Lecture 7: Upper limb & anterior forearm Flashcards
The arm is divided into anterior and posterior compartments by extensions of deep fascia called what?
Medial and lateral intermuscular septae
What is the anterior compartment of the arm occupied by?
Flexor compartment:
-Biceps brachii
-Coracobrachialis
-Brachialis
Innervated by the: Musculocutaneous nerve
What is the posterior arm compartment occupied by?
Extensor compartment:
-Triceps brachii
Innervated by the: Radial nerve
Origin & Insertion of the Biceps brachii:
Origin:
Short head-Coracoid process of scapula
Long head-Supraglenoid Tubercle of scapula
Insertion: Radial tuberosity and fascia of forearm via bicipital aponeurosis
Innervation: Musculocutaneous nerve
Origin & insertion of the Coracobrachialis:
Origin: Coracoid process of scapula
Insertion: Middle third of the medial surface of humerus
Innervation: Musculocutaneous nerve
Origin & Insertion of the Brachialis:
Origin: Distal half of the anterior surface of the humerus
Insertion: Ulnar tuberosity & coronoid process of ulna
Innervation: Musculocutaneous nerve
Origin & insertion of Triceps brachii:
Origin:
Long head- infraglenoid tubercle
Lateral head-Lateral, posterior humerus (superior to radial groove)
Medial head-Posterior surface of humerus (inferior to radial groove)
Insertion: Olecranon process of ulna
Innervation: Radial nerve
Where do the tendons of the forearm muscles pass through?
Distal part of the forearm and into the hand
What structures divide the forearm into anterior and posterior compartments?
Radius, Ulna, interosseous membrane, and intermuscular septum
Muscles of the anterior (flexor-pronator) forearm compartment are innervated by which nerve?
Median nerve
EXCEPT: FCU and medial half of FDP-these are innervated by the ulnar nerve
All muscles of the posterior (extensor-supinator) forearm compartment are innervated by which nerve?
Radial nerve
Most of the flexor-pronator muscles arise from the _______________ of the ____________ via _________________.
-medial epicondyle
-humerus
-common flexor tendon
The tendons of the flexor muscles of the forearm pass across _________ and are held in place by the ____________.
-the anterior surface of the wrist
-flexor retinaculum
The muscles of the anterior (flexor-pronator) compartment of the forearm are divided into three layers, what are these layers and which muscles are in each?
1) Superficial layer: Pronator teres(PT), flexor carpi radialis(FCR), palmaris longus (PL), flexor carpi ulnaris (FCU)
2) Intermediate layer: Flexor digitorum superficialis (FDS)
3) Deep layer: Flexor digitorum profundus(FDP), flexor pollicis longus (FPL), and pronator quadratus (PQ)
All muscles are innervated by the median nerve EXCEPT the FCU and medial half of the FDP-Ulnar nerve
The superficial layer of the extensor supinator muscles of the forearm are:
1) Brachioradialis (BR)
2) Extensor carpi radialis longus (ECRL)
3) Extensor carpi radiais brevis (ECRB)
4) Extensor digitorum (ED)
5) Extensor digiti minimi (Edm)
6) Extensor Carpi ulnaris (ECU)
7) Anconeus
The deep layers of the extensor supinator muscles of the forearm are:
1) Supinator
2) Abductor pollicis longus (APL)
3) Extensor pollicis brevis (EPB)
4) Extensor pollicis longus (EPL)
5) Extensor indicis (EI)
The Origin & insertion & function of brachioradialis:
-Distal humerus to distal radius
-Anterolateral forearm muscle
Function: Flexion of the elbow in “mid pronation”
(beer drinking muscle)
Innervated by: Radial nerve
Name the main muscle being used, action, and nerve associated with this muscle.
Biceps
Flexion w/ supination
Musculocutaneous nerve
Name the main muscle being used, action, and nerve associated with this muscle.
Brachialis
Flexion w/pronation
Musculocutaneous nerve
Name the main muscle being used, action, and nerve associated with this muscle.
Brachioradialis
Flexion in mid-pronation
Radial nerve
The forearm (antebrachial) fascia: The fascia thickens posteriorly over _______________ to form a transverse band called ____________________.
-the distal ends of the radius and ulna
-The extensor retinaculum
What thick fascia converts the anterior concavity of the carpus into the carpel tunnel?
The flexor retinaculum
As the extensor tendons pass over the dorsum of the wrist they are invested by ___________ which reduces friction between the extensor tendons and the bones.
Synovial sheaths
Origin & Insertion of Pronator teres
O: Humeral head-Medial epicondyle of humerus (via common flexor tendon)
Ulnar head-Coronoid process of ulna
I: Middle of the lateral surface of radius
Innervation: Median nerve
(Note: Impingement of median nerve between two heads of PT; pronator syndrome)
Origin & Insertion of flexor carpi Radialis (FCR):
O: Medial epicondyle of the humerus (via common flexor tendon)
I: Base of the 2nd & 3rd metacarpals
Innervation: Median nerve
(Radial A. Pulse)
Origin & Insertion of Palmaris Longus (PL):
O: Medial epicondyle of humerus (via common flexor tendon)
I: Palmar aponeurosis, flexor retinaculum
Innervation: Median Nerve
(Absent in 12-20% of the population)
Origin & Insertion of Flexor Carpi Ulnaris (FCU):
O: Humeral head- Medial epicondyle of humerus (via common flexor tendon)
Ulnar head- Olecranon process of ulna, Posterior border of ulna
I: Base of the 5th metacarpal, Hook of hamate, Pisiform
Innervation: Ulnar nerve
(Course of ulnar nerve is between FCU’s two heads)
How to find the first four flexors of the forearm:
From Pinky to Index finger:
1) FCU
2) PL
3) FCR
4) PT
Origin & Insertion of Flexor Digitorum Superficialis (FDS):
O: Humero-ulnar head- Medial epicondyle of humerus (via common flexor tendon), & coronoid process of ulna
Radial head: Proximal of anterior border of radius
I: Base of middle phalanges of fingers #2-5
Innervation: Median Nerve
INTERMEDIATE LAYER
(Irritation of the tendon sheath in CT & pressing the median nerve-Carpel tunnel)
Name the structures:
1) Flexor digitorum superficialis tendons
2) Carpal Tunnel
3) Flexor digitorum profundus tendons
4) Flexor retinaculum
5) Median Nerve
6) Flexor pollicis longus tendon
Origin & Insertion of Flexor Digitorum Profundus (FDP):
O: Proximal anterior & medial surface of ulna, Interosseous membrane
I: Base of distal phalanges of fingers #2-5
Nerve: Median & Ulnar nerve
(Role of medial and lateral halves of muscle in flexing the fingers)
(Tendons pass through the carpal tunnel)
Origin & Insertion of Flexor Pollicis Longus (FPL):
O: Anterior surface of the: radius, & interosseous membrane
I: Base of distal phalanx of thumb
Innervation: Median nerve
(One of the carpal tunnel muscles)
Origin & Insertion of Pronator Quadratus (PQ):
O: Anterior surface of distal 1/4 of ulna
I: Anterior surface if distal 1/4 of radius
Innervation: Median Nerve
