Posterior Forearm (Posterior Antebrachium) Flashcards
When looking at the forearm posteriorly, which side is considered medial?
Ulnar side
cutaneous innervation
Which nerve runs medially in the posterior antebrachium?
Medial antebrachial cutaneous nerve
cutaneous innervation
Which nerve runs laterally and in the middle of the posterior antebrachium?
Posterior antebrachial cutaneous nerve (radial nerve)
cutaneous innervation
Which nerve runs towards the wrist, laterally in the posterior antebrachium?
Lateral antebrachial cutaneous nerve
cutaneous innervation
Which nerve runs on the medial side of the posterior hand?
Dorsal cutaneous branch of ulnar nerve
cutaneous innervation
Which nerve runs on the lateral side of the posterior hand?
Superficial branch of radial nerve
cutaneous innervation
Which nerve will run to the posterior tips of the first four digits?
Median nerve
Which nerves innervate the flexors and pronators of the forearm?
Median nerve,
Anterior interosseous nerve
Which nerves innervate the extensors and supinators of the forearm?
Posterior interosseous nerve
Deep branch of radial nerve
Radial nerve
Which muscles in the posterior forearm are innervated by the radial nerve?
- Anconeus
- Brachioradialis
- Extensor carpi radialis longus
(all superficial layer)
Which muscles in the posterior forearm are innervated by the deep branch of radial nerve?
- Extensor carpi radialis brevis (superficial)
- Supinator (deep)
Which muscles of the superficial layer of the posterior forearm are innervated by the posterior interosseous nerve?
- Extensor digitorum
- Extensor digiti minimi
- Extensor carpi ulnaris
Which muscles of the deep layer of the posterior forearm are innervated by the posterior interosseous nerve?
- Abductor pollicis longus
- Extensor pollicis longus
- Extensor pollicis brevis
- Extensor indicis
Origin and insertion of anconeus
Origin: lateral epicondyle of humerus
Insertion: lateral side of the olecranon, and shaft of the ulna, joint capsule of the elbow
Innervation and spinal levels of anconeus
Radial nerve form C7, C8, T1
Actions of anconeus
Assists triceps brachii and extends joint capsule of the elbow during extension of the elbow
Origin and insertion of brachioradialis
Origin: upper 2/3rds of the lateral supracondylar ridge of the humerus
Insertion: lateral aspect of the styloid process of the radius
Innervation and spinal levels of brachioradialis
Radial nerve from C5, mostly C6, C7
Action of brachioradialis
Flexes a semiprone forearm
Origin and insertion of extensor carpi radialis longus
Origin: lower 1/3rd of the lateral supracondylar ridge of the humerus
Insertion: base of the 2nd metacarpal
Innervation and spinal levels of extensor carpi radialis longus
Radial nerve from C6 and C7
Actions of extensor carpi radialis longus
Extends the wrist
Acts in unison with flexor carpi radialis to abduct or radially deviate the hand
Fixes the wrist when acting with extensor carpi ulnaris
Origin and insertion of extensor carpi radialis brevis
Origin: lateral epicondyle of the humerus
Insertion: base of 3rd metacarpal
Innervation and spinal levels of extensor carpi radialis brevis
Deep branch of the radial nerve mostly from C7, C8
Action of extensor carpi radialis brevis
Assists extensor carpi radialis longus
Origin and insertion of extensor digitorum
Origin: lateral epicondyle of the humerus via common extensor tendon
Insertion: dorsal digital expansions of the medial four digits
Innervation and spinal levels of extensor digitorum
Posterior interosseous nerve from mostly C7 and C8
Action of extensor digitorum
Extend the metacarpophalangeal and interphalangeal joints
Origin and insertion of extensor digiti minimi
Origin: medial belly of extensor digitorum
Insertion: dorsal digital expansion of the little finger via 1 or 2 tendons
Innervation and spinal levels of extensor digiti minimi
Posterior interosseous nerve from mostly C7 and C8
Action of extensor digiti minimi
Assists extensor digitorum at the little finger
Origin and insertion of extensor carpi ulnaris
Origin: lateral epicondyle of humerus
Insertion: medial side base of the 5th metacarpal
Innervation and spinal levels of extensor carpi ulnaris
Posterior interosseous nerve from C7, mostly C8
Actions of extensor carpi ulnaris
- Acting with flexor carpi ulnaris, it will adduct or ulnar deviate the hand
- Acting with extensors carpi radialis longus and brevis, it will fix the wrist
- Can also extend the wrist
Origin and insertion of supinator
Origin: lateral epicondyle of the humerus, the radial collateral ligament, supinator crest of the ulna
Insertion: lateral surface of the proximal 1/3rd of the radius
Innervation and spinal levels of supinator
Deep branch of the radial nerve from C5, mostly C6
Action of supinator
Supinates forearm
Origin and insertion of abductor pollicis longus
Origin: posterior surfaces of the radius, ulna, and interosseous membrane
Insertion: base of the 1st metacarpal and trapezium
Innervation and spinal levels of abductor pollicis longus
Posterior interosseous nerve from C7 and mostly C8
Action of abductor pollicis longus
Abducts and extends the thumb
Origin and insertion of extensor pollicis brevis
Origin: posterior surface of the radius and interosseous membrane
Insertion: base of the proximal phalanx of the thumb
Innervation and spinal levels of extensor pollicis brevis
Posterior interosseous nerve from C7 and mostly C8
Action of extensor pollicis brevis
Extends the metacarpophalangeal joint
Origin and insertion of extensor pollicis longus
Origin: posterior shaft of the ulna and interosseous membrane
Insertion: base of the distal phalanx of the thumb
Innervation and spinal levels of extensor pollicis longus
Posterior interosseous nerve from C7 and mostly C8
Action of extensor pollicis longus
Extends the thumb at the interphalangeal and metacarpophalangeal joints
Origin and insertion of extensor indicis
Origin: posterior surface of interosseous membrane, posterior surface of the ulna
Insertion: dorsal digital expansion of the index finger
Innervation and spinal levels of extensor indicis
Posterior interosseous nerve from C7 and mostly C8
Action of extensor indicis
Extends index finger assisting extensor digitorum
What makes up the medial boundary of the anatomical snuff box?
Extensor pollicis longus
What makes up the lateral boundary of the anatomical snuff box?
Extensor pollicis brevis, abductor pollicis longus
The medial 1 and 1/2 digits are innervated by the…
ulnar nerve
The proximal 1/3rd, and lateral 3 and 1/2 digits are innervated by the…
superficial branch of the radial nerve
