Nerve Injury Positions of the Hand and Fingers

Written by Alec Bryson with Dr. Nabil Ebraheim

The presentation of a patient’s hand may provide insight to which nerve is damaged and the approximate location of the damage. When presenting with ulnar n. damage, a patient may show a claw hand, Wartenberg’s sign, or Froment’s sign. Claw hand will present with clawing of the fourth and fifth digits due to the inability to extend the fingers specifically at the interphalangeal joints. This presentation is due to the lack of innervation to the intrinsic muscles of the hands, and the unopposed action of the flexor digitorum profundus m. (Moore et al., 2018). This indicates damage near the distal end of the ulnar n., below the elbow, and potentially near the wrist. Wartenberg’s sign will be seen as the inability to adduct the fifth digit when extended as well as an inability to cross the second and third digit. This is due to ulnar n. injury leading to wasting of the fifth interosseous m. This causes the fifth digit to rest in a more abducted position due to the unbalanced action of the extensor digiti minimi m. (Ebraheim, 2021). There will also be loss of function of the lumbrical m. in the fourth and fifth digits. A Froment’s test will detect palsy of the ulnar n. resulting from compression in the cubital tunnel. When asking the patient to pinch a piece of paper between their thumb and second digit, a positive Froment’s Sign will show as the patient flexing their thumb’s interphalangeal joint to grip the paper as the paper is pulled away (Attum, 2021). This will result from a weak adductor pollicis m. due to ulnar n. palsy.

Depending on the location of a lesion to the median n., the patient will present with one of three signs. A positive Benedictine sign will be caused by proximal median n. damage. It will be seen as paralysis of the first and second digit, with weakness to the third digit. A proximal lesion would lead to paralysis of several muscles (FDS, FPL, FPB, and the radial half of FDP), leaving the ulnar half of the flexor digitorum profundus m. as the only remaining flexor (Ebraheim, 2021). When the patient is asked to make a fist, the hand will resemble the similar position taken during a blessing. A positive Benedict sign will also resemble the ulnar claw hand. However, the Benedict sign will present when the patient is flexing, not extending the fingers (Ebraheim, 2021). A median n. injury affecting the anterior interosseous n. branch will present as an inability to do the OK sign. This occurs due to paralysis of the flexor pollicus longus m. and the lateral part of the flexor digitorum m. (Moore et al., 2018). A positive Ape hand (Simian hand) is caused by paralysis of only the thenar m. from damage to the recurrent branch of the median n. to the thenar m. The thumb will be seen in the same plane as the other digits due the thumb being pulled more dorsal by the action of the adductor pollicis m., which is innervated by the ulnar n. (Moore et al., 2018).

Finally, proximal radial n. damage will be seen as wrist drop. This is usually caused by fractures of the distal third of the humeral shaft (Holstein-Lewis Fracture) and caused paralysis of the wrist and fingers extensors (Ebraheim, 2010). Lower radial n. injury will present in the patient as the ability to extend the wrist, but the loss of finger extension. There will be no wrist drop, but the patient would not be able to make a hitchhiking sign.

Reference List

Attum B. Physical exam of the hand [Internet]. Orthobullets. Lineage Medical, Inc.; 2021 [cited 2021Oct21]. Available from: https://www.orthobullets.com/hand/6008/physical-exam-of-the-hand

Ebraheim N. Anterior Interosseous Nerve Injury – Everything You Need To Know – Dr. Nabil Ebraheim [Internet]. YouTube. 2021 [cited 2021Oct21]. Available from: https://www.youtube.com/watch?v=M9y-iDKLDPE

Ebraheim N. Claw Hand, Ulnar Claw Hand – Everything You Need To Know – Dr. Nabil Ebraheim [Internet]. YouTube. 2017 [cited 2021Oct21]. Available from: https://www.youtube.com/watch?v=GyqaKGg3HmM

Ebraheim N. Nerve Injury Position of the Hand & Fingers – Everything You Need To Know – Dr. Nabil Ebraheim [Internet]. YouTube. 2021 [cited 2021Oct21]. Available from: https://www.youtube.com/watch?v=nwd1h0Dfo5o

Ebraheim N. Radial Nerve Palsy, injury – WRIST DROP . Everything You Need To Know – Dr. Nabil Ebraheim [Internet]. YouTube. 2010 [cited 2021Oct21]. Available from: https://www.youtube.com/watch?v=_Cu6ttAhe8Y

Moore KL, Dalley AF, Agur A. Clinically Oriented Anatomy. 8th ed. Philadelphia, PA: Lippincott Williams and Wilkins; 2018.

Cubital Fossa, Popliteal Fossa, & Femoral Triangle

Cubital Fossa, Popliteal Fossa, & Femoral Triangle

Arrangement of the neurovascular structures in these areas is important, but complicated. The purpose of this video is to describe briefly the contents of these structures.

Cubital Fossa

ccThe contents of the cubital fossa from medial to lateral are the median nerve (most medial structure). The second structure is the brachial artery. The brachial artery bifurcates into the ulnar artery and the radial artery. The biceps tendon is lateral to the brachial artery. The biceps tendon has one main insertion laterally to the radial tuberosity and another insertion going medially to the bicipital aponeurosis. The bicipital aponeurosis covers and protects the vital structures medially to the biceps tendon (brachial artery and median nerve). Lateral to the biceps tendon is the radial nerve and its major branch, the posterior interosseous nerve.

Popliteal Fossa

pp.PNGThe popliteal fossa is a shallow depression located at the back of the knee joint. The structures of the popliteal fossa from medial to lateral are the popliteal artery, popliteal vein, small saphenous vein, tibial nerve, and the common peroneal nerve which runs across the upper lateral border of the popliteal fossa.

Femoral Triangle

f.PNGThe femoral triangle is a superficial triangular space located on the anterior aspect of the thigh just inferior to the inguinal ligament. The femoral triangle contains three important structures from lateral to medial: the femoral nerve, the femoral artery, the femoral vein, and the the deep inguinal lymph nodes.

Lateral Circumflex Femoral Artery

https://www.youtube.com/watch?v=xRR6CPCIg6c

Lateral Circumflex Femoral Arteryl.png

The lateral circumflex femoral artery is a branch of the profunda femoris artery. The profunda femoris artery is the main blood supply to the thigh. The profunda femoris artery gives two circumflex arteries and four perforating branches. The two circumflex arteries are

  1. The medial circumflex femoral artery
  2. The lateral circumflex femoral artery

The lateral circumflex artery is directed towards the lateral side. From the femoral triangle of the thigh, the femoral nerve is lateral to the femoral artery. As the lateral circumflex femoral artery branches off of the profunda artery and goes laterally, it crosses the femoral nerve and passes under the Sartorius muscle, which is the lateral boundary of the femoral triangle. The lateral circumflex femoral artery gives three branches:

  1. Ascending Branch
  2. Descending Branch
  3. Transverse Branch

llThe ascending branch passes upwards beneath the tensor fascia lata and goes up to the anterior superior iliac spine (ASIS). The descending branch descends to the knee joint. The transverse branch goes towards the greater trochanter and also goes to the cruciate anastomosis. The ascending branch of the LCFA is important. The LCFA is at risk of injury with Smith-Petersen Approach or anterior approach to the hip. The LCFA is found in the intervenous plane between the tensor fascia lata and the Sartorius muscle. It also passes under the rectus femoris muscle. The LCFA will be found deeper to that and this artery must be found and ligated to prevent excessive bleeding.

Cubital Fossa

Cubital Fossa

Cubital FossaThis is about understanding the arrangement of the structures in the anterior elbow. This is an anatomy video, but this can also help surgeons in knowing how to approach the insertion of the distal biceps for repair or how to approach the proximal radius fracture anteriorly. If you look at the bony structures of the anterior elbow, you need to find out where the common flexor tendon origin is, where the brachialis muscle is inserted, and where the biceps is, supinator and the pronator teres located. These structures are definitely part of the anterior elbow. The cubital fossa is a triangular depression located in front of the anterior elbow. The medial border is formed by the pronator teres, which arises from the medial epicondyle of the humerus. The lateral border of the cubital fossa is formed by the brachioradialis muscle which arises from the lateral supracondylar ridge of the humerus. The meeting of these two muscles forms the apex of the cubital fossa. The brachioradialis muscle overlaps the pronator teres, so the lateral border overlaps the medial border. The base of the cubital fossa is superior and is represented by a horizontal line connecting the two epicondyles of the humerus, the lateral and medial epicondyles.

Structures Located In and Around The Cubital Fossa

The base of the cubital fossa is seen as an imaginary line drawn between the medial epicondyle and the lateral epicondyle of the distal humerus. The pronator teres is the medial border, and the brachioradialis muscle forms the lateral border. The contents of the cubital fossa from medial to lateral are median nerve, brachial artery, biceps tendon, and radial nerve. The floor of the cubital fossa is made up of the lower part of the brachialis muscle medially and the supinator muscle laterally. The roof of the cubital fossa is made up of skin, fascia, and the bicipital aponeurosis. CFS

The median nerve disappears by entering the forearm between the two heads of the pronator teres muscle. The brachial artery bifurcates into the ulnar artery and the radial artery. The brachial artery is over the brachialis muscle. The ulnar artery leaves the fossa by going under the deep head of the pronator teres muscle. The deep head of the pronator teres muscle separates the median nerve, which goes between two heads of the pronator teres muscle from the ulnar artery, which goes deep to the deep head of the pronator teres muscle. Another branch that is in the cubital fossa is the radial artery. The radial artery descends laterally and is overlapped by the brachioradialis muscle. The biceps tendon is lateral to the brachial artery within the cubital fossa. The biceps tendon has one main insertion laterally to the radial tuberosity and another insertion going medially to the bicipital aponeurosis. The bicipital aponeurosis covers and protects the vital structures medially to the biceps tendon (brachial artery and median nerve). The biceps tendon passes backwards (twisted) towards its insertion into the radial tuberosity. Lateral to the biceps tendon is the radial nerve and its major branch, the posterior interosseous nerve. Other important nerves in the vicinity of the cubital fossa include the superficial radial nerve which is below the brachioradialis and the lateral cutaneous nerve of the forearm which is a branch of the musculocutaneous nerve and lies below the biceps proximally and then finally lies laterally.