Anterior Forearm (Anterior Antebrachium) Flashcards
cutaneous innervation
What nerve runs in the most superior lateral portion of the anterior forearm?
Posterior antebrachial cutaneous nerve (from radial nerve (C6, C7, C8))
cutaneous innervation
What nerve runs in the lateral portion of the anterior forearm?
Lateral antebrachial cutaneous nerve (C5, C6)
cutaneous innervation
What nerve runs in the medial portion of the anterior forearm?
Medial antebrachial cutaneous nerve (C8, T1)
cutaneous innervation
What nerve runs in the lateral portion of the wrist?
Superficial branch of the radial nerve (C6)
cutaneous innervation
Which nerve runs in the medial portion of the wrist and palm?
Dorsal cutaneous branch of ulnar nerve (C8)
Which nerves run in flexors and pronators of the forearm?
Median nerve and anterior interosseous nerve
Which nerves run in extensors and supinators of the forearm?
Posterior interosseous nerve, deep branch of radial nerve, radial nerve
The median nerve comes from the lateral and medial roots from the…
lateral and medial cords
Which muscles does the median nerve innervate?
Wrist flexors and thenar muscles
What branches come from the median nerve?
A deep branch: anterior interosseous nerve
A branch that supplies the hand: recurrent branches of the median nerve
What reflex is associated with the median nerve?
No reflex
How is the median nerve tested?
Performing wrist flexion
Which muscles are in the superficial layer of the anterior forearm?
Pronator teres
Flexor carpi radialis
Palmaris longus
Flexor carpi ulnaris
Which muscle is in the intermediate layer of the anterior forearm?
Flexor digitorum superficialis
Which muscles are in the deep layer of the anterior forearm?
Flexor digitorum profundus
Pronator quadratus
Flexor pollicis longus
Pronator teres origin and insertion
Origin: humeral head: medial epicondyle
ulnar head: coronoid process
Insertion: midway along the lateral surface of the radius
Innervation and spinal level of pronator teres
Median nerve (runs between humeral and ulnar heads) from C6 and mostly C7
Action of pronator teres
Pronation of the forearm: rotation of radius on ulna, turning the palm medially and backward
The pronator teres is recruited when?
When force or speed is needed
Origin and insertion of flexor carpi radialis
Origin: medial epicondyle
Insertion: base of the 2nd and 3rd metacarpal
Innervation and spinal levels of flexor carpi radialis
Median nerve from C6, mostly C7
Actions of flexor carpi radialis
- Flexes 2nd carpometacarpal joint and the hand at wrist
- Radial deviation (abduction) with extensor carpi radialis
- Steadies the hand with flexor carpi ulnaris
Origin and insertion of palmaris longus
Origin: medial epicondyle
Insertion: flexor retinaculum and the palmar aponeurosis
Innervation and spinal levels of palmaris longus
Median nerve form C7, mostly C8
Actions of palmaris longus
Tenses the palmar aponeurosis and weakly flexes the wrist
Origin and insertion of flexor carpi ulnaris
Origin: medial epicondyle, medial aspect of the olecranon process, posterior border of the ulna
Insertion: pisiform, hamate, base of the 5th metacarpal
Innervation and spinal levels of flexor carpi ulnaris
Ulnar nerve from C7, C8
Actions of flexor carpi ulnaris
- Flexes the 5th carpometacarpal joint
- Adduction of the hand (ulnar deviation) with extensor carpi ulnaris
- Steadies the wrist with the flexor carpi radialis
Innervation and spinal levels of flexor digitorum superficialis
Median nerve from C7, mostly C8, T1
Action of flexor digitorum superficialis
Flexes the proximal interphalangeal joints and the metacarpophalangeal joints
Which muscle is considered the power grip muscle?
Flexor digitorum superficialis
Origin and insertion of flexor digitorum profundus
Origin: upper 3/4ths of the anteromedial aspect of the ulna and ulnar half of the interosseous membrane
Interion: its 4 tendons pass through the tendons of FDS at the bases of the middle phalanges to insert at the bases of the distal phalanges of digits 2-5
Innervation and spinal levels of flexor digitorum profundus
Anterior interosseous nerve and ulnar nerve from mostly C8, T1
Action of flexor digitorum profundus
Flexes the distal interphalangeal joints (DIPs) after the PIPs are flexed by FDS. Weak wrist flexor
Which muscle is the gentle grip flexor?
Flexor digitorum profundus
When all fingers are flexed into a fist, extensor tendons…
relax
When only 1 finger is flexed, which tendon remains active?
Antagonistic extensor tendon
What are the long flexor tendons in the palm?
Flexor carpi ulnaris, flexor carpi radialis, and flexor digitorum profundus (FDP)
Origins and insertion of flexor pollicis longus
Origin: radial head: anterior surface of the radius and interosseous membrane
humeral head: medial epicondyle and coronoid process of the ulna
Insertion: base of the distal phalanx of the thumb
Innervation and spinal levels of flexor pollicis longus
Anterior interosseous nerve from C7, mostly C8, T1
Action of flexor pollicis longus
Flexes the interphalangeal joint and the metacarpophalangeal joint of the thumb
Origin and insertion of pronator quadratus
Origin: distal 1/4th of the anterior surface of the ulna
Insertion: distal 1/4th of the anterior surface of the radius
Innervation and spinal levels of pronator quadratus
Anterior interosseous nerve from mostly C8, T1
Action of pronator quadratus
Pronation of the forearm
Which muscle is the principle pronator of the forearm?
Pronator quadratus
What are the six entrapment sites of the median nerve?
- Medial intermuscular septa
- Pronator teres
- FDS/FDP tunnel
- Pronator quadratus - AIN
- Carpal tunnel
- FPB/APB
