1.1. Axial skeleton

How does the skull of a newborn compare to the rest of its skeleton?

It is disproportionately large, with a relatively small facial skeleton and a relatively large calvaria

How does the skull of a newborn compare to the rest of its skeleton?

It is disproportionately large, with a relatively small facial skeleton and a relatively large calvaria

What percentage of adult skull size is reached by 12 months?

85%

By what age is skull ossification complete?

Age 8

By what age does bone union of the skull occur?

Age 20

What is a fontanelle?

An area of fibrous tissue that is the future site for intramembranous bone formation

What does an overly soft fontanelle indicate clinically?

Dehydration

What does a hard or protruding fontanelle indicate clinically?

Increased intracranial pressure

What is the purpose of skull sutures in newborns?

To allow easier childbirth by enabling the skull to flex

What is sagittal craniosynostosis?

Premature fusion of the sagittal sutures, requiring surgery

What is the function of the sinuses?

To help condition inspired air — they are mucus-lined spaces that warm and moisten air

Name the sinuses of the skull

Frontal sinuses, ethmoidal cells, orbital plate of ethmoid bone, maxillary sinuses

What structures make up the back?

Vertebral column, spinal cord, skin and subcutaneous tissue, muscles, ribs (thoracic region), spinal cord and meninges, segmental nerves and vessels

What are the two main functions of the vertebral column?

To protect the spinal cord and spinal nerves, and to support and transmit body weight to the pelvis

How long is the vertebral column in adults?

75cm, of which a quarter is formed by intervertebral discs

What are the three layers of intrinsic back muscles?

Superficial, intermediate, and deep

What is the erector spinae and what does it do?

A group of muscles on each side of the vertebral column; the chief extensors of the vertebral column

What are the three columns of the erector spinae?

Iliocostalis (lateral), Longissimus (intermediate), Spinalis (medial)

Where does the spinal cord begin and end?

Begins as a continuation of the medulla oblongata and extends to L1/L2

How long is the spinal cord?

45cm

What is the cauda equina?

A collection of spinal nerves that travel down the vertebral column below the spinal cord, resembling a horse's tail

Where does the cauda equina terminate in a newborn?

L3

What are the three spinal meninges?

Dura mater, arachnoid mater, pia mater

What is the function of the spinal meninges?

To surround and support the spinal cord and contain cerebrospinal fluid (CSF)

Describe the dura mater

Fibrous outermost layer; separated from periosteum by the epidural space; has an epidural space containing venous plexus and fat

Describe the arachnoid mater

Delicate middle layer that encloses the CSF-filled subarachnoid space

Describe the pia mater

Thin, transparent innermost layer; continues as the filum terminale; suspended in the dural sac by the filum terminale and denticulate ligaments

What is a lumbar spinal puncture used for?

To withdraw CSF from the lumbar cistern as a diagnostic tool, e.g. for meningitis or CNS diseases

What structures form the thoracic cage?

12 thoracic vertebrae, 12 pairs of ribs, and the sternum

What are the functions of the thoracic cage?

Protects thoracic viscera, provides sites for muscle attachments, and assists with breathing

Name the anatomical parts of a rib

Head, neck, tubercle, angle, articular facet, costal groove, shaft, articulation with costal cartilage

What does the skeletal system consist of?

Bones, tendons, cartilage, and joints

What are the functions of the skeletal system?

Protects the body, stores lipids and minerals, produces red blood cells

What is the appendicular skeleton?

Upper and lower limbs

What is the axial skeleton?

Skull, thoracic cage, vertebral column, and hyoid bone

How many bones does the skull consist of in a newborn?

44 bones

How many bones make up the neurocranium?

8 bones

How many bones make up the facial skeleton?

14 bones

Name the bones of the neurocranium

Parietal, frontal, temporal, occipital

Name the bones of the facial skeleton

Nasal, sphenoid, ethmoid, lacrimal, zygomatic, maxilla, mandible, vomer

What are the functions of the skull?

Protection, special senses (olfaction, vision, auditory, taste), muscular attachment, and support for upper respiratory/digestive systems

How does a male skull differ from a female skull at the forehead?

Male skulls have more prominent glabella and supraorbital ridges

How do eye orbits differ between male and female skulls?

Female skulls have rounder orbits

How do jaws differ between male and female skulls?

Female jaws are narrower and rounder

How do frontal bones differ between male and female skulls?

Female skulls have larger frontal eminences