Exam 2 Class 9 Forearm and Wrist

Intermediate layer of the anterior compartment of the forearm. How many muscles? What are they?

1- Flexor Digitorum Superficiales

Going from lateral to medial, from 1-9 what is the order of structures you should see just prior to entering the Carpal Tunnel

1. Brachioradialis 2. Radial artery 3. Flexor carpi radialis 4. Median nerve 5. Palmaris Longus 6. 4 tendons of the Flexor Digitorum Superficiales 7. Ulnar artery 8. Ulnar nerve 9. Flexor carpi ulnaris

The Radial nerve is vulnerable to injury under which conditions? Lesion causes what condition?

1. Injury in the triangular interval 2. In the radial groove 3. As it passes under the tendinous superior border of the Supinator aka the Arcade of Frohse. Lesion causes wrist drop

The Median Nerve is vulnerable to injury in what circumstances?

1. Supracondylar humeral fracture 2. B/w the heads of the Pronator Teres 3. Under the Flexor Digitorum Superficiales 4. Deep to the Flexor Retinaculum at the wrist

The Ulnar nerve is vulnerable to injury in what circumstances?

1. Under the Arcade of Struthers 2. At the Medial humeral epicondyle 3. B/w the 2 heads of the FCU under the Ligament of Osborne in the cubital tunnel.

Posterior osteofascial compartment of the forearm has how many layers of muscles?

2

The forearm is divided into? Which is meatier?

2 osteofascial compartments- the anterior compartment

How many carpal bones articulate directly with the distal forearm and wrist? What are they?

2- Scaphoid and Lunate

Anterior osteofascial compartment of the forearm. How many layers of muscles? Common site? Inflammation of this site aka? Correct condition?

3 layers of muscles. Medial humeral epicondyle is the site of common attachment of the common flexor tendon giving at least partial origin to 5 of the superficial and intermediate layers of the anterior forearm. Golfer's elbow- medial epicondylitis. False- it is actually inflammation of the common flexor tendon, not of the medial condyle.

Flexor Digitorum Superficiales. What layer is it in? How many origins? Inserts? What does it do primarily?

3 origins on all 3 bones of the elbow. Intermediate layer. An extrinsic flexor of digits 2-5. Inserts on the middle phalanges. Primarily responsible for flexing the PIP joints (proximal interphalangeal)

Deep layer of the anterior compartment of the forearm. How many muscles? What are they?

3- Flexor Pollicis Longus, Flexor Digitorum Profundus, and Pronator Quadratus

Superficial layer of the anterior compartment of the forearm. How many muscles? What are they? Which muscles do 20% of people not have?

4- Pronator Teres, Flexor carpi radialis, Palmaris Longus, and the Flexor carpi ulnaris. Palmaris Longus

What is the most commonly fractured bone in the body? 2nd most common?

Clavicle. Colles fracture- complete transverse fracture of the distal radius.

Which muscles are responsible for abduction of the wrist

Flexor carpi radialis, extensor carpi radialis longus, and extensor carpi radialis brevis

The wrist is bracketed by then tendons of how many muscles? Typical actions? Where does radial/ulnar deviation work in?

5 muscles for flexion (FCU, FCR) and extension (ECRL, ECRB, and ECU). There are no muscles for radial/ulnar deviation. The flexor and extensor muscles of the ulnar side will contract to adduct the wrist (ulnar deviation). The flexor and extensor muscles of the radial side will contract to abduct the wrist with the help of the thumb muscles (radial deviation).

Deep Muscles of the posterior forearm. How many are there? What are they? What are 3 grouped into?

5- Supinator, Abductor Pollicis Longus, Extensor Pollicis Longus, Extensor Pollicis Brevis, and Extensor Indicis. All of the Pollicis Muscles are referred to as the "Outcropping muscles".

Colles Fracture. What causes it typically? Leads to? Common?

Complete transverse fracture of the distal radius with displacement and/or angulation of the distal fragment dorsally. Most falls occur on an extended/abducted hand. Aka "Kitchen Fork" condition. 2nd most common fracture to a clavicular fracture

Radiocarpal joint. Joint type? B/w what bones? What lies b/w these? Movements permitted at this joint?

Condyloid/Ellipsoid joint. B/w the distal radius and the scaphoid and lunate carpal bones. There is a fibrocartilaginous triangular articular disc (TFCC) that binds the bones together. Permits flexion, extension, abduction (radial deviation), adduction (ulnar deviation), and circumduction

Superficial Muscles of the posterior forearm. How many? What are they? Arise from? Condition of this region?

6 Arising from the lateral supracondylar ridge are the Brachioradialis and the extensor carpi radius longus. Arising from the common extensor tendon attached to the lateral humeral epicondyle are the Extensor carpi radialis brevis, Extensor Digitorum, Extensor Digiti Minimi, and the Extensor Carpi Ulnaris Tennis Elbow

Carpal Tunnel. What passes through here? Deep to the?

9 tendons of the extrinsic digital flexors and the Median Nerve enter the hand by passing through here, deep to the Flexor Retinaculum

What type of joint is the radiocarpal joint? What does this mean?

Condyloid/Ellipsoid joint. It is biconvex- convex in the sagittal and coronal planes.

Outcropping muscles. What layer? Which side of the forearm?

Abductor Pollicis Longus, Extensor Pollicis Longus, Extensor Pollicis Brevis. Deep posterior forearm muscles.

Fibrocartilaginous triangular articular disc (TFCC). What is the apex? What is the base? Offers the most support in what position?

Apex is at the ulnar styloid. Base attaches to the medial margin of the distal radius. Offers most support in neutral position, b/w full pronation and full supination

Where is the site of possible compression of the radial nerve? Aka?

As it passes under the tendinous superior border of the Supinator aka the Arcade of Frohse.

Brachioradialis. What does it do? Minor role in?

Flexes the elbow- "Beer drinkers muscle". Minor role in both pronation and supination back to neutral. Never crosses the wrist, inserts on the radial styloid process.

Fibrocartilaginous triangular articular disc (TFCC). Where do we find these? What do they do? Where is the apex? Base? Disc offers most support in what position?

At the distal radioulnar joint, the radiocarpal joint and sits primarily in the ulnarcarpal space. Binds the bones together. Apex is at the ulnar styloid. Base attaches to the medial margin of the distal radius. Offers most support in neutral position, b/w full pronation and full supination

The full range of "wrist" mobility results from what joint movements? How does this affect where the flexors and extensors travel?

Both radiocarpal and midcarpal joint movements. As a rule, both the flexors and extensors of the wrist cross both carpal rows and insert directly or indirectly on metacarpal bones

Which muscles are responsible for adduction of the wrist

Flexor carpi ulnaris and Extensor carpi ulnaris

Flexor Pollicis Longus. What layer? What does it do?

Deep layer. Flexes the thumb

Flexor Digitorum Profundus. What layer? What does it do?

Deep layer. Inserts on the DIPs (distal interphalangeal) joints of digits 2-5 and flexes these DIP joints

Trapezoid bone

Distal row. B/w the Trapezium and the Capitate. Base of the index finger.

Capitate bone

Distal row. B/w the Trapezoid bone and the Hamate bone. Base of the middle finger. Largest carpal bone. Has the most articulation

Trapezium bone

Distal row. Most lateral distal row bone. At the base of the thumb.

Hamate bone

Distal row. Most medial distal row bone. Base of the 4th and 5th finger. Has a hook.

Midcarpal joint. Which distal bones are concave/convex? Which proximal bones are concave/convex?

Distal- Trapezium and Trapezoid are concave, Capitate and Hamate are convex Proximal- Scaphoid is convex and the Lunate and Triquetrum are concave

Ganglion (Bible) Cyst. Caused by? Bony prominence near there? How did it get this name?

Extensor tendons become inflamed- forms in between the EPB and EPL. Near the dorsal tubercle of the radius. In the old days, the person would put their hand on the table and smash it with a bible to pop it

What can cause damage to the anatomical snuff box? Can lead to? What can cause this?

Fracture of the scaphoid (floor). Avascular Necrosis of bone. A fall- the bone is waisted so it is most narrow in the middle, so it can cut the Radial artery

What is the most distal pulse point of the UE? How can you take it?

In the anatomical snuff box- can get a pulse by compressing the skin overlying the anatomical snuff box

What is b/w the Radius and Ulna?

Interosseous Membrane

Distal radioulnar joint. What type of joint? What do both the radius and ulna terminate into?

It is a synovial pivot joint. Both the radius and ulna terminate into styloid processes (Styloid process of the Radius and Styloid process of the Ulna). The ulnar styloid is smaller than the radial styloid

How do you find the location of the Median nerve just before it enters the carpal tunnel?

It is in the space b/w the Palmaris Longus and the Flexor carpi radialis

Where does the common extensor tendon originate?

Lateral epicondyle (Brachioradialis and ECUL originate on the lateral supracondylar ridge)

Tennis Elbow. What is the inaccurate diagnosis of this condition? The actual one?

Lateral epicondylitis. It is actually tendinosis (overuse syndrome) of the common extensor tendon.

Dislocation of which bone can result in the compression of Carpal Tunnel contents?

Lunate bone- essentially in the middle of the proximal attachment sites of the Flexor Retinaculum (Pisiform and the tubercle of the Scaphoid)

Where does the common flexor tendon originate?

Medial epicondyle

Golfer's elbow? What is the inaccurate cause of this? Corrected version? Associated with?

Medial epicondylitis- inflammation of the medial epicondyle. It is actually inflammation of the common flexor tendon. Often associated with Cubital tunnel syndrome- FCU is the roof

Radial nerve. Splits into? Where? What does it eventually become? When?

Splits into a superficial portion (cutaneous) and a deep branch. The deep branch travels through the Supinator muscle and becomes the Posterior Interosseous Nerve

What is the pneumonic device to help remember the proximal and distal row of the carpal bones?

Stop letting those people touch the cadaver's hand.

Carpal Tunnel. If you took a cross section of a hand, where would you see the 9 tendons? Nerve? What about another nerve that does not pass through this to enter?

Median Nerve would be right up against the Flexor Retinaculum. Under this, you'd see the lone Flexor Pollicis Longus tendon, then more medially and inferiorly you'd see the 4 tendons of the Flexor Digitorum Profundus (deep, so under the Superficiales) then above these you'd see the 4 tendons of the Flexor Digitorum Superficiales. Closer to the pinky, you'd see the Canal of Guyon in which the ulnar nerve and ulnar artery pass

All but 1.5 of the muscles of the anterior compartment of the forearm are innervated by which nerve? Arising from what cords of the brachial plexus? Containing fibers from which ventral rami?

Median nerve. Lateral and medial cords. C6-T1

Attachments for the Flexor Retinaculum. Distal Row? Proximal row?

On the distal row it is attached to the Hook of Hamate and the Trapezium. On the proximal row it is attached to the Pisiform and the tubercle of the Scaphoid

What is the main role of the Interosseous Membrane?

Plays a critical role in transferring forces from radius to ulna in addition to providing more surface area for the attachment of deep forearm muscles.

Begin in the anatomical (supinated) position. What muscles contract to pronate the forearm? What muscles contract to undo this and supinate the arm?

Pronator Teres and Pronator Quadratus contract to pronate the arm. Supinator will undo this and if necessary the biceps brachii contract to supinate the arm

Pisiform bone

Proximal row. Covers the Triquetrum. Pea shaped

Lunate bone

Proximal row. Medial to the Scaphoid. Proximal to the Capitate. One of the 2 carpal bones that articulates at the radiocarpal joint.

Scaphoid bone

Proximal row. Most lateral proximal bone. Proximal to the Trapezium. 1 of the 2 carpal bones that articulates at the radiocarpal joint.

Triquetrum bone

Proximal row. Most medial proximal bone. Covered by the Pisiform in the anterior view. Hamate contacts its lateral surface.

Carpal Bones. Proximal row? Distal row? Both lateral to medial.

Proximal- Scaphoid, Lunate, Triquetrum, and Pisiform Distal- Trapezium, Trapezoid, Capitate, Hamate

Muscles of the Posterior compartment are innervated by branches of which nerve? Branch of which cord of the brachial plexus? Containing fibers arising from which ventral rami?

Radial nerve. Posterior cord. C5-T1.

Flexor Retinaculum. Why is it significant? Maintains? Receives? Provides?

Roofs the carpal tunnel. Maintains the concave transverse carpal arch. Receives the insertion of the Palmaris Longus. Provides surface area for attachment of the thenar (base of the thumb) and hypothenar (base of the pinky) muscles.

Extensor Retinaculum. Spans? What passes through here? How many compartments are there? How many are we concerned with? Contains?

Spans the radius and ulna. 6 compartments deep to this thickening of antebrachial fascia. 1- contains the Outcropping muscles

What surrounds the tendons as the enter under the Flexor/Extensor Retinaculum?

Synovial membrane- lubricates them to prevent friction

How do you get a pulse point in the wrist? How do you get the pulse?

Taking the pulse of the radial artery. Compress this against the tendon of the Flexor carpi radialis

Posterior Interosseous Nerve. Terminal branch of?

Terminal branch of the deep radial nerve- after it passes through the Supinator muscle

Anatomical Snuff Box. What forms the boundaries? Roof? Floor? What passes through here?

The Extensor Pollicis Longus (up top) and the Extensor Pollicis Brevis (closer to the edge of the thumb). Roof is the Extensor Retinaculum. Floor is the scaphoid bone. Radial Artery- can get a pulse by compressing the skin overlying the anatomical snuff box

What are the 2 nerves that enter the hand? How does each enter?

The Median nerve- passes through the carpal tunnel, right under the Flexor Retinaculum. The Ulnar nerve which passes through the Canal of Guyon along with the ulnar artery

Size of the distal radius vs distal ulna? What is the significance of this?

The distal radius is much larger than the distal ulna and accepts 80% of the weight transferred from the hand across the wrist

Important structures on the distal portion of the radius?

The dorsal tubercle of the radius (do not confuse with the radial tubercle) and the ulnar notch

The remaining 1.5 muscles of the anterior forearm are innervated by which nerve? Which muscles are these? Arising from which cord of the brachial plexus? Containing fibers from which ventral rami?

Ulnar nerve. The Flexor Carpi Ulnaris and the medial half of the Flexor Digitorum Profundus. Medial Cord. C8-T1.

Ulnar vs Radial deviation. Which way has greater ROM? What is each limited by?

Ulnar- Adduction. Has greater ROM- smaller styloid process. Limited by the RCL Radial- Abduction. Limited by the UCL

Distal radioulnar joint. B/w what bones? What is b/w these bones? Movements permitted?

The rounded head of the ulna and the ulnar notch of the radius. There is a fibrocartilaginous triangular articular disc (TFCC) that binds the bones together. Pronation/supination

The posterior osteofascial compartment of the forearm contains?

Wrist extensors, extrinsic digital extensors, and the supinator muscle

The anterior osteofascial compartment of the forearm contains?

Wrist flexors, extrinsic digital flexors, and pronators