Lecture 22-24: Upper limb Flashcards
Describe the basic mammalian form of a limb.
A girdle attaching the limb to the axial skeleton, then a single proximal long bone, then two distal long bones, then pentadactyl hand/foot
What vertebrae supply the upper limb?
C5-T1
What is the rotation of the upper limb relative to the lower limb?
Upper limb: 90º external lateral rotation.
What are most features of the scapula for?
Muscular attachments.
What sacrifice does the shoulder joint make in return for such a broad range of motion?
It sacrifices stability.
What part of the scapula is labelled (1)?
What part of the scapula is labelled (11)?
What part of the scapula is labelled (8)?
What are the 3 posterior rotator cuff muscles? Where on the diagram are they located?
- Supraspinatus: located at (9) supraspinous fossa
- Infraspinatus: located at (7) infraspinous fossa and attaching along the medial border
- Teres minor: located at (7) along the lateral border
What is the anterior rotator cuff muscle? Where on the diagram is it located?
Subscapularis: located at (12) the scapula fossa
Where do bones normally fracture?
At their weakest site.
Where on the clavicle is most likely to fracture? How does this happen?
On the biggest curve: lateral 1/3 and medial 2/3. Medial end stays attached to the sternum and the lateral end moves with the upper limb
What type of bone is the humerus?
Long bone
Where do vessels and nerve enter a long bone?
The nutrient foramen, in the middle of the shaft (diaphesis)
What is the difference between the anatomical neck and the surgical neck?
Anatomical neck is usually the position of the growth plate
Surgical neck is the most common site of fracture of the humerus
What is the name of the articular surface at the ends of long bones?
Epiphysis
What separates the metaphysis and the epiphysis?
The epiphysial growth plate
Identify the lesser, greater, and deltoid tuberosities. What are their purposes?
1 - greater
2 - lesser
7 - deltoid
Sites of muscle attachment
What is the name and role of the groove between the lesser and greater tuberosities?
Bicipetal groove - groove for bicep ligaments.
Identify and name the epicondyles. What are their purposes?
10 - medial epicondyle; site of attachment for anterior/flexor muscles in the forearm
12 - lateral epicondyle; site of attachment for posterior/extensor muscles in the forearm
What are the bones of the forearm? Which is lateral and which is medial?
Ulnar (medial) and radius (lateral)
Which of the bone of the forearm articulates at the wrist?
Radius
Which of the bone of the forearm articulates at the elbow?
Ulnar
The bones of the wrist are organised in two rows; what are the bones in the proximal row (from lateral to medial)?
Scaphoid (anatomical snuff box), lunate, triquetrum, pisiform
The bones of the wrist are organised in two rows; what are the bones in the distal row (from lateral to medial)?
Trapezium (beneath the thumb), trapezoid, capitate, hamate
Which is the last carpal bone to ossify and at approximately what age?
Pisiform at about 13 years
By what age do all the carpal bones (except the pisiform) ossify?
7
What 3 humeral structures are endangered of fracture?
Surgical neck
Midshaft
Supracondylar
Describe how one may most likely dislocate their elbow.
Falling backwards onto a supinated hand. This fall causes a classic posterior dislocation at the elbow joint where the results in the olecranon in a posterior posiiton and the distal end of the humerus in an anterior position.
What boney structure is at risk of fracture in an elbow dislocation?
The coronoid process of the proximal ulnar.
Describe the path of the vascular supply on the scaphoid.
Scaphoid gets its blood supply at distal end, which then tracts back and supplies proximal end of the scaphoid.
What complication may arise from scaphoid fractures?
Scaphoid fractures can cause avascular necrosis of the proximal end.
What fracture of the upper limb is the most common in the elderly? Why?
Colle’s fracture: a fracture of the distal radius characterised by the dorsal displacement of the wrist and hand. A common fracture in the elderly because of osteoporosis.
What is a ‘parry fracture’?
Fracture at the shaft of the ulnar.
What important non-skeletal structure makes up for the shoulder joint’s lack of stability?
Fixator muscles of the rotator cuff.
What injury(s) is commonly associated with ball and socket joints?
Dislocations and subluxations
What are the three joints of the shoulder complex and what bones are involved?
Sternoclavicular joint
Acromioclavicular joint
Glenhumeral (shoulder) joint
What are the key features of the sternoclavicular and acromioclavicular joints?
Sternoclavicular - intra-articular disc, very strong capsule, limitation of movement by accessory costoclavicular ligament.
Acromioclavicular - weak capsule, mainly stabilized by coracoclavicular ligament that prevents upward rotation of the clavicle
What is the weakest point of the shoulder joint?
Area inferior to the glenohumeral joints because it is minimally reinforced.
What is the most common direction of dislocation/subluxation of the shoulder? Why?
Downward - as in the direction that a rugby tackle would push the humerus - because it is minimally reinforced inferior to the glenohumeral joint.
Why is the glenohumeral joint ‘intrinsically unstable’?
Large head with shallow/smaller socket
What structure helps deepen the glenoid fossa?
The glenoid labrum
Of what if the glenoid fossa made?
Fibrocartilage
What structure allows the shoulder joint so mobile?
The small fold in the inferior aspect of the joint capsule that allows a large range of abduction.
What three structures strengthen the shoulder joint?
Coracoacromial ligament protects the superior aspect.
Long head of the biceps.
The rotator cuff muscles that help stabilize and pull-in the head of the humerus.
What 2 structures may be irritated by upward movement of the humerus?
The sub-acromial bursa and the supraspinatus via an ‘impingement’ between the head of the humerus and the scapula.
How do the muscles of the rotator cuff increase the stability of the joint?
By blending with the joint capsule they pull the head of the humerus into the glenoid fossa.
What is the weakest aspect (view) of the rotator cuff muscles.
Inferior aspect of the rotator cuff muscles; reason for so many downward dislocations/subluxations.
With which joint is the subacromial bursa associated? Does it communicate?
It is superior to the glenohumeral joint and it does not communicate.
What may irritate the subacromial bursa?
Over head rotation of the upper limb.
What is bursitis? What is the arc of pain.
Bursitis - inflammation of the bursa by compression between bones, tendons, or muscles
Arc of pain – between 60-120º of abduction
What may happen to the joint capsule as a consequence of dislocation/subluxation?
Stretching or tearing
What non-synovial structure is at risk of damage in inferior shoulder dislocation?
Impingement of the axillary nerve
Hinge joints are always in what plane? What movements does this allow?
Saggittal; flexion/extension
What are collateral ligaments?
Those ligaments that run down the side of the hinge/hinge-like joint.
What structure at a hinge joint is always easy to identify and name?
The collateral ligaments
What pivot joint is located in the upper limb? What bone articulates? What movement does it allow?
The ulnar-radial joint just distal to the elbow joint; the radius (most lateral) pivots on the ulnar (most medial); It allows pronation and supination.
Name three places in the upper limb that have collateral ligaments.
Elbow
Fingers (interphalangeal joints)
Wrist (distal radius, scaphoid, and lunate)
Are collateral ligaments only found at hinge joints?
No; also found at hinge-like joints.
Fill in the blank: Muscle a located in __________, surrounded by ___________
Compartments; deep fascia
What are the fascia of the arm and forearm each called
Arm/upper arm: bracial fascia
Forearm: antebraial facia
What separates muscle comparments, eg in the forearm?
Interosseus membrane
What is the role of the facial septa?
Attaches to bone and separates individual muscles
What are the three roles of the interosseus membrane of the forearm?
Binds radisu and ulnar, provides attachments for muscles in the flexor and externsor compartments of the forearm, directs forces between the radius and the ulnar (eg, during a fall the force will be transfered from the radius to the ulnar and elbow joint)
What is Colle’s fracture?
Fracture at the wrist from landing on an open palm when falling.
What is the retinaculae?
Deep fascia at the wrist
What is the role of the retinaculae?
Holds tendons in place (ie, prevents them from bostringing) and protects nerves and vessels
What structure forms the roof of the carpal tunnel?
The flexor retinaculae
What is the contents of the carpal tunnel?
Tendons of the flexor compartment (9), 2 arteries, and the median nerve
The proximal border of the flexor retinaculae corresponds with what feature of the skin of the wrist?
The most distal wrist crease
What is the cause of ‘carpal tunnel syndrome’?
Compression of the carpal tunnel, eg from effusion, and thus compression of the median nerve
Why are pregnant women prone to carpal tunnel syndrome?
Increased systemic fluid retention
What are the four roles that muscles can take? (eg, primemover)
Primemovers, antagonists (opposing movement at a joint compared to the agonist), synergists (helps perform the same movement at a joint as the agonist), fixators
Why are superficial/extrinisic muscle of the back not considered to be true back muscles?
They have one attachment on the back and one attachment on the upper limb. They are primemovers of the shoulder girdle and at the shoulder joint.
What are the four extrinsic muscles of the back?
Levator scapulae, trapezius, latissimus dorsi, rhomboids
What are the three muscles of the anterior chest wall that act on the upper limb?
Pectoralis major, pectoralis minor, serratus anterior
What is the action of pectoralis major?
Powerful flexion at the shoulder
What is the action of pectoralis minor?
Protraction of the scapula
What is the action of serratus anterior?
Stabilizes the scapula against the chest wall
Why is there a risk of having a ‘winged’ scapula as a consequence of mastectomy?
May accidently damage a nerve and cause paralysis of the serratus anterior, thus it will not hold the scapula against the posterior chest wall and it will ‘wing’
What type of muscle are the scapula/rotator cuff muscles?
Fixators
What is the role of the rotator cuff muscles?
Since they blend with the joint capsule, they pull the head of the humerus deeper into the glenoid fossa. Therefore increasing compression and stability of the joint.
What are the muscle of the anterior arm/upper arm?
Biceps (long head and short head), brachialis, and coracobrachialis
What are the movements of the biceps?
Flexion at the shoulder joint and flexion at the elbow joint
What is the movement of the brachialis?
Flexion at the elbow
Are the superificial or the deep muscles of the forearm longer?
Superficial
What are the action of the anterior and posterior muscles of the forearm?
Anterior: extension at the wrist and fingers
Posterior: flexion at the wrist and fingers
Are the extensors or flexors in the forearm weaker?
Extensors are weaker, flexors are stronger
What are the four muscles of the flexor compartment of the forearm?
P.F.P.F
Pronator teres (PT)
Flexor carpi radialis (FCR)
Palmaris longus (PL)
Flexor carpi ulnaris (FCU)
Where is the common flexor origin of the forearm located?
Superficial flexor muscles of the forearms originate from the medial epicondyle.
Which of the superficial muscles of the flexor compartment of the forearm do NOT cross the wrist?
PT - pronator teres
What is the muscle of the intermediate layer of the forearm?
The flexor digitorum superficialis (FDS)
What are the three muscles of the the deep layer of the forearm?
Flexor pollicis longus (thumb) (FPL), flexor digitorum profundus (FDP), and pronator quadratus (PQ)
How many layers of muscle are there in the extensor compartment of the forearm?
2: superficial and deep
Where is the common extensor origin (CEO) of the muscles in the forearm?
The lateral epicondyle
How many wrist extensors and how many finger extensors are there in the superficial layer in forearm?
Wrist: 3
Finger: 2
True or false: the superficial extensor muscles of the forearm are used for broad, crude movements, like grip.
True
What kind of movement are the extensor muscles in the deep layer of the forearm used for?
Delicate, fine movements
How many muscles are there in the deep layer of the extensor compartment of the forearm? What are their actions?
Five
A supinator, 3 that extend/abduct the thumb, and one that extends the ring finger
True or false: when you want to curl your fingers only the muscles in the anterior compartment of the forearm are used. Justify your response.
False: the muscles in the posterior compartment act synargistically to prevent unwanted wrist flexion
What are the roles of the synovial sheath in the hand?
Reduce friction of the tendons and prevent bowstringing
What is the role of the intrinsic muscles of the hand?
Fine tune muscle of the fingers and thumb
What are the movements of the thenar muscles?
Flexion, extension, abduction, adduction, and rotation of the thumb
Hypothenar muscles are muscle belonging to which finger?
The pinky/little finger
What are the 4 arteries of the upper limb?
Axillary, brachial, radial, ulnar
Which artery is occluded when taking a blood pressure reading?
The brachial artery
True or false: the radial artery forms anastomosis with the ulnar arteries via the deep palmar arch.
False: the radial artery forms anastomosis with the ulnar arteries via the superficial palmar arch.
Which blood vessel in the wrist is pulpated for heart rate readinings?
The radial artery
Nail beds are supplied by which arteries?
digital arteries
Why are the digital arteries susceptible to avascular necrosis and vasospasm?
Digital arteries are considered ‘end’ arteries.
Why are lacerations of fingers are surgically important?
If the digital artery spurts blood then there is a good chance that the digital nerve has been damaged.
What is the easiest way to dislocated the elbow?
Falling backwards and landing on the hand with the elbow slightly flexed. The ulnar then displaces posteriorly.
What part of the ulnar is at risk of fracture in an elbow dislocation?
Coronoid process
If the coronoid process what blood vessel is at risk of damage?
The brachial artery
What is Volkman’s ischemia?
If there is limited, or no, blood supply to the forearm (radial and ulnar arteries) and leads to avascular necrosis of the forearm.
Where do the superficial veins of the arm begin?
The dorsal venous arch (back of hand)
What are the three main tributaries of the dorsal venous arch?
Cephalic, basilic,
Which blood vessel of the upper limb are venepunctures most often performed on?
The median cubital vein
What are venae comitantes?
A pair of venes lying either side of and that flow in the opposite direction of an artery.
What is the purpose of venae comitantes?
- Warm venous blood.
- Pulpations of the artery help venous return
All the lymphatic vessels of the upper limb drain to which lymph node?
The axillary lymph node
After they drain to the axillary lymph nodes, the lymphatic vessels of the upper limb then drain to which veins?
The veins in the necks
The right lymphatic duct drains lymph from what area of the body?
Right upper arm, right side of the head/neck, right side of the thoracic cavity
The thoracic trunk drains lymph from what area of the body?
All of the body that is not drained by the right lymphatic duct
What is a watershed area of lymph drainage? Where are the two watershed areas of lymph drainage?
Watershed area means can drain to both axillary nodes and inguinal nodes.
- Cervical-axillary watershed - the area in line with the clavical;
- Axillary -inguinal watershed - the area in line with the naval
Does lymph drainage cross the midline?
Yes
What is the clinical significance of the supraclavicular nodes?
If a cancer metastasises in the lymp they will collect in the lymph nodes. If your right supraclavicular node has a cancer in it then it will have come from the right thorax/upperlimb/head/neck wheres if your left supraclavicular node has a cancer in it then it could have come from anywhere else in the body.
Which spinal cord segments inervates the dermotomes of the skin? Which one inervates the middle three fingers?
C4-T2; C7
What is the name of the plexus that supplies the upper limb?
The brachial plexus
Which splinal cord segments supply the brachial plexus?
C5-T1
True or false: counter-intuitively, the posterior branches of the brachial plexus supply the flexor compartments and the anterior branches supply the extensor compartments of the upper limb.
False: the posterior branches of the brachial plexus supply the extensor compartments and the anterior branches supply the flexor compartments.
What are the 5 nerves of the brachial plexus? Which compartments do they supply?
3 * flexor compartment nerves: musculocutaneous, median, ulnar
2 * extensor compartment nerves: axillary, radial
Which spinal cord segments supply the musculocutaneous nerve? What muscles does it innervate?
C5, C6; supplies the flexors of the elbow and the lateral aspect of the forearm
Which spinal cord segments supply the median nerve? What muscles and skin segments does it innervate?
C5-T1; most muscles of the anterior compartment of the forearm, the skin and nail beds of the lateral 3.5 digits
What structure in the wrist does the median nerve pass through? Therefore, the median nerve is particularly susceptible to what injury?
Compression, especially in carpal tunnel syndrom.
Which spinal cord segments supply the ulnar nerve? What muscles and skin segments does it innervate?
C8, T1; remaining muscles of anterior compartment of the forearm and hand (except thumb), medial 1.5 digits (palmar and dorsal surfaces)
The ulnar nerve is particularly susceptible to what injury? (Think funny bone.)
Compression or stretch across the medial epicondyle
Does the ulnar nerve pass deep to or superficial to the retinaculum
Superficial
Which spinal cord segments supply the axillary nerve? What muscles and skin segments does it innervate?
C5 & C6; deltoids, skine over the should (military badge area)
The axillary nerve is susceptible to damage in what two injuries?
Shoulder dislocation and fracture to surgical neck of the humerus.
Which spinal cord segments supply the radial nerve? What muscles and skin segments does it innervate?
C5-T1; extensor muscles of the arm and forearm; skin of arm, forearm, and back of hand (including the lateral 3.5 digits)
The radial nerve is susceptible to damage in what injury of the upper limb?
Fracture of the shaft of the humerus.
What is Saturday night palsy?
Acute trauma to the radial nerve (eg, extended compression after a big one) that causes normally temporary, indefinite loss of sensation of the back of the forearm and hand and loss of control of extensor muscle. Results in ‘wrist drop.’
Define “dermotome.”
Area of skin supplied by a single spinal cord segment
What is Erb’s palsy? What position does the upper limb take?
‘Waiter’s tip’ position: paresthesia in dermatomes C5 & C6, paralysis of myotomes C5 & C6 (ie, elbow flexors and wrist extensors)
What is Klumpke’s palsy? What position does the upper limb take?
Paraesthesia in C8 & T1, paralysis of intrinsic hand muscles: creates a ‘claw’ hand and causes loss of fine motor control
Injury to what nerve structure may cause Erb’s palsy? Give an example of how this might happen.
Damage to the upper trunk of the brachial plexus. Eg, during forceful lateral flexion of the head on shoulder during a car crash or birth
Injury to what nerve structure may cause Klumpke’s palsy? Give an example of how this might happen.
Damage to the lower trunk of the brachial plexus. Eg, Sudder traction when arm is caught/hangning/during birth.
True or false: the brain is encoded for specific muscles?
False: the brain is encoded for specific movements
True or false: two muscles at the same joint with the same movement have the same myotome.
True
Snakes alive…
it’s C5
6 & 7…
down from heaven
5 & 6…
pick up sticks
7 & 8…
in the grate
Supine flicks…
that’s C6
7 & 8 (again)…
pronate
Royal wavin’…
6 & 7
7, 8…
Masturbate
T1…
adduction and abduction of the thumb and fingers
