Axial Skeleton Overview

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Questions and Answers

What are the primary curvatures of the vertebral column?

Thoracic and sacral curvatures

Cervical and coccygeal curvatures

Thoracic and pelvic curvatures (correct)

Cervical and lumbar curvatures

What is the main function of intervertebral discs?

Provide stability between vertebrae

Protect the spinal cord

Enhance spinal flexibility and absorb shock (correct)

Support the skull

Which group of vertebrae is found in the lower back?

Thoracic vertebrae

Cervical vertebrae

Coccygeal vertebrae

Lumbar vertebrae (correct)

At which age does the vertebral column start to develop its S-shape?

At 3 years Signup and view all the answers

What is the anatomical term for the mass of spongy bone in a vertebra?

Vertebral body Signup and view all the answers

Which abnormal curvature of the spine is characterized by a lateral deviation?

Scoliosis Signup and view all the answers

Which vertebrae are located at the base of the spine?

Sacral vertebrae Signup and view all the answers

What happens to intervertebral discs when they are under stress, such as lifting a heavy weight?

They bulge laterally Signup and view all the answers

What is the primary function of the cervical vertebrae?

Support the head and allow for its movements Signup and view all the answers

What distinguishes the lumbar vertebrae from the other vertebral categories?

Thick, stout body adapted for bearing weight Signup and view all the answers

At what age do the sacral vertebrae typically fuse into a single bony plate known as the sacrum?

26 Signup and view all the answers

What does the pelvic girdle primarily enclose and protect?

Viscera of the pelvic cavity Signup and view all the answers

Which component separates the greater pelvis from the lesser pelvis?

Pelvic brim Signup and view all the answers

Which vertebrae are unique in having transverse foramina?

Cervical vertebrae Signup and view all the answers

What term describes the entry into the lesser pelvis through which an infant’s head passes during birth?

Pelvic inlet Signup and view all the answers

How many pairs of ribs are associated with the thoracic vertebrae?

12 Signup and view all the answers

What is the lower margin of the lesser pelvis referred to as?

Pelvic outlet Signup and view all the answers

What anatomical feature distinguishes the male pelvis from the female pelvis?

Robustness of the bones Signup and view all the answers

How many pairs of ribs are in the human thoracic cage?

12 pairs Signup and view all the answers

Which of the following describes false ribs?

Ribs that attach to the sternum via costal cartilage Signup and view all the answers

What is the largest cavity in the skull and its volume?

Cranial cavity; 1,300 mL Signup and view all the answers

Which part of the sternum is also known as the handle?

Manubrium Signup and view all the answers

What comprises the neurocranium?

8 bones that enclose the brain Signup and view all the answers

What feature is found in the occipital bone?

Foramen magnum Signup and view all the answers

Which bones form the calvaria of the skull?

Multiple bones comprising the dome Signup and view all the answers

Which cranial fossa is shallow and accommodates the frontal lobes of the brain?

Anterior cranial fossa Signup and view all the answers

What does the temporal bone articulate with?

Several cranium bones including the mandible Signup and view all the answers

Which sinuses lighten the anterior portion of the skull?

Paranasal sinuses Signup and view all the answers

What type of joints appear as seams on the cranial surface?

Suture joints 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, pectoral girdle, and pelvic girdle.
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 points for limbs, thoracic cage, and postural muscles.
Consists of 33 vertebrae (not a single bone).
Vertebrae are connected by intervertebral discs.
Vertebral column is S-shaped after 3 years of age.
3 primary curvatures: Thoracic and sacral (present at birth).
2 secondary curvatures: Cervical and lumbar (develop later).

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: Spongy bone, weight-bearing.
Vertebral foramen: Forms the canal.
Vertebral arch: Pedicle + lamina.
Spinous process: Prominent projection.
Transverse process: Projection between lamina and pedicle.

Intervertebral Discs

Cartilaginous pads between vertebrae.
Help bind adjacent vertebrae, enhance spinal flexibility, support body weight, and absorb shock.
Excessive stress can cause herniated discs.

Regional Characteristics of Vertebrae (C1-C7)

Relatively small.
Function to support the head and allow for movement.
Unique structures for this purpose (transverse foramina) found only in C1 and C2.
C1 (atlas): Supports head.
C2 (axis): Rotation point for head.

Thoracic Vertebrae (T1-T12)

Vertebrae that correspond to 12 pairs of ribs.
Support the thoracic cage enclosing the heart and lungs

Lumbar Vertebrae (L1-L5)

Five vertebrae
Thick, stout bodies for bearing upper body weight.

Pelvic Skeleton

Five sacral vertebrae (S1-S5) fuse around age 16 to 26.
Sacrum: Forms the posterior wall of the pelvic cavity; protects organs.
Four (sometimes five) coccygeal vertebrae (Co1-Co5) fuse to form the coccyx around age 20.

Pelvic Girdle (Pelvis)

Bowl-shaped structure composed of sacrum, coccyx, and two hip bones (coxae).
Supports the trunk on the lower limbs.
Encloses and protects the viscera of the pelvic cavity.
Protects organs (colon, bladder, reproductive organs).

Skull (Cranial Cavity)

The skull is a complex part of the skeleton.
The calvaria (skullcap) is not a specific bone but rather parts of multiple cranial bones.
Comprised of 22 bones.

Skull Cavities

Cranial cavity: Largest cavity; encloses the brain.
Orbits (eye sockets)
Nasal cavity
Paranasal sinuses
Oral cavity (mouth/buccal cavity)
Middle and inner ear cavities

Cranial Fossae

Anterior cranial fossa: Shallow depression that houses frontal lobes.
Middle cranial fossa: Deeper depression like bird wings; accommodates temporal lobes.
Posterior cranial fossa: Deepest fossa; houses cerebellum.

Cranial Bones

Frontal bone: Forms forehead, articulates with the nasal, maxilla, zygomatic, lacrimal, ethmoidal, and sphenoid bones.
Parietal bone: Forms a large portion of the lateral and superior wall of the skull. Connects with the frontal, occipital, and temporal bones.
Temporal bone: Houses the external acoustic meatus (ear canal). Articulates with occipital, parietal, sphenoid, zygomatic, and mandible bones and forms the zygomatic arch with the zygomatic bone.
Occipital bone: Forms base of the skull, includes foramen magnum, articulates with the atlas.

Paranasal Sinuses

Frontal sinuses, ethmoid sinuses, sphenoid sinuses, and maxillary sinuses.
Connected to nasal cavity, lined by mucous membrane, and filled with air.
Lighten the skull and add resonance to the voice.

Foramina

Openings in the skull that allow passage for nerves and blood vessels.

Meninges

Three membranes that protect the brain tissue from the cranial bones:
- Dura mater
- Arachnoid mater
- Pia mater

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Description

Explore the anatomy and functions of the axial skeleton, including the vertebral column and its role in supporting the body. Learn about normal and abnormal spinal curvatures, such as scoliosis, kyphosis, and lordosis. This quiz will test your knowledge on these crucial aspects of human anatomy.