Flexor Forearm Compartment

Question 1

what is the order of flexor forearm compartment from superficial to deep?

Answer 1

skin→antebrachial fascia (bicipittal aponeurosis: attachment for biceps brachii)→muscles

Question 2

what is the fascia in the forearm and what does it form?

Answer 2

antebrachial fascia which thickens in the wrist and forms the flexor retinaculum

Question 3

what does the flexor retinaculum do?

Answer 3

1. Helps to prevent bow-stringing (shortening of tendons)

2. Provides roof for carpal tunnel

Question 4

what is the difference between and intrinsic and extrinsic muscle?

Answer 4

Intrinsic muscle: if muscle originates and inserts in the same anatomic region
➢ I.e. shoulder, arm, forearm

Extrinsic muscle: if muscle originates and inserts in different anatomic regions
➢ i.e. forearm→hand
➢ crossing joints usually using tendons

Question 5

what is the overall proximal attachment of the flexor forearm compartment?

Answer 5

medial part of humerus + supra condyle ridge

Question 6

what is the overall distal attachment of the flexor forearm compartment?

Answer 6

anterior aspect of the ulna

Question 7

what is the overall action of the flexor forearm compartment?

Answer 7

primary flexors of wrist

Question 8

what are the muscles of the superficial layer?

Answer 8

1. pronator teres
2. flexor carpi radialis
3. palmaris longus
4. flexor carpi ulnaris

Question 9

what is the action of the pronator teres?

Answer 9

pronate + flex forearm

Question 10

what is the action of the flexor carpi radialis?

Answer 10

flex + abducts hand

Question 11

what is the action of the palmaris longus?

Answer 11

flex hand + tense palm

15% of ppl dont have one

Question 12

what is the action of the flexor carpi ulnaris?

Answer 12

flex wrist

Question 13

what are the muscles of the intermediate layer and what is their action?

Answer 13

flexor digitorum superficialis

action: flex medial 4 digits

Question 14

what are the muscles of the deep layer and what is their action?

Answer 14

1. flexor digitorum profundus
   action: flex 4 medial digits
2. flexor pollicis longus
   action: flex thumb
3. pronator quadratus
   action: pronate forearm

Question 15

what is a proximal attachment trend of the deep layer of muscles?

Answer 15

all originate from proximal ulna + anterior interosseus membrane + anterior surface of mid radius

Question 16

what is the course of the median nerve?

how does it form/travel?

Answer 16

1. Forms from medial and lateral cords and Travels anteriomedially on arm
2. When it gets to cubittal fossa it travels beside brachial artery then deep to the bicipittal aponeurosis
3. Then travels deep to pronator teres + flexor digitorum superficialis (at wrist)
4. enters the carpal tunnel
   • Anterior interosseous nerve (main branch of median n.)
   • Travels down middle forearm
   • Nerve deep to pronator quadratus

Question 17

what is the course of the ulnar nerve?

how does it form/travel?

Answer 17

Formed from medial cord

Travels medially in arm until it twists around the medial epicondyle and emerge into forearm and travels to flexor carpi radialis

Question 18

what is the vasculature of the forearm?

Answer 18

Brachial artery
• Splits at cubittal fossa becomes radial (used to find pulse) + ulnar
• Ulnar sheath: where ulnar vein + artery travel together