topic 22: Branches of the ulnar nerve, functional loss of the ulnar nerve

Question 1

origin, course

Answer 1

-brachial plexus;medial cord
- course:

• • Course in the Arm:
    After its origin, the ulnar nerve descends along the medial aspect of the arm, traveling posterior to the brachial artery.
    It passes through the axilla, following a course between the axillary artery and the vein.

Course in the Cubital Fossa:
The ulnar nerve passes through the cubital fossa (anterior elbow region), running posterior to the medial epicondyle of the humerus.
It travels deep to the flexor carpi ulnaris muscle and medial to the biceps brachii tendon.

Passage through the Forearm:
After passing the elbow, the ulnar nerve continues its course along the anterior aspect of the forearm, deep to the flexor digitorum superficialis muscle.
It descends alongside the ulnar artery, which runs medially in the forearm.

Entry into the Hand:
The ulnar nerve enters the hand through the Guyon’s canal (also known as the ulnar canal) at the wrist.
Guyon’s canal is a fibro-osseous tunnel formed by the pisiform and hook of the hamate bones and is covered by the flexor retinaculum.
Within Guyon’s canal, the ulnar nerve divides into its superficial and deep branches.

Superficial Branch:
The superficial branch of the ulnar nerve passes superficially within the palm of the hand, providing sensory innervation to the skin of the hypothenar eminence and the medial one and a half digits on the palmar aspect.

Deep Branch:
The deep branch of the ulnar nerve continues deep into the palm, supplying motor innervation to the intrinsic muscles of the hand.
It gives off branches to innervate the muscles of the hypothenar eminence and continues to provide motor innervation to the intrinsic muscles of the hand, including the interossei muscles and the medial two lumbrical muscles.

Question 2

branches

Answer 2

Muscular Branches
Supply: Muscles in the anterior and posterior compartments of the forearm.
Examples: Flexor carpi ulnaris, flexor digitorum profundus (ulnar part), and the majority of intrinsic hand muscles (interossei, lumbricals, adductor pollicis, hypothenar muscles).

Dorsal Cutaneous Branch
Supply: Sensory innervation to the dorsal aspect of the hand and fingers, excluding the dorsal aspect of the little finger.

Palmar Cutaneous Branch
Supply: Sensory innervation to the palmar aspect of the hand, originating from the wrist.

Superficial (Palmar) Branch
Supply: Innervates the palmaris brevis muscle and provides sensory innervation to the skin of the hypothenar eminence.

Deep (Ulnar) Branch
Supply: Passes deep into the palm of the hand, supplying the deep muscles of the hand and giving rise to proper digital nerves.
Examples: Supplies the third and fourth lumbrical muscles and intrinsic muscles of the hand.

Question 3

functional loss

Answer 3

1.Cubital tunnel syndrome: when a person bends the elbows often (when pulling, reaching, or lifting), leans on their elbow a lot, or has an injury to the area so pain in med. side of lower 4arm & med. 2 fingers 1 dorsum of ulnar side

2.Ulnar nerve palsy: paresthesia and numbness along the fourth and fifth digits, pain along the medial forearm, and weakness of the lumbricals and flexor digtorum profundus.