Session 3: Elbow, forearm and wrist
Where does the subclavian vein become the axillary vein?
At the level of the first rib
Where can you palpate the radial artery?
At the wrist where it lies anteriorly on its radial aspect
Biceps and brachialis: insertion, action
Biceps: - biceps TENDON inserts onto radial tuberosity and bicipital aponeurosis (sheetlike layer of connective tissue that merges with connective tissue of the region) Brachialis: -attaches to coranoid process and tuberosity of the ulna Both are flexors of the region. Biceps is also a supinator.
Spinal roots of radial nerve
C5,6,7,8,T1
Spinal roots of median nerve
C6,7,8,T1
Spinal roots of ulnar nerve
C8, T1
Where does supinator muscle attach?
Comes off lateral epicondyle of humerus and is wrapped around the shaft of the radius
Where do the superficial flexor muscles of anterior compartment of forearm originate from?
Common flexor tendon/medial epicondyle of humerus
Deep venous drainage of forearm
Deep veins (venae comitantes) accompany the radial and ulnar arteries. Eventually flow to the brachial vein in the arm. (unlike arteries, brachial vein and axillary aren't part of the same system!!!)
Where does the ulnar artery descend?
Descends in anterior compartment of the forearm and passes into the hand anteriorly, on the ulnar side of the wrist (just lateral to FCU)
Where does the brachial artery divide and into what?
Divides at elbow (usually at level of the radial neck) into the ulnar artery and radial artery.
Overview of bones of the elbow
Elbow joint: -two condyles at the distal end (capitulum and trochlea) -capitulum articulates with the head of the radius and trochlea articulates with proximal end of the ulna
What holds the articular surfaces of radius and ulna together at the distal radio-ulnar joint?
Fibrocartilage articular disc *note that the distal radio-ulnar joint is continuous with the wrist joint via its articular disc (continuous with the cavity). This allows the radius to slide over the ulna during pronation and supination.
Movements of the elbow joint itself and muscles responsible
Flexion and extension. Main flexors: - brachialis -biceps -(brachioradialis) -(some assistance from pronator teres) Main extensors: -triceps -(anconeous)
Floor of cubital fossa
Floor - brachialis and supinator muscles. o Contains; biceps tendon, brachial artery (and bifurcations), median and radial nerve (and deep branch).
Terminology of forearm muscles
Forearm muscles can be classified into functional groups: Flexors (anterior) and Extensors (posterior) Movers of the wrist (the "carpi" muscles) act on the radial (radialis) or ulnar (ulnaris) aspects of the forearm. Movers of the digits:- act on groups of digits (digitorum muscles) or on individual digits (pollicis (thumb), indicis (index finger) digiti minimi (little finger)) (these muscles also contribute to wrist movements). Also note that if there's a longus, there's a brevis; if there's a superficialis, there's a profundus. The main complications are the muscles involved in pronation (anterior) and supination (posterior).
What muscles are supplied by median nerve?
In the forearm, median nerve supplies: a) pronator teres b) FDS c) lateral portion of FDP (to the index and middle fingers) d) FCR e) Pronator quadratus f) Palmaris longus MAIN MOTOR NERVE OF FOREARM MUSCLES
Boundaries of cubital fossa
Lateral: brachioradialis muscle Medial: pronator teres Superior: line between humeral epicondyles *it's a TRIANGLE
Position of ulnar nerve at the wrist
Lies between FCU (medially) and ulnar artery (laterally) Then passes into the hand where it supplies most of the intrinsic muscles.
In the humerus which epicondyle is more prominent?
Medial
Relationship between ulnar artery, ulnar nerve and FCU
Medial-->lateral a) FCU b) Ulnar nerve c) Ulnar artery
What connects cephalic and basilic veins?
Median cubital vein- at the level of the elbow. Common site for venepuncture; variable in anatomy *if median cubital vein absent, then blood taken from cephalic/basilic.
What type of joint is the distal radio-ulnar joint?
Pivot-type synovial joint Allows radius to rotate around the distal ulna
Illustration of pronation and supination at radio-ulnar joints
Pronation: -Distal part of radius crosses over the ulna. Supination: -Supinator comes off lateral epidondyle of humerus and is wrapped around shaft of the radius. -It will turn the radius back so hand is facing forwards.
What is the proximal attachment of the deep flexor muscles of forearm?
Proximal attachment on flexor surfaces of radius, ulnar and interosseous membrane.
Features of ulna: proximal end
Proximal end: - olecranon process -coranoid process - trochlear notch- articulates with trochlea of humerus - radial notch- articulates with head of radius - ulnar tuberosity- attachment for brachialis muscle
Shape of radius vs ulna
Proximal-->distal a) Radius: narrow-->wide b) Ulna: wide-->narrow
Overview of bones of the forearm
Proximal: -Olecranon and coranoid at the proximal end of the ulna -Proximal joint between radius and ulna isn't strictly part of elbow joint -Interosseous membrane (tough sheet fo connective tissue) connects the radius and ulna Distal: - styloid process in radius and ulna -articular circumference of head of ulna
Roof of cubital fossa
Roof - aponeurosis and skin. o Contains; median cubital vein, lateral/medial cutaneous nerves of the forearm.
Role of musculocutaneous nerve in the forearm
Sensory to the lateral forearm (as the lateral cutaneous nerve of the forearm)
What is a sesamoid bone? Example?
Sesamoid bone: bone forms within a tendon or muscle close to an insertion (eg pisiform- Doesn't actually articulate at the wrist joint)
Carpal bones
Some Lovers Try Positions, That They Cannot Handle. Read in RIGHT SUPINE position (i.e. left picture left) and from the right-->left. ♣ Scaphoid, Lunate, Triquetrum, Pisiform - Proximal. ♣ Trapezium, Trapezoid, Capitate, Hamate - Distal. ♣ The "hook of the hamate" and the "tubercle of trapezium" form the walls of the carpal tunnel.
What is the cubital fossa?
Space anterior to elbow joint
How is one-way flow of blood ensured in venous system?
Superficial and deep veins have numerous connections with valves allowing one-way flow from superficial to deep system.
What movements occur at proximal and distal radio-ulnar joints? Muscles producing these movements?
Supination: directs palm anteriorly a) supinator b) biceps brachii c) (EPL, ECRL) Pronation: directs palm posteriorly a) pronator quadratus (deep) b) pronator teres (superficial) c) (FCR, PL, brachioradialis) -->They act across between the two bones. -->When they contract they pull the two bones together and because they're held in place by annular ligament they'll rotate and cross over, producing pronation
What does the ulnar artery supply in the forearm?
Supplies the medial muscles of the forearm, via branches including the common interosseous artery, anterior interosseous artery and posterior interosseous artery. -common interosseous artery divides immediately to give anterior and posterior. -posterior interosseous artery pierces interosseous membrane and supplies posterior muscles
What type of joint is the elbow joint?
Synovial hinge joint
Where does the ulnar artery terminate?
Terminates in the hand to form the PALMAR ARCHES with the radial artery
Important point about wrist and distal radio-ulnar joint
The distal ulna does not articulate directly with the triquetrum carpal bone. An articular disc intervenes.
What is the flexor retinaculum?
The flexor retinaculum forms the roof of the carpal tunnel and is an important structure.
What type of joint is the wrist joint?
The wrist joint is an elipsoid synovial joint between the distal radius and its associated triangular fibrocartilage articular disc, with the proximal row of the carpal bones (scaphoid, lunate and triquetrum)
Sensory function of ulnar nerve
Ulnar nerve also gives sensory function to medial aspect of ventral forearm
What type of joint is the proximal radio-ulnar joint?
Uni-axial pivot-type synovial joint Allows head of the radius to rotate within the annular ligament.
Prime movers at wrist
o Flexion - FCR, FCU, PL. o Extension - ECU, ECRL, ECRB, APL. o Abduction - FCR, ECRL, ECRB, APL. o Adduction - FCU, ECU.
Prime movers at elbow joint
o Flexors - brachialis, biceps, brachioradialis, pronator teres. o Extensors - triceps, anconeus.
Prime movers at radio-ulnar joints
♣ Proximal and distal radio-ulnar joint: o Supination - biceps, supinator. o Pronation - pronator teres, pronator quadratus.
Flexor and extensor retinaculum
♣ The "flexor retinaculum" forms the roof of the carpal tunnel and is an important structure to consider in CTS. ♣ The "extensor retinaculum" anchors the extensors to the wrist.
What are the ligaments at elbow which stabilise the joint?
*these ligaments stabilise the joint but allow pronation and supination* 1. The medial (ulnar) collateral ligaments 2. The lateral (radial) collateral ligaments 3. The annular ligament (part of the proximal radio-ulnar joint)
Course of the median nerve
- descends in the anterior compartment of the forearm, within which it does not give any branches -anterior to the elbow, it lies MEDIAL to the BRACHIAL ARTERY- where it's at risk of damage by supracondylar fractures of the humerus -then descends into the forearm between the heads of PRONATOR TERES to become the principal motor nerve of the anterior compartment -at anterior wrist, the median nerve lies quite superficially between the tendons of FDS and FDP and deep to palmaris logus (if present) prior to entering the hand through the carpal tunnel
Organisation of flexors and extensors in forearm
- flexors (and pronators) anteriorly - extensors (and supinators) posteriorly
Features of radius: proximal end
- head -neck -radial tuberosity -medial (interosseous) border -articular surface for capitulum of humerus -articular surface for radial notch of ulna -body (shaft) of radius
Features of radius: distal end
- ulnar notch- accommodates ulnar head -radial styloid process (lateral) -dorsal tubercle
What is the anatomical snuff-box?
-Defined as the area between (tendons of): o Extensor pollicis longus (EPL). o Extensor pollicis brevis (EPB). -Contains: o Radial artery. o Scaphoid bone: Scaphoid bone has a blood supply that is recurrent on itself (goes past scaphoid but comes back), so injury to distal part of the bone can result in proximal necrosis. *Scaphoid bone is commonly injured if you fall and use your hands to protect yourself.
Where does the radial artery descend?
-Descends in the lateral aspect of the foreamr under the cover of the BRACHIORADIALIS MUSCLE. -then at the wrist it lies anteriorly on its radial aspect (where it can be palpated) -it then crosses the floor of the anatomical snuff box -ultimately anastamoses with branches of the ulnar artery to form the palmar arches
Palpation of anterior compartment of forearm
-FCR, PL and FCU can be palpated on the anterior forearm. -PL and FCR are very close to each other whilst FCU is on nearly the medial aspect of the wrist and joins the pisiform carpal bone. -The HEAD of the ulnar and radius is found proximally towards the elbow.
Superficial venous drainage of forearm
-Medial and lateral sides of dorsal venous arch--> a) cephalic: ascends laterally b) basilic: ascends medially (slightly DEEPER) -median cubital vein connects cephalic and basilic at the level of elbow -Basilic veins joins venae comitantes to form the axillary vein in the arm -Cephalic vein joins axillary vein in the axilla -Axillary vein becomes the subclavian vein at the level of the first rib
Lymphatic drainage of the forearm
-Superficial and deep systems, run with veins -Cubital lymph nodes -They can be indicative of infection or malignant disease. -In certain chronic conditions they can become swollen -Axillary nodes are also draining nodes for the distal parts of the upper limb
Course of the radial nerve
-Supplies all the muscles of the posterior compartments of the upper arm and forearm -Passes around the body of the humerus at its mid-shaft in the radial groove (at risk in humeral shaft fractures) -Supplies triceps in the arm -Courses via the anterior compartment of the upper arm more distally -Divides just above the level of the elbow into; a) Deep branch - the posterior interosseous nerve (motor). -deep branch of radial nerve descends into forearm between the heads of supinator to become posterior interosseous nerve! b) Superficial branch - the superficial radial nerve (sensory) -ENDS as a PSEUDOGANGLION below the extensor retinaculum
What is the carrying angle? Diff between men and women?
-The carrying angle is the deviation of the long axis of the radius and ulna from that of the humerus (in extension). -It is greater in women than men (women have wider pelvis so carrying angle changes to accommodate that) and averages 7 degrees
Overview of bones of the wrist
-The distal ends of the radius and ulna articulate with the proximal row of carpal bones, with the exception of pisiform (a sesamoid bone).
Describe the elbow joint
-The elbow is a synovial hinge joint between the humerus proximally and the ulna and radius distally. -The distal humerus articulates with the ulna via the trochlea whilst the radius articulates with the radius via the capitulum, but only in full flexion.
Overview of forearm muscles
-The hand and wrist are operated by 'remote control' by these muscles -The forearm muscles actually take origin from the distal humerus as well as the radius and ulna -Flexors (and pronators) anteriorly -Extensors (and supinators) posteriorly
What is the interosseous membrane and what is its function?
-This is a fibrous sheet that connects the radius and the ulna forming a fibrous joint (syndesmosis) between the two bones -separates the anterior and posterior compartments -site of attachment for muscles in the forearm. -transfers forces from the radius to the ulna to the humerus and vice versa
Where does median nerve lie at the wrist?
-at anterior wrist, the median nerve lies quite superficially between the tendons of FDS and FDP and deep to palmaris logus (if present) prior to entering the hand through the carpal tunnel
Course of the ulnar nerve
-has no branches in the arm -initially descends in anterior compartment but distally passes into posterior compartment to lie superficially, posterior to medial epicondyle of elbow (where it's at risk of damage) -then enters forearm by passing between heads of FLEXOR CARPI ULNARIS -descends on MEDIAL SIDE of forearm where it supplies more medial muscles in anterior compartment
Diff between head of ulna and radius
-head of ulna is at DISTAL END -head of radius is at PROXIMAL end
Olecranon bursa
-large bursa over the olecranon at the posterior of the elbow -frequently becomes inflamed.
Features of ulna: distal end
-ulnar head -styloid process
What are the muscles that move the thumb?
1. Abductor pollicis longus (APL) 2. Extensor pollicis brevis (EPB) 3. Extensor pollicis longus (EPL)
Muscles supplied by deep branch of radial nerve
1. ECRB 2. Supinator
Which muscles provide extension at wrist?
1. ECRL - important 2. ECRB - important 3. ECU - important 4. Long extensors of the thumb and fingers
Which muscles provide ulnar deviation/adduction at wrist?
1. ECU 2. FCU
Muscles supplied by posterior interosseous nerve
1. ED 2. ED minimi 3. ECU 4. APL 5. EPB 6. EPB 7. E indicis
What are the muscles that move the wrist joint?
1. Extensor carpi radialis longus (ECRL) 2. Extensor carpi radialis brevis (ECRB) 3. Extensor carpi ulnaris (ECU)
What are the muscles that move the digits?
1. Extensor digitorum (ED) 2. Extensor indicis (EI) 3. Extensor digit minimi (EDM)
Which muscles provide radial deviation/abduction at wrist?
1. FCR 2. ECRL 3. ECRB 4. APL 5. Extensor pollicis brevis
Which muscles provide flexion at wrist?
1. FCR - important 2. FCU - important 3. Long flexors of the thumb and fingers 4. (Palmaris longus) 5. (APL)
What movements occur at the wrist?
1. Flexion/extension 2. Radial deviation (abduction) and ulnar deviation (adduction) 3. Circumduction
Muscles of deep anterior compartment of forearm
1. Flexor digitorum profundus (FDP) 2. Flexor pollicis longus (FPL) 3. Pronator quadratus (PQ)
What categories of muscles do you have in the extensor compartment of the forearm?
1. Muscles that move the wrist joint 2. Muscles that move the digits 3. Muscles that move the thumb 4. Other muscles Diagram: Note that some parts of the proximal attachments are on the interosseous membrane
Main nerves of the upper limb
1. Musculocutaneous nerve (C5,6,7) 2. Ulnar nerve (C8,T1) 3. Median nerve (C6,7,8,T1) 4. Radial nerve (C5,6,7,8,T1)
Muscles of the superficial anterior compartment of forearm
1. Pronator teres (PT) 2. Flexor carpi radialis (FCR) 3. Palmaris longus (PL) 4. Flexor digitorum superficialis (FDS) *sometimes classed as intermediate/superficial compartment. 5. Flexor carpi ulnaris (FCU)
Two compartments in anterior compartment of forearm
1. Superficial 2. Deep
What are the bones of the elbow, forearm and wrist?
1. The Humerus 2 . The Radius 3. The Ulna 4. The carpal bones a) Proximal row: scaphoid, lunate, triquetrum, pisiform b) Distal row: trapezium, trapezoid, capitate, hamate ____ -Distal end of humerus forms proximal part of elbow joint -Radius and ulna are paired parallel bones (in anatomical position) -Carpal bones a) Proximal bones: form part of wrist joint
Summary of motor supply in the forearm
1. The Radial Nerve supplies all posterior muscles. 2. The Ulnar Nerve supplies only FCU and the Ulnar half of FDP . 3. The Median Nerve supplies all of the remaining anterior muscles.
Relevant muscles of the region
1. The anterior compartment of the arm 2. The posterior compartment of the arm 3. The anterior compartment of the forearm - superficial and deep compartments 4. The posterior compartment of the forearm
What are the joints of the region?
1. The elbow joint 2. The proximal radio-ulnar joint 3. The distal radio-ulnar joint 4. The wrist joint
Ligaments stabilising the wrist joint
1. The ulnar collateral ligament 2. The radial collateral ligament 3. The palmar radio-carpal ligament 4. The palmar ulnocarpal ligament 5. The dorsal radio-carpal ligament 6. The inter-carpal ligaments The radio-carpal and inter-carpal ligaments were previously thought to be relatively unimportant but they are now known to be very important clinically and are frequently injured.
Muscles in posterior compartment of the arm + innervation + actioni
1. Triceps: -crosses the elbow joint and attaches to posterior of olecranon process of ulna. -major extensor of forearm 2. Anconeous -extension but mainly involved in stabilisation. Radial nerve (C7,8)
Muscles of the anterior compartment of the arm + innervation
1. biceps 2. brachilais 3. coracobrachialis (doesn't act over the elbow) -->Musculocutaneous nerve (C5,6)
Muscles supplied by radial nerve in forearm
1. brachioradialis 2. ECL
Superficial extensors in forearm
1. brachioradialis 2. extensor carpi radialis longus (ECRL)] 3. extensor carpi radialis brevis (ECRB) 4. extensor digitorum (ED) 5. extensor digiti minimi (EDM) 6. extensor carpi ulnaris (ECU) 7. anconeus. 1+2: sometimes classed as lateral compartment of forearm
Other extensor muscles in forearm
1. brachioradialis 2. supinator
Which extensor muscles attach to lateral epidcondyle of the humerus?
1. extensor carpi radialis brevis (ECRB) 2. extensor digitorum (ED) 3. extensor digiti minimi (EDM) 4. extensor carpi ulnaris (ECU) ALSO SUPINATOR
Muscles supplied by ulnar nerve
1. flexor carpi ulnaris (FCU) 2. medial portion of flexor digitorum profundus (FDP) i.e. to the ring and little fingers.
Deep extensors in forearm
1. supinator 2. abductor pollicis longus (APL) 3. extensor pollicis brevis (EPB) 4. extensor pollicis longus (EPL) 5. extensor indices (EI).
Which joints allow flexion and extension at the wrist region?
1. wrist joint 2. midcarpal joint- between proximal and distal carpal bones 3. carpo-metacarpal joints
Inferior view of wrist joint showing movements
4 muscles acting across the wrist. -If radilias muscles act together--> abduction -Ulnaris muscles act together-->adduction
What are the palmar arches made of? (arteries)
Anastamosis between radial and ulnar arteries
What does the annular ligament attach the radius to?
Annular ligament attaches head of the radius to the margins of the radial notch of the ulna
On x-rays why doesn't ulna touch the carpal bones (triquetrium) while radius does (scaphoid?)
Articular disc present between ulna and carpal bones
