Human Anatomy: Axial Skeleton and Vertebral Column

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Questions and Answers

What is the main function of the cervical vertebrae?

To support the head and allow for its movements (correct)

To bear the weight of the body

To protect the thoracic cavity

To support the upper limbs

Which vertebrae begin to fuse around age 16, forming the sacrum?

Cervical vertebrae

Lumbar vertebrae

Sacral vertebrae (correct)

Thoracic vertebrae

How many thoracic vertebrae are there, and what is one of their functions?

8; they serve as attachment points for the neck muscles

12; they support the thoracic cage enclosing the heart and lungs (correct)

10; they support the head

14; they provide flexibility to the spine

What distinguishes lumbar vertebrae from other types of vertebrae?

They are adapted for bearing the upper body’s weight Signup and view all the answers

What structure forms the posterior wall of the pelvic cavity?

Sacrum Signup and view all the answers

Which part of the pelvis encloses the pelvic cavity?

Lesser pelvis Signup and view all the answers

What separates the greater and lesser pelvis?

Pelvic brim Signup and view all the answers

What is the primary composition of the pelvic girdle?

Sacrum, coccyx, and two hip bones Signup and view all the answers

Which sections of the vertebral column are considered primary curvatures?

Thoracic and pelvic Signup and view all the answers

What is the function of intervertebral discs in the vertebral column?

Absorb shock and enhance spinal flexibility Signup and view all the answers

How many total vertebrae are there in the vertebral column?

33 Signup and view all the answers

Which type of abnormal curvature is characterized by an exaggerated lumbar curve?

Lordosis Signup and view all the answers

What structure forms the vertebral canal?

Vertebral arch Signup and view all the answers

What is the correct number of cervical vertebrae in the vertebral column?

7 Signup and view all the answers

What is the primary role of the vertebral column?

Support the skull and trunk, allow movement, and protect the spinal cord Signup and view all the answers

What does the term 'coccygeal vertebrae' refer to?

The vertebrae at the base of the spine Signup and view all the answers

What is the lower margin of the lesser pelvis called?

Pelvic outlet Signup and view all the answers

Which part of the skeleton is the most sexually dimorphic?

Pelvis Signup and view all the answers

What distinguishes true ribs from false ribs?

True ribs connect directly to the sternum. Signup and view all the answers

Which of the following bones is NOT part of the cranial cavity?

Mandible Signup and view all the answers

What is the main function of the paranasal sinuses?

To lighten the skull and add resonance to the voice Signup and view all the answers

How many cranial bones collectively comprise the cranium?

22 bones Signup and view all the answers

Where is the foramen magnum located?

In the occipital bone Signup and view all the answers

Which part of the sternum is referred to as the 'handle'?

Manubrium Signup and view all the answers

What does the term 'neurocranium' refer to?

Cranial bones enclosing the brain Signup and view all the answers

Which sinus is located in the frontal bone?

Frontal sinus Signup and view all the answers

How many pairs of ribs are referred to as 'floating ribs'?

2 pairs Signup and view all the answers

Which of the following is NOT a structure formed by the ethmoidal bone?

Frontal sinus Signup and view all the answers

Which bone articulates with the atlas at the occipital condyle?

Occipital bone Signup and view all the answers

What is the outermost membrane separating the brain from the cranial bones called?

Dura mater Signup and view all the answers

Study Notes

Axial Skeleton

The skeleton is divided into two parts: appendicular and axial
Appendicular skeleton includes bones of the upper and lower limbs, and pectoral and pelvic girdles
Axial skeleton includes cranium, vertebral column, ribs, and sternum

Vertebral Column

Physically supports the skull and trunk
Allows for movement
Protects the spinal cord
Absorbs stresses from activities like walking, running, and lifting
Provides attachment for limbs, thoracic cage, and postural muscles
Consists of 33 vertebrae, not a single bone
Has intervertebral discs

Vertebral Column Subdivisions

Cervical vertebrae (7): located in the neck
Thoracic vertebrae (12): located in the chest
Lumbar vertebrae (5): located in the lower back
Sacral vertebrae (5): fused in a single plate, the sacrum
Coccygeal vertebrae (4): tiny vertebrae, fused to form coccyx

Curvatures of the Vertebral Column

Beyond age 3, vertebral column slightly S-shaped with four bends
Cervical, thoracic, lumbar, and pelvic curvatures
Thoracic and pelvic are primary curvatures (C-shaped)
Cervical and lumbar are secondary curvatures

Abnormal Spinal Curvatures

Scoliosis: abnormal lateral deviation
Kyphosis: exaggerated thoracic curvature (common in old age)
Lordosis: exaggerated lumbar curvature (common in pregnancy and obesity)

General Structure of a Vertebra

Vertebral body: weight-bearing spongy bone
Vertebral foramen: forms the vertebral canal
Vertebral arch: pedicle + lamina
Spinous process: prominent, palpable projection
Transverse process: protrusion between lamina and pedicle

Intervertebral Discs

Cartilaginous pads between vertebral bodies
23 discs in total
Absorb shock, bind adjacent vertebrae, enhance spinal flexibility, and support body weight
Excessive stress can cause herniated discs

Regional Characteristics of Vertebrae (C1 and C2)

Cervical vertebrae (C1-C7) are relatively small
Function to support the head and allow for movement
C1 (atlas) and C2 (axis) have unique structures for this purpose
Transverse foramina present only in C1-C7

Thoracic Vertebrae

There are 12 thoracic vertebrae (T1-T12)
Each corresponds to a pair of ribs
Support the thoracic cage, which encloses the heart and lungs

Sternum

Bony plate anterior to the heart
Subdivided into manubrium, body, and xiphoid process

Ribs

12 pairs of ribs
First 7 ribs are true ribs (connect directly to the sternum)
Ribs 8-10 are false ribs (connect indirectly to the sternum)
Ribs 11-12 are floating ribs (don't connect to the sternum)

Skull and Cranial Cavity

Skull is the most complex part of the skeleton
Made up of 22 bones, sometimes more
Bones are joined by sutures

Skull Cavities

Cranial cavity: largest cavity, houses the brain (approximately 1300 mL in adults)
Orbits (eye sockets)
Nasal cavity
Paranasal sinuses
Oral cavity
Middle and inner ear cavities

Paranasal Sinuses

Air-filled cavities in the skull bones (frontal, ethmoid, sphenoid, and maxillary)
Lighten skull, act as chambers for resonance in the voice.

Cranial Bones

Neurocranium (cranial): encloses the cranial cavity (8 bones)
Splanchnocranium (facial bones): makes up the face (14 bones)

Suture, Landmarks, and Foramina

The skull is composed of multiple bones, most joined by sutures (immovable joints)
Sutures are identifiable seams on the cranium's surface. Key sutures (coronal, sagittal, lambdoid, squamosal) connecting bones are important for identification
Foramina ("holes") in the skull are essential for nerves and blood vessels. (e.g., foramen magnum, optic canal, jugular foramen, etc.)

Cranial Fossae

The cranial base has three depressions (anterior, middle, and posterior fossae) that shape the brain's inferior surface.
Cranial fossa accommodate the brain's lobes (e.g., the anterior cranial fossa houses the frontal lobes, while the middle cranial fossa protects the temporal lobes).

Pelvic Girdle or Pelvis

Composed of the sacrum, coccyx, and two hip bones (coxal bones)
Ligaments and muscles form pelvic cavity floor and walls.
Supports the trunk, encloses viscera (mainly lower colon, urinary bladder, reproductive organs)
Pelvic inlet and outlet, important for childbirth

Pelvis Differences (Male vs. Female)

Males: heavier and thicker pelvis, due to stronger muscles
Females: pelvis adapted for pregnancy and childbirth, features like a wider pelvic outlet.

Thoracic Cage

Thoracic cage consists of thoracic vertebrae, sternum, and ribs.
Conical enclosure for lungs and heart
Provides attachment for pectoral girdle and upper limb

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Description

This quiz covers the axial skeleton, including the cranium and vertebral column. It explores the structure, function, and subdivisions of the vertebral column, along with its curvatures and support system. Test your knowledge on human skeletal anatomy in this informative quiz.