L7 Anatomy of the forearm Flashcards
Elbow joint - type
Synovial hinge joint - flexion/extension
Proximal radioulnar joint - type
- Pivot joint for supination/pronation
Elbow ligaments
- Annular ligament
- Radial collateral ligament
- Ulnar collateral ligament
What is the cubital fossa
- Triangle region over anterior elbow
Clinical relevance of the median cubital vein
- Important for venepuncture
Forearm compartments
- Flexor compartment
- Extensor compartment
Superficial muscles of the anterior forearm
- 3 flexors of wrist (carpi)
- 1 pronator
Intermediate muscles of the anterior forearm
- 1 flexor of digits 2-5 (digitorum)
Deep muscles of the anterior forearm
- 1 flexor of digits 2-5 (digitorum)
- 1 flexor of thumb (pollicis)
- 1 pronator
What is golfers elbow
- Epicondylitis at CFO(common flexor origin)
- Tendon inflammation due to overuse/excessive gripping)
Muscle that forms the intermediate layer of the anterior forearm
- Flexor digitorum superficialis
Muscles that form the deep layer of the anterior forearm
- Flexor pollicis longus
- Flexor digitorum profundus
+ pronator quadratus
Muscles in extensor compartment of the posterior forearm
Superficial muscles:
- 3 extensors of wrist (carpi)
- 1 extensor of digits 2-5 (digitorum)
- 1 accessory extensor to digit 5 (digiti minimi)
- Brachioradialis and anconeus
Deep muscles:
- 2 Extensors of thumb (pollicis)
- 1 Abductor of thumb (pollicis)
- 1 Accessory extensor to digit 2 (indicis)
- 1 supinator
Muscles that form the superficial layer of the extensor compartment
- Extensor carpi radialis longus/brevis
- Extensor digitorum
- Extensor digiti minimi (accessory to extensor digitorum)
- Extensor carpi ulnaris
What is tennis elbow
- Epicondylitis at common extensor origin (tendon inflammation due to overuse/forceful extension)
Other superficial muscles involved in the control of the forearm
Brachioradialis - flexor when half pronated
Anconeus - stabilises elbow
Muscles that form the deep layer of the extensor compartment
- Supinator
- Abductor pollicis longus
- Extensor pollicis brevis
- Extensor pollicis longus
- Extensor indicis (accessory to extensor digitorum)
Muscles of the deep layer of the extensor compartment that go through the anatomical snuff box
- Abductor pollicis longus
- Extensor pollicis brevis
- Extensor pollicis longus
What is wrist abduction performed by
- Flexor carpi radialis
- Extensor carpi radialis (longus + brevis)
What is wrist adduction performed by
- Flexor carpi ulnaris
- Extensor carpi ulnaris
Muscles involved in supination
- Biceps brachii
- Supinator
Muscles involved in pronation
- Pronator teres
- Pronator quadratus
Joints involved in pronation and supination
- Proximal radioulnar joint
- Distal radioulnar joint
(During pronation, the radius rotates over the ulna)
What is the carpal tunnel a tunnel for
- Tunnel for flexor tendons to digits and median nerve
Function of flexor retinaculum (transverse carpal ligament)
- Prevents bowing of tendons
Contents of the carpal tunnel
- Median nerve
- Flexor policis longus
- Flexor digitorum superficialis
- Flexor digitorum profundus
What is carpal tunnel syndrome
- Median nerve compression
- Due to increased pressure in carpal tunnel (associated with trauma, obesity, pregnancy)
Purpose of extensor retinaculum
- Prevents bowing of tendons
- Separates tendons into compartments
Long tendon insertions
Tendons to digits 2-5
Extensor digitorum - into middle + distal phalanx
Flexor digitorum profundus - into distal phalanx
Flexor digitorum superficialis - into middle phalanx
Arterial supply to the forearm
Cubital fossa - brachial artery divides into:
Radial artery - under brachioradialis
Ulnar artery - under flexor carpi ulnaris, gives off common interosseous
- Anastomosis around elbow joint
What does the ulnar artery give rise to
- Common interosseous artery –> Posterior interosseous artery + anterior interosseous artery
Location of the median nerve
- Lies mid forearm between FDS and FDP
What does the median nerve give rise to
- Anterior interosseous nerve (to deep flexor muscles)
- Passes through carpal tunnel
- Motor supply to anterior compartment except FCU/medial part of FDP
- Sensory supply to lateral palm + d1, d2, d3, 1/2 d4
Innervation provided by the ulnar nerve
- Motor supply to FCU and medial part FDP
- Sensory supply to medial hand including 1/2 d4 + d5
What is cubital tunnel syndrome
Cubital Tunnel Syndrome is a condition that involves pressure or stretching of the ulnar nerve (also known as the “funny bone” nerve), which can cause numbness or tingling in the ring and small fingers, pain in the forearm, and/or weakness in the hand.
Path of radial nerve
- Enters forearm on lateral side under brachioradialis
Divides into two branches:
Superficial branch (sensory) + deep branch - posterior interosseous nerve (motor)
Path of the superficial branch of the radial nerve
- Under brachioradialis
- Winds round to dorsum of hand
Path of the deep branch of the radial nerve
- Passes through supinator muscle
- Enters extensor compartment
What is wrist drop
Condition in which the wrist and the fingers cannot extend at the metacarpophalangeal joints. The wrist remains partially flexed due to an opposing action of flexor muscles of the forearm. As a result, the extensor muscles in the posterior compartment remain paralyzed.
What does the deep branch of the radial nerve provide innervation to
- Deep branch supplies posterior compartment
What does the superficial branch of the radial nerve provide innervation to
- Superficial branch supplies lat dorsum hand
