from the respective margins of the central part of palmar aponeurosis.

APPLIED ANATOMY:

The inflammatory contracture of the palmar aponeurosis is known as Duputren’s contracture. 

It manifests as:

• Proximal and middle phalanges are acutely flexed as the palmar fascia is attached to them
• Terminal phalanges remain unaffected

Intrinsic muscles of Hand:

Thenar muscles are:

1. Abductor pollicis brevis
2. Flexor pollicis brevis
3. Opponens pollicis
4. Adductor policis

Hypothenar muscles are:

1. Abductor digiti minimi
2. Flexor digiti minimi
3. Opponens digiti minimi

Other muscles are:

• Palmaris brevis
• Four lumbrical muscles
• Four palmar interossei
• Four dorsal interossei

Lumbrical Muscles:

Four small muscles resembling the shape of earthworm, ascaris lumbricoides and hence the name. They are numbered from lateral to medial side

Origin: From the four tendons of flexor digitorum profundus. First two lumbricals are unipennate and the other two lumbricals are bipennate

Insertion: In to the dorsal digital expansion of medial four fingers

Nerve supply: First and second lumbricals are supplied by the median nerve.

Third and fourth lumbricals are supplied by the deep branch of ulnar nerve.

Actions:

They are the ‘link muscles’ connecting the flexor tendons with the extensor tendons.

Flex the metacarpophalangeal joints and extend the interphalangeal joints – important for gripping pens, brush etc.

Interosseous Muscles of Hand:

Palmar interossei

Dorsal interossei

Palmar interossei:

Four muscles – all are unipennate

Act as adductors of fingers (REMEMBER AS PAD)

The middle finger is the axis – and it has no adduction.

Origin:

All are unipennate and arise from the medial side of 1^st and 2^nd meta carpal bones and 3^rd and 4^th arise from lateral side of 4^th and 5^th meta carpal bones.

Insertion:

Partly attached to the proximal phalanges and partly into the dorsal digital expansion of digits

Dorsal interossei:

Four muscles – all are bipennate

Act as abductors of fingers (REMEMBER AS DAB)

As the middle finger is the axis, it has 2 abductors (2 dorsal interossei)

Origin:

All are bipennate and arise from the adjacent sides of the meta carpal bones.

Insertion:

1^st and 2^nd dorsal interossei are inserted into the lateral sides of the proximal phalanges of the index and middle fingers and into their dorsal digital expansion.

3^rd and 4^th dorsal interossei are inserted into the medial sides of the proximal phalanges of the middle and ring fingers.

Nerve supply: Deep Branch of ulnar nerve.

Superficial Palmar Arch: 

It is an arterial arch which lies beneath the palmar aponeurosis

Formation:

          The arch is formed by the superficial terminal branch of ulnar artery joined on lateral side by any of the following arteries-

1. Superficial palmar branch of radial artery
2. Arteria princeps pollicis (principal artery of thumb)
3. Arteria radialis indicis (Artery on radial side of index finger)
4. Median artery

Branches:

Four palmar digital arteries

One proper digital side to the left finger

Three common digital arteries

Deep palmar arch:

          It is arterial arch which lies deep to oblique head of adductor pollicis. The deep branch of ulnar nerve accompanies the concavity of the deep palmar arch.

Formation: Formed by the terminal end of radial artery joining the deep branch of ulnar artery.

Branches:

Three palmar metacarpal arteries

Three perforating arteries

Recurrent branches

Fascial spaces in the palm:

There are fascial lined potential spaces in the palm and the palmar aspect of the terminal phalanges

They are:

• Mid palmar space
• Thenar space
• Pulp space

Situation: In the palm, deep to long flexor tendons and lumbrical muscles, lies the fascial spaces limited on each side by the medial and lateral palmar septa.

Mid palmar space:

Triangular in shape

It presents the following boundaries:

Infront: Flexor tendons of little, ring, middle fingers with their lumbrical muscles ( 3^rd and 4^th)

Behind: the dense fascia covering the interossei and the meta carpal bones of 3^rd and 4^th spaces.

Medially: hypothenar muscles separated by the medial palmar septum

Laterally: Intermediate fibrous septum

Proximally: the space is closed

Distally: the space extends as diverticula to the webs of fingers along the fascial sheaths of 3^rd and 4^th lumbrical muscles.

Thenar space: 

Triangular in shape

It presents the following boundaries :

Infront:

Muscles of thenar eminence

Flexor tendon of index finger

1^st and 2^nd lumbrical muscles

Behind: Adductor pollicis muscles

Medial Side: Intermediate palmar septum

Laterally: Flexor pollicis longus tendon

Proximally: The space is closed

Distally: it is continuous as diverticula to the webs of fingers along 1^st and 2^nd lumbrical muscles.

Pulp Spaces:

          The spaces intervening between the palmar slum and distal phalanges of all digits of the hand are called pulp spaces.

They lie distal to the fibrous sheaths of flexor tendons.

In each pulp space, the skin is connected by the fibrous septa to the periosteum of the distal phalanx and is divided into many compartments.

The digital arteries for the distal fourth fifth of the distal phalanx pass through these septa.

Applied Anatomy:

Pus in the thenar space and mid palmar space can be drained surgically by splitting the corresponding web spaces and exploring the lumbrical canal.

Infection of the pulp space is called whitlow. It can cause avascular necrose of the distal part of the phalanges if untreated. It can be drained by the lateral incision which opens all the inter septal compartment.