The Skeleton 2: Lecture notes

A&P

Axial Skeleton – Skull

How many cranial bones are there?

8

Axial Skeleton – Skull

What do cranial bones do?

Surround and protect the brain

Axial Skeleton – Skull

What are the two types of cranial bones?

Paired and single bones

Axial Skeleton – Skull

What do cranial bones form?

3 fossae (depressions in the skull)

Q: How many facial bones are there?

14

Paranasal Sinuses

What connects paranasal sinuses to the nasal cavity?

Small openings

Paranasal Sinuses

What do sinuses produce?

Mucus

Paranasal Sinuses

How many bones contain sinuses?

4 bones

Hyoid Bone

Where is the hyoid bone located?

Anterior neck, below the mandible

Hyoid Bone

Does the hyoid bone articulate with other bones?

No

Hyoid Bone

What is the function of the hyoid bone?

Raises and lowers the larynx during speech and swallowing

Vertebral Column

What makes the vertebral column flexible?

Plain joints + fibrocartilage discs

Vertebral Column

What does the vertebral column protect?

Spinal cord

Vertebral Column

What attaches to the vertebral column?

Ribs and back muscles

Vertebral Column

What is another function of the vertebral column?

Transfers weight to lower limbs

Vertebrae Numbers

How many cervical vertebrae?

7

Vertebrae Numbers

How many thoracic vertebrae?

12

Vertebrae Numbers

How many lumbar vertebrae?

5

Vertebrae Numbers

How many sacral vertebrae?

5 (fused)

Vertebrae Numbers

How many coccyx vertebrae?

4 (fused)

Spinal Curves

Which curves are concave posteriorly?

Cervical and lumbar

Spinal Curves

Which curves are convex posteriorly?

Thoracic and sacral

Abnormal Curves

What is scoliosis?

Lateral (sideways) curvature of the spine

Abnormal Curves

Cause of scoliosis?

Unequal muscle pulling

What is kyphosis?

Exaggerated thoracic curve (hunchback)

Common cause of kyphosis?

Osteoporosis

What is lordosis?

Exaggerated lumbar curve (swayback)

Cause of lordosis?

Compensation for weight in front (e.g., pregnancy)

Ribs

How many pairs of ribs are there?

12 pairs

Ribs

Where do ribs attach posteriorly?

Thoracic vertebrae

What are true ribs?

Ribs 1–7 (directly attach to sternum)

What are false ribs?

Ribs 8–12

What are vertebrochondral ribs?

Ribs 8–10 (indirect attachment)

What are floating ribs?

Ribs 11–12 (no sternum attachment)

Appendicular Skeleton - Pectoral Girdle

What bones make up the pectoral girdle?

Scapula and clavicle

Upper Limb (30 bones)

• Bone of the arm?

• Bones of the forearm?

• Wrist bones?

• Palm bones?

• Finger bones?

• Humerus

• Radius and ulna

• Carpals

• Metacarpals

• Phalanges

Pelvic Girdle

What bones make up the pelvic girdle?

Ilium, ischium, pubis

Function of pelvic girdle?

Transfers weight + protects organs

Male vs Female Pelvis

Female pelvis?

Broader and shallower

Male pelvis?

Narrower and deeper

Lower Limbs (30 bones)

Why are lower limbs thicker/heavier?

Support body weight

What forces affect lower limbs?

Jumping and running stress

• Thigh bone?

• Kneecap?

• Leg bones?

• Ankle bones?

• Sole bones?

• Toe bones?

• Femur

• Patella

• Tibia and fibula

• Tarsals

• Metatarsals

• Phalanges

Foot Arches

Why are foot arches important?

Support weight + act like springs

What provides arch support?

Ligaments and tendons

What happens without support?

Flat feet

What are the 3 arches?

Medial longitudinal, lateral longitudinal, transverse

Development & Aging Fontanelles

What are fontanelles?

Soft spots in fetal skull (4)

Why are they important?

Allow skull compression during birth

Growth

How is the skull at birth?

Proportionally large

What happens to limbs during growth?

Grow faster to catch up

When does the face develop?

Ages 6–13

• What is the spine shape at birth?

• What happens later?

• C-shaped

• Secondary curves develop

Aging Effects

What happens to intervertebral discs with age?

Thinner, less hydrated, less elastic

Result of disc changes?

Herniation + height loss

What happens to the thorax with age?

Cartilage ossifies → harder to breathe

What happens to bones with age?

Lose mass → more fragile

Which bones are most affected?

Vertebrae and femur head