Lecture 7 Flashcards
The arm is divided into anterior & posterior compartments by extensions of deep fascia called __ _ __ __ __.
medial and lateral intermuscular septae
What is the anterior compartment of the arm occupied by?
flexor muscles - biceps brachii, coracobrachialis, & brachialis
What innervates the anterior compartment of the arm?
musculocutaneous nerve
What is the posterior compartment of the arm occupied by?
extensor muscle - triceps brachii
What innervates the posterior compartment of the arm?
radial nerve
What is the origin and insertion of biceps brachii?
origin:
short head - coracoid process of scapula
long head - supraglenoid tubercle of scapula
insertion: radial tuberosity and fascia of forearm via bicipital aponeruosis
What is the function of biceps brachii?
- flexion of arm of the forearm (elbow joint)
- supination of the forearm (elbow joint)
- flexion of the arm (shoulder joint)
What is the origin and insertion of the coracobrachialis?
origin: coracoid process of scapula
insertion: middle third of the medial surface of humerus
What is the function of the coracobrachialis?
- flexion of the arm (shoulder joint)
- adduction of the arm (especially in horizontal adduction)
What is the origin and insertion of the brachialis?
origin: distal half of the anterior surface of humerus
insertion: ulnar tuberosity, coronoid process of ulna
What is the function of the brachialis?
- flexion of the forearm at the elbow
What is the origin and insertion of the triceps brachii (long, lateral, & medial heads)?
origin:
long head - infraglenoid tubercle
lateral head - lateral, posterior humerus (superior lateral to radial groove)
medial head - posterior surface of humerus (inferior medial to radial groove)
insertion: olecranon process of ulna
What is the function of triceps brachii?
- extension of the forearm (elbow)
- extension of the arm (long head only) (shoulder joint)
What do the tendons of the forearm muscles pass through?
distal part of forearm and into the hand
What divides the forearm into anterior (flexor-pronator) & a posterior (extensor-supinator) compartments?
radius, ulna, interosseous membrane connecting them + intermuscular spetum
What is the forearm divided into?
anterior (flexor-pronator) and a posterior (extensor-supinator) compartments
What is known as the arm?
the shoulder to elbow
What is the function of the anterior compartment of the arm?
- flexion of arm at shoulder
- flexion of forearm at elbow
- supination of forearm
What is the function of the posterior compartment of the arm?
- extension of the arm at shoulder
- extension of forearm at elbow
What is the most superficial muscle of the anterior arm compartment?
biceps brachii
What is the function of the longhead of biceps brachii BY ITSELF?
flexion of the arm at the shoulder
What is the function of the biceps brachii belly (both heads together)?
flexion of the forearm at the elbow
Why is biceps able to initiate supination?
Becuase it attached to the radius
What muscle is working when doing a flexion of the forearm in pronation (hammer curl)?
brachialis
What is the origin of the lateral and medial head of the triceps brachii named after?
their orientation around the radial groove
What is the function of the triceps brachii that only the long head can do?
extension of the arm
What are the main actions of the anterior compartment of the forearm?
- flexion and pronation
What is the anterior compartment of the forearm innervated by?
median and ulnar nerves
What is the function of the posterior compartment of the forearm?
- extension and supination
What is the innervation of the posterior compartment of the forearm?
radial nerve
What are the muscles of the superficial layer of the flexor-pronator muscles of the forearm?
Pronator teres (PT), flexor carpi radialis (FCR), palmaris longus (PL), flexor carpi ulnaris (FCU)
What are the muscles of the intermediate layer of the flexor-pronator muscles of the forearm?
Flexor digitorum superficialis (FDS)
What are the muscles of the flexor-pronator muscles of the deep layer of the forearm?
Flexor digitorum profundus (FDP), flexor pollicis longus (FPL), and pronator quadratus (PQ)
What is the tendon that most of the flexor-pronator muscles arise from?
common flexor tendon
T/F: Forearm muscles turn into tendons as they approach the wrist
True
What protects 9 tendons as they go from forearm into hand?
carpal tunnel
Why is flexion way more important than extension?
survival - eating
Anything that attaches to the common flexor tendon does what action?
weak flexion of forearm
The tendons of most flexor muscles pass across the anterior surface of the wrist & are held in place by __ __.
flexor retinaculum
If anterior tendons cross the wrist, what action occurs?
flexion of wrist
If anterior tendons cross the phalangeal joints, what action occurs?
flexion of digits
What muscles are apart of the extensor-supinator superficial layer of the forearm?
- brachioradialis (BR)
- extensor carpi radialis longus (ECRL)
- Extensor carpi radialis brevis (ECRB)
- Extensor digitorum (ED)
- Extensor digiti minimi (Edm)
- Extensor carpi ulnaris (ECU)
- Anconeus
What muscles are apart of the extensor-supinator deep layer of the forearm?
- Supinator
- Abductor pollicis longus (APL)
- Extensor pollicis brevis (EPB)
- Extensor pollicis longus (EPL)
- Extensor indicis (EI)
The most superficial extensor forearm muscles originate from the __ __ of the humerus via a __ __ __
lateral epicondyle; common extensor tendon
The deep extensor forearm muscles arise from the __ __, __, and __ __
posterior ulna, radius, & interosseous membrane
What innervates ALL posterior extensor-supinator muscles of the forearm?
radial nerve
What are the main functions of the superficial layer of the flexor-pronator muscles of the forearm?
- flexion of wrist
- pronation of forearm
What are the main functions of the intermediate layer of the flexor-pronator muscles of the forearm?
flexion of digits 2-5 at MCP & PIP
What innervates the intermediate layer of the flexor-pronator muscles of the forearm?
median nerve
What are the main functions of the deep layer of the flexor-pronator muscles of the forearm?
- flexion of thumb
- flexion of digits 2-5 at all joints
What innervates the muscle that flexes the thumb?
median nerve
What innervates the muscles that flex the digits?
2-3 = median
4-5 = ulnar
All extensor-supinator muscles of the forearm are innervated by what nerve?
radial nerve
What are the extensor-supinator muscles of the forearm organized into?
superficial and deep layer
What is the tendon that most extensor-supinator muscles of the forearm arise from?
common extensor tendon
if posterior muscles cross the wrist what action occurs?
extension of the wrist
If posterior muscles cross the digits, what action occurs?
extension of digits
If a patient manages to damage their musculocutaneous nerve will they still be able to flex their elbow? Why?
Yes, because brachioradialis is a flexor and is innervated by the radial nerve
Who is the “wannabe” anterior arm muscle?
brachioradialis
What is the origin and insertion of brachioradialis?
origin: distal humerus
insertion: distal radius
What is the main function of bracioradialis?
flexion of elbow in “mid-pronation”
What is the function of the extensor retinaculum?
to retain the extensor tendons in place
What creates the extensor retinaculum and flexor retinaculum?
forearm fascia that has thickened posteriorly
What is the purpose of the flexor retinaculum?
to convert the anterior concavity of the carpus into a carpal tunnel
What passes through the carpal tunnel?
flexor tendons of the forearm: flexor digitorum superficialis, flexor digitorum profundus, and flexor pollicis longs
and median nerve
What does the retinacula prevent?
bowstringing of the tendons when the hand flexed or hyperextended at the wrist joint
As the extensor tendons pass over the dorsum, they are invested by what to reduce friction between the extensor tendons and the bonds?
synovial sheaths
What is the origin & insertion of pronator teres (PT)?
origin:
- humeral head: medial epicondyle of humerus (via common flexor tendon)
- ulnar head: coronoid process of ulna
insertion: middle of lateral surface of radius
What is the function of pronator teres (PT)?
- pronation of forearm
- weak flexion of forearm (elbow)
What innervates pronator teres?
median nerve
What happens if the pronator teres muscle hypertrophies due to over working?
the median nerve will be impeached and loss of median nerve function in the forearm
What is the origin and insertion of flexor carpi radialis (FCR)?
origin: medial epicondyle of humerus (via common flexor tendon)
insertion: base of 2nd & 3rd metacarpalsW
What are the main functions of flexor carpi radialis?
- flexion of hand
- flexion of forearm (weak)
- abduction (radial deviation) of wrist
What is the innervation of flexor carpi radialis?
median nerve
What is another word for abduction of the wrist?
radial deviation
What forearm muscle is missing in about 12-20% of population?
palmaris longus
What is the origin and insertion for palmaris longus?
origin: Medial epicondyle of humerus (via common flexor tendon)
insertion:
- Palmar aponeurosis (thick band of tissue that covers the palm of your hand – protection) - Flexor retinaculum
What are the main functions of palmaris longus?
- flexion of hand
- flexion of forearm (weak)
What is the innervation of palmaris longus?
median nerve
What is the origin and insertion of flexor carpi ulnaris?
origin:
- humeral head: Medial epicondyle of humerus (via common flexor tendon)
- ulnar head:
- olecranon process of ulna
- posterior border of ulna
insertion:
- base of 5th metacarpal
- hook of hamate
- pisiform
What are the main functions of flexor carpi ulnaris?
- flexion of hand (at wrist)
- flexion of forearm (weak)
- adduction (ulnar deviation) of hand
What is another word for adduction of the wrist?
ulnar deviation
What is the innervation of flexor carpi ulnaris?
ulnar
Name the muscles laterally to medial.
- pronator teres
- flexor carpi radialis
- palmaris longus
- flexor carpi ulnaris
What is the origin and insertion of flexor digitorum superficialis?
origin:
- humero-ulnar head: Medial epicondyle of humerus (via common flexor tendon); Coronoid process of ulna
- radial head: Proximal of anterior border of radius
insertion: Base of middle phalanges of fingers # 2-5
What is the function of the flexor digitorum superficialis?
- flexion of fingers 2-5 @ MCP & PIP joints
- flexion of hand at wrist
- flexion of forearm (weak)
The course of the ulnar nerve is between which muscles two heads?
flexor carpi ulnaris
What is the innervation of flexor digitorum superficialis?
median nerve
What surrounds the tendon of the muscle?
tendon sheath
What is the origin and insertion of the flexor digitorum profundus?
origin:
- proximal anterior and medial surface of ulna
- interosseous membrane
insertion: base of distal phalanges of fingers #2-5
Where there is inflammation of the tendon sheath what happens?
presses of median nerve –> carpal tunnel syndrome
What are the functions of the flexor digitorum profundus?
- flexion of fingers #2-5 at MCP, PIP, & DIP joints
- flexion of hand at wrist
What is the innervation of flexor digitorum profundus?
median - radial (lateral) 1/2 of muscle
ulnar - ulnar (medial) 1/2 of muscle
What is the origin and insertion of flexor pollicis longus?
origin: anterior surface of radius & interosseous membrane
insertion: base of distal phalanx of thumb
What are the main functions of the flexor pollicis longus?
- flexion of thumb @ CMC, MCP, and IP joints
- flexion of hand at wrist
What is the innervation of flexor pollicis longus?
median nerve
T/F: Flexor pollicis longus is one of the carpal tunnel muscles
True
What is the origin and insertion of pronator quadratus?
origin: anterior surface of distal 1/4 of ulna
insertion: anterior surface of distal 1/4 of radius
What is the main function of the pronator quadratus?
- pronation of forearm
What is the innervation of pronator quadratus?
median nerve
