15-1.
Four Major Nerves Cross the Elbow Joint
"Mothers usually always right" - Lost musculocutaneous nerve by the time we get to elbow, finished innervations and only cutaneous 1. Median: near brachial artery (middle of cubital fossa) 2. Ulnar: posterior at elbow 3. Lateral antebrachial cutaneous: lateral cutaneous nerve of forearm 4. Radial:
Median n + radial n
375
Pulled elbow
379 Tennis elblow, golfers eblow + pulled elbow
Ulnar nerve
380
5 flexor muscles of forearm
5 Flexors: come from medial epicondyle of the humerus 1. Pronator Teres: Shortest 2. Flexor Carpi Radialis 3. Flexor digitorum superficialis (not shown here) 4. Palmaris Longus: thin ,fans out under palmar surface = palmar aponeurosis 5. Flexor carpi ulnaris: running along ulna up medial side of forearm
Flexor Digitorum Profundus
Action: Innervation: ulnar half = ulnar nerve radial half = radial nerve
Flexor pollicis Longus muscle
Action: Innervation:
Pronator Quadratus muscle
Action: Innervation:
Abductor Pollicis Longus muscle
Action: Innervation: radial nerve Deep muscle Run from middle forearm out to fingers
Extensor indicis muscle
Action: Innervation: radial nerve Deep muscle Run from middle forearm out to fingers
Extensor pollicis brevis muscle
Action: Innervation: radial nerve Deep muscle Run from middle forearm out to fingers
Extensory pollicis longus muscle
Action: Innervation: radial nerve Deep muscle Run from middle forearm out to fingers
Aconeus muscle
Action: Innervation: radial nerve Deep muscle Work on radius/ulna (do not go far down)
Supinator muscle
Action: Innervation: radial nerve Deep muscle Work on radius/ulna (do not go far down)
Extensor digiti minimi muscle
Action: Innervation: radial nerve Intermediate muscle Runs whole arm to phalanges (humerus to four phalanges - all 4 fingers)
Extensor digitorum muscle
Action: Innervation: radial nerve Intermediate muscle Runs whole arm to phalanges (humerus to pinky - only digit) - Pinky served by ext digitorum + extensor digiti minimi
Extensor Carpi Ulnaris
Action: Innervation: radial nerve Superficial muscle Runs full extent of arm humerus to metacarpals - does not cross wrist joint
Extensor carpi radialis brevis muscle
Action: Innervation: radial nerve Superficial muscle Runs full extent of arm humerus to metacarpals - does not cross wrist joint
Extensor carpi radialis longus muscle
Action: Innervation: radial nerve Superficial muscle Runs full extent of arm humerus to metacarpals - does not cross wrist joint
Flexor Carpi Radialis
Action: Origin: Common flexor origin: Medial humeral epicondyle
Flexor Carpi Ulnaris
Action: Origin: Common flexor origin: Medial humeral epicondyle
Pronator Teres
Action: Origin: Common flexor origin: Medial humeral epicondyle
flexor digitorum superficialis
Action: Origin: Four tendons from on muscle that go out into the hand/fingers to flex them Common flexor origin: Medial humeral epicondyle
Palmaris Longus
Action: Origin: thin ,fans out under palmar surface = palmar aponeurosis Common flexor origin: Medial humeral epicondyle
Brachioradialis muscle
Action: does not cross the wrist joint so actions limited to flexion, pronation/supination of forearm at the elbow Innervation: radial nerve Superficial muscle Runs humerus to radius - not full arm - does not cross wrist joint
Brachioradialis muscle
Action: flexion of arm + pronation/supination (depending on position) Innervation: Radial nerve
Pronator Teres muscle
Action: spin radius in pronation while giving a little flexion of forearm at elbow Teres = Round muscle From humerus to radius Innervation:
What tissue types are in the adult radial head? What tissue type is in the radial head of a young child? Whose radial head is much more easily deformed such that it can slip distally away from the ligament that encircles it?
Adult: Hyaline cartilage + bone Child: Hyaline cartilage only Child's is much more easily deformed
In the forearm and cubital fossa, what is the depth of the cephalic vein, median cubital vein + basilic vein? What fan of tendon separate them from the depth of the brachial artery?
All Subcutaneous - cephalic, median cubital + basilic veins Bicipital aponeurosis: broad aponeurosis of the biceps brachii which is located in the cubital fossa of the elbow and separates superficial from deep structures in much of the fossa Bicipital aponeurosis separates (cephalic, median cubital and basilic veins) from the brachial artery - do not want to poke through here and get to brachial artery if your intention is to draw blood from the vein
Extensor Compartment of forearm
All innervated by radial nerve Superficial: - Brachioradialis - Extensor Carpi radialis longus - Ext carpi radialis brevis - Ext carpi ulnaris Intermediate: - Extensor digitorum - Ext digiti minimi Deep: - Aconeus - Supinator - Abd poll longus - Ext poll brevis - Ext poll longus - Ext indicis
What ligament holds the radial head in place against the radial notch of the proximal ulna? Why can't this ligament attach directly to the radius?
Annular ligament of radius Radius has to be free to rotate in supination and pronation
Is that nerve anterior to the lateral epicondyle of the humerus or posterior to it?
Anterior
Arteries and Nerves in Deep Cubital Fossa
Arteries/nerves in deep cubital fossa: Brachial artery - bifurcates into redial and ulnar arteries at inferior cubital fossa (most people - some people bifurcates in axilla) Ulnar artery - goes deep to pronator teres muscle Radial artery - stays more superficial going out lateral
Why is the cephalic vein in the forearm not an idea vein for venipuncture?
Because the lateral antebrachial cutaneous nerve (lateral cutaneous nerve of the forearm) accompanies the cephalic vein.
Elbow - Anterior Medial Quadrant
Biceps Brachii Tendon to Medial Epicondyle Median nerve Brachial artery
What muscle inserts on the radial tuberosity of the radius? Name its partner, which attaches to the coronoid process of the ulna. What action do these two muscles share?
Biceps Brachii muscle Brachialis muscle Flexion of the forearm at the elbow
Forearm Flexor Forearm Actions
Biceps Brachii: flexion + supination Brachialis: flexion only (ulnar insertion) Pronator Teres: flexion + pronation Brachioradialis: flexion + pronation/supination - beverage carrying muscle, keeps you from spilling by protonation or supination Benefits: stability and options for forces that can be applied to the hand
What fan of tendon separates them from the depth of the brachial artery?
Bicipital aponeurosis of biceps brachii
What major vessel is lateral to the medial nerve? Lateral to that is the biceps brachii tendon.
Brachial artery
What other major structures are at the same depth as the brachial artery?
Brachial vein and median nerve. (If there is a relatively proximal terminal branching of the brachial vessels, the radial and ulnar arteries and veins will be present in the cubital fossa.)
What other major structures are the same depth as the brachial artery?
Brachial vein and median nerve. (If there is a relatively proximal terminal branching of the brachial vessels, the radial and ulnar arteries and veins will be present in the cubital fossa.)
Action of Brachioradialis muscle
Brachioradialis muscle: brings the forearm to an intermediate position between pronation and supination. When the forearm is in the supinated position, it will provide a pronating torque. When the forearm is in the pronated position, brachioradialis will provide a supinating torque. Relative to the more massive biceps brachii and brachialis muscles, the brachioradialis muscle is weak. But try comparing the brachioradialis muscle to the other forearm muscles. Its cross-sectional area and distance from the axis of rotation of the elbow suggest that, among the forearm muscles, brachioradialis is the most powerful forearm flexor.
Posterolateral muscles wrap posteriorly from brachioradialis
Brachioradialis muscle: does not cross the wrist joint - actions limited to flexion, pronation/supination of forearm at the elbow - takes arm to intermediate position (if in pronation will supinate, if supinated will pronate) Lateral + posterior from Brachioradialis: Extensor muscle mass Over bicep tendon from Brachioradilis: Flexor muscle mass
Ulnar artery
Branch of Brachial artery (bifurcates to ulnar + radial artery at cubital fossa) Travels deep to pronator teres muscle Supplies blood to the little finger side of the arm and the palm of the hand
Cubital Fossa soft tissues
Cubital Fossa: inside of elbow Antecubital Vein: any vein of the cubital fossa that is used for venipuncture - do not need to name the vein precisely if you only wish to record that you accessed a vein at the elbow Basilic vein: medial side Medial Cubital vein: crossing between the two Cephalic vein: lateral side (crossing near cubital fossa)
Actions of Flexor digitorum + flexor pollicis longus
Distal insertions of flexor digitorum profundus + pollicis longus give them actions at most distal joints of the digits: Wrist Metacarpophalangeal Proximal interphalangeal Distal interphalangeal 1st inerphalangeal Flexor digitorum superficialis: inserted on middle phalanges (so does not do extra curling - distal interphalangial joint) Deeper muscle goes further - a hole in flexor digitorum superficialis tendon allowing flexor digitorum profundus to pass through
The name of the pronator teres muscle makes one of its actions obvious. What is the other anatomical action of the pronator teres on the forearm at the elbow?
Flexion of the forearm at the elbow
What is the Brachialis muscle's only significant anatomical action on the forearm at the elbow?
Flexion of the forearm at the elbow
Flexor Digitorum Superficialis muscle - cut out superficial to see
Flexor Digitorum Superficialis muscle Four tendons from on muscle that go out into the hand/fingers to flex them What has been reflected or removed to show what we see here: (Top to bottom) 1/2: origin/insertion of pronator teres 3: Flexor carpi radialis muscle tendon 4: Palmaris Longus muscle tendon Median nerve runs deep to Flexor Digitorum Superficialis muscle
Forearm muscles + hands
Forearm has set of muscles that are there to serve the hand - Extensor mass in posterior Compartment - Flexor mass in Anterior Compartment If you had all this musculature in your hand it would be too large, the tendons run to hand allowing good movement Other Examples: Many muscles terminate in the forearm: biceps (radius), brachialis (attached to ulna) Pronator teres: starts on humerus ends on radius Brachioradialis: starts on humerus down to radius
What ligament attaches to the shaft of the radius?
Interosseus membrane of forearm
Elbow - Anterior Lateral Quadrant
Lateral Epicondyle to Biceps Brachii Tendon lateral antebrachial cutaneous nerve: more superficial Radial nerve: triceps, extensor musculature in posterior compartment of forearm
Lateral Humeroulnar ligament
Lateral collateral ligament complex on lateral side Complex: cannot anchor a big ligament from humerus to radius or it wouldn't spin - Lateral humeroulnar ligament reach ulnar at middle elbow from humerus to give stability For stability
Elbow - Posterior Medial Quadrant
Medial Epicondyle to Olecranon process of ulna Ulnar nerve
Medial Collateral ligament of elbow
Medial side of elbow Medial epicondyle of humerus to ulna (on medial side) - does not need to be very elaborate for stability Provides stability
What nerve goes "right up the middle" of the cubital fossa?
Median nerve
Two heads of pronator teres are separated by what?
Median nerve Point of possible impingement
Name the nerve in the arm that ends with a cutaneous branch that passes near the lateral side of the biceps brachii tendon. What is the name of that cutaneous nerve?
Musculocutaneous nerve
What ligaments attach to the head of the radius?
NO ligament attaches to the head of the radius.
Elbow - Posterior Lateral Quadrant
Olecranon process of ulna to Lateral Epicondyle No major or minor nerves
3 Extensor carpi muscles do not cross the wrist
Posterior side - extensor muscles Extensor carpi's that do not cross wrist joint: 1. Extensor carpi radialis longus 2. Extensor carpi radialis brevis 3. Extensor carpi ulnaris
We have discussed three of four "quadrants" of the elbow (a nerve and vessels in the anteromedial quadrant, one nerve in the posteromedial quadrant, two nerves in the anterolateral quadrant). Which of the four quadrants has no major nerve?
Posterolateral Quadrant
Anatomical Snuff Box
Radial Artery - palpable pulse Scaphoid Bone - floor of snuffbox Muscles: 1. abductor pollicis longus (base of first metacarpal) - pulls thumb out into abduction 2. extensor pollicis brevis (stops on proximal phalanx) 3. extensor pollicis longus
The fourth nerve is buried a little more lateral than that. Name it.
Radial Nerve
Elbow stable + mobile parts
Stable: B/w the trochlea of humerus + olecranon notch of ulna (stability limits movement of whole forearm for flexion/extension at elbow) Mobile: radius meets capitulum of humerus (flexes + extends and rotates) - b/w radius and ulna that lets radius roll/glide relative to ulna that stays in one place
Locations of nerves at elbow
Superficial + Deep radial nerve: lateral side of forearm Median nerve: Middle of the forearm as well Ulnar nerve: Medial in the forearm Musculocutaneous nerve (lateral antebrachial cutaneous nerve) and medial antebrachial cutaneous nerve not shown here
In the forearm and cubital fossa, what is the depth of the cephalic vein, median cubital vein and basilic vein?
Superficial fascia
What action does the Biceps Brachii muscle you named get by attaching to the radius and not the ulna?
Supination of the radius relative to the ulna
Radial artery
The major artery in the forearm; it is palpable at the wrist on the thumb side. Branch of Brachial artery (bifurcates to ulnar + radial artery at cubital fossa) - stays more superficial going out lateral
Which nerve is the only major nerve that passes posterior to the elbow joint (posterior to an epicondyle of the humerus)?
Ulnar nerve
Ulnar nerve vs. Median nerve muscles of forearm
Ulnar nerve: - Flexor carpi Ulnaris - Ulnar half of flexor digitorum profundus Median nerve: (all others) - pronator teres - palmaris longus - flexor digitorum superficialis - flexor carpi radialis - Radial half of flexor digitorum profundus - flexor pollicis longus - pronator quadratus
Median and Ulnar nerves in the hand
Ulnar nerve: medial in wrist - lots of ulnar nerve distribution in the hand Median nerve: comes in middle of wrist, coming out in the middle of hand - many branches throughout hand
Annular Ligament
binds the head of the radius to the ulna Allows supination and pronation while holding the radial head in place - All parts attach to ulna (no parts attach to radius) - Ulna to ulna (ring) Subluxation: In toddlers joint cartilages are soft and radial head is not prominent so escaping from the annular ligament (subluxation) is common - Pulled Elbow
Cubital Fossa
elbow pit Superior border: line between epicondyles Medial border: Pronator teres muscle Lateral border: brachioradialis muscle
Antecubital Vein
means any vein of the cubital fossa that is used for venipuncture. You do not have to name the vein precisely if you only wish to record that you accessed a vein at the elbow rather than the hand, neck, thigh, foot, or anywhere else.
