The Human Skeleton and Skull Anatomy

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Questions and Answers

What is the primary shape of the sphenoid bone described as?

Square

Circle

Butterfly (correct)

Triangle

Which bone connects the brain to the spinal cord through the foramen magnum?

Zygomatic bone

Sphenoid bone

Mandible

Occipital bone (correct)

Which of the following bones is NOT part of the facial bone structure?

Mandible

Zygomatic

Maxilla

Frontal bone (correct)

Which of the following bones contains the pituitary gland within the sella turcica?

Sphenoid bone Signup and view all the answers

What structure does the maxilla NOT contribute to?

Lower jaw Signup and view all the answers

Which bone forms the lateral wall of the nasal cavity?

Inferior nasal conchae Signup and view all the answers

Which bone is described as slender and forms part of the nasal septum?

Vomer Signup and view all the answers

Which type of bone forms the hard palate along with the palatine process of the maxilla?

Palatine bones Signup and view all the answers

Which part of the skeleton is referred to as the appendicular skeleton?

Upper and lower limbs along with girdles Signup and view all the answers

What is the total number of bones in the human skeleton?

206 Signup and view all the answers

Which bone forms the anterior portion of the cranium?

Frontal Signup and view all the answers

How many types of bones make up the cranial portion of the skull?

6 types of 8 bones Signup and view all the answers

What structure connects the occipital bone with the parietal bones?

Lambdoidal suture Signup and view all the answers

Which bone is described as having several regions known as squamous, tympanic, and mastoid?

Temporal bone Signup and view all the answers

What is the primary characteristic of the temporal bones?

They appear grey due to hair color changes in that area. Signup and view all the answers

How many foramina, fissures, and canals are typically contained in the skull?

85 openings Signup and view all the answers

What is the primary purpose of the sacral hiatus?

To provide a region for sacral anesthesia Signup and view all the answers

Which part of the sternum articulates with the clavicle?

Manubrium Signup and view all the answers

How many pairs of ribs directly attach to the sternum?

7 pairs Signup and view all the answers

Which of the following lists the components of the pectoral girdle?

Clavicle and Scapula Signup and view all the answers

Which type of ribs are not attached to the sternum at all?

Floating ribs Signup and view all the answers

What is the role of the glenoid cavity?

It serves as a socket for the head of the humerus Signup and view all the answers

Which description accurately characterizes the structure of the clavicle?

Slender and doubly curved Signup and view all the answers

What bones constitute the forearm?

Radius and Ulna Signup and view all the answers

How many phalanges are involved in the great toe compared to other toes?

2 bones Signup and view all the answers

What role do the arches of the foot serve?

Absorb pressure Signup and view all the answers

What risk is associated with weakened ligaments and tendons in the foot?

Development of flat foot Signup and view all the answers

What happens to the water content of intervertebral discs as individuals age?

It declines Signup and view all the answers

Which of the following is not one of the four fontanels found in a newborn infant?

Occipital fontanel Signup and view all the answers

Which bone is located on the thumb side of the forearm?

Radius Signup and view all the answers

How many bones comprise the wrist (carpal) region?

8 Signup and view all the answers

Which of the following bones is NOT part of the coxal bone?

Femur Signup and view all the answers

What is the main function of the patella?

Guards the knee joint Signup and view all the answers

Which of the following statements about the tibia is true?

It articulates with the femur to form the knee joint Signup and view all the answers

How many bones make up the fingers (phalanges)?

14 Signup and view all the answers

What forms the socket that articulates with the head of the femur?

Acetabulum Signup and view all the answers

Which of the following is true about the fibula?

It articulates with the tibia Signup and view all the answers

Study Notes

The Skeleton

The human skeleton is composed of 206 bones, joints, ligaments, and cartilage.
Cartilage is found in the nose, ribs, joints, vertebral discs, and other areas.
The skeleton is divided into two main parts: the axial skeleton and the appendicular skeleton.
The axial skeleton consists of the skull, vertebral column, and bony thorax.
The appendicular skeleton consists of the upper and lower limbs and the pectoral (shoulder) and pelvic (hip) girdles.

Skull

Composed of 22 bones, divided into the cranium and facial bones.
Contains numerous smaller cavities, including the inner ear, nose, eyes, and others.
Has 85 openings, known as foramina, fissures, and canals.

Cranium

Forms the majority of the skull.
Has two main parts: the vault and the base.
The vault forms the superior, lateral, and posterior aspects of the skull, including the forehead.
The base forms the inferior aspect of the skull.
Composed of eight bones:
- Frontal (1)
- Parietal (2)
- Temporal (2)
- Occipital (1)
- Sphenoid (1)
- Ethmoid (1)

Cranium Bones

Frontal: Forms the anterior portion of the cranium and forehead.
Parietal: Forms the superior and lateral aspects of the skull.
Temporal: Named for the grey hair that typically appears in this region. Consist of several regions: squamous, tympanic, zygomatic process, styloid, and mastoid.
Occipital: Forms the lower posterior wall and base of the skull. Contains two occipital condyles and the foramen magnum, which connects the inferior part of the brain to the spinal cord.
Sphenoid: Butterfly-shaped bone. Considered the "keystone" of the cranium because it articulates with all cranial bones. Contains a central body and three pairs of processes: wings (greater and lesser) and pterygoid. Contains a saddle-like depression called sella turcica which houses the pituitary gland. Also has several foramina, including the optic and ovale.
Ethmoid: Complicated, irregular bone located between the sphenoid and nasal bones.

Facial Bones

Perform numerous functions:
- Provide a framework for the face
- Form cavities for sensory organs, air and food passages
- Provide a base for teeth
- Anchor facial muscles.
Maxilla (2): Forms the upper jaw, orbital floor, roof of the mouth, and sidewalls of the nose. Contains the infraorbital foramen.
Mandible: U-shaped bone that forms the lower jaw. The largest and strongest bone in the face. Articulates with the temporal bones to form the movable joints of the skull.
Zygomatic (2): Forms the cheek and outer margin of the orbit.
Nasal (2): Forms the superior part of the nose, with cartilage forming the lower part.
Lacrimal (2): Forms the nasal cavity and medial wall of the orbit.
Palatine (2): L-shaped bones that form the hard palate with the palatine process of the maxilla.
Inferior Nasal Conchae (2): Forms the lateral wall of the nasal cavity.
Vomer: Slender bone that forms part of the nasal septum.

Additional Structures

Orbits: Bony cavities that house the eyes.
Nasal Cavity: Contributes to the sense of smell, warms and moistens the air, and filters particles.
Paranasal Sinuses: Air-filled cavities within the skull bones.
Hyoid Bone: U-shaped bone located in the neck that serves as a point of attachment for muscles of the tongue and neck.

Vertebral Column

Composed of 26 bones called vertebrae:
- Cervical (7)
- Thoracic (12)
- Lumbar (5)
- Sacral (1, fused)
- Coccygeal (1, fused)
Provides a framework for the body and protects the spinal cord.

Vertebrae

Cervical Vertebrae (7): Support the head and allow for a wide range of neck motions.
Thoracic Vertebrae (12): Articulate with the ribs.
Lumbar Vertebrae (5): Support the weight of the upper body.
Sacrum (1, fused): Forms the posterior wall of the pelvis.
Coccyx (1, fused): Tailbone, a small, triangular bone.

Sacrum and Coccyx

The sacral hiatus is a region on the dorsal surface of the sacrum that allows for sacral anesthesia.

Bony Thorax (Rib Cage)

The chest cavity is formed by the ribs in combination with the sternum and the vertebral column.

Sternum (Breastbone)

Composed of three bones:
- Manubrium: The superior portion, articulates with the clavicle (a bone of the pectoral girdle) and the first two ribs.
- Body: The midportion, articulates with the second to seventh ribs.
- Xiphoid: The small, inferior end of the sternum.

Ribs

Twelve pairs of ribs.
Each rib articulates with both the body and the transverse process of its corresponding thoracic vertebra.
True ribs (1-7): Attach directly to the sternum through a costal cartilage.
False ribs (8-10): Join the cartilage of the true ribs, indirectly attached to the sternum.
Floating ribs (11-12): Not attached to the sternum.

Appendicular Skeleton: Pectoral Girdle and Upper Limb

Pectoral Girdle:
- Supports the upper limbs and allows for a wide range of motion.
- Comprises the Clavicle and Scapula.
- Clavicle: Slender, doubly curved bone. Articulates with the sternum (sternal end) and the scapula (acromial end).
- Scapula: Triangular, flat bone with borders, projections, and processes. The Glenoid cavity (where the head of the humerus fits) forms one of the borders.
- Acromion: A projection on the scapula that allows the clavicle to attach.
Upper Limb:
- Consists of the Arm, Forearm, and Hand.
- Arm: Consists of a single bone, the Humerus, which has a head that articulates with the Glenoid cavity. The distal end of the humerus contains two epicondyles and the Trochlea. The medial epicondyle forms the protrusion of the elbow when viewed from the anterior perspective.
- Forearm: Consists of two parallel bones: the Radius and Ulna. The Radius is on the thumb side and has a nail-shaped end. The Ulna is on the little finger side, longer than the radius, and forms the elbow joint.
- Hand: Includes the Wrist, Palm, and Fingers.
  - The Wrist (Carpal) is formed by eight bones bound closely together by ligaments.
  - The Palm (Metacarpal) is made of five bones.
  - Fingers (Phalanges) have three bones (distal, middle, and proximal) except for the thumb which has only two.

Appendicular Skeleton: Pelvic Girdle and Lower Limb

Pelvic Girdle:
- Composed of two Coxal bones.
- The Coxal bones articulate anteriorly at the pubic symphysis and posteriorly with the sacrum at the sacroiliac joint.
- Coxal bone has three parts: Ilium, Ischium, and Pubis.
- These three bones are joined together to form a deep, hemispherical socket called the Acetabulum. The head of the femur fits into the Acetabulum.
Lower Limb:
- Consists of the Thigh, Leg, and Foot.
- Thigh: Composed of the Femur bone (the largest, longest, and strongest bone in the body). It has a head, neck, and trochanters at the proximal end and a condyle and patellar surface at the distal end.
- Leg: Consists of two bones, the Tibia and Fibula. The Tibia is larger, stronger, and located on the medial side of the leg. The Fibula is smaller and located on the lateral side.
- Foot: Includes the Tarsus, Metatarsus, and Toes.
  - Tarsus: Composed of seven bones including the Calcaneus (heel) which carries the Talus on its superior surface.
  - Metatarsus: Includes 5 bones.
  - Toes (Phalanges): Each toe has three bones, except for the big toe which has only two.

Arches of the foot

The foot has three arches:
- lateral longitudinal
- medial longitudinal
- transverse
The elasticity of these arches helps to absorb pressure.
Strong ligaments and tendons support arch position. Weakened ligaments and tendons can lead to flat feet.

Developmental Aspects

Newborn infant skulls have incomplete bones connected by unossified fibrous membranes known as fontanels.
These fontanels allow the infant's head to compress during birth and accommodate brain growth.
Four fontanels can be detected:
- Anterior (between frontal and parietal bones)
- Posterior (between parietal and occipital bones)
- Sphenoid
- Mastoid

Herniation

As we age, the water content of the vertebral discs declines.
This leads to a higher risk of herniation, or "disc slipping".
Herniation can occur due to trauma, which often ruptures the annulus fibrosus of the disc, causing the nucleus pulposus to protrude.
Herniation can place pressure on the spinal cord and spinal nerves.
Herniations can be treated with bed rest, surgery, or enzymatic drugs.

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Description

Explore detailed aspects of the human skeleton, encompassing 206 bones, cartilage, and the division into axial and appendicular structures. This quiz covers the skull's composition, including its cranium and facial bones, and their functions within the skeletal system.