Upper Limb VArm and Elbow

Brachial/Anterior Cubital Region; Elbow JointJohn Halle, Ph.D., PT August 24th, 2004 (8:00)

Moore & Dalley: Clinically-Oriented Anatomy, 4th ed: pp. 668-672, 699-705, 720-733, 795-799; Table 6.5.

Sauerland: Grant’s Dissector, 12th ed.: pp. 199-202Agur & Dalley: Grant’s Atlas of Anatomy, 11th ed: Plates 6.1-6.2, 6.4-6.14, 6.17-6.63.Hansen: Frank H. Netter, M.D., Atlas of Human Anatomy, 3rd ed/Interactive Atlas (CD-ROM):

Plates 403, 404, 408, 412, 414-419, 421, 422, 430, 433, 434, 456-461, 464-466; C21-25, C346Weir & Abrahams: Imaging Atlas of Human Anatomy, 3rd ed.: 67a, b & c; 72; 81a, c & dRohen, Yokochi & Lütjen-Drecoll: Color Atlas of Anatomy, 5th ed.: 360-3, 367, 374-5, 379, 386-90, 394, 400-1,

405-9

As a result of attending the audiovisual presentations, reading/viewing the textbook, atlas and notes, and participating in the lab experience, VSM I students should understand and be able to:1. On a skeleton or on a radiograph, demonstrate the bones & bony landmarks of the distal humerus,

radius & ulna, and describe the movements, which occur at the elbow & radioulnar joints.2. Describe and demonstrate in anatomical or radiographic cross-sections, the organization of the deep

fascia of the arm and forearm, and the fascial compartments in terms of functional muscular groups contained, innervations of, and major vessels coursing within each compartment. This should include the specific muscles in each compartment, their individual attachments and specifics regarding their actions.

3. Describe and identify (on a written examination, on an angiogram, or on the cadaver) the components of the collateral circulation around the shoulder and elbow. Identify the portions of the axillary-brachial artery.

4. Describe the pattern of drainage of the deep veins and the superficial and deep lymphatics of the arm and forearm. Describe the form in which deep veins of the limbs generally occur.

5. Delineate the courses of the musculocutaneous, radial, median and ulnar nerves within the arm. Describe the clinical anatomy of each with regard to their course and distribution in the arm and through the cubital fossa (i.e., the most common sites of injury of each nerve, the structures affected, method of testing for, and clinical manifestations of the subsequent palsies).

6. What structures delineate the cubital fossa? What structures lie within the cubital fossa? What is their relationship to one another?

7. Define, locate, and demonstrate the following structures that comprise the elbow and proximal radioulnar joints: a) collateral ligaments, b) olecranon bursa, c) annular ligament, d) interosseous membrane, and e) articular capsule

8. Be able to describe the following as related to the elbow joint: a) movements and carrying angles, b) nerve supply, and c) bursae associated with the elbow joint.

9. Describe subluxation (incomplete dislocation) and dislocation of the head of the radius. Within the description, be able to identify ligament(s) torn, direction the radius will typically move, and the classic position held of the elbow and forearm.

10. Describe the relationship of the median cubital vein to the brachial artery and the connective tissue that separates them.

11. Define the following fractures of the humerus. For each fracture, identify which nerve is likely to be injured and what deficits would be observed as a result of this lesion? a) surgical neck, b) avulsion of the greater tubercle, c) transverse fracture, d) spiral fracture, and e) condylar fractures.

1

Upper Limb VArm and Elbow

Brachial/Anterior Cubital Region; Elbow Joint

“Big Picture Overview” The Arm - consists of the following: (Dalley’s COA Figure 6.5 and Plate 418 [Netter’s])

* 1 bone - humerus* 2 muscle compartments

anterior compartment- innervated by the musculocutaneous nerve (C5-6 to the motor components - has some C7 involved with the sensory component of the lateral cutaneous nerve of the forearm)

posterior compartment - innervated by the radial nerve (C6-8)* Blood supply - main blood supply is derived from branches of the deep artery of the arm

(profunda brachii artery), with some contributions from the brachial artery. median nerve ulnar nerve

The Elbow - consists of the following structures, spaces and characteristics: (Plate 6.12b [Grant’s], 418, as well as plates 417 and 416 [Netter’s])* 3 bones:

humerus ulna radius

* Cubital fossa - a triangular region located on the volar surface of the elbow* Common forearm flexor attachment - the medial epicondyle, where many of the forearm

flexors attach (more detail later)* Common forearm extensor attachment - the lateral epicondyle, where many of the

forearm extensors attach (more detail later)* The elbow's circulation is characterized by an extensive anastomosis (more detail later)* Hilton’s law - states that the nerves supplying a joint also supply the muscles moving the

joint or the skin covering their attachments. Therefore, knowing muscles that cross the elbow provides information about the innervation of the joint and the skin of the region of the elbow (more detail later).

Osteology Components of the Scapula - viewed from an anterior perspective (Plate 6.31b [Grant’s])

* acromion* coracoid process - means “crowlike”* superior, margin/angle* medial and lateral margins* infraglenoid tubercle - attachment for the long head of the triceps brachii* subscapular fossa* glenoid fossa* inferior angle - located at about the T7 level

Scapula - viewed from a posterior perspective (Plate 6.31d, [Grant’s])* spine - base of the spine of the scapula is located at approximately T3* supraspinatus fossa

2

* infraspinatus fossa* superior or suprascapular notch

Components of the Humerus - viewed from an anterior perspective (Plate 403A [Netter’s]* head* greater tubercle* lesser tubercle* crest of the greater tubercle and lesser tubercle* intertubercular groove* deltoid tuberosity* lateral and medial supracondylar ridge* medial epicondyle* lateral epicondyle* medial condyle* lateral condyle* radial fossa* capitulum - lateral* coronoid fossa* trochlea - medial* Note: The humerus has 3 borders (anterior, medial and lateral)

Humerus - viewed from a posterior perspective (Plate 404A [Netter’s])* groove for the radial nerve, as it winds around the humerus* olecranon fossa* trochlea* groove for the ulnar nerve, as it passes under the medial epicondyle

Radius - viewed from an anterior perspective (Plate 422A [Netter’s])* head - narrow end of the bone (at the elbow)* neck* tuberosity of radius* anterior surface/margin* interosseous membrane* styloid process

Ulna - viewed from an anterior perspective (Still using Plate 422A [Netter’s])* head - narrow end of the bone at the wrist* olecranon * trochlear notch* coronoid process* radial notch of ulna* anterior surface/margin of the ulna* tuberosity of ulna* styloid process of ulna

General Orientation of the Free Upper Limb (Plate 456 [Netter’s]) Surfaces - anterior and posterior

3

Borders - medial and lateral Arm = one bone, the humerus Forearm = two bones, the radius and ulna Elbow = posterior aspect Cubital fossa = anterior aspect Forearm descriptions typically use the radial and ulnar border, since the forearm is so easily

manipulated in space Carrying angle - the angle made by the intersection of the long axis of the arm and forearm.

It is normally 10o to 15o in men, and greater than 15o in women. The greater carrying angle in women is associated with the typically wider pelvis, that assists with moving the forearm away from the body when carrying heavy items.

Muscle Groups and Fascia (Plates 418A and 418B [Netter’s]) Muscle groups -Arm

* flexor compartment of the arm = anterior compartment* extensor compartment of the arm = posterior compartment

Fascia* Superficial fascia of the arm = brachial fascia, that consists of loose areolar tissue and

variable amount of fat* Deep fascia of the arm = brachial fascia, that consists of dense connective tissue, and two

thickenings: (1) lateral septa, and (2) medial septa. These two septa are boundaries that form the compartments of the arm

Dermatomes (Plate 465a [Netter’s]) An area of skin supplied by one spinal root level, e.g., C5

* Dermatomes overlap considerably which means that the loss of one spinal cord level (nerve root), usually does not result in the complete loss of sensation for that strip of skin. Typically, three adjacent spinal cord levels must be lost before a significant sensory deficit is apparent (but, loss of one level often results in some diminishment of sensation or an odd sensation in the affected dermatome)

* Dermatomes of the upper extremity. C3 C4 C5 C6 C7 C8 T1

Peripheral nerve cutaneous innervation (Plate 6.4a [Grant’s])* This is the region of skin innervated by a named peripheral nerve. Sensory deficits that

are associated with the following peripheral nerves when injured occur within the upper extremity (thus not at the level of the nerve root exiting the foramina in the neck [between two adjacent vertebrae]), and typically have a different pattern than the dermatomes.

* Peripheral cutaneous nerves of the upper extremity Supraclavicular nerve Axillary nerve - superior lateral cutaneous

4

Radial nerve - three components: (1) inferior lateral cutaneous, (2) posterior cutaneous nerve of the forearm, and (3) superficial radial nerve

Medial cutaneous nerve of the arm (brachial cutaneous nerve) and medial cutaneous nerve of the forearm (antebrachial cutaneous nerve) - these both are direct branches from the medial cord of the brachial plexus

Lateral cutaneous nerve of the forearm (lateral antebrachial cutaneous nerve - the sensory component that is the continuation of the musculocutaneous nerve

Median nerve Ulnar nerve

Superficial Veins (Plate 466A [Netter’s]) Cephalic vein (found laterally in the forearm and arm, between the deltoid and pectoralis

major)* pierces the clavipectoral fascia* empties into the axillary vein

Basilic (found on the medial side of the arm)* ulnar side of forearm* pierces brachial fascia and ascends in anterior compartment of arm and empties into

axillary vein

Muscles of the Anterior Compartment (Plate 414A [Netter’s]) Coracobrachialis muscle

* Origin - tip of coracoid process* Insertion - middle 1/3rd of medial surface of humerus* Action - flexion and adduction of the arm (affects the glenohumeral joint)* Nerve - Musculocutaneous (C5-6)[C7]

Brachialis muscle (Plate 414B [Netter’s])* Origin - distal 1/2 of anterior surface of the humerus* Insertion - coronoid process and tuberosity of the ulna* Action - forearm flexion (elbow) - most important flexor of the elbow, regardless of the

position of the forearm ("workhorse" of the motion of elbow flexion)* Nerve - Musculocutaneous (C5-6)[C7]

Biceps Brachii muscle - as its name implies, it has two heads (Plate 414A [Netter’s])* Origin:

short head - tip of coracoid process of scapula long head - supraglenoid tubercle of the scapula - from this point, the tendon passes

through the glenohumeral joint, is surrounded by synovial membrane, and traverses the intertubercular groove (the position of the tendon is maintained in this groove by the transverse humeral ligament)

* Insertion - into the tuberosity of the radius and the fascia of the forearm via the bicipital aponeurosis

* Action - supinates foream and, when it is supinated, flexes the forearm (Supinating a pronated forearm is the primary action of the biceps brachii).

* Nerve - Musculocutaneous (C5-6)[C7]* MSR - biceps reflex, C5 primarily (C5-6)

Muscles of the Posterior Compartment (Plate 415B and 415A [Netter’s])

5

Triceps Brachii muscle* Origin:

Long head - infraglenoid tubercle of scapula Lateral head - posterior surface of humerus, superior to the radial groove Medial head - posterior surface of humerus, inferior to the radial groove. This is the

true counterpart of the brachialis muscle, and it is active with all voluntary elbow extensions

* Insertion - proximal end of olecranon and fascia of the forearm* Action - forearm extension (the elbow). The medial head is always active and the lateral

and long heads provide additional power* Nerve - radial (C6-8)* MSR - C7 primarily (C7-8)

Anconeus muscle (Plate 6.51b [Grant’s])* Origin - lateral epicondyle of the humerus* Insertion - lateral side of the olecranon and superior part of the posterior surface of the

ulna* Action - forearm extension and stabilization of the joint* Nerve - radial (C7-T1)

Nerves of the Anterior Compartment of the Arm (Plates 456, 457, 458, 459, 460, 461A [Netter’s]) Musculocutaneous nerve (C5-6[C7]) - the nerve of elbow flexion, forearm supination, and it

provides the sensation for the lateral aspect of the forearm, once it emerges distally under the cover of the biceps brachii muscle (lateral cutaneous nerve of the forearm [old name = lateral antebrachial nerve of the forearm])

Median nerve (C5-T1) - Proximally, located anterolateral to brachial artery in the arm, but becomes medial to the brachial artery in the cubital fossa. Sends a branch to the pronator teres muscles (passes through the two heads of the pronator teres), and enters the flexor compartment of the wrist and hand. Provides sensation to the thumb, index, middle and 1/2 of the ring finger (palmar surface and tips of those fingers dorsally)

Ulnar nerve ([C7]C8-T1) - Located posteromedial to the brachial artery in the arm. At a point approximately 1/2 way down the arm, the nerve pierces the medial intramuscular septum, then travels in the posterior compartment of the arm, passing behind (under) the medial epicondyle of the humerus (ulnar groove), into the forearm. This nerve will supply two muscles in the forearm and be the predominant nerve supply to the intrinsics in the hand. The ulnar nerve supplies sensation to both the palmar and dorsal surfaces of the little finger and the ulnar half of the ring finger.

Radial nerve (C5-T1) - In the proximal arm, the radial nerve is located posterior to the brachial artery. Below the teres major, the radial nerve enters the posterior compartment (along with the accompanying deep artery of the arm [profunda brachii artery]), then passes between the lateral and medial heads of the triceps (lies in the radial groove directly on the humerus). Ultimately, the radial nerve spirals around and pierces the lateral intramuscular septum to lie in the anterior compartment of the arm, just proximal to the elbow. In the region of the lateral epicondyle, the radial nerve divides into two branches that enter the forearm: (1) superficial radial nerve (sensory only), that supplies sensation to the dorsum of the thumb, index, middle and 1/2 of the ring finger, except for the tips (supplied by the

6

median nerve), and (2) the deep radial nerve (posterior interosseous nerve after passing through the supinator), that innervates the extensors of the forearm.NOTE: Since the radial nerve lies directly on the humerus for a portion of its course, it is more vulnerable to injury with fractures of the humerus.

The Brachial Artery (Plates 6.49d [Grant’s] and 417 [Netter’s]) Is the direct continuation of the axillary artery (name changes to the brachial as the artery

passes the lower border of the teres major). During its course through the arm, the brachial artery lies on the coracobrachialis and brachialis muscles.

Terminates in the cubital fossa, dividing into the two major arteries of the forearm, the radial and ulnar arteries

Major branch is the deep artery of the arm [profunda brachii artery] (that travels with the radial nerve) - this is the chief source of blood supply to the arm, with branches to the humerus, branches contributing to the anastamoses of the shoulder and elbow. Named branches that stem off of the deep artery of the arm [profunda brachii artery] include:* Radial collateral artery* Middle collateral artery* Superior ulnar collateral artery (arises in the middle of the arm and travels with the ulnar nerve, and* Inferior ulnar collateral artery (arises above the elbow, and provides an anastomosis with

the posterior and anterior recurrent arteries (from the ulnar artery) - this network assists with blood flow around the elbow.

The Brachial Veins (Plate 412 [Netter’s]) The brachial veins are deep veins (collect blood from deep tissue), paired, and they ascend

one on each side of the brachial artery They are derived from the union of the radial and ulnar veins, returning blood from the

forearm The brachial veins terminate proximally into the axillary vein

The Cubital Fossa (Plates 6.49c, 6.49d and 6.49b [Grants])

The cubital fossa is a space in the anterior aspect of the elbow that contains all the major nerves and vessels, except for the ulnar artery (that does not pass through this space since it passes posterior to the medial epicondyle of the humerus)

Boundaries:* Floor - brachialis muscle* Roof - antebrachial fascia* Medial boundary - pronator teres* Lateral boundary - brachioradialis muscle

Contents of the cubital fossa:* Biceps tendon* Brachial artery (and beginning bifurcation of the ulnar and radial arteries)* Median nerve (that may give off a branch [anterior interosseous nerve], while still in the

cubital fossa)* Radial nerve (with both the superficial and deep components)* Basilic and cephalic veins

7

The Elbow Joint (Plate 419A [Netter’s]) A compound synovial joint. Two bones, the radius and the ulna, both articulate with the

humerus bone. Characteristics of the elbow joint:

* The joint cavity is continuous with that of the proximal radioulnar joint (Thus, a single capsule)

* The joint between the humerus and the ulna is a uniaxial hinge joint, permitting only flexion and extension

Elbow joint articular surfaces (Plate 419B [Netter’s])* Proximally, the articular surfaces consist of the capitulum of the humerus and the trochlea

of the humerus* Distally, the articular surfaces consist of the head of the radius and the trochlear notch of

the ulna* In the anatomical position, the humeroradial joint is located laterally, and the

humeroulnar joint is located medially Elbow Joint - capsule, ligaments and bursae(Plates 6.54c and 6.55c [Grant’s])

* Articular capsule Thin, anteriorly and posteriorly Reinforced by collateral ligaments

* Ligaments - most of these are thickenings of the joint capsule and are difficult to visualize as discrete ligaments during dissection, particularly on the medial side of the joint Annular ligament (ring ligament) - passes from the radial notch around the head of

the radius Ulnar collateral ligament - from the medial epicondyle to the olecranon process, to

the coronoid process (Often identified as having three parts, an: (1) anterior, (2) posterior, and (3) oblique band)

Radial collateral ligament - from the lateral epicondyle and blends with the annular ligament

Bursae - subcutaneous olecranon bursae

8

Elbow Joint Movements (Plates 433 and 434 [Netter’s]) Flexion - made possible by the following:

* Brachialis* Biceps brachii* Brachioradialis* Wrist and hand flexors (and extensor [brachioradialis]), that cross the elbow joint (i.e.,

forearm flexors that insert into the common flexor tendon, and forearm extensors that insert into the common extensor tendon that pass anterior to the axis of the elbow joint)

Extension - made possible by the following:* Triceps brachii* Anconeus* Wrist and hand extensors (that insert into the common extensor tendon - these include the

ECRL, ECRB, ECU and the ED)

Elbow Joint Nerve Supply (Plate 430 [Netter’s]) Via Hilton's Law, four nerves supply the joint:

* Musculocutaneous nerve (anteriorly)* Median nerve (anteriorly)* Radial nerve (posteriorly)* Ulnar nerve (posteriorly)

Elbow Joint Circulation (Plate 417 and Clinical Correlate C22 [Netter’s]) Deep artery of the arm [Profunda brachii artery] and its branches, the radial collateral artery

and the middle collateral artery Brachial artery and its branches, the superior ulnar collateral artery and the inferior ulnar

collateral artery Ulnar artery, with branches that pass back into the elbow via the anterior ulnar recurrent

artery, the posterior ulnar recurrent artery, and the interosseous recurrent artery Radial artery, receives the radial recurrent artery Anastomoses and collateral circulation - rich anastomosis for the elbow joint NOTE: Due the number of arteries and nerves in the region of the elbow joint, a serious injury to this joint can also result in a neurovascular injury

Other Clinical Correlates (Plates C25 and C23 [Netter’s]) Elbow injury in children - subluxation of the radial head Dislocation of the elbow joint● Elbow fractures

Questions??

9