Bones of the Appendicular Skeleton: Key Terms and Structures

Study Guide - Smart Notes

Tailored notes based on your materials, expanded with key definitions, examples, and context.

Bones of the Appendicular Skeleton

Overview

The appendicular skeleton consists of the bones of the limbs and the girdles that attach them to the axial skeleton. It is essential for movement, support, and manipulation of the environment. The following study notes cover the major bones and their anatomical features, grouped by region.

Upper Limb

Scapula

The scapula (shoulder blade) is a flat, triangular bone located on the posterior thoracic wall. It provides attachment points for muscles and articulates with the clavicle and humerus.

Acromion: Lateral projection forming the highest point of the shoulder; articulates with the clavicle.
Coracoid process: Anterior projection for muscle attachment.
Glenoid fossa (glenoid cavity): Shallow socket that articulates with the head of the humerus.
Borders: Superior, medial (vertebral), and lateral (axillary) borders define the edges of the scapula.
Body of scapula: Main flat portion.
Scapular spine: Prominent ridge on the posterior surface.
Infraspinous fossa: Depression below the scapular spine.
Supraspinous fossa: Depression above the scapular spine.
Scapular notch: Indentation along the superior border.
Angles: Superior, inferior, and lateral angles mark the corners of the scapula.

Clavicle

The clavicle (collarbone) is a slender, S-shaped bone connecting the sternum to the scapula.

Sternal end (medial end): Articulates with the manubrium of the sternum.
Acromial end (lateral end): Articulates with the acromion of the scapula.

Humerus

The humerus is the bone of the upper arm, articulating proximally with the scapula and distally with the radius and ulna.

Head of humerus: Rounded proximal end; fits into the glenoid cavity.
Anatomical neck: Slight constriction just below the head.
Surgical neck: Common site of fractures; below the tubercles.
Greater and lesser tubercles: Sites for muscle attachment.
Deltoid tuberosity: Lateral shaft; attachment for deltoid muscle.
Medial and lateral epicondyles: Projections at the distal end for muscle attachment.
Capitulum: Lateral condyle; articulates with the radius.
Trochlea: Medial condyle; articulates with the ulna.
Olecranon, coronoid, and radial fossae: Depressions for corresponding processes of the ulna and radius.

Ulna

The ulna is the medial bone of the forearm, forming the elbow joint with the humerus.

Olecranon process: Forms the point of the elbow.
Coronoid process: Anterior projection; fits into the coronoid fossa of the humerus.
Trochlear notch: Articulates with the trochlea of the humerus.
Radial notch: Articulates with the head of the radius.
Styloid process: Distal projection for ligament attachment.
Head of ulna: Distal end; articulates with the wrist.

Radius

The radius is the lateral bone of the forearm, important for wrist movement.

Head of radius: Disc-shaped proximal end; articulates with the capitulum of the humerus.
Radial tuberosity: Attachment for the biceps brachii muscle.
Neck of radius: Narrow region below the head.
Styloid process: Distal projection for ligament attachment.

Carpal Bones

The carpal bones are eight small bones forming the wrist, arranged in two rows.

Proximal row: Scaphoid (navicular), lunate, triquetrum, pisiform
Distal row: Trapezium, trapezoid, capitate, hamate (with hook of hamate)

Metacarpal Bones and Phalanges

The metacarpals (1-5) form the palm, and the phalanges are the bones of the fingers.

Proximal phalanges (1-5): Closest to the metacarpals.
Middle phalanges (2-5): Absent in the thumb.
Distal phalanges (1-5): Tips of the fingers.

Lower Limb

Coxal Bone (Pelvic Bone)

The coxal bone is formed by the fusion of three bones: ilium, ischium, and pubis. It forms the pelvis and supports the weight of the upper body.

Acetabulum: Deep socket for the head of the femur.
Obturator foramen: Large opening for nerves and blood vessels.
Pubic arch: Angle formed below the pubic symphysis.

Ilium

Anterior/posterior superior/inferior iliac spines: Bony projections for muscle attachment.
Iliac crest: Superior border; palpable landmark.
Iliac fossa: Depression on the medial surface.
Greater sciatic notch: Passage for sciatic nerve.
Auricular surface: Articulates with the sacrum.
Ala: Wing-like portion.

Ischium

Ischial tuberosity: Supports weight when sitting.
Ischial spine: Pointed projection.
Lesser sciatic notch: Passage for nerves and vessels.
Inferior ramus: Extension joining the pubis.

Pubis

Pubic symphysis: Cartilaginous joint between pubic bones.
Inferior and superior ramus: Extensions forming part of the obturator foramen.

Femur

The femur is the longest and strongest bone in the body, forming the thigh.

Head of femur: Articulates with the acetabulum.
Fovea capitis: Pit in the head for ligament attachment.
Greater and lesser trochanters: Muscle attachment sites.
Intertrochanteric line and crest: Connect trochanters.
Trochanteric fossa: Depression near the greater trochanter.
Linea aspera: Ridge on the posterior shaft.
Medial and lateral condyles: Articulate with tibia.
Patellar surface: Articulates with the patella.
Epicondyles, adductor tubercle, popliteal surface, intercondylar fossa: Various projections and depressions for muscle and ligament attachment.

Patella

The patella (kneecap) is a sesamoid bone embedded in the quadriceps tendon.

Base: Superior portion.
Apex: Inferior point.
Articular surface: Contacts the femur.

Tibia

The tibia is the medial bone of the leg, bearing most of the weight.

Medial and lateral condyles: Articulate with the femur.
Tibial tuberosity: Attachment for patellar ligament.
Medial malleolus: Forms the inner ankle.
Anterior border: Sharp ridge; palpable.
Tibial plateau, intercondylar eminence, articular facets: Surfaces for articulation.

Fibula

The fibula is the lateral bone of the leg, important for muscle attachment and ankle stability.

Lateral malleolus: Forms the outer ankle.
Head and body of fibula: Proximal and shaft regions.

Tarsal Bones

The tarsal bones are seven bones forming the ankle and proximal foot.

Talus: Articulates with tibia and fibula; includes trochlea of talus.
Calcaneus: Heel bone; includes sustentaculum tali and calcaneal tuberosity.
Navicular, cuboid, lateral/intermediate/medial cuneiforms: Other tarsal bones.

Metatarsal Bones and Phalanges

The metatarsals (1-5) form the foot, and the phalanges are the bones of the toes.

Proximal phalanges (1-5): Closest to the metatarsals.
Middle phalanges (2-5): Absent in the big toe.
Distal phalanges (1-5): Tips of the toes.

Summary Table: Major Bones and Key Features

Bone	Key Features	Location/Function
Scapula	Acromion, coracoid process, glenoid cavity, spine	Shoulder; muscle attachment, articulates with humerus and clavicle
Clavicle	Sternal end, acromial end	Connects upper limb to trunk
Humerus	Head, tubercles, epicondyles, fossae	Upper arm; articulates with scapula, radius, ulna
Ulna	Olecranon, coronoid process, trochlear notch	Forearm; forms elbow joint
Radius	Head, neck, styloid process	Forearm; wrist movement
Carpals	Scaphoid, lunate, etc.	Wrist flexibility
Metacarpals/Phalanges	Numbered 1-5, proximal/middle/distal	Palm and fingers
Coxal bone	Acetabulum, obturator foramen	Pelvis; supports body weight
Femur	Head, trochanters, condyles	Thigh; weight bearing
Patella	Base, apex, articular surface	Kneecap; protects knee joint
Tibia	Condyles, tuberosity, malleolus	Leg; main weight bearing
Fibula	Head, lateral malleolus	Leg; ankle stability
Tarsals	Talus, calcaneus, cuneiforms	Ankle and foot
Metatarsals/Phalanges	Numbered 1-5, proximal/middle/distal	Foot and toes

Additional info:

These notes expand on the provided list of terms by grouping them into anatomical regions and providing definitions and context for each structure. Understanding the features of each bone is essential for identifying them in lab and for clinical applications such as fracture diagnosis and joint movement analysis.