Hand and Brachial Plexus Flashcards
Bones of the hand
From proximal to distal: carpal, metacarpal and phalanges
Which bones bones compose the proximal row of carpals?
Scaphoid, lunate, triquetrum, and pisiform
Which carpal bone is the most commonly fractured and where is it found?
The scaphoid, which lies beneath the anatomical snuffbox.
Where do the proximal row of carpal bones articulate?
Distal radius
Which bones compose the distal row of carpals?
Trapezium, trapezoid, capitate (round bone), and hamate (hook bone)
With what structures does the distal row of carpals articulate with?
Proximal row of carpal + Metacarpals
Metacarpal characteristics
Numbered 1 to 5 (thumb to little finger)
Posses a base, shaft, and head
Associated with head of first metacarpal
Which metacarpal bone is most commonly fractured?
5th metacarpal
Phalanges characteristics
Posses a base, shaft, and head
Termed proximal, distal, and proximal
Which phalange is most commonly fractured?
Distal phalange of middle finger
What movements does the carpal joint provide?
Provide gliding movements and significant wrist extension and flexion.
What are the 4 carpal joints of the hand?
- Carpometacarpal
- Metacarpophalangeal
- Proximal interphalangeal (the first phalange [the thumb] only posses this one)
- Distal phalangeal
Carpometacarpal and thumb joint ligaments and characteristics
- Palmar and dorsal (dorsal is strongest)
- Interosseous
Allow flexion, extension, ABduction, ADduction, and circumduction
Run from carpals to metacarpals of digits 2-5
Metacarpophalangeal joint ligaments characteristics
- Radial and ulnar collateral- tight in flexion and loose in extension
- Palmar (volar) plate- if broken digit, cast in flexion or it will shorten
Interphalangeal joint ligaments characteristics
- Two collaterals- oriented obliquely
2. Palmar (volar) plate- prevents hyperextension
Where do intrinsic hand muscles originate and what do they do?
They originate and insert in the hand and carry out fine, precise movement.
Which muscles are more important in powerful hand movements?
Forearm muscles
Intrinsic hand muscles
- Thenar eminence (thumb)
- Hypothenar eminence (little finger)
- Interosseous
- Lumbrical
Which muscles create the thenar eminence and which nerve supplies them?
- Flexor pollicis brevis
- Abductor pollicis brevis
- Opponens pollicis
Median Nerve
Which muscles make up the Hypothenar eminence and what nerve supplies them?
- Flexor digiti minimi brevis
- Abductor digiti minimi
- Opponens digiti minimi
Innervated by ulnar nerve
Abductor pollicis brevis: attachment and function
Origin: flexor retinaculum and tubercle of scaphoid and trapezium
Insertion: lateral side of base of proximal phalanx of thumb
Function: ABducts thumb
Flexor pollicis brevis: attachment and function
Origin: flexor retinaculum and tubercle of trapezium
Insertion: lateral side of base of proximal phalanx of thumb
Function: flexes proximal phalanx of thumb
Opponens pollicis: attachment and function
Origin: flexor retinaculum and tubercle of trapezium
Insertion: lateral side of first metacarpal bone
Function: opposes thumb towards center of palm and rotates it medially
ADductor pollicis: attachment and function
Origin
- Oblique head: bases of 2nd and 3rd metacarpals and capitate
- Transverse head: anterior surface of body of 3rd metacarpal
Insertion: medial side of base of proximal phalanx of thumb
Function: ADduct thumb towards middle digit
ABductor digiti minimi: attachment and function
Origin: pisiform and tendon of flexor carpi ulnaris
Insertion: medial side of base of proximal phalanx of 5th digit
Function: ABducts 5th digit
Flexor digiti minimi brevis: attachment and function
Origin: hook of hamate and flexor retinaculum
Insertion: medial side of base of proximal phalanx of 5th digit
Function: flexes proximal phalanx of 5th digit
Opponens digiti minimi: attachment and function
Origin: hook of hamate and flexor retinaculum
Insertion: medial side of base of proximal phalanx of 5th metacarpal
Function: draws the 5th metacarpal anteriorly and rotates it, bringing 5th digit into opposition with thumb
Lumbricals 1 and 2: attachment and function
Origin: lateral two tendons of flexor digitorum profundus
Insertion: lateral side of extensors expansions of 2nd and 3rd digits
Function: flex digit at MCP joints and extend to IP joint
Lumbricals 3 and 4: attachment and function
Origin: medial three tendons of flexor digitorum profundus
Insertion: lateral side of extensors expansion of 4th and 5th digits
Function: flex digit at MCP joints and extend to IP joint
Dorsal interossei: attachment and function
Origin: adjacent sides of two metacarpals
Insertion: extensor expansions and bases of proximal phalanges of 2nd to 4th digits
Function: ABducts digits; flexes digits at MCP joints and extend to IP joints
Palmar interossei: attachment and function
Origin: sides of 2nd, 4th, and 5th metacarpal bones
Insertion: extensor expansions and bases of proximal phalanges of 2nd, 4th, and 5th digits
Function: ABducts digits; flexes digits at MCP joints and extend to IP joints
What surrounds the long tendons as they pass through the hand towards the fingers and what binds them to the phalanges?
Synovial Sheath
Fibrous digital sheath
What is the anatomical snuff box created by the extensor tendons of the thumb on the dorsum of the hand composed of?
- Medially, the tendon of the extensor pollicis longus
- Laterally, the tendons of the abductor pollicis longus and extensor pollicis brevis
How is the brachial plexus divided?
Five roots (ventral rami)
Three trunks
Six divisions (three anterior, three posterior)
Three cords (named for their relationship to the axillary artery)
Five large terminal branches
From where does the brachial plexus arises?
Ventral rami of spinal nerves C5-T1
Where is C4 found?
From the cervical plexus over the shoulder.
What nerve root spans from the lateral arm, over deltoid and triceps?
C5
What area does nerve root C7 supply?
Skin of the hand, primarily second through third or fourth digits
Whic areas are supplied by C8 and T1?
C8: medial two digits (fourth and fifth digits), hypothenar eminence, and medial forearm
T1: medial arm
