Anatomy & Medical Imaging: Upper Limb

Comprehensive practice flashcards covering the osteology, joints, muscular compartments, neurovascular pathways, and regional anatomy of the upper limb from the CLS4014-B Anatomy & Medical Imaging lecture.

What are the four main segments of the human upper limb?

The shoulder (built on half of the pectoral girdle), the arm (brachium), the forearm (antebrachium), and the hand (manus).

Which bones form the pectoral girdle, and what bone completes it anteriorly?

The pectoral girdle is formed by the clavicle and scapula, and is completed anteriorly by the manubrium of the sternum.

What mechanical function does the clavicle perform in relation to the upper limb?

The clavicle acts as a strut that pushes and keeps the scapula and humerus away from the trunk, permitting a free range of movement and flexibility.

Which muscles make up the anterior group of the pectoral girdle and extrinsic shoulder?

The anterior pectoral girdle muscles are the subclavius and pectoralis minor, along with the extrinsic shoulder muscle pectoralis major.

Which muscles comprise the posterior pectoral girdle and extrinsic shoulder group?

The posterior pectoral girdle muscles are the levator scapulae, trapezius, rhomboid major, and rhomboid minor, along with the extrinsic shoulder muscle latissimus dorsi.

What anatomical structure forms the apex of the four-sided pyramidal space known as the axilla?

The cervico-axillary canal (located between the clavicle and the first rib).

What anatomical structures form the anterior and posterior walls of the axilla?

The anterior wall is formed by the pectoralis major and pectoralis minor muscles; the posterior wall is formed by the subscapularis, latissimus dorsi, and teres major muscles.

What structures form the lateral wall, medial wall, and floor of the axilla?

The lateral wall is formed by the humerus (intertubercular sulcus), the medial wall is formed by the lateral thoracic wall (rib cage), and the floor is formed by axillary fascia and skin.

What are the four primary neurovascular contents transmitted through the axilla?

The axillary artery, axillary vein, axillary lymph nodes, and the brachial plexus.

What type of joint is the glenohumeral joint, and what makes it the least stable joint in the upper limb?

It is a ball-and-socket synovial joint between the shallow glenoid cavity of the scapula and the large head of the humerus, where extreme mobility is prioritized over stability.

Why is the fibrous joint capsule of the glenohumeral joint designed with laxity and a redundant fold inferiorly in adduction?

To prevent tightness and allow the head of the humerus sufficient looseness to move through a full range of motion.

What four muscles comprise the rotator cuff?

Supraspinatus, Infraspinatus, Teres minor, and Subscapularis (mnemonic: SITS).

How are the rotator cuff muscles positioned between the anterior and posterior surfaces of the scapula?

One muscle sits anteriorly (subscapularis on the subscapular fossa), and three sit posteriorly (supraspinatus above the scapular spine, infraspinatus below the spine, and teres minor along the lateral border).

In this hand-model illustration of rotator cuff attachments on the left humerus, which muscle inserts onto the lesser tubercle under the thumb?

Subscapularis (while supraspinatus, infraspinatus, and teres minor insert onto the greater tubercle under the fingers).

Which spinal cord nerve roots give rise to the brachial plexus?

Spinal nerve roots $C5$, $C6$, $C7$, $C8$, and $T1$.

What muscular and cutaneous structures are innervated by the axillary nerve?

It innervates the deltoid and teres minor muscles, and provides cutaneous innervation via the superior lateral cutaneous nerve of the arm.

What muscles are innervated by the musculocutaneous nerve?

The anterior compartment muscles of the arm: biceps brachii, brachialis, and coracobrachialis.

Which nerve arising from the brachial plexus innervates the posterior extensor muscles of both the arm and forearm?

The radial nerve.

Which nerve is compressed within a fascial canal in the wrist in carpal tunnel syndrome, affecting the thumb and first two fingers?

The median nerve.

Which nerve is compressed when striking the "funny bone" at the elbow, producing tingling in the little finger and medial ring finger?

The ulnar nerve.

In the illustrated cross-section of the upper arm, what fascial septa divide the anterior compartment from the posterior compartment?

The medial intermuscular septum and the lateral intermuscular septum extending from the brachial fascia to the shaft of the humerus.

How do the origins, insertions, and actions of brachialis and coracobrachialis differ?

Coracobrachialis originates on the coracoid process and attaches midway on the humerus to flex only the shoulder; brachialis originates halfway down the humerus and inserts on the ulnar tuberosity to act as a pure elbow flexor.

What are the three heads of the triceps brachii muscle, and where is their common insertion point?

The long head, lateral head, and medial head; all three insert onto the olecranon process of the ulna.

What distinct bony landmark on the posterior distal humerus accommodates the hook of the ulna during elbow extension?

The olecranon fossa.

How do the positions and head shapes of the radius and ulna differ in the anatomical position?

The radius sits on the lateral side and has a round, disc-shaped head; the ulna sits on the medial side and has a hooked olecranon and trochlear notch.

What mechanical movement occurs between the radius and ulna during forearm pronation as shown in the diagram?

The disc-shaped head of the radius spins at the elbow while its distal end rotates and crosses over the stationary ulna, turning the palm from anterior to posterior.

How are the $19$ muscles of the forearm organized into compartments and subgroups?

The anterior compartment contains flexors and pronators (superficial, intermediate, and deep subgroups); the posterior compartment contains extensors and supinators (superficial, deep, and radialis subgroups).

What are the eight carpal bones of the human wrist listed from lateral to medial across the proximal and distal rows?

Proximal row: Scaphoid, Lunate, Triquetrum, Pisiform. Distal row: Trapezium, Trapezoid, Capitate, Hamate.

What mnemonic was taught in the lecture to recall the eight carpal bones in order ($\text{S-L-T-P-T-T-C-H}$)?

"Some lovers try positions that they can't handle" (Scaphoid, Lunate, Triquetrum, Pisiform, Trapezium, Trapezoid, Capitate, Hamate).

Which two carpal landmarks are clearly visible on the palmar surface but completely hidden on the dorsal view?

The pisiform bone and the hook of the hamate (the dorsal view appears smooth and displays only $7$ visible carpal bones).

Which specific carpal bones articulate directly with the distal end of the radius at the radiocarpal joint?

The scaphoid and lunate bones (the ulna does not directly articulate with the carpals, being separated by an articular disc).

Assuming no anatomical variations, what is the total count of phalanges across both human hands?

$28$ phalanges in total ($14$ per hand: $2$ in each thumb and $3$ in each of the four fingers).

What anatomical name is given to the knuckle joints formed between the metacarpals and the proximal phalanges?

Metacarpophalangeal joints (MCP joints).

How do radial deviation and ulnar deviation of the hand differ?

Radial deviation (lateral deviation) draws the hand laterally toward the radius; ulnar deviation pulls the hand medially toward the ulna.