Week 10 - finished Flashcards
What articulations comprise the elbow complex?
- humeroulnar joint
- Distal and Prox radioulnar joint
- humeroradial joint
What is the carrying angle of the elbow?
- the valgus angulation of the forearm in relation to the humerus
- approx. 5-10 degrees in men
- approx. 10-15 degrees in women
At what age does each of the major bony structures of the elbow ossify? How does this influence “pulled elbow”?
elbow ossification centres = “come rub my tree of love”
- Capitulum = 1 yoa
- Radial head = 5 yoa
- Medial epicondyle = 5 yoa
- Trochlea = 11 yoa
- Olecranon = 12 yoa
- Lateral epicondyle = 13 yoa
pulled elbow = sublaxation of the radial head, most common in traumatic elbow injury in children, usually around 2-5 yrs as radial head ossifies after this age, as well as the thickening of the annular ligament
What ligaments support the radioulnar joint?
Ladies, RU A Quiet Orgasmer Inside
- annular ligament = attaches to the ant and post borders of the radial notch, creating a ring in which the rim of the radial head is enclosed
- quadrate ligament = extends from the inf edge of the radial notch (ulna) to the neck of the radius. Reinforces the inf jt capsule and maintains approximation of radial head to radial notch. Limits the spin of the radial head in pronation and supination
- Oblique cord = Extends from inf to the radial notch (ulna) to inf to the bicipital tub of the radius. Prevents separation of the ulna and radius and limits supination. Fibre orientation is perpendicular to that of the interosseous membrane
- interosseous membrane = The interosseous mem connects the med border of the radius & lat border of the ulna. It is a strong, broad collagenous sheet, which begins 2-3cm distal to the radial tub. The distal end is continuos, via a tract, with the distal radioulnar joint capsule and articular disc. Its fibres run distally and medially from radius to ulna & functions to:
- Provides stability to both radioulnar joints
- Transmits forces from the hand and distal radius to the ulna
- Provides proximal attachment for the deep muscles of the forearm - Radioulnar ligaments = The dorsal & palmar radioulnar ligs are capsular ligs found @ the margins of the disc in the distal radioulnar jt. In full supination the palmar ligament is taut and dorsal is lax. In full pronation the dorsal ligament is taut and the palmar is lax
List the mms which flex the elbow
3b’s bend the elbow
- brachialis
- biceps brachii
- brachioradialis
secondary flexors
- PT
- FCR
- FCU
- FDS
- PL
List the mms which supinate the elbow
- Supinator
- Biceps brachii
List the borders and the contents of the cubital fossa
BORDERS
- Superior = imaginary line b/w med an lat epicondyles
- Medial = lateral border of PRONATOR TERES
- Lateral = medial border of BRACHIORADIALIS
- Floor = brachialis and supinator muscles
- Roof = Brachial fascia, bicipital aponeurosis, superficial fascia and skin
CONTENTS (LAT TO MED)
- radial nerve
- biceps tendon
- brachial artery
- median nerve
Which bones contribute to the radiocarpal joint? What is the midcarpal joint?
radiocarpal = radius, scaphoid, lunate, triquetrum
midcarpal = articulation b/w the prox and distal rows of carpal bones
Which carpal most commonly becomes unstable? How can this relate to carpal tunnel syndrome? What orthopaedic tests are used to asses carpal stability?
- The scaphoid is often involved in carpal instability
- lunate 2nd most common
- Due the carpal tunnel attachments the carpal tunnel may be affected by the movement of the scaphoid.
- If the scaphoid has become unstable due to traumatic events eg. FOOSH we will see swelling/ inflammation within the carpal tunnel causing carpal tunnel syndrome SSX.
- Scapholunate rupture = Waton’s test (scaphoid shift test)
- To check lunate stability = ballotement test (shearing whist holding lunate)
What carpal is most commonly fractured? What variation in blood supply is significant in this fracture?
- Scaphoid in a FOOSH injury (with partially ulna deviation)
- About 10% of people have blood supply from only the radial artery which enters from the distal aspect of
the bone. A fracture may result in avascular necrosis of the PROXIMAL-===== portion.
List the mms that extend the wrist
- ECRL and ECRB
- ECU
secondary extensors
- ED
- EI
- EDM
- EPL
List the borders and contents of the anatomical snuff box
floor = scaphoid and trapezium
lateral border = AbPL and EPB
medial border = EPL
contents = radial artery, radial nerve (sup. branch), cephalic vein
What is the path of the ulnar artery and nerve into the hand?
ULNAR ARTERY
- branch of brachial (bifurcation inferior to elbow around neck of radius)
- lies b/w FDP and FDS
- passes medially to pisiform and into hand via tunnel of Guyon
ULNAR NERVE
- over flexor retinaculum
- through Guyon’s canal and and into medial hand
List the muscles supplied by the musculocutaneous nerve
- Biceps brachii
- Brachialis
- Coracobrachialis
Why is palmar sensation and 5th digit sensation generally spared in cases of carpal tunnel syndrome?
Palmar innervation is via the superficial palmar branch of
the median N which travels superiorly to the flexor retinaculum (AKA transverse carpal ligament)
5th digit (and 1/2 of the 4th digit) palmar surface is supplied by the ulnar nerve which travels through the tunnel of guyon (where the flexor retinaculum is the floor)
Where is the radial nerve prone to injury?
before dividing
- lateral triangular spce
- axilla
- surgical neck of humerus
- radial groove
deep branch
- radial tunnel
- arcade of Froshe
- supinator
superficial branch
- b/w tendons of ECRL and brachioradialis
Where is the ulnar nerve prone to injury? What deformity normally results?
- cubital tunnel (posterior to medial condyle = altered sensation of ulna nerve distribution, weakness in wrist flexion, grip strength, hypothenar atrophy )
- tunnel of Guyon (Roof is formed by volar carpal ligament and pisohamate ligament)
Severe = claw
An ulnar claw may follow an ulnar nerve lesion[3] which results in the partial or complete denervation of the ulnar (medial) two lumbricals of the hand. Since the ulnar nerve also supplies the 3rd and 4th lumbricals, which flex the MCP joints (aka the knuckles), their denervation causes these joints to become extended by the now unopposed action of the long finger extensors (namely the extensor digitorum and the extensor digiti minimi). The lumbricals and interossei also extend the IP (interphalangeal) joints of the fingers by insertion into the extensor hood; their paralysis results in weakened extension. The combination of hyperextension at the MCP and flexion at the IP joints gives the hand its claw like appearance.
What structures contribute to the carpal tunnel? What structures pass through the carpal tunnel?
- Carpal Tunnel: The trapezoid, trapezium, capitate, hamate, Transverse carpal ligament and transverse intercarpal ligaments form the carpal tunnel.
- Contains:
o Median nerve,
o The tendons of FDS, FDP, FPL.
Enters the flexor retinaculum:
o The tendon of flexor carpi radialis (Enters within separate compartment- variable)
-Palmaris Longus and flexor carpi ulnaris DO NOT ENTER the flexor retinaculum. PL goes superficial and the FCU goes to the pisiform.
What are the functions of the flexor retinaculum of the wrist?
- Holds the flexor tendons in position at the wrist “Retaining band”
- Stops the tendons from “bowstringing” across any angle created
- Converts the anterior surface of the carpus into the carpal tunnel
- Protects/ acts as a passage way for the median nerve FDP, FDS, FPL
What is carpal tunnel syndrome? What are the clinical signs and symptoms? What is the distribution of numbness and paraesthesia?
- Compression of the median nerve in the carpal tunnel
SSx
- Altered sensation (numbness, heaviness, pins & needles) in the lateral 3 1⁄2 digits of hands
- Weakness and loss of mm bulk in thenar eminence.
- Relieved by shaking/wringing of hands or dropping them over side of bed
- Often worse at night due to increased fluid, wrist flexion and weight.
What tests are used to diagnose carpal tunnel syndrome?
- Tinnels (25-60%) - Phalenes (70%) -OKAY sign (FDP and FPL) - most accurate test is clinical picture
What factors or conditions can contribute to carpal tunnel syndrome?
- Anything that causes fluid retention – pregnancy, kidney disease, lymph node removal
- Overuse / Vibrating equipment
- Fibrosis of transverse ligament
- Carpal instability/Colles # (distal radius)
- RA/OA (in carpals = rare), - Tendonitis/ synovitis
- Posture/gait
What are the differential diagnoses?
Bone:
- Facet causing radiculopathy at (C6/7)
- Radial nerve (impingement: TX outlet, Axilla, quadrangular space, radial groove, within radial tunnel, arcade of frosche, within supinator, snuff box)
- De Quervains tenosynovitis
- mononeuropathy
- polyneuropathy - eg diabetes
- vascular cause (radial artery)
- Double Crush
What is the double crush pnenomenon?
Double crush is a phenomenon that refers to the presence of nerve irritation at two locations along the path of the nerve. Nerves in our body leave our spine and travel through the body to their final destinations. Thus, nerves leaving the neck, or cervical spine, become nerves that innervate the wrist. Double crush means that irritation at one site, such as the neck, causes enough damage to make the same nerve more susceptible to damage elsewhere, such as the wrist. For carpal tunnel syndrome, a pinched nerve leaving the neck, as seen in cervical radiculopathy, may require less pinching of the median nerve in the wrist to produce painful symptoms than would otherwise be expected if the nerve was only pinched at one location.
How may supracondylar fracture threaten blood supply to the forearm?
Supracondylar fracture (MEDIAL) can cause damage to brachial artery resulting in ischaemia to the forearm. Ischaemic contracture of muscles of the forearm and hand.
Brachial artery is rather superficial in its course. It is overlapped from the lateral side by biceps brachii muscle. It lies upon the triceps and the coracobrachialis muscles. In the proximal region the artery lies medial to the humerus where it is palpable. In the lower part of its course the artery gains an anterior position relative to the humerus. The brachial artery accompanies the median nerve which crosses it from lateral to medial side in the middle of the arm
