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Dr. Ajith Kumar J MD
Dept. of Emergency Medicne
Travancore Medicity, Kollam
India
editor
BASIC ANATOMY OF HAND
Hand consists of 27 bones
14 phalangeal bones
5 metacarpal bones
8 carpal bones
8 carpal bone (Lateral to medial)
First row
Scaphoid
Lunate
Triqueteral
Pisiform
Second row
Trapezium
Trapezoid
Capitate
Hamate
Intrinsic Muscles of Hand
These are muscles originating from the hand and insertion within the hands.
They include thenar muscles, hypothenar emineces, adductor pollicis, interossei, lumbricals.
Thenar Muscles
It includes abductor pollicis brevis, opponens pollicis brevis, flexor pollicis brevis.
They originate from flexor retinaculum and carpal bone and insert at the base of first metacarpal and first proximal phalanx.
Supplied by median nerve.
Hypothenar muscle
They include abductor digiti minimi, oppenens digit minimi, flexor digit minimi.
They originate from flexor retinaculum and carpal bones & insert at proximal phalanx and metacarpal of the little finger.
Adductor pollicis
They originate from 2nd & 3rd metacarpal & insert in first proximal phalanx.
Both hypothenar and adductor pollicis is supplied by ulnar nerve.
Interossei
There are 3 palmar and 4 dorsal interrosei muscles.
They lie & originate between metacarpal bone.
The palmar interosseous muscle and palmar portion of dorsal interosseus muscle have an insertion into extensor hood.
Adduction of index, ring & little finger is done by palmar interossei.
Abduction of index, ring & little finger by dorsal portion of dorsal interossei.
Supplied by ulnar nerve.
Lumbricals
They arise from flexor digitorum profundus tendon in the palm and course radially to metacarpophalangeal joint, reinforcing the interosseous lateral band on the radial side of digit.
They mainly help in interphalangeal joint extension.
Median nerve innervates radial two lumbricals whereas ulnar nerve innervates ulnar 2 lumbricals.
TENDONS OF THE FLEXOR COMPARTMENT
Tendon | Origin & Insertion | Action | Supply |
Flexor Carpi Radialis | Origin : Common flexor tendon from medial epicondyle of humerus. Insertion : Base of 2nd & 3rd metacarpals | Flexion of the wrist Abducts the hand | Median Nerve |
Flexor Carpi ulnaris | Origin : Common flexor tendon and from medial border of olecranon & upper 2/3 rd of the posterior border of ulna.
Insertion : Pisiform hook of hamate & base of 5th metacarpal. | Flexion of wrist Adducts hand | Ulnar Nerve |
Flexor digitorum Superficialis | Origin :
Insertion : Muscle ends in a tendon which splits into four smaller tendons, one for each digit except the thumb. The tendons for the middle and ring fingers lie superficial to those for index and little finger. Opposite the proximal phalanx the tendon for each digit splits to form two slips, medial and lateral. | Flexion of MCP joints & P IP Joints. | Median Nerve |
Flexor digitorum profundus | Origin : Posterior border of the ulna ; Proximal 2/3rd of medial border of ulna & interosseous membrane
Insertion : Base of the distal phalanx of digit 2-5. | Flexion of MCP, PIP Joint, DIP joint | Median Nerve |
Palmaris Longus | Origin : Common flexor tendon from the medial epicondyle of the humerus.
Insertion ;Palmaris aponeurosis | Flexes the wrist | Median nerve |
Courtesy : Wikipedia
Flexor Compartment of the Forearm
EXAMINATION OF HAND INJURIES
Attitude and deformity
Ape thumb deformity
Thumb being in the line with other metacarpal due to paralysis of oppenens pollicis (Median nerve palsy).
Pointing Index
On asking the patient to make a fist the index finger remains straight.
It is due to paralysis of flexor digitorum superficialis and that of lateral half of flexor digitorum profundus muscle in median nerve palsy at a level proximal to elbow.
Claw hand
A deformity in which metacarpophalangeal is extended while proximal and distal interphalangeal joints are flexed. It is due to paralysis of lumbricals.
In ulnar nerve palsy only the medial two fingers develop clawing while all the four fingers develop clawing in combined median and ulnar nerve palsies.
Wrist drop
Lesion of radial nerve injury.
Policeman's receiving tip
Characterised by an arm hanging by the side of the body and internally rotated with forearm extended at the elbow and fully pronated.
Tendon Injury
Tendon has to be checked for full range of movements against resistance.
It is important to check against resistance upto 90% of a tendon can be lacerated with preserved range of movements without resistance.
Pain along the tendon during resistance is suggestive of tendon injury.
|
Sensory
Two point discrimination test :Normal two point discrimination is <6mm at the finger tips and is often <2mm.
Courtsey : Wikepedia
Sensory supply. Blue : Ulnar Nerve, Rose : Radial Nerve, Brown : Median Nerve
Examination of the Median Nerve (Individual muscles)
Abductor pollicis brevis : The action of this muscle is to do abduction. To test this muscle the patient is asked to lay his hand flat upon the table with the palm looking upwards and touch with his thumb a pen held in front of it : The pen test.
Opponens pollicis : The patient is unable to touch the ends of the little finger with tip of the thumb.
Flexor Pollicis Longus : The patient is unable to bend the terminal phalanx of the thumb while the proximal phalanx is held firmly by the clinician to eliminate this action of the short flexors.
Flexor Digitorum Superficialis & Profundus : Paralysis of these muscle leads to ' pointing index' which is easily demonstrated by Oschner's clasping test when the patient is asked to clasp the hands the index finger of the affected side fails to flex.
ANATOMY OF MEDIAN NERVE
Course in the forearm
Course in the hand
|
Courtsey : Wikipedia
Major motor branches of the median nerve | |
In the arm | Nil |
In the forearm Proximal 1/3 rd | All the flexor muscles except flexor carpi ulnaris and medial half of flexor digitorum profundus. |
In the Distal 1/3 rd | Nil |
In the hand | Thenar muscles (Flexor pollicis brevis, opponens pollicis and abductor pollicis) except adductor pollicis First two lumbricals |
Examination of Ulnar Nerve
Flexor carpi ulnaris :
The patient is asked to palmar flex the wrist against gravity. By doing so the hand deviates to the radial side.
Abductor digiti minimi:
The patient is asked to abduct the little finger against resistance while keeping the hand flat on the table.
Interossei :
Ask the patient to abduct & adduct the fingers.
Give the patient a card or a piece of a paper and ask him to grip it between the fingers : Card test. (Palmar interossei)
Egawa's Test : With hand kept flat on a table the patient is asked to move his little finger sideways. (Dorsal Interossei)
Abductor Pollicis : When the muscle is paralyzed the patient is unable to grip a piece of paper between the thumb and index finger. (Froment's sign)
ANATOMY OF ULNAR NERVE
Course in the forearm
Course at the wrist
|
Major motor branches of the ulnar nerve | |
In the arm | Nil |
In the forearm proximal 1/3 rd | Flexor carpi ulnaris, medial half of the flexor digitorum profundus |
Distal 1/3 rd | Nil |
Hand | Hypothenar muscles Adductor pollicis All interossei and medial two lumbricals |
Examination of radial nerve
Triceps : The patient is asked to extend his elbow against resistance applied by the examiner, feel for contraction.
Brachioradilais: The patient is asked to flex the elbow from 90 degrees onwards, keeping the forearm midprone. Feel for contraction of the muscle.
Wrist extensor : In radial nerve injury the patient will be unable to extend the wrist (WRIST DROP), thumb and MCP joints of the fingers.
Extensor digitorum : It causes extension of metacarpo-phalageal joints. Patient cannot do this if its paralysed.
Extensor pollicis longus : This causes extension at inter-phalangeal joint of thumb. It should be examined after stabilizing metcarpo-phalangeal joint.
ANATOMY OF RADIAL NERVE
Course in the arm
|
Simple Sensory and motor function test for nerves when there is injury at the level of elbow
| Radial | Median | Ulnar |
Sensory System | Dorsum of the thumb index web space | Two point discrimination over the tip of the index fingers. | Two point discrimination test over the little finger. |
Motor System | Extend both wrist and fingers against resistance | “ OK” sign with thumb and index finger . Abduction of the thumb | Abduct index finger against resistance. |
Updated on 15/12/2014
Reference
Tintinalli
Essential Orthopedics, By J. Maheshwari
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emmedonline
Dr. Ajith Kumar J MD
Dept. of Emergency Medicne
Travancore Medicity, Kollam
India
editor