Anatomy OT forearm bones and anterior compartment

What are the compartments of the forearm?

• Anterior compartment = Flexors & Pronators

• Posterior compartment = Extensors & Supinators

What structures are part of the forearm compartments?

• Lateral intermuscular septum

• Interosseous membrane

• Deep fascia

Describe the radius.

Small proximally : articulates with humerus

Large distally: Distally articulates with carpal bones (forms wrist joint)

Shaft of Radius

• 3 border ( anterior, posterior, and interosseous)

• 3 surfaces ( anterior, posterior, and lateral)

• oblique line

What are the landmarks of the distal radius?

• Ulnar notch ( distal radio-ulnar joint)

• Radial styloid process

• Facets for carpal bones (scaphoid and lunate)

• Dorsal tubercle (posterior)

Describe Ulna

large proximally: articulates with humerus

small distally: articulates with carpal bones (forms wrist joint)

Shaft of Ulna

3 boarders ( anterior, posterior, and interosseous) *

3 surfaces ( anterior, posterior, medial)

Ulna distal end

Ulnar styloid process

how many carpal bones

8

First row of carpal bones

Scaphhoid

Lunate

Triquetrum

Pisiform

She Looks Too Pretty

Second row of carpal bones

TRapezium

Trapeziod

Capitate

Hamate

TRy To Catch Her

Hand bones

• Distal phalanges

• Middle phalanges ( NOT THUMB)

• Proximal phalanges

• Metacarpals I - V

Joints

• Distal interphalangeal (DIP) joints:

• Proximal interphalangeal (PIP) joints: between proximal and middle phalanges, 1 PIP for thumb

• Metacarpo-phalangeal (MCP) joints: between metacarpal bone & proximal phalanges

• Carpo-metacarpal (CMC) joints: between carpal bones & metacarpal bones. Large ROM for thumb not fingers.

• Intercarpal joints: between carpal bones, Limited ROM

• Wrist joint: Carpal bones articulate w/ radius & ulnar that forms wrist jonts

Most anterior muscles (8) are innervated by? expect what

Median N

expect flexor carpi ulnaris, flexor digitorum Profundus (medial part) by Ulnar N

Name the 4 superficial anterior forearm muscles.

• Flexor Carpi Ulnaris

• Palmaris Longus

• Flexor Carpi Radialis

• Pronator Teres

What do all superficial anterior forearm muscles have in common?

They originate from the medial epicondyle.

Flexor Carpi Ulnaris Orgin?

• Humeral head: medial epicondyle of humerus

• Ulnar head: Olecranon and posterior border of ulna

Flexor Carpi Ulnaris Insertion?

pisiform, hamate, base of metacarpal V (five)

Flexor Carpi Ulnaris Innervation?

Ulnar nerve ( C7 - T1)

Flexor Carpi Ulnaris Action

Flex and add wrist

Palmaris Longus Origin

medial epicondyle of humerus

Palmaris Longus Insertion

palmar aponeuosis of hand

Palmaris Longus Innervation

median nerve (C7 - C8)

Palmaris Longus Action

Flex wrist

Flexor Carpi Radialis Origin

medial epicondyle of humerus

Flexor Carpi Radialis Insertion

bases of metacarpals II and III

Flexor Carpi Radialis Innervation

Median nerve ( C6-C7)

Flexor Carpi Radialis Action

flex and ABD wrist

Pronator Teres Origin

• Humeral head: medial epicondyle of humerus, medial supraepicondylar ridge

• Ulnar head: cornoid process of ulna

Pronator Teres Insertion

radius (lateral, mid-shaft)

Pronator Teres Innervation

median nerve ( C6- C7)

Pronator Teres Action

pronate forearm

Which muscle is the only intermediate anterior forearm muscle?

Flexor Digitorum Superficialis

Also has an origin from MEDIAL EPICONDYLE of humerus

Flexor Digitorum Superficialis Origin

• humero-ulnar head: medial epicondyle of humerus, coronoid process of ulna

• Radial head: anterior oblique line of radius

Flexor Digitorum Superficialis Insertion

• 4 tendons : middle phalanges of index, middle, ring, and little fingers

• SPLIT tendon

Flexor Digitorum Superficialis Innervation

median nerve ( C8- T1)

Flexor Digitorum Superficialis Action

• flex wrist

• flex metacarpo-phalangeal joints (MCP) and Proximal interphalangeal jonts (PIP) of the 4 fingers

Name the 3 deep anterior forearm muscles.

• Flexor Digitorum Profundus

• Flexor Pollicis Longus

• Pronator Quadratus

DO NOT have an origin from MEDIAL EPICONDYLE of the humerus

Flexor Digitorum Profundus Origin

• Anterior and medial surfaces of ulna

• Interosseous membrane

Flexor Digitorum Profundus Insertion

• 4 tendons: base of distal phalanges of index, middle, ring and little fingers

Goes THROUGH the split tendons of SUPERFICIALIS

Flexor Digitorum Profundus Innervation

• median nerve ( anterior interosseous nerve), C7 - C8): LATERAL TENDONS(index and middle fingers)

• ULNAR NERVE(C8- T1): MEDIAL TENDONS (ring and little fingers)

Flexor Digitorum Profundus Action

• flex wrist

• flex metacarpo-phalangeal joints (MCP) , Proximal interphalangeal jonts (PIP) and Distal interphalangeal joints (DIP) joints of the 4 fingers

Flexor Digitorum Profundu is deep to what?

flexor digitorium superficialis

Flexor Pollicis Longus Origin

• Anterior surfaces of radius

• Interosseous membrane

Flexor Pollicis Longus Insertion

• base of distal phalange of thumb

Flexor Pollicis Longus Innervation

• Median nerve ( ANTERIOR INTEROSSEOUS NERVE, C7- C8)

Flexor Pollicis Longus Action

• flex metacarpo-phalangeal joints (MCP)

• flex IP joint of thumb

Pronator Quadratus Origin

distal end of ulna

Pronator Quadratus Insertion

distal end of radius

Pronator Quadratus Innervation

• Median nerve ( ANTERIOR INTEROSSEOUS NERVE, C7- C8)

Pronator Quadratus Action

Pronate forearm