Forearm - Anterior Compartment

How many muscles are innervated by the Median nerve in anterior forearm? What are they? What are the other muscles innervated by?

1 1/2 muscles are innervated by the Ulnar nerve. The rest are innervated by the Median nerve. The only ones innervated by the Ulnar Nerve are the Flexor Carpi Ulnaris and the lateral 1/2 of the Flexor Digitorum Profundus.

What are the actions and nerves of the Anterior Compartment of forearm? of the Posterior Compartment?

Anterior: Flexors and Pronators. Median and Ulnar Nerves. Posterior: Extensors and Supinators. Radial Nerves.

What is the forearm? What are the components (bone and CT)?

Area between elbow and wrist. Contains Ulna, Radius, and interosseous membrane.

What is the "floor" of the Carpal Tunnel?

Carpals (osseous floor)

Action of Flexor Digitorum Profundus?

Flexes distal finger joints 2-5. Assists with Wrist flexion.

Actions of the Flexor Pollicis Longum?

Flexes distal phalanx at thumb joint. Assists with wrist flexion.

What is the action of Palmaris Longus?

Flexes with wrist and wrest of the flexor group. If isolated, tenses the fascia of palm (ie "palming a basketball")

Action of Flexor Digitorum Superficialis?

Flexes wrist with rest of flexor group. Flexes digits 2-5

Action of the Flexor Carpi Ulnaris?

Flexes wrist with rest of the flexor group. Isolated with extensor, causes wrist ADduction

Action of Flexor Carpi Radialis?

Flexes wrist; When isolated with extensor, causes wrist ABduction (moving it up if palm facing medial or laterally, and away if palm facing superiorly or inferiorly)

Which 1 1/2 muscles would still provide innervations if the Median Nerve was injured? What actions would they be able to do?

Flexor Carpi Ulnar m. and the 1/2 of the Flexor Digitorum Profundus (FDP). Actions: Some wrist flexion and wrist ADduction. Some flexion of distal fingers 2-5

What are the deep muscles of the anterior flexor compartment? What is the main difference between the deep forearm muscles and the superficial forearm muscles?

Flexor Pollicis Longus (FPL) Flexor Digitorum Profundus (FDP) Pronator Quadratus (PQ) These DO NOT originate from the Common Flexor Tendon, thus they do not cross the elbow joint so they DO NOT assist in the flexion of the elbow joint.

Where is the Flexor Digitorum Profundus located? What is special about it's innervation?

Found on medial side of forearm, running along Ulna bone. Deep to the superficial forearm muscles (TR(I)P US). Innervation is special because innervated by BOTH the Ulnar nerve and Median nerve.

What does TR(I)P US stand for?

From most lateral to medial the order of the superficial forearm muscles: pronator Teres flexor carpi Radialis Palmaris longus flexor carpi Ulnaris flexor digitorum Superficialis

Action of pronator quadratus?

Initiates pronation, pronator teres assists in rapid actions. (Ex) Turning screw driver or door knob)

Where is the Flexor Pollicis Longus located? What does it run along?

It is lateral to the Flexor Digitorum Profundus. Deep to the superifical forearm muscles (TR(I)P US). It is the only anterior forearm muscle that takes origin on the LATERAL side of the forearm. It runs along the radius bone.

Where is the Flexor Carpi Radialis? What is lateral to the distal tendon?

It is located medial to the Pronator Teres. It is superficial - not covered by the Brachioradialis. Radial artery is immediately lateral to the distal tendon.

Where is the Palmaris Longus? What does it do? What is unique about this?

It is the 3rd most lateral, or 2nd most media of the 4 most superficial forearm muscles. It extends into an aponeurosis (palmar aponeurosis) distally, connecting the digits 2-4. It helps you "palm" a basketball. 15% of people don't have this muscle!

What is the Carpal Tunnel? What passes through it?

It is the fibrous/Osseous tunnel at the anterior wrist. Allows passage of the finger and thumb tendons (Flexor Digitorum Superficialis, Flexor Digitorum Profundus, and Flexor Pollicis Longus) and Median Nerve into hand.

Where is the Flexor Carpi Ulnaris located? What makes it's location an important land mark?

It is the most medial (3rd most lateral) of the superficial flexors. The Ulnar Nerve and Artery are immediately lateral to the distal tendon.

1: Biceps Brachii 2: Brachialis 3: Brachioradialis 4: 5: Flexor Digitorum Superficialis 6: Flexor Carpi Ulnaris 7: Palmaris Longus 8: Flexor Carpi Radialis 9: Pronator Teres 10: Common Flexor Tendon (Median Epicondyle of Humerus) 11: Tricep (long head?)

Label:

Where is the Flexor Digitorum Superficialis located?

Located deep to the superficial forearm muscles (Palmar Teres, Flexor Carpi Radialis, Palmaris Longus, Flexor Carpi Ulnaris)

Flexor Pollicis origin, insertion, innervation?

O: Along radius bone I: Distal phalanx #1 N: Median Nerve

Palmaris Longus origin, insertion, and innervation?

O: Common Flexor Tendon I: Palmar aponeurosis N: Median Nerve

Flexor Carpi Ulnaris origin, insertion, and innervation?

O: Common flexor tendon I: Medial side of hand, at base of 5th most metacarpal N: Ulnar Nerve

Flexor Digitorum Superficialis origin, insertion, and innervation?

O: Common flexor tendon I: Tendons split to insert at middle phalanx digits 2-5 N: Median Nerve

Flexor Carpi Radialis origin, insertion, and innervation?

O: Common flexor tendon (median humeral epicondyle) I: Lateral side of hand, close to where the index finger is. N: Median Nerve

Pronator quadratus origin, insertion, innervation?

O: Distal Ulna bone I: Distal Radius bone N: Median Nerve

Pronator Teres origin, insertion, and innervation:

O: Medial humeral epicondyle via the Common Flexor Tendon I: Mid-lateral shaft of radius N: Median Nerve

Flexor Digitorum Profundus origin, insertion, and innervation?

O: Ulna Bone I: Tendons pass through split in flexor digitorum superficialis to reach Distal phalanx 2-5. (Tendons go to distal portion of fingers, not shown in picture).

What is the aponeurosis called connected to Palmaris Longus?

Palmar Aponeurosis

Which muscle inserts by way of a single superficial tendon into the aponeurosis of the palm?

Palmaris Longus

Who does what? Pronation: Wrist Flexion: Wrist ABduction: Wrist ADduction: FLexion of Digits:

Pronation: Pronator Teres, Pronator Quadratus Wrist Flexion: Flexor Carpi Radialis Palmaris Longus Flexor Carpi Ulnaris Flexor Digitorum Superficialis Flexor Digitorum Profundus Flexor Pollicis Longum Wrist Abduction: Flexor Carpi Radialis Wrist ADduction: Flexor Carpi Ulnaris Flexion of Digits: Flexor Digitorum Superficialis Flexor Pollicis Longum Flexor Digitorum Profundus

Name the 5 superficial muscles of the anterior forearm?

Pronator Teres Flexor Carpi Radialis Palmaris Longus Flexor Carpi Ulnaris Flexor Digitorum Superficialis (located deep to the 4 above, but still considered superficial because muscle deep to it)

Actions of Pronator Teres?

Pronator; forearm flexion. Assists in elbow flexion with Biceps Brachi, Brachialis, and Brachioradialis since crosses humerus.

Where is the Pronator Teres located? How does it look?

Round like a cigar, deep to the brachioradialis (peeks out), runs medial to lateral (lateral portion is deep to the brachioradialis) but most lateral of the superficial flexor group.

Where is the Pronator Quadratus located? How does it look?

Square shaped muscle proximal to wrist. Deepest of anterior forearm. Does not cross wrist

What is the name of the fibrous "roof" of the Carpal Tunnel?

The Flexor Retinaculum. Keeps the tendons flush against wrist.

What makes up the Cubital Fossa? What nerves run here?

The Medial and Lateral epicondyles, and the Pronator Teres and Brachioradialis. Nerves that run here are the radial and medial nerves. Blood is drawn here. Nerves run superficial here so at risk for compression.

Patient has Carpal Tunnel Syndrome, which nerve is compressed?

The Median Nerve, most wrist action is compromised.

What nerve/artery does NOT pass through Carpal Tunnel?

Ulnar Nerve and Artery