The Hand Flashcards
Carpus
2 rows of 4 small bones that articulate with each other at small joints
Metacarpals
Located distal to carpals
Numbered 1-5 from lateral (thumb) to medial (little finger)
Phalanges
Bones of the digits
3 phalanges in each finger
2 phalanges in thumb
Name of 3 phalanges in each finger
Proximal
Middle
Distal
Name of phalanges in thumb
Proximal
Distal
Carpometacarpal joints
Between distal row of carpal bones and proximal bases of metacarpals
First carpometacarpal joint
Between trapezium and thumb
Saddle joint
Metacarpophalangeal joints
Knuckles
Condyloid synovial joints
Interphalangeal joints
Hinge synovial joints
Movements of the fingers
Flexion
Extension
Abduction
Adductiom
Movements of the thumb
Flexion
Extension
Abduction
Adduction
Opposition
Opposition
A mixture of Flexion, Adduction, and internal rotation of the thumb metacarpal
Power grip
To hold or squeeze objects tightly
Hook grip
Carrying objects with handles
Precision grip
Hold objects between the pads of our thumbs and fingers eg pen
3 types of grip
Power grip
Hook grip
Precision grip
Extrinsic muscles of the hand
Muscles of anterior and posterior forearm
Anterior forearm muscles that are primary flexors of the wrist
Flexor carpi radialis
Flexor carpi ulnaris
Palmaris longus
Where does the flexor carpi radialis insert
2nd metacarpal
Where does the flexor carpi ulnaris insert
5th metacarpal
Where does the Palmaris longus insert
Palmar fascia
Anterior compartment muscles that flex the digits
Flexor digitorum superficialis
Flexor digitorum profundus
Flexor pollicis longus
Tendon of flexor digitorum superficialis insertion
Splits into 2 slips which insert either side of the middle phalanx of digits 2-5
Tendon of flexor digitorum superficialis function
Flexes the metacarpophalangeal and proximal interphalangeal joints of digits 2-5
Tendon of flexor digitorum profundus insertion
Passes through the gap in the Tendon of flexor digitorum superficialis to inert onto the palmar aspect of the distal phalanx of digits 2-5
Tendon of flexor digitorum profundus function
Flexion of distal interphalangeal joints
Also flexes MCP and PIP joints of digits 2-r5
Which tendon is the only tendon that can cause Flexion of the distal interphalangeal joints
Tendon of flexor digitorum profundus
Tendon of flexor pollicis longus insertion
Distal phalanx of thumb
Tendon of flexor pollicis longus function
Flexes the interphalangeal joint of the thumb
What encloses long flexor tendons
Fibrous tendon sheaths enclosed within a synovial sheath
Function of flexor tendon sheaths
Maintain the position of the flexor tendon in the midline of each finger
Function of synovial sheaths
Reduce friction and allows the tendons to slide freely within the fibrous sheath
Thick palmar aponeurosis
Protects the long flexor tendons , tendon sheath and vessels as they pass through the palm of the hand
Tenosynovitis
Inflammation of the tendon and synovial sheath
Intrinsic muscles of the hand
4 groups:
Thenar eminence
Hypothenar eminence
Lumbricals
Interossei
And adductor pollicis
Thenar eminence muscles
Flexor pollicis brevis
Abductor pollicis brevis
Opponens pollicis
Opponens pollicis
Deep to flexor and abductor
Opposes the thumb
Insertion of the flexor pollicis brevis
Proximal phalanx of thumb
Insertion of the abductor pollicis brevis
Lateral aspect of proximal phalanx of thumb
Insertion of the opponens pollicis
First metacarpal of thumb
What innervates all of the thenar eminence muscles
Recurrent branch of median nerve
Where does the recurrent branch of the median nerve branch off
After the carpal tunnel
Adductor pollicis muscle location
Deep in the palm
Adductor pollicis insertion
3rd metacarpal and proximal phalanx of thumb
Function of adductor pollicis muscle
Pulls thumb towards the palm
Innervation of adductor pollicis muscle
Ulnar nerve
Importance of thenar eminence muscles
Precision grip
What muscles comprise the fleshy mass on the palm of the hand at the base of the thumb
Thenar eminence muscles
What constitutes the fleshy mass on the medial side of the palm of the hand proximal to the little finger
Hypothenar eminence
Muscles of the hypothenar eminence
Flexor digiti minimi
Abductor digiti minimi
Opponens digiti minimi
Insertion of the flexor digiti minimi
Proximal phalanx of digit 5
Insertion of the abductor digiti minimi
Proximal phalanx of digit 5
Insertion of the opponens digiti minimi
5th metacarpal
Innervation of all muscles of the hypothenar eminence
Deep branch of ulnar nerve
Muscles of the lumbricals
4 muscles - one for each finger
Origins of the lumbricals
Tendons of the flexor digitorum profundus
Insertion of the lumbricals
Dorsal aspect of digits 2-5
Function of the lumbricals
Flex the metacarpophalangeal joints and extend the interphalangeal joints simultaneously
Innervation of the lumbricals
Digits 2/3 = median nerve
Digits 4/5 = ulnar nerve
Location of interossei muscles
Between the metacarpals and insert into the dorsal aspects of digits 2-5
2 groups of interossei muscles
Palmar group
Dorsal group
Number of palmar interosseous muscles
3
Number of dorsal interosseous muscles
4
Function of palmar interosseous muscles
Adduction of the fingers
Function of the palmar interosseous muscles
Abduction of the fingers
Muscles found in the dorsum of the hand
4 dorsal interosseous muscles
What does the dorsal venous network of the hand drain into
Cephalic vein laterally
Basilic vein medially
Extensor expansion/ extensor hood
Fibrous structure located on the dorsal aspect of the hand
Attached to the base of the proximal phalanges and gives rise to a central slip and 2 marginal slips
Central slip of extensor expansion
Inserts onto the middle phalanx
Marginal slips of the extensor expansion
Converge on the distal phalanx
Function of extensor expansion
Tendons of extensor digitorum, extensor indicis and extensor digiti minimi insert onto dorsal aspect of it helping to keep the tendons fixed in the midline of the digits
Lumbricals and interossei insert into sides of the proximal parts helping to contribute to extension of interphalangeal joints
Anatomical snuffbox
A triangular- shaped depression in the lateral aspect of the wrist at the base of the thumb
Boundaries of the anatomical snuffbox
Extensor pollicis longus medially
Tendons of the extensor pollicis brevis and abductor pollicis longus laterally
Clinical significance of anatomical snuffbox
Floor = scaphoid bone
Radial artery travels through it
Cephalic vein travels across it
Superficial branch of radial nerve travels over it
Blood supply of the hand
Radial and ulnar arteries
Terminal branches of brachial artery
Radial and ulnar
Anastomoses of the radial and ulnar artery
Form 2 palmar arches
Superficial and deep
Superficial palmar arch
Formed largely by the ulnar artery
Deep palmar arch
Formed largely by the radial artery
What do the palmar arches give rise to
Metacarpal and digital arteries that supply the palm and digits
Course of the radial artery
Lateral aspect of forearm
Course of ulnar artery
Medial aspect of forearm
Which 3 peripheral nerves innervate the skin of the hand
Median
Ulnar
Radial
Territories of the median nerve
Palmar surface of the lateral side of the hand
Palmar surface of the lateral 3 1/2 digits
Skin over the dorsum of the distal phalanges of the lateral 3 1/2 digits
Territories of the ulnar nerve
Palmar and dorsal surfaces of the medial side of the hand and medial 1 1/2 digits
Territories of the radial nerve
Dorsal surface of the lateral side of the hand
Skin over the dorsum of the lateral 3 1/2 digits as far as the distal interphalangeal joint
How to test for sensation of the median nerve
Central palm just proximal to middle finger
How to test for sensation of the ulnar nerve
Medial border of the hand
How to test for sensation of the radial nerve
Dorsum of the hand in the thumb and index webspace
Region innervated by C4
Superior aspect of shoulder
Region innervated by C5
Lateral shoulder over the deltoid
Anterior and posterior aspects of the arm
Region innervated by C6
Lateral side of anterior and posterior aspects of forearm
Lateral sides of anterior and posterior surfaces of the palm
Anterior and posterior surfaces of the thumb and index finger
Region innervated by C7
Anterior and posterior surfaces of middle finger and middle palm (over the 3re]d metacarpal)
Region innervated by C8
Medial side of the anterior and posterior surfaces of the forearm
Medial side of the anterior and posterior surfaces of the palm
Anterior and posterior surfaces of the ring and little finger
Region innervated by T1
Medial side of the anterior and posterior surfaces of the arm
Peripheral nerves supplying the upper limb
Supraclavicular nerve
Axillary nerve
Intercosto-brachial nerve
Medial cutaneous nerve of the arm
Posterior cutaneous nerve of the forearm
Lateral cutaneous nerve of the forearm
Medial cutaneous nerve of the forearm
Radial nerve
Median nerve
Ulnar nerve
How to test for the C5 dermatome
Upper lateral arm over the deltoid muscle
How to test for the C6 dermatome
Thimb
How to test for the C7 dermatome
Middle finger
How to test for the C8 dermatome
Little finger
How to test for the T1 dermatome
Medial border of the arm just proximal to the elbow
Testing the tendons of FDP and FPL
In the case of palmar injuries (e.g., a laceration over the palmar aspect of a finger), we need to assess if the long flexor tendons are intact. The tendons of FDS and FDP both cross, and hence can move, the PIP joint. However, only FDP can move the DIP joint. To test FDP, the PIP joint is held immobile by the examiner and the patient is asked to flex the finger. If the FDP tendon is intact, flexion is seen at the DIP joint. To test the tendon of FPL, movement at the IP joint of the thumb is assessed.
Dupuytren’s contracture
In this condition, the fingers (usually the little and ring fingers) are pulled into flexion by progressive fibrosis of the palmar fascia and palmar aponeurosis. The palmar fascia is attached to the flexor tendon sheaths of the fingers. The fascia shortens and pulls the fingers into flexion. The fascia can be released surgically.
Arthritis
Osteoarthritis is ‘wear and tear’ arthritis and is more common in older people. It primarily affects large, ‘load bearing’ joints like the hips and knees. However, rheumatoid arthritis is an autoimmune condition that affects various synovial joints, and the small joints of the hands are typically involved. The MCP and PIP joints are predominantly affected. Rheumatoid arthritis can damage these joints causing significant deformity such as ulnar deviation of the digits at the MCP joints, and fixed flexion and extension deformities of either of the interphalangeal joints. This can lead to significant functional impairment for these patients.
Fracture of the 5th metacarpal
Otherwise known as a ‘boxer’s fracture’, as it is typically sustained by punching something hard, there is usually pain, swelling and tenderness over the 5th metacarpal.
Which joints are predominantly afffeccted by rheumatoid arthritis
MCP and PIP
- Which bone lies in the floor of the anatomical snuffbox?
Scaphoid
- Which neurovascular structures are associated with the anatomical snuffbox?
Cephalic vein
Radial artery
Superficial branch of radial nerve
- In a patient with a T1 nerve root injury, which muscles will be weak / paralysed? Which area of skin will be affected?
Small muscles of the hand will be weak
Sensory impairment over medial arm
- Which fingers have two extensor muscles and tendons?
Index finger
Little finger
- Which muscles comprise the thenar eminence? Which nerve innervates them?
Abductor pollicis brevis
Extensor pollicis brevis
Opponens pollicis
Recurrent branch of median berve
- How would you test the function of the interosseous muscles?
Abduction and Adduction of the fingers
- How would a patient present if they injured their median nerve at their wrist? In comparison, how would a median nerve injury at the elbow present?
Wrist- weakness of the thenar eminence muscles and lateral 2 lumbricals
Sensory of palmar aspect of lateral 3 1/2 fingers but NOT lateral palm
Elbow- also weakness of anterior forearm muscles except for FCU and medial half of FDP
o Median nerve injury at the wrist results in weakness / paralysis of the muscles innervated by the nerve distal to the wrist i.e. the thenar eminence muscles and the lateral two lumbricals.
o The patient presents with weakness of the thumb (but not of adduction) and over time, atrophy of the thenar eminence occurs. o The patient will also have sensory deficits over the palmar aspect of the lateral 3 ½ fingers, but not the lateral palm as the palmar sensory branch of the median nerve branches from the median nerve proximal to the wrist.
o Median nerve injury at the elbow results in weakness / paralysis of the muscles innervated by the nerve distal to the elbow i.e. all the anterior forearm muscles (except for FCU and the medial / ulnar half of FDP), the thenar eminence muscles and the lateral two lumbricals.
o The patient is unable to flex the DIP and PIP joints of the 2nd and 3rd digits (i.e. index and middle fingers). o Flexion of the MCP joints of these fingers is also impaired due to loss of function in the lumbricals to these fingers.
o Movements of the thumb (except adduction and extension) are also weak due to weakness of FPL and the thenar eminence muscles.
o The patient would also have sensory deficits over the palmar aspect of the lateral 3 ½ fingers and lateral palm.
o Sensation over the lateral palm would also be impaired in this case, as the branch of the median nerve that innervates the palm leaves the median nerve in the distal forearm, so would be affected by a lesion at the elbow.
Where does the palmar sensory branch of the median nerve branch
Proximal to the wrist
- A patient with carpal tunnel syndrome has normal sensation over the lateral side of their palm. Why is this?
o Compression of the median nerve in the carpal tunnel typically leads to sensory disturbance over the palmar aspect of the lateral 3 ½ digits, as the sensory branches to these regions of skin leave the median nerve distal to the carpal tunnel.
o Although the lateral palm is also innervated by the median nerve, the branch to the lateral palm leaves the median nerve in the distal forearm, proximal to the wrist. It travels superficially to the flexor retinaculum (i.e. not through the carpal tunnel), hence is unaffected by compression of the median nerve in the carpal tunnel.
What does the Musculocutaneous nerve become
Lateral cutaneous nerve of the forearm
What innervates the interossei muscles
Ulnar nerve
What forms nerves
Epineurium
Fascicles
