Upper Limb Anatomy Flashcards
Why are the axillary lymph nodes clinically significant, especially in breast cancer?
Axillary lymph nodes are crucial in breast cancer staging, as cancer cells often spread to these nodes. The involvement of different nodes helps assess cancer progression.
The pectoral nodes are often the first to be checked in breast cancer exams.
Describe the course of the nerves around the elbow joint and their associated arteries.
Think about how the radial, ulnar, and median nerves relate to nearby arteries.
The radial nerve runs with the deep branch of the brachial artery. The ulnar nerve runs alongside the superior ulnar collateral artery, and the median nerve accompanies the brachial artery
Understanding these relationships is crucial for avoiding nerve damage in elbow procedures.
Why is it useful to understand both dermatome maps and peripheral nerve maps?
Dermatome maps help trace issues to spinal roots, while peripheral nerve maps pinpoint specific nerves in the limbs. Each map is like a treasure map for locating nerve problems!
Two maps, one mission: finding and fixing nerve issues.
Think about the spool-shaped structure at the distal humerus.
Where is the trochlea of the humerus, and what does it articulate with?
The trochlea articulates with the ulna, forming part of the elbow joint.
Critical for hinge movement of the elbow.
What are common causes of Erb-Duchenne palsy?
Picture situations that might forcefully stretch the neck and shoulder apart.
Common causes of Erb-Duchenne palsy include:
- Trauma, such as a motorcycle accident
- Forceful downward shoulder pull (e.g., during childbirth or backpack pressure)
Often termed Backpacker’s palsy due to its common mechanism.
Imagine the median nerve as the ‘palm reader’ nerve.
Which regions does the median nerve own?
The median nerve is the “palm reader,” covering the palm side of the thumb, index, middle, and part of the ring finger.
The median nerve gives life to the palm’s magic.
Try to remember the family tree structure.
Use a fun mnemonic to remember the parts of the brachial plexus.
Use the mnemonic: “Rad Tacos Destroy Crunchy Burritos” for Roots, Trunks, Divisions, Cords, Branches.
Each part of the plexus is like a branch in the family tree.
What is the role of the posterior rami, and which areas do they serve?
The posterior rami supply the muscles and skin of the back, including the deep muscles like the erector spinae, and the skin near the spine.
Consider the nerves branching from the posterior cord.
What is a posterior cord injury, and which major nerves are affected?
Posterior cord injuries primarily affect the axillary nerve (deltoid and teres minor) and radial nerve (extensor muscles of the arm and forearm), leading to characteristic motor and sensory deficits.
Posterior cord injuries affect the upper limb’s extensor muscles.
Think about the attachment point for a major arm muscle.
What is the radial tuberosity and why is it important?
The radial tuberosity provides the attachment for the biceps brachii tendon.
Essential for forearm supination and elbow flexion.
Think of the radial nerve as the ‘sunbather’ nerve on the back side.
What areas does the radial nerve cover?
The radial nerve soaks up the posterior arm and forearm, plus the back of the hand. It’s like the sun-loving nerve, basking in the back.
Radial road covers your arm’s ‘backyard’
Consider hand contact with environmental surfaces.
Why does high exposure to contaminants make the thenar and midpalmar spaces prone to infection?
The palm frequently contacts environmental surfaces, increasing the risk of cuts or punctures, which allow bacteria to enter and spread within these spaces.
Frequent hand exposure to surfaces can introduce pathogens into deeper hand tissues.
Think of this as the nerve for ‘close hugs.’
Which nerve watches over the medial side of the upper arm?
The medial cutaneous nerve of the arm gives sensation to the inner upper arm, perfect for a close hug’s touch.
This nerve is your arm’s inner hug detector.
What are the clinical implications of potential spaces in the palm?
Several potential spaces in the palm can become sites of infection. The thenar space exists just anterior to the adductor pollicis muscle, while the midpalmar space lies posterior (deep) to the central compartment containing the long flexor tendons and lumbrical muscles.
Infections can spread through these spaces, affecting the surrounding structures.
Consider the complications associated with untreated fractures.
Why is early Dx of a scaphoid Fx important?
Scaphoid fractures may lead to avascular necrosis due to poor blood supply.
Scaphoid fractures can sometimes be missed on initial X-rays; follow-up imaging may be needed.
Consider the C5 and C6 dermatome regions.
Which sensory deficits are seen in Erb-Duchenne palsy?
Patients often experience numbness or sensory loss along the lateral arm and shoulder, corresponding to the C5 and C6 dermatomes.
Think about abduction, adduction, and finger joint functions.
Describe the function of the palmar and dorsal interosseous muscles.
The palmar interosseous muscles adduct the middle three fingers, while the dorsal interosseous muscles abduct them. Both muscle groups also assist in flexing the metacarpophalangeal joint and, due to their attachment, extend the proximal and distal interphalangeal joints.
Interosseous muscles play a key role in fine motor control and stabilization of the fingers.
Consider causes that compress the axilla
What are common causes of posterior cord injury?
Posterior cord injuries can result from:
- Crutch Palsy: Prolonged crutch use, compressing the axilla.
- Saturday Night Palsy: Falling asleep with the arm draped over a hard surface, compressing the radial nerve.
Compression in the axilla is the usual cause of posterior cord injuries.”
Think of the inner bump near the elbow.
Distal Humerus: Describe the medial epicondyle and its function.
The medial epicondyle serves as an attachment point for forearm flexor muscles.
Commonly known as the origin of the ‘funny bone’ sensation.
What is the general path of lymphatic drainage in the axilla?
Lymph in the axilla flows through stages of nodes: Humeral, Subscapular, Pectoral, Central, Apical, and then finally to the Supraclavicular nodes.
Imagine this map as ‘city streets’ named after nerves, not roots.
How does the peripheral nerve map differ from the dermatome map?
Consider the source of innervation for specific nerves versus spinal roots.
The peripheral nerve map shows areas of skin innervated by specific peripheral nerves, not by spinal roots. It’s like a city map where each “street” has a name—Median Street, Ulnar Avenue, and Radial Road.
Peripheral nerve maps help identify nerve injuries outside the spinal cord.
Where is the coracoid process found, and what attaches here?
Think about the hook-like, anterior projection near the glenoid cavity.
The coracoid process is a bony projection on the anterior scapula, providing attachments for the *biceps brachii short head, coracobrachialis, and pectoralis minor. *
Helps stabilize the shoulder joint
Think of a villain that leaves the wrist in a ‘drop’ position.
What happens in a posterior cord injury, and what is the resulting condition?
Known as Saturday Night Palsy or Crutch Palsy, this villain paralyzes the posterior arm muscles, causing “wrist drop.”
Posterior cord injuries affect the radial nerve, leading to wrist drop.
Think of apical nodes as the final stage in the axilla.
What do the apical lymph nodes drain, and where does lymph go next?
Apical lymph nodes receive lymph from the central nodes and drain into the supraclavicular nodes and eventually into the venous system.
These nodes are the final checkpoint before lymph returns to the bloodstream.
Think about the groove between tubercles.
What is the intertubercular sulcus, and what runs through it?
The intertubercular sulcus aka bicipital groove, lies b/n the greater and lesser tubercles, housing the *tendon of the long head of the biceps brachii. *
Also a pathway for the bicipital aponeurosis.
Think of a claw-like villain named Klumpke.
Who is the villain of lower brachial plexus injuries?
Klumpke’s Paralysis is a lower injury villain, causing a “claw hand” by paralyzing the hand’s intrinsic muscles, with sensory loss in the medial hand and forearm.
Klumpke’s ‘claw hand’ leaves the hand in a fixed position.
Think about the narrowing just below the humeral head.
Describe the anatomical neck of the humerus.
The anatomical neck is the narrow region directly below the humeral head, marking the boundary between articular surface and the humeral shaft.
Serves as a site for the attachment of the joint capsule.
Think of the primary nerve roots affected by neck stretching.
What are upper brachial plexus injuries, and what nerve roots are primarily involved?
Upper brachial plexus injuries typically involve the C5 and C6 nerve roots, which can be injured by excessive lateral neck stretching away from the shoulder.
Common causes include trauma from falls, motorcycle accidents, or forceful shoulder pulls.
Think about which rami form plexuses and which stay localized.
What is a key difference between anterior rami and posterior rami in terms of structure?
Anterior rami form large nerve plexuses (e.g., brachial, lumbar) and supply the body wall and limbs, while posterior rami are smaller and supply only the back muscles and skin.
Anterior rami serve larger, more complex areas; posterior rami serve the back.
Think about how the arm’s range of motion is affected.
What is the overall impact of Erb-Duchenne palsy on movement and function?
Erb-Duchenne palsy limits shoulder abduction, elbow flexion, and external shoulder rotation, resulting in a frozen, restricted upper limb posture. This impairs daily tasks like reaching or lifting the arm.
Without treatment, this can cause long-term functional limitations.
Think about the location just below the glennoid cavity.
Describe the infraglenoid tubercle and its role.
The infraglenoid tubercle is found below the glenoid cavity and serves as the attachment point for the long head of the triceps brachii.
Important for arm extension and shoulder support.
Think of the pointy part of the elbow.
Describe the olecranon process of the ulna.
The olecranon process forms the point of the elbow and provides attachment for the triceps brachii.
Vital for elbow extension
Think of the ground level where people gather.
Describe the base of the axilla and its main features.
The base is like the “Axillary Plaza,” with landmarks like the Axillary Fossa and Anterior and Posterior Axillary Folds—places where movement and structure meet.
The base is like the plaza where everything flows and connects.
Imagine the central nodes as the main collection basin
What is the role of the central lymph nodes in axillary lymphatic drainage?
Central lymph nodes receive lymph from the humeral, subscapular, and pectoral nodes and drain into the apical nodes.
They are the key hub for lymph collected from the entire axilla.
Why are there multiple venae comitantes in the upper limb but fewer in the lower limb?
In the upper limb, venae comitantes benefit from arterial pulsation to move blood without gravity’s resistance. In the lower limb, larger single veins like the femoral vein work with muscle pumps to combat gravity effectively.
Upper limbs use arterial pulses; lower limbs rely on larger veins and muscle pumps.
Try ‘Happy Students Prefer Constantly Amazing Science’.
Use a fun mnemonic to remember the order of axillary lymph nodes.
H: Humeral
S: Subscapular
P: Pectoral
C: Central
A: Apical
S: Supraclavicular
This mnemonic helps recall the lymph node order in axillary drainage.
Think about the palmar spaces and tendon sheaths.
Why are the spaces within the hand prone to similar infections as the thenar and midpalmar spaces?
In addition to the thenar and midpalmar spaces, the digital tendon sheaths in the fingers can trap infections, especially after puncture wounds, leading to tenosynovitis (inflammation of the tendon sheaths).
Infections here can spread rapidly along tendon sheaths, requiring prompt treatment.
Think about the projection below the trochlear notch.
What is the coronoid process of the ulna, and where is it located?
The coronoid process is a triangular projection on the anterior ulna, fitting into the coronoid fossa of the humerus during elbow flexion.
Enhances elbow stability during flexion.
Think of T1 as the ‘inner arm protector.”
Where does T1 hang out, and what area does it guard?
The T1 dermatome provides sensory innervation to the medial side of the forearm and arm, close to the axilla.
T1 is often assessed in cases of thoracic outlet syndrome.
Imagine C5–C7 as the arm’s ‘security team’ on the outer side.
What spinal nerves innervate the lateral side of the upper limb in the dermatome map?
The lateral upper limb is protected by C5, C6, and C7—like bodyguards for the arm, each guarding specific zones.
C5 guards the shoulder, C6 covers the thumb, and C7 watches over the middle finger.
Think about the muscle heroes in the back alley
Who hangs out in the back wall of the axilla neighborhood?
In the “Back Alley,” we find the Subscapularis (the strong, silent type), Teres Major (Subscapularis’s reliable sidekick), and Lat Dorsi (the muscle giant). The Long head of Triceps Brachii joins as the quiet powerhouse.
The Back Alley Heroes keep the neighborhood strong and stable.
Consider scenarios with upward arm traction.
What activities or injuries can lead to lower brachial plexus injuries?
Common causes include:
- Falls with the arm pulled overhead.
- Difficult births, particularly with breech deliveries where the baby’s arm is pulled upward.
