Anatomy: Dissection 1

Deep brachial artery

close to humerus, wraps around in radial groove of humerus

What is the structure/ function of fascia in upper limb?

covers each muscle of the upper limb muscles associatd w one region are surrounded by another layer of fascia that packages the muscles of region into a compartment

Hand regions

Palm region Dorsum

What are brachialis, coracobrachialis, and both heads of biceps brachii innervated by?

musculocutaneous

What can muscles do?

only contract, only pull (cannot push a joint)

Which nerve is endangered by humeral fractures distal to the surgical head of the humerus?

radial nerve innervates extensors

Arm regions

Anterior (Flexor) Compartment - muscles flex the arm at the shoulder and flex the elbow; one of the muscles supinates the forearm as well (biceps brachii m.) Posterior (Extensor) Compartment - muscles extend the arm at the shoulder and extend the elbow

Forearm regions

Anterior (Flexor) Compartment: 3 layers--> superficial= m that flex wrist or pronate arm middle/ deep layers: flex digits and thumb Posterior (Extensor) compartment: 2 layers--> superficial= extends wrist and digits deep= supinates forearm and acts specifically on the thumb

What muscles are used in tennis?

superficial extensor muscles of the forearm With tennis elbow, the repeated flexion and extension of the wrist strains the attachment of the common extensor tendon, producing inflammation of the periosteum of the lateral epicondyle and the common extensor attachment of the muscles

What is the extensor retinaculum?

thickening of antebrachial fascia that holds tendons on the dorsal side of the wrist in place

what is the extensor retinaculum?

thickening of antebrachial fascia that holds tendons on the dorsal side of the wrist in place

What does the brachial a divide into?

radial and ulnar a

What innervates the extensor compartment of the arm?

radial nerve

Middle layer of forearm: attachment, joints crossed, innervation, action FOREARM FLEXOR

attachment: Common Flexor Tendon from medial epicondyle - phalanges of digits joints crossed: Elbow, Wrist, Metacarpophalangeal (MP), Proximal Interphalangeal (PIP) innervation: Median n. action: Flexes wrist, MP, & PIP

Pronator Teres (muscle in superficial layer of forearm) attachment, joints crossed, innervation, action FOREARM FLEXOR

attachment: Common Flexor Tendon from medial epicondyle - shaft of radius joints crossed: elbow innervation: median n action: pronates forearm

Superficial layer of forearm: attachment, joints crossed, innervation, action FOREARM FLEXOR

attachment: Common Flexor Tendon from medial epicondyle of humerus — base of metacarpals joints crossed: elbow, wrist innervation: median and ulnar** (** for flexor carpi ulnaris m) action: flexes arm at elbow, flex wrist

Deep layer of forearm EXTENSOR: attachment, joints crossed, innervation, action

attachment: Posterior surface of radial & ulnar shafts and interosseous membrane - phalanges of thumb joints crossed: MP and interphalangeal joint of thumb innervation: Radial n. action: Extends and abducts thumb

Deltoid: attachment, joints crossed, innervation, action

attachment: clavicle, acromion, spine of spacula-deltoid tuberosity of humerus joints crossed: shoulder innervation: axillary n action: abducts arm at shoulder

Supinator (muscle of deep layer) forearm EXTENSION attachment, joints crossed, innervation, action

attachment: common extensor tendon-- shaft of radius joints crossed: elbow innervation: radial nerve action: supinates forearm

Coracobrachilalis: attachment, joints crossed, innervation, action ARM FLEXOR

attachment: coracod process- midshaft of humerus joints crossed: shoulder innervation: musculocutaneous n action: flex and adduct arm at shoulder

Brachialis: attachment, joints crossed, innervation, action ARM FLEXOR

attachment: midshaft of humerus- proximal ulna joints crossed: elbow innervation: musculocutaneous action: flexes forearm at elbow

Biceps brachii: attachment, joints crossed, innervation, action ARM FLEXOR

attachment: scapula- radial tuberosity joints crossed: shoulder and elbow innervation: musculocutaneous action: flexes arm at shoulder, flexes forearm at elbow

Triceps brachii: attachment, joints crossed, innervation, action ARM EXTENSOR

attachment: scaular (one head) and humerus- oleocranon process joints crossed: shoulder and elbow innervation: radial n action: extends arm at shoulder, extends forearm at elbow

Palm region of hand

4 compartments: thenar, hypothenar, central, adductor/ interosseous compartments thenar= thumb hypothenar= pinky central= tendons from the forearm flexors that flex the digits and thumb adductor/ interosseous= muscles that adduct thumbs and digits

If the musculocutaneous nerve is severed at its origin from the brachial plexus, flexion at the elbow is greatly weakened but not abolished. What muscle remains operative and can contribute to flexion?

Brachioradialis Brachioradialis is a muscle innervated by the radial nerve--it flexes the elbow and assists in pronating and supinating the arm.

Brachioradialis:

Brachioradialis originates from the upper two-thirds of the lateral supracondylar ridge of the humerus flexes elbow, assists in pronation and supination

The pulse of the radial artery at the wrist is felt immediately lateral to which tendon?

Flexor carpi radialis The radial artery runs on the radial side of the wrist, lateral to the tendon of flexor carpi radialis. So, the radial pulse will be felt immediately lateral to this tendon. Remember--the radial artery enters the wrist on the anterior side. This means that the extensor tendons, which are on the posterior side of the wrist, will not be involved with the radial artery!

What muscle is innervated by branches of both the median and ulnar nerves?

Flexor digitorum profundus The median and ulnar nerve both innervate flexor digitorum profundus.

Shoulder regions

Pectoral Region - pectoral muscles; flex and adduct the arm at the shoulder Scapular Region - rotator cuff muscles; muscles act on the shoulder and reinforce the shoulder joint Deltoid Region - deltoid muscle; abducts arm at the shoulder

After falling on the ice, it was determined that a patient had a Colles' fracture. Care must be taken to relieve tension on the broken distal end of the radius created by the pull of which muscle?

The Colles' fracture is a fracture to the distal end of the radius. So, you need to look in the answer choices for a muscle that inserts on the distal end of the radius. Brachioradialis inserts on the lateral side of the base of the styloid process of the radius, so this muscle could pull the broken piece of the radius out of place.

A worker doing repetitive lifting develops an inflammation in the tendon of origin of the extensor carpi radialis brevis muscle, commonly called "tennis elbow". The focal point of pain would most likely be near which palpable bony landmark?

The extensor carpi radialis brevis muscle originates from the common extensor tendon off the lateral epicondyle of the humerus. So, an injury to this tendon would result in pain near the lateral epicondyle. Tennis elbow is due to the repetitive use of superficial extensor muscles of the forearm--the pain is often felt at the lateral epicondyle and it radiates down the posterior surface of the forearm.

a patient fell against a tree and fractured the shaft of the humerus at midlength. What nerve may be injured because of its close proximity to the injury?

The radial nerve and the deep brachial vessels spiral around the shaft of the humerus in the radial groove. If the humerus is fractured, the radial nerve and the deep brachial vessels may be injured, since these structures are closely associated with the shaft of the humerus.

A woman riding a mountain bike on a rough trail hits a rut and is thrown from the bike. Her upper arm hits a tree, fracturing the humerus just above the insertion of the teres major muscle. Later, during examination, it is noted that she cannot extend her forearm at the elbow or hand at the wrist. Which nerve must have been injured?

The radial nerve spirals around the posterior surface of the shaft of the humerus in the radial groove. It is endangered by humeral fractures distal to the surgical head of the humerus, which is a pretty good description of this patient's injury. The loss of extension at the elbow and wrist also implies damage to the radial nerve--remember, the radial nerve innervates the extensors!

What is the primary blood supply to the upper limb?

axillary artery courses through axilla, giving off numerous branches to supply shoulder muscles and joint continues into arm as brachial a at inferior margin of teres major m.

What nerve is injured by injuryu AT the surgical head of the humerus?

axillary-- arm abduction

What does the ulnar artery give off at its proximal end, just distal to cubital fossa area?

common interosseous a., that divides into anterior interosseous a. and posterior interosseous a Common interosseous a. Anterior interosseous a. → deep layer of anterior (flexor) compartment of forearm Posterior interosseous a. → posterior (extensor) compartment of forearm Superficial palmar arterial arch → hand & digits

What are nerves that innervate individual muscle compartments called?

compound nerves, consisting of fibers from more than one spinal cord level ex: musculocutaneous, which innervates anterior compartment muscles of arm, fibers from C5 and C6

Where does the deep brachial artery run?

deep arm, wrapping around humerus in radial groove if you fracture humerus at mid arm, you could damage this vessel or the radial nerve

What does the radial nerve travel with?

deep brachial vessel (profunda brachii artery) both spiral around the shaft of the humerus in the radial groove

What innervates the shoulder?

deltoid muscle- axillary a

What muscle is involved in tennis elbow?

extensor carpi radialis brevis (and common extensor attchment muscles: brachioradialis) tennis elbow= repetitive use of superfiical extensor muscles of forearm inflammation of lateral epicondyle and common extensor attachment of muscles

What do "compartments" of muscles do?

have a primary action with individual muscles having more detailed, nuanced actions, typically innervated by a single nerve (terminal nerve of brachial plexus) and supplied by a single artery

What innervates the anterior flexor compartment of hte forearm

median and ulnar n median n median n: supplies all of the muscles of the forearm except for 1.5 muscles: the flexor carpi ulnaris m. and ½ of the flexor digitorum profundus m. (which are innervated by the ulnar n) ulnar nerve: supplies 1.5 muscles in anterior forearm, he flexor carpi ulnaris m. (ulnar-side wrist flexor) and the ulnar half of the flexor digitorum profundus m. (deep flexors of the digits) -continues to supply most of the hand muscles

What innervates the flexor digitorum profundus

median and ulnar nerves

What innervates the flexor compartment of the arm?

musculocutaneous nerve

What innervates the posterior extensors compartment of the forearm?

radian n: continues from posterior compartment of arm across lateral epicondyle of humerus where it branches into deep muscular branch supplying muscles of posterior forearum and superficial cutaneous branch where it supplies skin of dorsum of hand and fingers

What supplies blood to the elbow?

several branches from several different arteries that supply the joint area, forming anastomoses that provide collateral supply to joint and surrounding tissue

What are the four major segments of the upper limb?

shoulder: pectoral, scapular, deltoid regions arm: anterior and posterior regions forearm: anterior, posterior regions (separated by the interosseous membrane that connects the radius and ulna) hand: wrist, palm, dorsum, digits regions

What does the ulnar a supply?

ulnar / medial side of forearm flexors as it courses through anterior forearm courses across wrist (pulse point) into hand to supply superficial palmar region of hand

Supination of the hand and forearm would be diminished by loss of radial nerve function. But one very powerful supinator would remain intact and unaffected, namely:

biceps brachii Biceps brachii supinates the arm, but it is not innervated by the radial nerve--instead, it is innervated by the musculocutaneous nerve.

If you loss radial nerve function, you would lose supination of hand and forearm, but one powerful supinator would still work. Which?

biceps brachii, supinates arm but innervated by musculocutaneous

If the musculocutnaoues nerve is severed, flexion at the elbow can still happen bc...

brachioradialis muscle is innervateed by radial nerve, and flexes the elbow and assists in pronating and supinating the arm

a worker below is struck by its sharp edge. The panel hits across the anterior surface of his right arm at midlength and the impact severs all of the tissue to the bone. When examined in the emergency room it is noted that the patient can only weakly flex his elbow and the lateral side of his forearm is numb. In addition to the muscles, which nerve is injured?

The musculocutaneous nerve innervates biceps brachii and coracobrachialis--muscles which flex the arm. Since this man cannot flex his arm, it appears that the musculocutaneous nerve has been damaged. He had also lost sensation over the lateral part of his forearm, indicating that the lateral antebrachial cutaneous nerve has been damaged. This nerve is a branch of the musculocutaneous nerve.

Where do ulnar and radial arteries anastomose?

anastomose (via deep and superficial palmar arches created by the radial and ulnar arteries) in the palmar region of the hand

Deep layer of forearm: attachment, joints crossed, innervation, action FOREARM FLEXOR

attachment: Anterior surface of radial and ulnar shafts and interosseous membrane - phalanges of digits joints crossed: Wrist, MP, PIP, Distal Interphalangeal (DIP) innervation: Median n. & *Ulnar n. *1/2 of flexor digitorum profundus m. action: Flexes wrist, MP, PIP, DIP, & thumb

Superficial layer of forearm EXTENSOR: attachment, joints crossed, innervation, action

attachment: Common Extensor Tendon from lateral epicondyle of humerus - metacarpals or phalanges joints crossed: Wrist, MP, PIP, DIP innervation:Radial n. action:Extends wrist and digits

The pulse of radial artery is felt immediately laterally to...

flexor carpi radialis tendon radial arteyr enters wrist on the anterior side, meaning that extensor tendons, which are on hte posterior side of the wrist, will not be involved w radial artery

what is a Colles fracture?

fracture of the distal end of radius, usually occurs when someone tries to catch themselves from falling on an outstretched arm brachioradialis inserts on lateral side of the base of styloid process of radius, so this muscle could pull broken piece of radius out of place

Radial groove

humerus

What muscles does musculocutaneous innervate and waht are their functions?

musculocutaneous nerve innervates biceps brachii and coracobrachialis--muscles which flex the arm lateral antebrachial cutaneous nerve= branch of musculocutaneous and gives sensation to the lateral part of the forearm

Dorsum region of hand

primarily tendons from extensor compartment of forearm only muscles intrinsic to dorsum are dorsal interosseous muscles that abduct digits

What does the radial a supply?

radial side (lateral) of the forearm flexors as it courses through the anterior forearm at its distal end, courses onto dorsum of lateral hand to run between tendons of extrinsic thumb muscles, reffered to as anatomical snuff box courses through snuff box onto dorsum between thumb and index finger, diving through muscle there to supply deep palmar region of hadn

What causes tennis elbow?

repetitive use of superficial extensor muscles of the forearm--the pain is often felt at the lateral epicondyle and it radiates down the posterior surface of the forearm