Unit 3.2 - NURS Anatomy

Appendicular Skeleton

Appendicular skeleton 

Includes the bones of the upper extremities (arms, forearms, and hands), the pectoral (shoulder) girdle, the pelvic (hip) girdle, and the bones of the lower extremities (thigh, knee, leg, and foot). Its components are outside the body main axis

Upper extremity (64 bones)

Upper limb bones: scapula, humerus, ulna, radius, carpals, metacarpals, phalanges.

• Scapula (shoulder blade) connects the upper limb to the trunk and provides attachment for shoulder muscles.

• Humerus articulates with the scapula at the shoulder and with the ulna and radius at the elbow.

• Ulna forms the elbow joint with the humerus.

• Radius and ulna connect with the carpals at the wrist.

• Carpals (wrist bones) articulate with metacarpals (hand bones), which connect to phalanges (finger bones).

Lower extremity (62 bones)

Lower limb bones: pelvis, femur, patella, tibia, fibula, tarsals, metatarsals, phalanges
Pelvis: connects lower limb to trunk and supports body weight.
Femur: articulates with pelvis at hip and tibia at knee.
Patella: protects the knee and improves thigh muscle leverage.
Tibia: bears weight and connects with femur and ankle.
Fibula: provides muscle attachment and ankle stability.
Tarsals: connect to metatarsals, which lead to phalanges (toes).

Pelvic girdle 

Composed of clavicle (anterior) and scapula (posterior), the pectoral girdle anchors upper limbs to the axial skeleton. The clavicle articulates with the sternum medially and the scapula laterally, serving as attachment for pectoral and deltoid muscles. The scapula provides numerous muscle insertions

Clavicles 

Slender, curved bones across the upper thorax that brace the scapulae and limbs away from the chest. Clavicles strengthen with muscle use and are sensitive to tension from shoulder movement

Scapulae

Flat, triangular bones with 2 surfaces (subscapular and supraspinous fossae), 3 borders, and 3 angles. The lateral border features the glenoid cavity, articulating with the humerus, while the acromion connects with the clavicle at the acromioclavicular joint to anchor the upper limb

Pelvic girdle

Attaches the lower limbs to the axial skeleton and transmits body weight. Strong ligaments secure it, and its deep, reinforced sockets (acetabula) articulate with the femur. Formed by two coxal bones, each composed of three fused parts—ilium, ischium, and pubis—uniting anteriorly and with the sacrum posteriorly to form the bony pelvis

Pelvic bone

Comprised of two hip bones joined at the pubic symphysis anteriorly and to the sacrum posteriorly

Arm (Brachium):

Single bone — Humerus, a typical long bone.

• Proximal head fits into the glenoid cavity of the scapula.

• Distal end has two condyles articulating with the radius and ulna at the elbow

Forearm

Two parallel bones — Radius and Ulna.

• Ulna: Longer; forms the elbow joint with the humerus. Shaft is triangular; proximal end articulates with humerus, distal head separated from wrist by fibrocartilage. (Pinky side)

• Radius: Shorter; articulates proximally with humerus and ulna, distally with carpals. Major contributor to wrist motion. (Thumb side)

• Connected along their length by the interosseous membrane and articulate at radioulnar joints.

Hand

• Carpus (8) – wrist bones

• Metacarpals (5) – palm bones

• Phalanges (14) – finger bones

Femur

Strongest bone in the body. The greater and lesser trochanters serve as muscle attachment points for the thigh and buttocks. Medial and lateral condyles form the rounded articular surfaces at the distal end, while medial and lateral epicondyles lie above them, providing attachment sites for ligaments and tendons

Condyle 

Rounded articular surface at the end of a bone that forms part of a joint

Epicondyle

Raised area above a condyle that serves as an attachment point for muscles, ligaments, and tendons

Condyle vs Epicondyle

• Condyle appears more prominent than the epicondyle.

• Condyles are usually more round-shaped than epicondyles.

• Condyle is smooth and large, whereas epicondyle is rough and small.

• Condyle articulates with a bone, but epicondyle provides a surface for muscle and ligament attachment

What is the difference between the Tibia and Fibula?

Tibia is larger and stronger than fibula.

• Fibula does not form the knee joint, whereas tibia does.

• Tibia is a weight bearing bone, whereas fibula is non-weight bearing bone.

• Proximal end of tibia articulates with femur, while that of fibula articulates with the tibia.

• The thickness of the tibia is much greater than the fibula.

Patella 

A flat triangular bone located at the front of the knee joint.

Protects the anterior articular surface of the knee joint. It is the largest sesamoid bone in the human body

Male pelvis

• Narrow, heavy, thick

• Inlet/outlet smaller

• Pubic arch < 90°

• Sacrum longer, more curved

• Acetabulum large

• Obturator foramen round

Female pelvis

• Wide, light, thin

• Inlet/outlet broader

• Pubic arch > 90°

• Sacrum shorter, less curved

• Acetabulum small

• Obturator foramen oval