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Bone Markings

• Bone shape is determined by tissues attaching to or passing near/through it.
• Protrusions form where muscles attach.
• Holes/grooves form where nerves/blood vessels pass.

Terminology of Bone Markings

• Foramen: Round hole in a bone.
• Fissure: Slit-like opening in a bone.
• Canal/Meatus: Tube-like passage in a bone.
• Cavity/Sinus: Hollow space in a bone.
• Crest: Extensive ridge on a bone.
• Line: Thin ridge on a bone.
• Trochanter/Tuberosity/Malleolus: Large projection on a bone.
• Tubercle/Process: Small projection on a bone.
• Spinous/Styloid Process: Pointed/spear-like projection on a bone.
• Fovea: Small depression in a bone.
• Fossa: Larger and deeper depression in a bone.
• Notch: Half-moon shaped depression.
• Sulcus/Groove: Long depression in a bone.
• Condyle/Head: Rounded end where bones articulate, capped with hyaline cartilage.

Axial vs. Appendicular Skeleton

• The skeleton divides into axial and appendicular portions.
• The axial skeleton forms the central axis.
• The appendicular skeleton includes the pectoral/pelvic girdles and extremities.
• Axial skeleton includes skull, auditory ossicles, teeth, hyoid, vertebrae, sacrum, coccyx, ribs, and sternum.
• Appendicular skeleton includes clavicle, scapula, humerus, radius, ulna, carpals, metacarpals, phalanges, os coxae, femur, tibia, patella, fibula, tarsals, and metatarsals.

Relationship Between Upper and Lower Limbs

• Upper and lower limbs are serial homologues, meaning they share similar structures.
• Examples include vertebrae and ribs.

Bone Development

• Upper and lower limbs start in a neutral position during embryonic development.
• Post-birth, the upper limb rotates laterally 90 degrees, and the lower limb rotates medially 90 degrees.
• The elbow and knee bend in opposite directions due to rotation; elbow flexion brings the forearm anteriorly, while knee flexion brings the leg posteriorly.

Bones of the Upper Extremity

• The pectoral girdle is formed by the clavicle and scapula
• It connects the upper limb to the axial skeleton.

Clavicle & Scapula

• Clavicle acts as a strut between the sternum and the acromial process.

Scapula Features

• Superior Angle
• Inferior Angle
• Spine of the Scapula: Ridge on the posterior side.
• Acromial Process: Process at the end of the spine.
• Coracoid Process: Anterior projection from the superior scapula.
• Supraspinous Fossa: Depression above the spine.
• Infraspinous Fossa: Depression below the spine.
• Subscapular Fossa: Depression on the anterior side.
• Glenoid Fossa: Depression on the lateral side, articulates with the humerus (glenohumeral joint).

Humerus

• The arm bone.
  • Head: Articulates with the scapula to form the shoulder joint.
  • Greater Tubercle: Projection on the superior, lateral side.
  • Lesser Tubercle: Projection on the superior, anterior side.
  • Intertubercular Groove: Between the greater and lesser tubercles.
  • Deltoid Tuberosity: Insertion site for the deltoid muscle.
  • Trochlea: Medial articular surface at the distal end, articulates with the ulna.
  • Capitulum: Lateral articular surface at the distal end, articulates with the radius.
  • Medial Epicondyle: Projection of bone above the trochlea.
  • Lateral Epicondyle: Projection of bone above the capitulum.
  • Olecranon Fossa: Depression on the posterior, distal end, associated with the olecranon process of the ulna.

Radius

• Lateral bone of the forearm.
  • Head: Articulates with the capitulum of the humerus.
  • Radial Tuberosity: Rough bump of bone at the proximal end.
  • Styloid Process: Narrow projection at the distal end.

Ulna

• Medial bone of the forearm.
  • Olecranon Process: Projection of bone at the proximal end.
  • Trochlear Notch: Articular surface, forms the elbow joint with the trochlea of the humerus.
  • Coronoid Process: Anterior projection from the trochlear notch.
  • Styloid Process: Narrow projection of bone at the distal end.

Interosseous Membrane

• Dense connective tissue connecting the radius and ulna shafts.

Bones of the Hand

• Carpals, metacarpals, and phalanges.
  • Carpals form the wrist (carpus) in the proximal hand.
  • Metacarpals are long bones within the palm.
  • Phalanges are long bones of the fingers.
• Metacarpals/digits numbered I-V, thumb to small finger.

Carpals

• Group of 8 short bones in the wrist, organized in two rows of four bones.

Proximal Row

- Scaphoid
- Lunate
- Triquetral (aka Triquetrum)
- Pisiform (only anterior/palmar view, sits on the anterior side of the triquetral)

Distal Row

- Trapezium
- Trapezoid
- Capitate
- Hamate

Metacarpals

• Five long bones in the palm.

Phalanges

• Long bones in the fingers, each finger/digit has three phalanges (proximal, intermediate, distal), thumb has two (proximal, distal).

Joints of the Upper Extremity

Shoulder Joint (Glenohumeral Joint)

- Between the glenoid fossa of the scapula and the head of the humerus.
- Ball and socket joint, multiaxial, most mobile.
- Surrounded by ligaments and rotator cuff muscles for support.
- Glenohumeral and coracohumeral ligaments.
- Movements: Medial/lateral rotation, abduction/adduction, flexion/extension.

Elbow Joint

- Between the trochlea of the humerus, trochlear notch of the ulna, and the head of the radius and capitulum of the humerus.
- Hinge joint, uniaxial.
- Ulnar (medial) and radial (lateral) collateral ligaments.
- Movements: Flexion and extension.

Radioulnar Joint

- Between the radius and ulna, has two articulations (proximal and distal).
- The annular ligament hold the head of radius against the ulna.
- Pivot joint, uniaxial.
- Movements: Supination and pronation

Wrist Joint

- also called the radiocarpal joint
- Between the distal radius and carpals
- Condylar joint, biaxial
- Movements include flexion, extension, abduction (radial deviation), adduction (ulnar deviation).

Metacarpophalangeal Joints

- Between metacarpals and phalanges.
- Condylar joints, biaxial.
- Movements: Flexion, extension, abduction, and adduction.

Interphalangeal Joints

- Between phalanges.
- Two joints in digits 2-5, one in the thumb.
- Hinge joints, uniaxial.
- Movements: Flexion, and extension.

Muscles of the Upper Extremity

Muscles that Move the Scapula

- The trapezius, rhomboids, levator scapulae, pectoralis minor, and serratus anterior.
- Trapezius, rhomboids, and levator scapulae are superficial of the back and neck.
- Pectoralis Minor: A muscle of the chest located deep to the pectoralis major.
- Serratus Anterior: Originates from the anterior side of the ribs and moves posteriorly between the scapula and rib to insert on the medial border of the scapula.

Muscles that Move the Arm

• Pectoralis major and coracobrachialis are found on the anterior side of the body and both flex and adduct the arm at the shoulder
• Latissimus dorsi and teres major are found on the posterior side of the body and both extend and adduct the arm at the shoulder.
• The rotator cuff muscles are supraspinatus, infraspinatus, teres minor, and subscapularis

Muscles that Move the Forearm

• Biceps brachii and brachialis are found in the anterior compartment of the arm, and flexes the elbow
• The brachioradialis muscle is found primarily in the forearm, this also flexes the elbow
• Triceps brachii is three headed, and positioned in the posterior compartment of the arm, it extends the elbow
• Pronator muscles and supinator are found in the forearm.

Muscles That Move the Hand and Fingers

• There is many muscles in the forearm and hand that move the hand at the wrist and the fingers at various joints
• Anterior compartment muscles flex the wrist, fingers, and thumb and posterior compartment muscles extend the wrist, fingers, and thumb and abduct the thumb.