Anatomy Unit 3: Bones of the Pectoral Girdle and Upper Limb

On which side of the ulna is the radial notch located?

Lateral

Elbow joint

allows for flexion and extension. It is a diarthrotic and synovial joint (hinge joint). Allows for flexion and extension, motion in one plane At the elbow, the humerus articulates with both the: 1. Ulna at the humeroulnar joint 2. radius at the humeroradial joint The trochlea is medial while the capitulum is lateral

Which bones are components of the pectoral girdle?

Scapula and clavicle

The forearm and hand

The radius is the lateral bone of the forearm. The ulna medial.

Sternoclavicular and Acromioclavicular Joints

The sternoclavicular and acromioclavicular joints are synovial joints based on structure, and diarthrotic joints based on function. Through these joints we can get retraction and protection movements of the scapula, and elevation and depression movement of the scapula

Upper Limb

Within the upper limb, there are 30 bones: -brachium: 1 (humerus) -antebrachium: 2 (radius and ulna) -wrist: 8 (carpals) -hand: 5 (metacarpals) -digits: 14 (phalanges)

Carpal bones

Proximal row lateral to medial: scaphoid, lunate, triangular (triquetrum or triquetral), pisiform. Distal row lateral to medial: trapezium (closest to the thumb), trapezoid, capitate, hamate. remember the order by this nemonic: "some lovers try positions they can't handle" There are joints in-between the carpal bones called intercarpal joints. They are synovial joints (plane joints), allows for a little bit of gliding.

The upper limb consists of 30 bones

The arm or brachium: humerus (1) The forearm or antebrachium: radius and ulna (2) The wrist: carpals (8) The hand: metacarpals (5) The digits: phalanges (14)

Humerus

The proximal end of the humerus articulates with the glenoid fossa of the scapula at the glenohumeral or shoulder joint. Distally, the humerus articulates with the radius and ulna at the humeri-radial and humero-ulnar or elbow joint.

Metacarpals and Phalanges

There are 14 phalanges (each digit has 3 phalanges, but the thumb only has 2) From Lateral to Medal: • Digit 1 = pollex (thumb) (only has proximal and distal phalanges) • Digit 2 = index • Digit 3 = medius • Digit 4 = annularis • Digit 5 = minimus (pinky) The metacarpals will articulate proximally with the carpal bones and distally with the proximal phalanges metacarpophalangeal joints (MP) are between the metacarpal bones and the proximal phalanges of the fingers. These joints are condyloid, allows for motion in two-planes They allow or flexion, extension, adduction, abduction, allows for circumduction Interphalangeal Joint (IP) are the hinge joints between the phalanges of the fingers that provide extension and flexion towards the palm of the hand The thumb digit has only two phalanges (bones) so it only has one joint.

What two fossae are separated by the scapular spine?

Infraspinous fossa and supraspinous fossa

Scapula

Know as the shoulder blade Lies in-between the levels of the second and seventh ribs (T2-T7) Anterior side of scapula will be up against the ribs. The anterior side has a large fossa called the subscapular fossa. Sitting in the subscapular fossa is a muscle called the subscapularis muscle. A number of different muscles attach to the coracoid process. The pectorals minor muscle, coracobrachialis, and the short head of the biceps brachii. On the posterior side of scapula is a spine that runs diagonally across the scapula. The lateral end of the spine will flatten out to form the acromion which is called the acromion process. Superior to the spine is the supraspinous fossa (where the supraspinatus muscle is found). Inferior to the spine is the infraspinous fossa (where the infraspinatus muscle is found). On the lateral side of the scapula we found the glenoid cavity which is the articulation site for the head of the humerus (forming the shoulder joint known as the glenohumeral joint). Superior to this is the supraglenoid tubercle (this is where the long head of the biceps brachii attaches). Inferior to the glenoid cavity is the infraglenoid tubercle (where the long head of the triceps brachii attaches) The medial border (known as the vertebral border) of the scapula is thin edge of the scapula closest to the vertebral column. The lateral border is the thick edge of the scapula closest to the upper limbs. The superior border is the superior edge of the scapula. The inferior angle is between the medial border and lateral border. The superior angle is between the superior border and medial border.

Humerus

Known as the arm or the brachium the humerus is the largest bone in the upper limb the head of the humerus articulates with the glenoid cavity to form the glenohumeral joint (synovial joint, ball-and-socket). The glenohumeral joint allows for flexion, extension, abduction, adduction, circumduction, medial rotation, lateral rotation. The head of the humerus will point medially and a little bit posteriorly. The humerus has two heads. The anatomical neck is distal to the head, and found between the head and the tubercles. Distal to the tubercles is the surgical neck. The surgical neck is most frequently fractured site on the proximal end of the humerus. The greater tubercle and lesser tubercle are important sites for muscle attachments, especially muscles that move the shoulder. Inferior to the tubercle is a greater crest (more lateral) and lesser crest (more medial). These two crests will separate the intertubercular sulcus. (also known as the bicipital groove). Running through the intertubercular sulcus will be the cord-like tendon of the long head of the biceps brachii. Deltoid tuberosity is found anteriorly and laterally. Is a roughened region along the shaft where the deltoid muscle will insert. At the distal end of the humerus, there is the coronoid fossa (medially) and radial fossa (laterally). On the posterior side, there is a much larger fossa called the olecranon fossa (this is where the olecranon of the ulna enters when you extend the elbow). When you flex your elbow joint, the head of radius enters the radial fossa and the coronoid process of the ulna enters the coronoid fossa. At the distal end of the humerus, there are two condyles, trochlea (medial) and capitulum (lateral). The trochlea articulates with the trochlea notch of the ulna. The capitulum articulates with the head of the radius. The lateral epicondyle and the medial epicondyle are important for the attachments of the muscles of the forearm. The spiral groove (radial groove) is found in the posterior aspect of the shaft. This groove extends inferolaterally. It spirals around the shaft of the humerus. This is also where the radial nerve is. Here is also the deep brachial artery.

Radius and Ulna

Known as the forearm bones (antebrachii), this is the region between the elbow and the wrist. The radius and ulna are parallel to one another in anatomical position. The radius is lateral and the ulna is medial. (ulna is associated with your pinky and the radius is associated with you thumb) The ulna is the longest bone of the forearm. On the proximal end of the ulna is the olecranon process (elbow). On the anterior side, there is the trochlear notch (this articulates with the trochlear of the humerus) On the distal end of the ulna is where the head of the ulna is found. Here is also the styloid process of the ulna (bump of the wrist) On the proximal end of the ulna and lateral aspect, there is the radial notch where it articulates with the radius head The radius is the lateral and shorter bone of the forearm. Has a disk-like head at the proximal end. The head of the radius with articulate with the capitulum of the humerus and the radial notch of the ulna. Inferior, there is the radial tuberosity which is the attachment point of the tendon of the biceps brachii The shaft of the radius increases in size from proximal to distal. It will also bow laterally. The styloid process of the radius is always pointing at the thumb. The distal end of the radius will articulate with a few of the carpal bones to form the wrist joint. The ulna does not play a role in the wrist joint. The groves on the posterior distal end of the radius will contain the extensor muscle tendons. The interosseous membrane connects the radius and the ulna together. It is a strong fibrous sheet. It will also provide attachment points for the deep muscles of the forearm. The styloid process of the radius is more distal/inferior than the styloid process of the ulna. The styloid process of the radius is a common fracture site when falling on an outstretched upper limb, this causes it to get pushed more proximal. This causes the styloid process of the radius and the styloid process of the ulna to line up. This type of fracture is called a Colles' fracture.

Which bony part listed below rests on the table when you lean on your elbow?

Olecranon process

On which bone is the coracoid process found?

Scapula

Clavicle

The clavicles are S-shaped bones Know as the collarbones Found lying in a horizontal position just superior to the first rib The medial half of the clavicle is convex anteriorly. The lateral half is convex posteriorly The medial end of the clavicle (sternal end) articulates with the clavicular notch of the manubrium to form the sternoclavicular joint -it is more blunt or rounded The lateral end of the clavicle (acromial end) articulates with the acromial end of the scapula to form the acromiocalvicular joint To differentiate a left from right clavicle: -find the medial end which is very blunt -on the anterior side, it should be convex anterior and then convex posterior as you go from medial to lateral -on the inferior surface, there is a conoid tubercle (it is at the lateral end) The clavicle is a very important bone fro transmitting mechanical force from the upper limb to the trunk. If too much mechanical force is being transmitted through the clavicle (such as falling), the force will be transmitted through the forearm, arm, shoulder, acromicoclavicular joint, clavicle, to the axial skeleton. Due to this, the clavicle is one of the most frequently broken bones. The fracture is typically at the middle since that bend is weakest point.

Which of the following statements about the humerus is CORRECT?

The coronoid fossa receives the coronoid process during elbow flexion. The radial nerve travels in the spiral groove. The capitulum articulates with the head of the radius. The most frequent site of fracture at the proximal end of the humerus is at the surgical neck.

Radioulnar Joints

The head of the radius is sitting in a ring (composed of bone) and the annular ligament, which allows the head of the radius to pivot. This is a pivot joint. (synovial, diarthrotic) Allows for rotation, called supination and pronation. For pronation, we take the distal end of the radius and rotate it about the ulna, the ulna and radius are now in a criss-cross position. In supination, the ulna and radius are once again parallel The radius and the ulna articulate at the: 1. proximal radioulnar joint: between the head of the radius and the radial notch of the ulna; head held in place by the annular ligament 2. distal radioulnar joint: between the head of ulna articulates with the ulnar notch in the distal end of the radius

Bones of the hand

The only articulation between the antebrachium (forearm) and the hand is that of distal radius with scaphoid and lunate, two of the carpal bones 1. The carpal bones. There are eight small bones in the wrist. The four bones in the proximal row form lateral to medial are: scaphoid, lunate, triangular (triquetrum), and pisiform. The distal row from lateral to medial are: trapezium, trapezoid, capitate, and hamate 2. The metacarpal bones. These five hand bones are numbered from lateral to media, one through five. They articulate with carpals proximally and with phalanges distally. 3. The phalanges (one is a phalanx) are the bones of the digits. There are five digits numbered from lateral to medial, one through five. In that order they are named: pollex (thumb), index, medius, annularis, minimus Digits two through five each have three phalanges: a proximal (articulates with a metacarpal at the metacarpo-phalangeal, or M-P, joint), a middle, and a distal phalanx

Pectoral Girdle

The pectoral girdle is composed of the clavicle and the scapula. The upper limb attaches to the axial skeleton through the pectoral girdle. The pectoral girdle attaches to the axial skeleton at the sternoclavicular joint (between the medial end of the clavicle and the clavicular notch of the manubrium). -The sternoclavicular joint is a diarthrotic joint (freely moveable) and a synovial joint, specifically a plane joint (little bit of gliding or translation) The sternoclavicular joint is where the appendicular skeleton attaches to the axial skeleton The pectoral girdle and its muscles form the shoulder Girdle is usually a belt-like structure that circles the body, but this description doesn't match with the pectoral girdle The clavicle articulates laterally with the scapula at the acromioclavicular joint Medial border of the scapula do not articular with one another, nor do they articular with the axial skeleton (thus, it is not a complete belt-like structure). Instead, the scapulae are attached to the thorax and vertebral column only by muscles The lack of articulation posteriorly of the scapulae allows for a greater freedom of movement of the upper limb and scapulae

Radiocarpal (Wrist) Joint

The radiocarpal joint is between the radius and two carpal bones, namely the scaphoid and the lunate. This is a condyloid joint allows for motion in two-planes They allow or flexion, extension, adduction, abduction, allows for circumduction

The broad, flattened part of the clavicle that articulates with the scapula is the _______.

acromial end

The __________ lies on the posterior aspect of scapula.

scapular spine