Musculoskeletal System: Upper Limbs

Where do upper limbs attach to the body?

Attaches at the one spot where clavicle articulates with sternum

Gives large range of motion

Innervation of the upper limb

Innervated by dermatone —— area of skin innervated by a single spinal nerve

What is brachial plexus?

Set of 5 nerves (C5, C6, C7, C8, T1) that come out from spine and recombine in trunks to form nerves that innervate muscles of the upper limb

Form 5 branches:

• Axillary nerve

• Musculocutaneous nerve

• Radial nerve

• Median nerve

• Ulnar nerve

Muscles that move pectoral girdle (posterior)

• Trapezius (innervated by CXI)

• Levator scapulae (elevates scapula)

• Rhomboids (pulls scapula back to midline)

Muscles that move pectoral girdle (anterior)

• Pectoralis minor (pulls foward)

• Serratus anterior (moving shoulder foward)

Muscles that move the arm (originating on axial skeleton)

• Anterior: Pectorialis major m. (flex, adduct, and rotate arm)

• Posterior: Latissimus dorsi (extends, adduct, and rotate arm)

Muscles that move the arm (originating from scapula)

Anterior

• Deltoid (innervated by axillary) (flex, extend, abduct)

• Coracobrachalis (innervated by musculocutaneous)

• Biceps brachii (innervated by musculocutaneous)

Posterior

• Teres major (pulls the arm posteriorly)

• Rotator cuff

  • SITS (stabilizes)

  • Abduct and rotate arm at shoulder

Anterior portion of the arm contains only ____ muscles

flexor

• flex at shoulder and ends at elbow

• ADDucts arm at shoulder

• Muscles: Biceps brachialis, coracobrachalis, brachialis

• Musculotaneous nerve

Posterior portion of the arm contains only ___ muscle

extensor

• extends and shoulder and elbow joint

• Muscles: triceps brachialis

• Radial nerve

Bones of the forearm?

Radius + Ulna!

Joined unit by interosseous membrane —> syndesmosis

Anterior (Flexor) of forearm nerves

Median

• Pronates (rotates thumbs inward)

• Flexor of hand at wrist and digits

Ulnar

• Flexor of hand at wrist and digits

Radial (Exception here)

• Brachioradialis (flexes at elbow)

Posterior (extensor) of forearm nerves

Radial (supinator)

• Extensor of hand at wrist and digits

Carpal tunnel

Median nerve is compressed in wrist, thus putting pressure on the tendons and causing pain, but they will still work

If you injured median nerve, you will not lose function. Median nerve innervates upper arm

Thenar (Intrinsic muscle of hand)

Flex, abduct, and oppose thumb

Innervated by median nerve

Hypothenar (Intrinsic muscle of hand)

Flex, abduct, and oppose 5th digit (pinky)

Innervated by ulnar nerve

Midpalmar (intrinsic muscle of hand)

Fine movements of digits

Primary innervated by ulnar