Hands: Nerve and Arterial Supply to upper limb Flashcards
What is the brachial plexus?
A network of nerves arising from C5-T1.
Supplies motor and sensory innervation to the upper limb.
Located partly in the neck and axilla.
What are the components of the brachial plexus?
Roots: C5-T1.
Trunks: Superior, Middle, Inferior.
Divisions: Anterior and Posterior for each trunk.
Cords: Lateral, Medial, Posterior.
Terminal branches.
What are the anatomical landmarks for the brachial plexus?
Roots: Between scalenes.
Trunks: Beneath the clavicle.
Divisions: Behind the clavicle.
Cords: Around the pectoralis minor in the axilla.
What are the branches from the roots of the brachial plexus?
Dorsal Scapular Nerve (C5): Innervates Rhomboids, Levator Scapulae.
Long Thoracic Nerve (C5-C7): Innervates Serratus Anterior.
Phrenic Nerve (C3-C5): Innervates Diaphragm.
What nerves arise from the lateral cord of the brachial plexus?
Lateral Pectoral Nerve: Supplies Pectoralis Major.
Musculocutaneous Nerve: Supplies Biceps Brachii, Brachialis, Coracobrachialis.
Lateral part of the Median Nerve.
Describe the median nerve.
Origin: Lateral and Medial cords.
Motor supply: Forearm flexors (except FCU, FDP medial half), thumb muscles, and 1st and 2nd lumbricals.
Sensory supply: Palmar aspect of the thumb, 2nd, 3rd, and half of the 4th finger.
Clinical relevance: Carpal tunnel syndrome.
What nerves arise from the medial cord of the brachial plexus?
Medial Pectoral Nerve: Supplies Pectoralis Major and Minor.
Ulnar Nerve: Supplies FCU, medial half of FDP, and intrinsic hand muscles.
Medial Cutaneous Nerves: Supplies sensation to arm and forearm.
What are the motor and sensory functions of the ulnar nerve?
Motor: FCU, medial FDP, hypothenar muscles, lumbricals 3 & 4, interossei, Adductor Pollicis.
Sensory: Medial hand, 5th finger, and half of the 4th finger.
Landmarks: Posterior to the medial epicondyle, Hook of Hamate.
What nerves arise from the posterior cord of the brachial plexus?
Radial Nerve
Axillary Nerve
Thoracodorsal Nerve
Describe the radial nerve.
Motor supply: Triceps, Anconeus, Brachioradialis, wrist extensors.
Sensory supply: Posterior arm, forearm, dorsal hand (1st, 2nd, 3rd fingers).
Landmarks: Spiral groove, passing through supinator.
What is the clinical relevance of the axillary nerve?
Motor supply: Deltoid and Teres Minor.
Sensory supply: Skin over the shoulder joint.
Landmarks: Surgical neck of the humerus.
Injury: Fractures of the surgical neck or shoulder dislocations.
Describe the arterial supply to the upper limb.
Subclavian Artery: From aortic arch to lateral border of 1st rib.
Axillary Artery: Continuation of Subclavian to inferior border of Teres Major.
Brachial Artery: Continuation of Axillary, supplies arm.
Radial and Ulnar Arteries: Branches of the Brachial, supply forearm and hand.
What are the 5 main functions of the hand?
Manipulation
Sensation
Stability
Protection
Communication
What are the intrinsic muscles of the hand?
Thenar muscles: Abductor Pollicis Brevis, Flexor Pollicis Brevis, Opponens Pollicis, Adductor Pollicis.
Hypothenar muscles: Abductor Digiti Minimi, Flexor Digiti Minimi, Opponens Digiti Minimi, Palmaris Brevis.
Intermediate muscles: Lumbricals, Palmar Interossei, Dorsal Interossei.
What are the origins, insertions, and actions of Abductor Pollicis Brevis?
Origin: Tubercles of scaphoid and trapezium, flexor retinaculum.
Insertion: Proximal phalanx and extensor hood of thumb.
Action: Abducts thumb at MCP and CMC joints.
Nerve Supply: Median nerve (C8-T1).
What is the action of Opponens Pollicis?
Medially rotates the thumb at the first CMC joint to enable opposition.
Nerve Supply: Median nerve (C8-T1).
What are the hypothenar muscles and their actions?
Abductor Digiti Minimi: Abducts the little finger.
Flexor Digiti Minimi: Flexes the little finger.
Opponens Digiti Minimi: Laterally rotates metacarpal V.
Palmaris Brevis: Improves grip.
Nerve Supply for all: Ulnar nerve (C8-T1).
What are the lumbricals, and what is their action?
Origin: Tendons of Flexor Digitorum Profundus.
Insertion: Extensor hoods of fingers.
Action: Flex MCP joints and extend IP joints.
Nerve Supply:
Lateral two: Median nerve.
Medial two: Ulnar nerve.
What are the interossei muscles, and their functions?
Palmar Interossei (3-4): Adduct fingers (PAD).
Dorsal Interossei (4): Abduct fingers (DAB).
Both flex MCP joints and extend IP joints.
Nerve Supply: Ulnar nerve (C8-T1).
What are the arches of the hand?
Transverse Arches:
Carpal Arch: Rigid, concave structure formed by carpal bones.
Metacarpal Arch: Flexible, widens during grasping.
Longitudinal Arch: From the wrist to the fingers, provides stability and mobility.
Oblique Arch: Involves thumb opposition to other fingers.
What is the carpal tunnel, and its clinical relevance?
Borders:
Roof: Flexor retinaculum.
Floor: Carpal bones.
Contents: Median nerve, tendons of FDS, FDP, and FPL.
Clinical Relevance: Carpal Tunnel Syndrome caused by compression of the median nerve.
What is prehension, and what are its types?
Definition: Use of hands and fingers to grasp or pick up objects.
Types:
Power grip: Palmar, cylindrical, or spherical grasp.
Precision grip: Pincer (tip-to-tip), pad-to-pad, key grip.
What muscles are involved in a power grip?
Long flexors of fingers (FDS, FDP).
Thenar muscles.
Wrist extensors (synergistic role).
What is the key grip, and what is its significance?
A type of lateral prehension where the thumb pad opposes the lateral side of the index finger.
Most powerful precision grip.
What is the nerve supply to the hand?
Median nerve: Thenar muscles, lateral two lumbricals.
Ulnar nerve: Hypothenar muscles, interossei, medial two lumbricals, Adductor Pollicis.
Radial nerve: No intrinsic muscles, provides sensation to dorsal hand.
What are the sensory territories of the hand nerves?
Median nerve: Palmar surface of the thumb, index, middle, and half of the ring finger.
Ulnar nerve: Medial aspect of the hand, 5th finger, and half of the 4th finger.
Radial nerve: Dorsal hand over the thumb and index finger.
What is the role of the palmaris brevis?
Improves grip by tensing the skin on the ulnar side of the hand.
Nerve Supply: Ulnar nerve (C8-T1).
