Anatomy (Arm and Elbow - 11/4) Flashcards
Dermatomes C5 C6 C7 C8
C5 Shoulder
C6 Thumb
C7 Middle Finger
C8 Little Finger
Dermatomes
T4
T10
T4 - Nipple
T10 - Umbilicus
Dermatomes L1 L5 S1 S2,3,4
L1 - Groin
L5 - Medial Foot
S1 - Lateral Leg/Foot
S2,3,4 - Anal Area
Myotomes C5 C6 C7 C8/T1
C5 - UE Abduction
C6 - Flexion of arm/forearm
C7 - Extension of forearm
C8/T1 - Intrinsic hand muscles
Myotomes L2 L3,4 S1 L5 S1,2
L2 Flex thigh L3,4 Extend leg S1 Flex leg L5 dorsiflexes foot S1,2 Plantar flexes foot
What lies in intertubercular sulcus?
Long head of biceps
What does capitulum articulate with?
Head of radius
- lateral side
What does trochlea articulate with?
Trochlear notch of ulna
- medial side
What moves into coronoid fossa with flexion of forearm?
Coronoid process (front of ulna)
What moves into radial fossa with flexion of forearm?
Head of radius
Medial epicondyle = origin site for
flexor muscles of forearm/head
Lateral epicondyle = origin site for
extensor muscles of hand
Radial groove (location and what’s there)
Posterior surface of humerus - radial nerve and deep brachial vessels
Olecranon fossa
posterior side of distal humerus, olecranon process of ulna there on extension of forearm
Ulnar nerve
Derived from medial cord –> continues through arm region –> passes posterior to medial epicondyle (“funny bone”)
Brachial fascia
Surrounds muscles, blood vessels, nerves of arm
Medial and lateral intermuscular septae
Extend inward from brachial fascia –> attach to humerus –> divide arm into anterior flexor compartment and posterior extensor compartment
Triceps brachii
Long head: Infraglenoid tubercle (scapula) - long w/ tendon, more medial
Lateral head: Posterior surface of humerus lateral to radial groove - most lateral
Medial head: Medial to radial groove Under them (deep)
*To olecranon process of ulna
Extend forearm, extend/adduct arm
Radial nerve
When cut lateral head of triceps diagonally near radial groove, see:
Medial head of triceps, radial nerve w/ deep brachial artery
Biceps brachii
Long head: Supraglenoid tubercle of humerus
Short head: Coracoid process of scapula
Tendon inserts on radial tuberosity + Bicipital aponeurosis
Innervated by musculocutaneous nerve
Flex forearm, supinate
Coracobrachialis
Superiorly - coracoid process, inferiorly on humerus at midpoint on medial side Musculocutaneous nerve (also passes through to lie between biceps/brachialis muscles it also innervates) Flex, adduct arm
Rupture of Tendon of Long head of biceps
Tendon tears with forceful flexion of arm against excessive resistance –> popeye deformity
Brachialis
Anterior lower half of humerus –> coronoid process/tuberosity of ulna
Musculocutaneous nerve
Flexes forearm
Pathway of musculocutaneous nerve
From Lateral cord –> Passes through coracobrachialis –> distally lying on brachialis muscle, covered by biceps brachii –> exits lateral border of biceps and continues into forearm as lateral cutaneous nerve of the forearm (lateral antebrachial cutaneous nerve)
Pathway of radial nerve
Passes through posterior compartment of arm through lateral intermuscular septum to lie beneath brachioradialis muscle –> superficial branch (sensory) under brachioradialis to dorsum of hand, and deep branch that pierces supinator muscle to reach posterior forearm - extensors
Cubital fossa
Triangular space defined by imaginary line between medial/lateral epicondyles, brachioradialis, pronator teres muscle
Cicipital aponeurosis/deep fascia = roof, brachialis + supinator muscles = floor
Brachial artery
Begins at lateral border of teres major muscle (continues from axillary artery) Accompanies median nerve in arm 3 major branches--> 1. Deep brachial artery 2. Superior ulnar collateral artery 3. Inferior ulnar collateral artery
Deep brachial artery
1st branch of brachial artery
Passes posteriorly and accompanies radial nerve in radial groove
Superior ulnar collateral artery
2nd brach of brachial artery
Accompanies ulnar nerve and passes behind medial epicondyle
Inferior ulnar collateral artery
3rd (smallest) brach of brachial artery
Supplies area of elbow joint and anastomoses with recurrent branches of ulnar/radial arteries
Anterior flexor compartment
biceps brachii, coracobrachialis, brachialis
Innervated by musculocutaneous nerve
Posterior extensor compartment
Triceps brachii
Innervated by radial nerve
What muscle supinates the forearm?
Biceps brachii (also flexes)
Quandrangular space
Formed by teres minor, long head triceps, humerus, teres major
Transmits posterior circumflex humeral artery and axillary nerve
Triangular interval
Formed by teres major, long and lateral heads of triceps
Location of deep brachial artery and radial nerve, which both go into radial groove
Where is tendon of long head of biceps?
Runs over head of humerus, ensheathed by layer of synovial membrane that follows the tendon as far as the surgical neck of the humerus. Held in intertubercular groove by transverse humeral ligament and tendon of pec major.
Bicipital aponeurosis
Overlies/protects brachial artery in cubital fossa
Extension of biceps tendon
Where does long head of biceps have origin?
Supraglenoid tubercle of scapula
Where do most ruptures of long head of biceps occur?
From attachment at supraglenoid tubercle of scapula
What tendon is most associated with tendonitis of biceps?
Long head attachment that goes through intertubercular groove (back and forth under synovial sheath)
Ulnar nerve injury
Common in fracture of medial epicondyle - funny bone
Denervates most intrinsic hand muscles.
Power of wrist adduction is impaired
When try to flex the wrist joint –> hand drawn to the lateral side by the FCR (supplied by the median nerve) in the absence of the “balance” provided by the FCU.
Difficulty making a fist because, in the absence of opposition, the metacarpophalangeal joints become hyperextended, and he or she cannot flex the 4th and 5th digits at the distal interphalangeal joints when trying to make a fist.
Person cannot extend the interphalangeal joints when trying to straighten the fingers.
Claw hand
The deformity results from atrophy of the interosseous muscles of the hand supplied by the ulnar nerve.
Median nerve injury
Cannot make fist - hand of benediction (2,3 fingers remain extended)
Cannot abduct/adduct thumb
Sensory loss
Radial nerve injury
Common with humerus fractures at surgical neck, incorrect use of crutches with axillary pressure (posterior cord)
If happens higher up - may denerve triceps (cannot extend elbow)
If lower - just brachioradialis, supinator, extensor muscles of forearm/wrist
Wrist drop
Musculocutaneous nerve injury
Usually protected - maybe stabbing
Denerve biceps brachii, coracobrachialis –> weak flexion of arm, supination of forearm
Also brachialis - weak flexion of elbow
Branches of brachial artery
Profunda brachii artery (deep
artery of the arm)
superior and inferior ulnar collateral
arteries
Profunda brachii artery
Follows radial nerve – anastomose around elbow
Superior ulnar collateral artery
Follows ulnar nerve – anastomose around elbow
Median nerve location
First located lateral to, then crosses, and is finally medial to brachial artery
No branches/innervation in arm (goes to hand)
Musculocutaneous nerve location
Pierces coracobrachialis muscle (sending branches to it), the biceps and brachialis muscles
Continues as lateral antebrachial cutaneous nerve
Radial nerve location
Passes in radial groove on back of humerus with deep brachial artery, pierces lateral intermuscular septum and divides into superficial and deep branches in front of lateral epicondyle
In arm - branches to triceps and skin
Ulnar nerve location
Located medial to axillary and brachial arteries until middle of arm where it pierces the medial intermuscular septum to enter posterior compartment and run with superior ulnar collateral artery in groove behind medial epicondyle of humerus
No branches/innervation in arm (goes to hand)
Boundaries of cubital fossa
2 humeral epicondyles, brachioradialis, Pronator teres, deep fascia/bicipital aponeurosis, brachialis/supinator
Deep structures in antecubital fossa
Median nerve, brachial artery, biceps tendon, radial nerve
