L10: The elbow and Forearm Flashcards
What type of joint is the elbow joint?
Complex hinge joint
Composed of 3 or more skeletal elements
What are the articulations within the elbow?
Humeroulnar joint
Humeroradial joint
What are the articulations within the humeroulnar joint?
Trochlear of the humerus Trochlear notch (sigmoid nothc) of the ulna
What are the articulations within the humeroradial joint?
Capitellum of the humerus
Radial head
What other joint is found within the joint capsule but not part of the elbow joint?
Proximal radio-ulnar joint
Between the side of head of radius and the radial notch of the ulnar
Describe the anatomy of the distal humerus?
Medial and lateral condyles –>Trochlear and capitellum
Medial and lateral epicondyles–> attachment for forearm muscles
Radial fossa
Coronoid fossa
Posterior side–> olecranon fossa
Medial and lateral supracondyle ridge
What group of muscles attach to the medial condyle?
Flexor-pronator groups of anterior forearm
What groups of muscles attach to the lateral epicondyle?
Extensor muscles of posterior forearm
What accommodates the radial and coronoid fossae during flexion?
The radial head and coronoid porcess of ulnar
What accommodates the olecranon fossa during extension?
The olecranon on ulna
Describe the anatomy of the proximal radius? Why?
Radial head–> concave articulating surface, thicker medially–> proximal radio-ulnar joint
Radial neck–> Inferior to head, thinner, at risk of fracture
Radial tuberosity–> bone projection, attachment of biceps brachii
Describe the anatomy of the proximal ulnar?
Sigmoid (trochlear) notch–> formed by the olecranon and coronoid process–> articulates with the trochlear
Coronoid process–> ridge of bone projects outwards anteriorly
Olecranon–> large projection of bone proximally, ‘tip’ of elbow–> triceps attaches superior surface
Radial notch–> lateral surface
Tuberosity of ulna–> roughening immediatley distal to coronoid process–> brachialis attaches
Supinator crest–> anterior surface of ulnar–> supinator muscle attaches
What strengthens the medial and lateral aspects of the elbow?
Radial (lateral) collateral ligaments
Ulnar (medial) collateral ligaments
What are the attachment sites radial collateral ligament? What does it do?
Radial–> lateral epicondyle of humerus and annular ligament of radius (fan shaped ligament)
Keeps head of radiua and capitellum in close association during pronation and supination
What are the attachment sites of the ulna collateral ligament?
Ulnar–> medial epicondyle of humerus and coronoid process and olecranon of ulnar (triangular shaped)
3 bands
Anterior–> strongest
Posterior–> fan like weakest
Inferior (Slender oblique)–> deepens the socket for the trochlear of humerus (transversely between the anterior and posterior ligaments)
What stabilies the proximal radio-ulna joint?
Annular ligament
Forms a collar around the radial head in which the radial head can rotate
Maintain contact with radial notch on ulna
What movements are possible at the elbow?
Flexion and extension
What is the carrying angle?
The angle at which the ulnar makes with the long axis of humerus at full extension
Usually around 5-10 in men and 10-15 degrees in women
What is the point of the carrying angle?
Allows the arm to clear the hips in swinging movements
What are deviations to the carrying angle known as?
Cubital valgus–> angle greater than 5-10/10-15 degrees
Cubital varus–> angle less than 5-10/10-15 degrees
What are the main muscles that flex the elbow?
Brachialis
Biceps brachii
Brachioradialis
What are the main muscles that extend the elbow?
Triceps brachii
Anconeus
What are the main muscles involved in supination?
No resistance- Supinator
Resistance- Biceps brachii
What are the main muscles in involved in pronation?
Pronator quadratus
Pronator teres
What are the important bursae in the elbow joint? Where are they located?
Olecranon bursae–> subcutaneous CT overlying the olecranon
Subtendinous bursae–> between the triceps tendon and tip of olecranon
What type of joint is the distal radio-ulna joint?
Pivot joint
Located immediately proximal to the wrist
Ulnar notch of radius rotates anteriorly around the ulna head
Where does the axis of rotation for supination/pronation pass?
Longitudinally through the head of radius proximally and through the styloid process of the ulna distally
What keeps the radius and ulnar together at the distal radioulnar joint? What else does this structure do?
Triangular fibrocartilage complex
Also separates the distal radioulnar joint from the wrist joint
What other structure also helps to keep the radius and ulnar together during the movements of pronation and supination?
The interosseous membrane
Fibrous joint
Fibres run diagonally from the radius proximally to the ulnar more distally
What is a good way of remembering the anterior forearm muscles?
4-1=3 4 superficial (pass, fail, pass, fail--> thumb on medial epicondyle) 1 intermediate 3 deep
What are the 4 superficial muscles of the anterior compartment?
Pass, Fail, Pass, Fail Pronator Teres Flexor carpi radialis Palmaris longus Flexor carpi ulnaris
What is the origin, insertion, innervation and function of the pronator teres?
O:
- -> Humeral head–> medial epicondyle
- -> Ulna head–> coronoid process of ulna
I: Mid-shaft of the radius
F: Pronation
Innervation: Median nerve
What is the origin, insertion, innervation and function of the Flexor carpi radialis?
O: Median epicondlye
I: Base of 2nd and 3rd metacarpals
F: Flexion and abduction at wrist
Innervation: Median nerve
What is the origin, insertion, innervation and function of the Palmaris longus?
O: Median epicondyle
I: Flexor retinaculum of wirst and palmar aponeurosis
F: Weak flexor
Innervation: Median nerve
How can the palmaris longus be located?
Flex the wrist
Oppose the thumb and little finger
Tendon will protrude
What lies immediately deep to the Palmaris Longus?
The median nerve
What is the origin, insertion, innervation and function of the Flexor carpi ulnaris?
O:
- -> Humeral head–> Median epicondlye
- -> Ulnar head—> Medial margin of the olecranon
I: Pisiform bone, hook of hamate and base of 5th metacarpal bone
F: Flexes and adducts at the wrist
Innervation: Ulnar nerve
(nerve passes between the two heads)
What is the common flexor origin?
Superficial flexor muscles all have a common tendon form the medial epicondyle of humerus
What is the intermediate muscle of the forearm?
Flexor digitorum superficialis
What is the origin, insertion, innervation and function of the flexor digitorum superficialis?
O:
–>Humeroulnar head–> Medial epicondyle of humerus, ulnar collateral ligament and cornonoid process
–> Radial head–> anterior surface of the radius
Not discrete origins form a continuous tendinous arch
I: Base of middle phalanges of the finger digits
F: Flexes metacarpophalangeal joints and proximal interphalangeal joints, flexion of wrist
Innervation: Median nerve
(median nerve and ulnar artery pass between the two heads)
What is the origin, insertion, innervation and function of the Flexor digitorum profundus?
O: proximal 2/3 of shaft of ulna and associated interosseous membrane
I: 4 tendons onto base of distal phalanges of four fingers
F: Flex distal interphalangeal joints, flexes metacaropophalangeal joint and flexes wrist
Innervation: Ulnar half (medial half) --> ulnar nerve Radial half (lateral half)--> anterior interosseous branch of median nerve
What is the origin, insertion, innervation and function of the Flexor pollicis longus?
O: Middle of anterior surface of radial shaft and adjacent interosseous membrane
I: Base of distal phalanx of thumb
F: Flexes interphalangeal joint and metacarpophalangeal of the thumb
Innervation: Anterior interosseous branch of median nerve
What is the origin, insertion, innervation and function of the pronator quadratus?
O: Anterior surface of the distal ulnar
I: Anterior surface of distal radius
F: Pronates the forearm
Innervation: Anterior interosseous branch of the median nerve
What is the root values of the median nerve?
C6-T1
Input from medial and lateral cords of brachial plexus
What is the motor innervation of the median nerve?
Anterior flexor and pronator muscles of the forearm
Except flexor carpi ulnaris and 1/2 flexor digitorum profundus
Also 1 1/2 LOAF
1 1/2 lumbricals (lateral)
Opponens pollicis
Abductor pollicis brevis
Flexor Pollicis Brevis (not deep head)
What is the sensory innervation of the median nerve?
Small and confined to hand
Palmar cutaneous branch–> radial (lateral) aspect of hand
Digital cutaneous branch–> radial 3.5 fingers on palmar surface and dorsum of their respective distal phalanages
What is the anatomical course of the median nerve?
- Orginated in the axilla
- Descend the arm lateral to the brachial artery
- Halfway down crosses over to be situated medially
- Enter anterior forearm through the cubital fossa
- Travels between the heads of the pronator teres and deep to tendious arch of flexor digitorum superficialis
- Distally passes betwen the FDS and FDP
- Gives off anterior interosseous branch
- Gives off palmnar cutaneous branch–> Passes superficial to the carpal tunnel to suplly skin of lateral palm
- Median nerve enters hand via the carpal tunnel
- Terminates by dividing into two branches
- -> Recurrent branch–> thenar muslces (expect Adductor pollicis and deep head of FPB)
- -> Palmar digital branch–> palmar surface and fingertips of radial (lateral) 3.5 digits and lateral two lumbricals
What is the root value of the ulnar nerve?
C8 and T1
What is the motor innervation of the ulna nerve?
Flexor carpi ulnaris
1/2 flexor digitorum profundus
Intrinsic muscle of the hand EXCEPT (1.5 LOAF)
–> Opponens Pollicis
–> Abductor Pollicis brevis
–> Flexor Pollicis brevis (superficial head)
–> Lateral 2 lumbicals
What is the sensory innervation of the ulnar nerve?
Palmar and dorsal surface of the ulna (medial) one and a half fingers and ulnar aspect of palm and dorsum of the hand
What is the anatomical course of the ulnar nerve?
- Medial aspect of arm
- Posterior to medial epicondyle of humerus
- Cubital tunnel –> articular branch supplied elbow
- Between two heads of FCU into forearm
- Deeps to FCU muscles adjacent to ulna
- 3 branches in forearm
- -> Muscular branch–> FCU and 1/2 FDP
- -> Palmar cutaneous branch–> ulnar (medial) 1/3 palm
- -> Dorsal cutaneous branch–> dorsal surface of ulna (medial) one and half fingers and associated dorsal area of the hand
- At wrist travels superiorly to flexor retinaculum and medial to ulnar artery
- Enters the hand via the ulnar canal
- Terminated by giving rise to superficial and deep branches
- -> Deep branch innervates majority of intrinsic muscles -hypothenar muscles, PADs, DABs, ulnar (medial) lumbricals, adductor pollicis, palmaris brevis, deep head of flexor pollicis brevis
- -> Superficial arises in the palm and innervates the palmar surface of ulna (medial) one and half fingers via palmar digital nerves
What is Froment’s sign?
Test for ulnar nerve palsy
Paralysis of adductor pollicis
Pt hold piece of paper between the thumb and index finger
Paper is pulled away
Negative sign–> pt holds paper with no difficulty
Positive sign–> pt flex the thumb at the interphalangeal joint to maintain hold on paper
What is the root values of the musculocutaneous nerve?
C5, 6 and 7
What is the motor innervation of the musculocutaneous nerve?
Muscle of the anterior arm BBC muscles
What is the sensory innervation of the musculocutanous nerve?
Becomes the lateral cutaneous nerve of the forearm supplying the lateral surface of the forearm
What is the course of the musculocutaneous nerve?
- Leaves the axilla
- Pierces the coracobrachialis muscle supplying it
- Passes down arm superficial to bracialis, deep to biceps brachii
- Pierces deep fascia lateral to biceps brachii
- Emerges lateral to biceps tendon and brachioradialis
- Continues as lateral cutaneous nerve of the forearm close to cephalic vein
- Sensory innervation to the lateral forearm