Elbow Forearm and Wrist Flashcards
The forearm contains two bones:
Radius and Ulna
Connects radius and ulna
Interosseous membrane
What type of joint is the elbow?
Hinge type synovial joint
The elbow is composed by 3 separate joints:
Humero-ulnar joint
Humeroradial joint
Proximal Radio-ulnar joint
Humero-ulnar joint
Between the trochlea of the humerus and the trochlear notch of the ulna
Also, the coronoid process of the ulna is in contact with the coronoid fossa of the humerus during flexion of the elbow.
Humeroradial Joint
Between the capitulum of the humerus and the head of the radius is in contact with the radial fossa of the humerus
Function:
Flexion and extension of the forearm
Supination and pronation
Proximal Radio-ulnar joint
Between the radial notch of the ulna and the head of the radius
Pivot joint
The head of the radius is attached to the ulna through the anular ligament
Function:
Pronation and Supination
Ligaments of the elbow joint
Radial collateral ligament
Anular ligament
Ulnar collateral ligament
Anular ligament of radius
Provides support to the radial ulnar joint
Radial collateral ligament
Provides support to the Humeroradial joint
Ulnar collateral ligament
Contains an anterior band, posterior band, and oblique band
Provides support humeroulnar joint
Distal Radio-Ulnar Joint
The head of the ulna is accommodated by the ulnar notch of the radius
Fibrocartilaginous, triangular articular disc of the distal radio-ulnar joint (triangular ligament) binds the ends of the ulna and radius together and is the main uniting structure of the joint
Supinator
Forearm muscle, brings support to elbow joint.
Innervated by ulnar nerve
Function: Supination of forearm
Pronator Teres
Primary pronator muscle of the forearm (proximal to elbow joint)
Innervated by median nerve (C6,C7)
Function
Pronation of forearm
Pronator quadratus
Secondary pronator muscle of the forearm (proximal to elbow joint)
Innervated by ulnar nerve
Function
Pronation of forearm
Clinical correlations
subcutaneous olecranon bursitis
AKA “miners elbow” “students elbow”
Subcutaneous olecranon bursa is exposed to injury during falls on the elbow
Repeated excessive pressure and friction may cause this bursa to become inflamed
Clinical correlations
subtendinous olecranon bursitis
Less common
Results from excessive friction between the triceps tendon and olecranon, for example, resulting from repeated flexion-extension of the forearm.
Pain is most severe during flexion of the forearm because of pressure exerted on the inflamed subtendinous olecranon bursa by triceps tendon
Clinical correlations
Avulsion of medial epicondyle
In children can result from a fall that causes severe abduction of the extended elbow. An abnormal movement of this articulation. The resulting traction on the ulnar collateral ligament pulls the medial epicondyle before entering the forearm.
The anatomical basis of this avulsion is that the medial epicondyle may not fuse with the distal end of the humerus until age 20
Clinical correlations
Subluxation and dislocation of radial head
The child is suddenly lifted by the upper limb while the forearm is pronated. Sudden pulling of the upper limb tears the distal attachment of the angular ligament, which it is loosely attached to the neck of the radius.
Radial head then moves distally, partially out of the socket formed by the anular ligament
Tennis elbow (lateral epicondylitis)
Painful musculoskeletal condition that may follow repetitive use of superficial extensor muscles of the forearm.
Pain is felt over the lateral epicondyle and radiates down the posterior surface of the forearm.
Muscles of the forearm
Anterior compartment (Flexor and pronator compartment)
Superficial layer
Pronator teres
Flexor carpi radialis
Palmaris longus
Flexor carpi ulnaris
Pronator Teres
Has two heads
Ulnar head and Radial head
Innervation: Median nerve (C6,C7)
Function: Pronates and flexes forearm
Flexor Carpi radialis
Innervated by Median nerve (C6,C7)
Flexes and abducts hand
Palmaris longus
Innervated by: Median Nerve (C7,C8)
Flexes hand and tenses palmar aponeurosis
Flexor carpi ulnaris
Has two heads
Ulnar head and Radial head
Innervation: Ulnar nerve (C7,C8)
Flexes and adducts the hand
Muscles of the forearm
Anterior compartment (Flexor and pronator compartment)
Intermediate layer
Flexor Digitorum Superficialis
Flexor Digitorum Superficialis
Has two heads
Humero-ulnar head and Radial head
Innervation: Median nerve (C7,C8,T1)
Function: Flexes middle phalanges at proximal interphalangeal joints of middle four digits: acting more strongly, it also flexes proximal phalanges at metacarpophalangeal joints.
Muscles of the forearm
Anterior compartment (Flexor and pronator compartment)
Deep layer
Flexor Digitorum profundus
Flexor Pollicis longus
Pronator Quadratus
Flexor Digitorum profundus
Contains Medial and Lateral Part
Medial Part is innervated by Ulnar Nerve (C8,T1)
Main action: Flexes distal phalanges 4 and 5 at distal interphalangeal joints
Lateral Part is innervated by the anterior interosseous nerve, from median nerve (C8,T1)
Main action: Flexes distal phalanges 2 and 3 at distal interphalangeal joints
Flexor Pollicis longus
Innervated by anterior interosseous nerve, from median nerve (C8,T1)
Main action: Flexes phalanges of 1st digit
Pronator Quadratus
Innervated by anterior interosseous nerve, from median nerve (C8,T1)
Pronates forearm, deep fibers bind radius and ulna together
Muscles of the forearm
Posterior compartment (Extensor and supinator compartment)
Superficial layer
Brachioradialis
Muscles that originate from the lateral epicondyle
Extensor carpi radialis brevis
Extensor carpi radialis longus
Extensor digitorium
Extensor digiti minimi
Extensor carpi ulnaris
Brachioradialis
Innervation Radial nerve (C5,C6,C7)
Function: Relatively weak flexion of forearm; maximal when forearm is in mid-pronated position
Extensor carpi radialis brevis
Innervation: Radial Nerve (C6, C7)
Function: Extend and abduct hand at the wrist joint ; ECRL active during fist clenching
Extensor carpi radialis longus
Innervation Deep Branch of radial nerve (C7,C8)
Function: Extend and abduct hand at the wrist joint ; ECRL active during fist clenching
Extensor digitorum
Innervation: Deep Branch of radial nerve (C7,C8)
Function: Extends medial four digits primarily at metacarpophalangeal joints, secondarily at interphalangeal joints
Extensor digiti minimi
Innervation: Deep Branch of radial nerve (C7,C8)
Function: Extends 5th digit primarily at metacarpophalangeal joints, secondarily at interphalangeal joints
Extensor carpi ulnaris
Innervation: Deep Branch of radial nerve (C7, C8)
Function:Extend and adduct hand at the wrist joint ; ECRL active during fist clenching
Muscles of the forearm
Posterior compartment (Extensor and supinator compartment)
Deep layer
Supinator
Abductor pollicis longus
Extensor pollicis brevis
Extensor pollicis longus
Extensor indicis
Supinator
Innervation: Deep branch of radial nerve (C7,C8)
Function: Supinates forearm: rotates radius to turn palm anteriorly or superiorly (if elbow is flexed)
Abductor pollicis longus
Innervation: Posterior interosseous nerve (C7, C8), a continuation of deep branch of radial nerve
Function: Abducts thumb and extends it at the carpometacarpal joint
Extensor pollicis brevis
Innervation: Posterior interosseous nerve (C7,C8), a continuation of deep branch of radial nerve
Function: Extends proximal phalanx of thumb at metacarpophalangeal joint; extends carpometacarpal joint
Extensor pollicis longus
Innervation: Posterior interosseous nerve (C7,C8), continuation of deep branch of radial nerve
Function: Extends distal phalanx of thumb at metacarpophalangeal joint; extends carpometacarpal joint
Extensor indicis
Innervation: Posterior interosseous nerve (C7,C8), continuation of deep branch of radial nerve
Function: Extends 2nd digit (enabling its independent extension) helps extend hand at wrist
