27 - flexor retinaculum mcqs

1q: a 16 years old girl failed in her final examination. Disgusted with life, she cut across the front of the wrist at the flexor retinaculum, she was rushed to hospital . the surgeon noticed that cut was superficial . all the following structures would have been damaged except ?

a. ulnar nerve
b. median nerve
c. palmar cutaneous branch of median nerve
d. superficial branch of radial artery

answer b . median nerve

explanation : median nerve would escape injury in a superficial cut as it lies deep to the flexor retinaculum . here is a list of structures which pass superficial and deep to flexor retinaculum .

structures lying superficial to flexor retinaculum of hand are :

1. ulnar nerve
2. ulnar vessels
3. palmar cutaneous branch of ulnar nerve
4. palmar cutaneous branch of median nerve
5. Palmaris longus tendon

Structures lying deep to flexor retinaculum of hand are :

1. median nerve
2. ulnar bursa
3. radial bursa
4. tendons like flexor digitorum profundus, flexor digitorum superficialis, flexor pollicis longus and flexor carpi radialis .

This question was asked in the november 2002 AIIMS paper . 

26 - ulnar nerve anatomy part 2

MUSCULAR BRANCHES AND INNERVATION :  the ulnar nerve and its branches innervate the following muscles in the forearm and hand:

An articular branch that passes to the elbow joint while the ulnar nerve is passing between the olecranon and medial epicondyle of the humerus.

 In the forearm, via the muscular branches of ulnar nerve:

 1. Flexor carpi ulnaris

2. Flexor digitorum profundus (medial half)

 In the hand, via the deep branch of ulnar nerve:

 1. Hypothenar muscles

2. Opponens digiti minimi

3. Abductor digiti minimi

4. Flexor digiti minimi brevis

5. Adductor pollicis

6. The third and fourth lumbrical muscles

7. Dorsal interossei

8. Palmar interossei

 

In the hand, via the superficial branch of ulnar nerve:

 1. Palmaris brevis

 CUTANEOUS INNERVATION : the ulnar nerve also provides sensory innervation to the part of the hand corresponding to the fourth and fifth digits:

 1. Palmar branch of ulnar nerve - anterior

2. Dorsal branch of ulnar nerve – posterior

 ULNAR NERVE ENTRAPMENT : the ulnar nerve can be trapped or pinched in various ways as it proceeds down the arm from the brachial plexus to the ring and middle fingers. One common cause is cubital tunnelsyndrome, where the tunnel runs the inner outside side of the elbow. Pinching of the nerve often causes tingling symptoms in the little and ring fingers. In some cases moderate to severe pain is experienced from pinching this nerve. Often such pins and needles sensations can be caused by sleeping wrongly on your arm, or by cycling for extended periods of time, but sometimes the problems last for days. In severe cases, surgery is performed to move the nerve.

25 - ulnar nerve anatomy part 1

INTRODUCTION:  In human anatomy, the ulnar nerve is a nerve which runs near the ulna bone. The ulnar nerve is the largest unprotected nerve in the human body (meaning, unprotected by muscle or bone), and the only unprotected nerve that does not serve a purely sensory function (those nerves specifically meant to perceive changes in the environment, such as nerves in the skin). This nerve is directly connected to the little finger, and the adjacent half of the ring finger, supplying the palmar side of these fingers, including both front and back of the tips, perhaps as far back as the fingernail beds.

Aggravation of this nerve is commonly referred to as hitting one's "funny bone." this name is thought to be a (conscious or subconscious)pun, based on the sound resemblance between words "humerus" and "humourous" .

COURSE IN ARM : The ulnar nerve comes from the medial cord of the brachial plexus, and runs inferior on the posterior and medial (posteromedial) aspects of the humerus down the arm, going behind the medial epicondyle, through the cubital tunnel, at the elbow (where it is exposed for a few centimeters, just above the joint). Because of the mild pain and tingling throughout the forearm associated with an inadvertent impact of the nerve at this point, it is usually called the funny bone. (it may also have to do with its location relative to the humerus, as the name "humerus" is a homophone to the word "humourous").

 COURSE IN FOREARM : It enters the anterior (flexor/front) compartment of the forearm through the two heads of flexor carpi ulnaris and runs alongside the ulna. There it supplies one and a half muscles (flexor carpi ulnaris & medial half of flexor digitorum profundus). It soon joins with the ulnar artery, and the two travel inferiorly together, deep to the flexor carpi ulnaris muscle.

 Here it gives off the following branches: 

 1. Muscular branches of ulnar nerve

2. Palmar branch of ulnar nerve

3. Dorsal branch of ulnar nerve

COURSE IN HAND :  After it travels down the ulna, the ulnar nerve enters the palm of the hand. Unlike the median nerve which travels below the flexor retinaculum of the hand and through the carpal tunnel, the ulnar nerve and artery pass superficial to the flexor retinaculum via the ulnar canal.

 Here it gives off the following branches: 

 1. Superficial branch of ulnar nerve

2. Deep branch of ulnar nerve