7. Upper Limb (Part 2) Flashcards
What are the bones in the wrist and hand what do they articulate with?
- Carpals, Metacarpals, Phalanges (proximal, intermediate, distal)
- Carpals articulate with the radius at the wrist
What kind of joint is the wrist joint?
Synovial condyloid joint (a.k.a. ellipsoid)
What structures are involved in the wrist joint?
The joint is formed by articulations between the distal end of the radius and articular disc of the distal radioulnar joint with the proximal row of the carpal bones except the pisiform.
Label this.
Name all of the carpals, starting from the side of the thumb.
Distal: Trapezium, Trapezoid, Capitate, Hamate
Proximal: Scaphoid, Lunate, Triquetrum, Pisiform
Give a good mnemonic for remembering the carpals.
Some lovers try positions that they can’t handle.
This gives the proximal then distal rows, each from lateral to medial side in the anatomical position.
Out of the triquetrum and pisiform, which is on the palmar side of the hand?
Pisiform
Describe how a scaphoid fracture might occur, symptoms and why it is dangerous.
- Occurs when falling onto outstretched hand
- Characterised by pain in the anatomical snuffbox
- In many people the blood supply to the scaphoid is only in the distal to proximal direction, so a fracture can cause avascular necrosis of the proximal portion of the scaphoid
Describe what each of the carpals articulates with in the wrist joint.
- Scaphoid -> Articulates with radius
- Lunate -> Articulates with radius
- Triquetrum -> Articulates with articular disc
The pisiform is a … bone.
Sesamoid
What attaches to the pisiform?
Flexor retinaculum of the wrist
What type of joint is the first carpometacarpal joint (base of thumb) and what movement does this allow?
Synovial saddle joint, allows opposition and reposition
What movements are possible at the wrist joint?
The wrist joint is capable of flexion-extension, radial deviation and ulnar deviation, which may be combined to create a circumduction-like movement.
What type of joint are the second, third, fourth and fifth carpometacarpal joints (between the wrist and the four fingers)?
Plane synovial joints
What movement does the metacarpophalangeal joint of the thumb not allow?
Abduction/adduction - this is instead allowed by the first hypermobile carpometacarpal joint
What type of joint are the second to fifth metacarpophalangeal joints and what movements does this allow?
Synovial ellipsoid joints, allow: - Flexion/extension - Abduction/adduction
What type of joints are the distal and proximal interphalangeal joints and what stabilises them?
Synovial hinge joints, stabilised by collateral ligaments
What are the movements of the pollux/thumb?
- Abduction (movement away from the hand along sagittal plane)
- Adduction (movement towards the hand along sagittal plane)
- Extension (movement away from the hand along the coronal plane)
- Flexion (movement towards and across the hand along the coronal plane)
- Opposition (UNIQUE, ability to touch little finger with thumb)
- Reposition (UNIQUE, ability to return hand to normal shape after opposition)
Summarise where the flexors and extensors of the wrist and hand joints originate.
- Flexors -> At the medial epicondyle of the humerus, as the common flexor tendon.
- Extensors -> At the lateral epicondyle as the common extensor tendon.
What is the carpal tunnel and what does it contain?
- A specialised fibro-osseous canal in the wrist joint
- It contains:
- 4 x tendons of flexor digitorum profundus (FDP)
- 4 x tendons of flexor digitorum superficialis (FDS)
- 1 x tendon of flexor pollicis longus (FPL)
- Median nerve
What makes up the floor and roof of the carpal tunnel?
- Floor = Arch of the carpal bones
- Roof = Flexor retinaculum
What are the names of the wrist and finger flexors you need to know?
- Flexor carpi radialis -> Flexes and abducts wrist
- Flexor carpi ulnaris -> Flexes and adducts wrist
- Flexor digitorum superficialis -> Flexes proximal and middle phalanges of fingers
- Flexor digitorum profundus -> Flexes distal phalanges of fingers
- Flexor pollicis longus -> Flexes thumb
What is the flexor retinaculum?
It is a fibrous band above the carpals that forms the roof of the carpal tunnel. It is essentially a ligament.
What nerves innervate what muscles in the hand and wrist?
- Wrist and finger extensors are innervated by the radial nerve.
- Medial wrist and finger flexors are innervated by the ulnar nerve.
- Lateral wrist, finger and thumb flexors innervated by the median nerve.
- All intrinsic muscles of the hand except the LOAF muscles are innervated by the ulnar nerve.
- LOAF muscles are innervated by the median nerve.
Describe the flexor carpi radialis, including function, attachments and innervation.
- Function: Flexes and abducts the wrist
- Origin: Common flexor tendon
- Insertion: Base of 2nd and 3rd metacarpal bones
- Innervation: Median nerve
Describe the flexor carpi ulnaris, including function, attachments and innervation.
- Function: Flexes and adducts the wrist
- Origin: Common flexor tendon and posterior border of ulna
- Insertion: Pisiform bone
- Innervation: Ulnar nerve
Describe the flexor digitorum superficialis, including function, attachments and innervation.
- Function: Flexes middle and proximal phalanges of medial four digits
- Insertion: Proximal part of middle phalanges
- Innervation: Median nerve
Describe the flexor digitorum profundus, including function, attachments and innervation.
- Function: Flexes distal phalanges of medial four digits
- Insertion: Distal phalanges
- Innervation: Ulnar half of this muscle is supplied by the ulnar nerve and the median nerve supplies the rest of the muscle.
Describe the flexor pollicis longus, including function, attachments and innervation.
- Function: Flexes thumb
- Insertion: Distal phalanx of thumb
- Origin: Flexor surfaces of radius and ulna
- Innervation: Median nerve
What are the flexors of the fingers contained in?
They are enclosed in a lubricating synovial sheath. These can, however, act as conduits through which infections can track.
What are the names of the wrist and finger extensors you need to know?
- Extensor digitorum -> Extends fingers
- Extensor pollicis longus -> Extends thumb
- Extensor pollicis brevis -> Extends thumb
- Abductor pollicis longus -> Abducts thumb and wrist
Describe the extensor digitorum, including function, attachments and innervation.
- Function: Extends fingers
- Origin: Common extensor tendon
- Insertion: Middle and distal phalanges of ulnar four digits
- Innervation: Radial nerve
Describe the extensor pollicis longus, including function, attachments and innervation.
- Function: Extends thumb
- Origin: Posterior surface of ulna and interosseus membrane
- Insertion: Distal phalanx of thumb
- Innervation: Radial nerve
Describe the extensor pollicis brevis, including function, attachments and innervation.
- Function: Extends thumb
- Origin: Posterior surface of radius
- Insertion: Proximal phalanx of thumb
- Innervation: Radial nerve
Describe the abductor pollicis longus, including function, attachments and innervation.
- Function: Abducts thumb and wrist
- Origin: Posterior surface of radius and ulna
- Insertion: Metacarpal of thumb
- Innervation: Radial nerve
Which nerve innervates all of the extensors of the wrist and fingers?
Radial nerve
Where is the anatomical snuff box? Why is it important?
- A triangular fossa on the lateral aspect of the dorsum of the hand, which can be “lit up” when the thumb is fully extended.
- This is an important anatomical landmark, as the radial artery crosses its floor obliquely.
- Fractures of the scaphoid typically cause tenderness on palpation of the anatomical snuffbox.
What makes up the borders of the anatomical snuff box?
- Medial border -> Tendon of extensor pollicis longus
- Lateral border -> Tendons of abductor pollicis longus and extensor pollicic brevis
- Floor -> Scaphoid bone
Draw the position of the tendons, nerves and vessels at the wrist.
What is trigger finger?
- Inflammation of the tendon sheath of the flexor muscles can result in a swelling forming a knot or thickening in the tendon.
- As it passes through the tendon sheath there may be a clicking of the involved finger as the tendon eventually slips through.
- Eventually the finger may lock in the bent position.
- Splinting or the injection of anti-inflammatory drugs relieves the symptoms in the majority of cases.
What is mallet finger?
Rupture of the extensor tendon at the distal interphalangeal joint causes the joint to take on an abnormally flexed position. Whilst the joint can be extended passively this movement cannot be actively generated by the patient.
Which of the nerves is most likely to be injured in wrist drop?
Radial nerve (since it innervates the extensors of the wrist and fingers)
What is the palmar aponeurosis?
- The central part of the deep fascia of the palm which is a highly specialized thickened structure with little mobility.
- It is triangular in shape and it covers the underlying neurovascular and tendon structures.
What is the palmaris longus?
- The most superficial muscle of the superficial forearm flexors
- It is absent in around 14% of the population
What are palmar fascial spaces?
- Spaces of hand are formed by fascia and fascial septae.
- Fascia and fascial septae of the hand are arranged in such a manner that many spaces are formed.
- These spaces are important as they can get infected and distended with pus.
What can lead to clawing of the hand?
- Lacerations to the wrist and subsequent ulnar nerve damage causes paralysis of most of the intrinsic hand muscles.
- Paralysis of the medial two lumbricals cause unopposed extensor muscle action (extensor digitorum) on the MCP joints of the 4th and 5th digits.
- Weakened extension of the interphalangeal joints due to lumbrical and interossei paralysis causes these joints to become flexed.
- Combined together, this lesion gives the hand a claw-like appearance.
Draw a diagram of the arterial supply of the upper limb.
Where does the subclavian artery pass?
The subclavian artery passes between the clavicle and first rib.
Describe the superficial and deep palmar arches.
- The radial and ulnar arteries divide into superficial and deep branches, which form the superficial and deep palmar arches.
- The superficial arch lies more distal to the deep arch, and thus forms the digital arteries.
Describe the upper limb pulse points.
- Axillary pulse: located inferiorly of the lateral wall of the axilla
- Brachial pulse: located on the inside of the upper arm near the elbow
- Radial pulse: located on the lateral of the wrist
- Ulnar pulse: located on the medial of the wrist
Describe the venous drainage of the upper limb.
Superficial arteries:
- The dorsal venous arch of the hand drains to both the basilic (ulnar side) and cephalic (radial side) veins of the forearm.
- The cephalic and basilic veins connect via the median cubital vein at the anterior aspect of the elbow.
Deep veins:
- Above the elbow, the basilic vein joins with the brachial vein to become the axillary vein.
- The cephalic vein then drains in.
- The axillary vein then drains into the subclavian vein at the base of the neck.
Draw the venous drainage of the upper limb.
Draw the brachial plexus.
What are the different levels of the brachial plexus?
What are some important branchings off from the brachial plexus that you need to know?
- Innervation of the serratus anterior (long thoracic nerve) arises from the roots
- Suprascapular nerve arises from the upper trunk of the brachial plexus
Name all of the nerve roots controlling the different upper limb movements.
Draw the dermatomes of the upper limb.
What are the effects of damage to the upper trunk of the brachial plexus?
- Loss of C5 and C6
- Main effects: Loss of shoulder abduction, lateral rotation and elbow flexion.
What are the effects of damage to the lower trunk of the brachial plexus?
- Loss of C8 and T1
- This mainly affects the hand
Draw a diagram to show the innervation of the main body compartments [although you don’t need to know most of these probabaly].
Draw the sensory territories of the different upper limb nerves.
For the musculocutaneous nerve, draw a diagram to show which muscles are innervated by it.
For the median nerve, draw a diagram to show which muscles are innervated by it. [EXTRA?]
For the ulnar nerve, draw a diagram to show which muscles are innervated by it. [EXTRA?]
For the radial nerve, draw a diagram to show which muscles are innervated by it.
Describe the functional position of the forearm and hand.
- Wrist in 20-30° of extension and slight ulnar deviation.
- Fingers in 45-60° of MPC, 10-15° of PIP and 5-10°DIP flexion
- Thumb in 45° of abduction
