Venous Return & Upper Limb Vasculature
This vein, running superficially along the lateral arm, empties into the axillary vein and is often used for IV access.
What is the cephalic vein?
Identify the roots of the brachial plexus that contribute to the long thoracic nerve and explain why multiple roots are needed.
What are C5, C6, and C7? (Multiple roots provide redundancy for innervating serratus anterior)
Damage to this nerve causes weak shoulder abduction and lateral rotation. Which muscles are involved?
Axillary nerve; deltoid and teres minor
Define the anatomical boundaries of the axilla and explain why it’s considered a “pyramidal space.”
First rib (apex), teres major (base), humerus & scapula (walls); pyramid shape accommodates neurovascular bundle
A patient has weak elbow flexion and reduced sensation in the lateral forearm. Name the nerve and spinal roots.
Musculocutaneous nerve; C5–C6
This vein runs deep and medially along the arm and is often joined by the brachial veins before reaching the axillary vein.
What is the basilic vein?
The superior and middle trunks contribute to which cord, and what terminal branches arise from that cord?
Lateral cord; gives rise to musculocutaneous and part of median nerve
The dorsal scapular nerve arises from C5. List the muscles it innervates and describe a clinical sign if damaged.
Levator scapulae, rhomboid major/minor; clinical sign: depressed/retracted scapula, impaired scapular elevation/retraction
Explain the significance of the “fat M” in identifying terminal branches of the brachial plexus.
Helps locate musculocutaneous, median, ulnar nerves; practical for predicting nerve injury patterns
Injury to C5 fibers only affects which terminal branches and muscles?
Axillary (deltoid, teres minor), musculocutaneous (biceps, brachialis); limited shoulder abduction & elbow flexion
The axillary vein lies medial to this artery and follows it from the inferior border of the first rib to the teres major. Name one clinical implication of this relationship.
What is the axillary artery? (Implication: risk of arterial injury or compression during venous access or surgery)
Explain the functional rationale for having three anterior and three posterior divisions before forming the three cords.
Divisions allow fibers to be sorted for flexor (anterior) and extensor (posterior) compartments before converging into cords
Explain why injury to the long thoracic nerve results in scapular winging and which part of the scapula is most affected.
Loss of serratus anterior function → medial border protrudes posteriorly
Describe the relative positions of anterior vs posterior divisions to the axillary artery and their clinical significance.
Anterior divisions → in front; posterior divisions → behind; important for nerve block and surgical planning
Explain how scapular winging can distinguish between dorsal scapular vs long thoracic nerve injury.
Dorsal scapular → medial scapular retraction impaired; long thoracic → medial border protrudes, especially during arm push
In some individuals, accessory veins may create alternative pathways for venous return in the upper limb. Name one such vein and its significance.
What is the median cubital vein? (Significance: commonly used for venipuncture; connects cephalic and basilic veins)
A patient presents with weakness in both elbow flexion and wrist extension. Identify which cord(s) and terminal branches might be implicated.
Lateral cord → musculocutaneous (elbow flexion); posterior cord → radial (wrist extension)
Which posterior cord nerves contribute to both proximal (shoulder) and distal (forearm/hand) muscle function, and what are the implications for rehabilitation?
Radial nerve; loss affects elbow, wrist, and finger extension → therapy must target multiple joint movements
Most cords lie above the clavicle. Discuss why this anatomical detail affects clinical interpretation of brachial plexus injuries.
Injuries at neck vs axilla produce different deficits; surgical exposure may require clavicle mobilization
Posterior cord injury can affect multiple distal and proximal functions. Name at least three terminal branches and associated deficits.
Radial → wrist/finger extension; axillary → shoulder abduction; thoracodorsal → shoulder adduction/internal rotation
Describe the simplified clinical pathway of venous return from the hand to the subclavian vein and why knowing this simplification matters for therapists.
Superficial veins (cephalic, basilic) → axillary vein → subclavian vein; simplifies understanding of blood flow for positioning, edema management, and vascular assessment.
Explain how anatomical variations in C7 or T1 contributions can alter the presentation of median or ulnar nerve injuries.
If C7 contributes inconsistently to median nerve, wrist/finger flexion strength may vary; if T1 contributes inconsistently to ulnar nerve, hand intrinsic muscles may be partially spared
Identify the three subscapular nerves, their cord origin, and the muscles they innervate. Explain a scenario where an isolated posterior cord injury affects upper limb rotation.
Upper subscapular → subscapularis; lower subscapular → subscapularis & teres major; thoracodorsal → latissimus dorsi; injury → loss of internal rotation, adduction, extension at shoulder
Variations in terminal branch contributions (C7/T1) can alter clinical testing outcomes. Give an example for the median nerve.
C7 absent → weaker wrist/finger flexion; may appear as partial median nerve injury
A patient presents with weak grip and inability to adduct fingers. Trace the likely lesion from root to terminal branch and explain why.
C8–T1 roots → medial cord → ulnar nerve → intrinsic hand muscles affected