LIF101 Anatomy

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LIF101Anatomy

• Lecture 11
• Muscles of the Arm and Hand

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Muscle Groups of the Upper Arm

• Abductor muscle of upper arm
• Deltoid
• Flexor muscle of upper arm
• Biceps brachii
• Extensor muscle of upper arm
• Triceps brachii

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Flexors

• Groups of muscles at the front (anterior) of arm
  act as FLEXORS
• Biceps are Flexor muscles of upper arm
• Ventral side

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Arm Movement

• ADDuctors draw limbs closer to the torso

• ABDuctors carry limbs out to the side
• ALIENS

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Extensors

• Work against the flexors (Antagonist)
• Posterior (back side) Straighten the joints
• Dorsal Side

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Deltoid

• Named for triangular shape (Greek delta ?)
• Origin lateral end of clavicle acromion process
  and spine scapula
• Insertion lateral humerus

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Deltoid

• Abducts humerus (raises arm)
• Rotates humerus in abducted position
• Anatomical landmark deltoid furrow

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Flexor Muscles of Upper Arm

• Biceps brachii
• You can feel your biceps muscles move when you
  turn a doorknob (rotate your forearm)
• Attaches to scapula in two places (bi)
• Two heads

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Biceps Brachii

• Named for two divisions long head and short head
• Brach, Brachio Latin for arm
• Origin upper anterior of scapula
• Insertion proximal end of radius

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Biceps Brachii (Biceps)

• Flexes and supinates forearm
• Other features to know
• Bicipital tendon
• Bicipital aponeurosis
• Cubital fossa

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Brachialis

• Directly beneath biceps
• Origin anterior humerus
• Insertion coranoid process of ulna
• Assists biceps in flexion of forearm
• Can be seen peeking out on either side of biceps
  brachii.

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Extensor Muscles of Upper Arm

• Triceps
• Roles
• Extends and
• Pronates

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Triceps Brachii (Triceps)

• Named for three divisions lateral head, medial
  head, long head
• Originates at three places (three heads) one on
  scapula and two on humerus
• Insertion olecranon process of ulna (via
  tendinous plate)

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Triceps Brachii (Triceps)

• All three heads together extend forearm (and
  supinate it)
• You can feel this muscle in motion when you push
  or punch.

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Forearm Muscles

• Divided into two main compartments
• Flexors/pronators (on ventral/palmar side)
• Extensors/supinators (on dorsal side)
• Functions rotate arm from palms up (supine)
  position to palms down (pronate) position

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Forearm Muscles

• Some move wrist/hand others move fingers
• Body of muscles create fullness at proximal
  forearm, then
• Taper distally into long insertion tendons.
• Insertion tendons are anchored into place by the
  annular ligament.

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Words Roots to Know

• Brachial, brachio, brachialis means upper arm
• Radial, radio, radialis means radial (thumb)
  side of forearm
• Ulnar, ulno, ulnaris means ulnar (pinky) side
  of forearm
• Digiti finger

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In General

• forearm muscles on the ventral side flex.
• forearm muscles on the dorsal side extend.
• forearm muscles on the radial side abduct.
• forearm muscles on the ulnar side adduct.

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General Areas of Origin

• The flexor/pronator group originates at or around
  the medial epicondyle of the humerus.
• The extensor/supinator group originates at or
  around the lateral epicondyle of the humerus.

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Extensor/Supinator Muscles of Forearm(guess what
they do)

• Brachioradialis
• Extensor carpi radialis longus
• Extensor carpi radialis brevis
• Extensor digitorum
• Extensor digiti minimi
• Extensor carpi ulnaris
• Anconeus

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From Simblets Book
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Extensor/Supinator Group The Radial Side

• Brachioradialis
• supinates forearm in extension
• pronates forearm in flexion
• Extensor carpi radialis longus
• extends and abducts wrist/hand
• sometimes blends with brachioradialis
• Extensor carpi radialis brevis
• extends and abducts wrist/hand
• shorter than E.C.R.L.
• not as superficial as E.C.R.L.

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Dorsal (Back) Side of Hand

• Extensor digitorum
• digitorum fingers
• extends fingers 25 (not thumb)
• also spreads fingers
• anatomical landmark tendons of extensor
  digitorum on back of hand

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Extensor/Supinator Group The Rest

• Extensor digiti minimi
• Extends...well... you tell me!
• Very thin peeks out between the twins.
• Anconeus (ancon elbow)
• Helps extend forearm
• Triangular shape at proximal ulna does not have
  long tendon like the others.
• Ulnar crest separates flexor group from extensor
  group

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Flexor/Pronator Muscles of Forearm(in three
layers)

• Most superficial layer
• Flexor carpi ulnaris
• Flexor carpi radialis
• Palmaris longus
• Next layer
• Flexor digitorum superficialis
• Deepest layer
• Flexor digitorum profundus

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Flexor/Pronator Muscles of Forearm(Three muscles
on most superficial layer)

• Flexor carpi radialis
• pronates forearm flexes and abducts wrist and
  hand
• Flexor carpi ulnaris
• flexes and adducts wrist and hand

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Palmar aponeurosis

• palmar aponeurosis
• helps with (strengthens) grip

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Flexor/Pronator Muscles of Forearm(Next Two
Layers)

• Flexor digitorum superficialis
• Flexor digitorum profundus
• both flex hand and fingers (not thumb)
• superficialis more superficial
• profundus deeper flexes distal phalanges
• Biceps tendon separates flexors from extensors

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Its easy to tell one tendon from the other.

• Flexor carpi radialis tendon is closer to the
  radial (thumb) side of the arm, as its name
  implies. Once that's been established, one can
  deduce that the other tendon is most likely that
  of palmaris longus.

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The palmaris longus tendon is also more
superficial than the flexor carpi radialis tendon
because it runs outside the annular ligament.

• After surpassing the annular ligament, the
  palmaris longus tendon inserts directly into the
  palmar aponeurosis and tenses it to help
  strengthen the grip.

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The Ventral Forearm What are those Tendons?

• But the distal end of the ventral forearm does
  have a few prominent surface landmarks.
• I write "a few" instead of a specific number
  because the number depends on the individual
• Palmaris Longus is one of the tendons that's
  often seen at this location is actually missing
  in 12-15 of the human population!

• not less complicated than the dorsal side
• few of its muscles show clearly
• smooth and uncomplicated.
• "underbelly"-- paler and less hairy than its
  dorsal counterpart
• fewer hair follicles and less melanin production.

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In most cases, there are two fairly visible
tendons down the approximate center of the
ventral wrist.

• Degree of visibility also depends on genetics and
  hand position
• Those two tendons come from the palmaris longus
  muscle and the flexor carpi radialis muscle.
• How do we know this is the ventral side of the
  forearm?

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Do you have a palmaris longus tendon?

• Make a claw fist to find out.

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Muscles of the Hand

• Dorsal Interossei
• between metacarpals
• on dorsal side of hand
• abduct (spread) fingers
• First dorsal interosseus m. is surface landmark
• We also have palmar interossei

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Other Hand Structures

• Thenar muscles
• Hypothenar muscles
• Palmar aponeurosis
• Annular ligament

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Annular Ligament

• The annular ligament is a ring-like ligament
  ("annular" is Latin for "ring-like") that wraps
  around the wrist like a bracelet and retains the
  position of the tendons that run from the forearm
  and into the hand.

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Other Hand Structures

• Anatomical snuffbox
• tendon of extensor pollicus longus (more dorsal)
• tendon of extensor pollicus brevis (more ventral)

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Assignments

• QUIZ Covers muscles of the arm and hand.