UPPER LIMB - ARM AND CUBITAL FOSSA
I. UPPER LIMB (brachium)
A. Landmarks - shoulder and arm
1. Jugular (suprasternal) notch
2. Clavicle
3. Coracoid process
4. Acromion
5. Tubercle of humerus
6. Anterior axillary fold - pectoralis major
7. Posterior axillary fold - lat. dorsi and teres major
8. Biceptal grooves
9. Intermuscular septa
10. distal humerus and landmarks
B. Superficial features of the upper limb
1. Superficial veins:
a. Basilic vein
i. ulnar continuation of dorsal venous arch
ii. pierces brachial fascia at level of midarm to enter neuromuscular compartment
iii. joins brachial veins to form axillary vein
b. Cephalic vein
i. radial continuation of dorsal venous arch
ii. joins basilic via median cubital vein
iii. ascends in biceptal groove and enters deltopectoral triangle
iv. pierces brachial fascia and costocoracoid membrane to enter axillary v.
c. Drainage (deep veins)
i. Brachial veins > axillary vv. > subclavian v. + internal jugular
ii. brachiocephalic v. > superior vena cava > heart (rt. atrium)
2. Cutaneous nerves of upper limb
a. Shoulder
i. Supraclavicular nerves - from cervical plexus (C1-4, mostly C3-4, ventral rami)
b. Arm and forearm
i. Superior lateral brachial cutaneous nerves (br. axillary nerve)
ii. Posterior brachial cutaneous nerves (br. radial nerve)
iii. Medial brachial cutaneous (medial cord)
iv. Intercostobrachial nerve (T2) - lat. cutaneous br. - anastomosis w/ med. brachial cutaneous n. - important for referred pain from cardiac region
v. Lateral antebrachial cutaneous (br. musculocutaneous nerve)
vi. Posterior antebrachial cutaneous (br. radial nerve)
vii. Medial antebrachial cutaneous (medial cord)
c. Wrist and hand – see diagram for the approximate (typical) positions of these nerves in the hand=>
i. Radial nerve (“R”)
(a). superficial branches - medial and lateral
ii. Ulnar nerve (“U”)
(a). dorsal branch
(b). palmar branch
iii. Median nerve (“M”)
(a). palmar branch
(b). digital branches
(c). motor branch - to thenar muscles
II. ARM (BRACHIUM)
A. Humerus
B. Brachial fascia: deep fascia - continuous with pectoral and axillary fascia
1. Intermuscular septa (2): divide arm into anterior (flexor) and posterior (extensor) compartments
2. Neurovascular compartment
a. contains
i. brachial artery
ii. venae comitantes
iii. median nerve
iv. basilic vein
v. medial antebrachial cutaneous nerve
C. Preaxial muscles of the arm = flexors-musculocutaneous innervation
1. Biceps brachii
a. Attachments:
i. long head - supraglenoid tubercle of scapula
ii. short head - coracoid process
iii. biceptal aponeurosis - blends with antebrachial fascia
iv. distal - radial tuberosity
b. Nerve: musculocutaneous
c. Artery: brachial
d. Action: flexion, supination when limb flexed (screwdriver motion)
2. Coracobrachialis
a. Attachments: Coracoid process to medial humerus
b. Nerve: musculocutaneous (passes through the muscle)
c. Artery: brachial
d. Action: flexion, adduction
3. Brachialis
a. Attachments: lower ant. humerus to coronoid process of ulna
b. Nerve: musculocutaneous
c. Artery: radial recurrent, brachial
d. Action: flexion (most powerful flexor of arm)
D. Postaxial muscles of arm -Extensors - Radial innervation
1. Triceps brachii
a. Attachments:
i. long head: infraglenoid tuberosity of scapula
ii. lateral head: posterior/lateral humerus
iii. medial head: posterior humerus
iv. distal: to posterior olecranon and deep fascia
b. Nerve: radial
c. Artery: profunda brachii
d. Action: Extends forearm, adduction
2. Anconeus
a. Attachments: lateral epicondyle of humerus to olecranon and posterior ulna
b. Nerve: radial
c. Artery: profunda brachii
d. Action: extension of forearm, weak, assists triceps
E. Nerves of the arm - terminal branches of brachial plexus
1. Axillary nerve: shoulder region (T. minor and Deltoid)
2. Median nerve: no branches in arm
3. Ulnar nerve: no branches in arm
4. Musculocutaneus nerve: pierces coracobrachialis m. - supplies preaxial mm. - become lateral antebrachial cutaneous -lies on brachialis muscle
5. Radial nerve: supplies postaxial mm. - divides into deep and superficial branches, lies in spiral groove
a. posterior antebrachial cutaneous
b. lateral brachial cutaneous
F. Blood vessels of the arm
1. Brachial artery - continuation of axillary below teres major
a. Deep (profunda) brachial artery - in radial groove, accompanies radial nerve
i. middle collateral artery forms anastomoses with interosseus recurrent a.
ii. radial collateral artery: anastomoses with radial recurrent (radial a.)
iii. ascending branch
b. Nutrient humeral artery: enters nutrient canal
c. Superior ulnar collateral artery: anastomoses with
i. posterior ulnar recurrent (radial a.)
ii. inferior ulnar collateral (br. of brachial)
d. Inferior ulnar collateral artery:
i. anterior branch: anastomoses with anterior ulnar recurrent (ulnar a.)
ii. posterior branch: anastomoses with superior ulnar collateral and posterior ulnar recurrent
2. Brachial veins
a. paired either side of brachial artery
b. medial and lateral branches form axillary vein
c. cephalic vein
d. basilic vein
e. median cubital vein
G. Brachial lymphatics
1. cubital nodes > lateral and central nodes > Apical > Subclav. Lymph Tr.
III. CUBITAL FOSSA
A. Triangular space at bend of elbow-important area related to neurovascular structures
B. Boundaries
1. Superiorly: line connecting epicondyles of humerus
2. Medial: pronator teres muscle
3. Lateral: brachioradialis muscle
4. Floor: brachialis and supinator muscles
5. Roof: deep fascia and biceptal aponeurosis
C. Contents
1. Biceps tendon – to radial tuberosity
2. Brachial artery
3. Median nerve
4. Radial nerve - under brachioradialis m.
5. Superficial to roof
a. median cubital vein
b. medial antebrachial cutaneous nerve
c. lateral antebrachial cutaneous nerve
IV. PERIPHERAL NERVE LOSS VERSUS SPECIFIC SEGMENTAL LOSS
A. Sample actions to test specific nerves and/or specific levels
1. axillary n. - abduct arm (C5-6)
2. musculocutaneous n. - flex supinated forearm (C5-6)
3. radial n. - extend hand and fingers (C6-T1) extend fingers (C7-8)
4. median n. - flex wrist and fingers (C6-T1)
5. femoral n. - extend knee (L2-4)
6. obturator n. - adduct thigh (L2-4)
7. peroneal n. - dorsiflex ankle and extend toes (L4-S2)
8. tibial n. - plantar flex and flex toes (L4-S3)
B. Sample reflexes to test specific muscle innervation and help determine levels
1. Extremities - deep reflexes
a. biceps reflex (pictured below) - musculocutaneous n. (C5-6)
b. triceps reflex - radial n. (C6-7)
c. wrist extension - radial n. (C7-8)
d. patellar - femoral n. (L2-4)
e. Achilles - tibial n.(S1-2)
2. Skin reflexes
a. interscapular - rhomboids (C4-5)
b. abdominal - abdominal wall (T7-12)
c. cremasteric - cremasteric m. (L2)
d. gluteal - gluteus m. (L5-S1)
e. plantar - toe flexors (L4-S3)