5. The Skeletal System – Axial Division Review - Kines 262 PDF

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Human Anatomy, Fifth Edition, Martini/Timmons/Tallitsch

The Skeletal System – Axial Division

The Axial Skeleton A lot of this is review from lab which will help you on the bones exam so look it over  The Skull and Associated Bones Functions of: • Supports and protects organs anterior and posterior • Stabilizes the appendicular skeleton • Attachment sites for muscles • Houses sense organs - taste – smell – hearing – balance – vision ● Of the 22 bones of the skull, 8 form the cranium, or braincase. 1. The cranial cavity is a fluid filled chamber that supports and protects the brain. It is made up of the (this is all lab stuff) a. b. c. d. e. f.

Occipital Parietal (2) Frontal Temporal (2) Sphenoid Ethmoid

● Sutures are joints that unite the skull bones. 1. The five major sutures are the a. Lambdoid - back of the head b. Sagittal –. Top of the head but back to front c. Coronal – (frontal) – front of the head but from side to side d. Squamous –side of the head e. Frontonasal – nose partion area ● Bones of the Cranium 1. The Occipital Bone is the inferior and posterior most bone of the skull.

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Human Anatomy, Fifth Edition, Martini/Timmons/Tallitsch

The Skeletal System – Axial Division a. The foramen magnum is a very large midline hole in the inferior surface of the occipital bone. This is the connection between the cranial cavity and spinal cavity and the spinal cord exits the skull through it. The occipital condyles are large rounded projections lateral to the foramen magnum that articulate with the first vertebra AKA the atlas. b. The occipital crest is a ridge extending posteriorly from the foramen magnum and ending in an enlargement called the external occipital protuberance. 2. The paired Parietal Bones make most of the superior and lateral walls of the skull. 3. The Frontal Bone makes up the forehead and roof of the orbits.. a. Before age 8 the frontal bone is divided anteriorly at the midline due to its development from bilateral ossification centers. The dividing line is called the frontal (metopic) suture. b. The frontal bone contains two parts: o The frontal part makes up the forehead and is vertical. 

It begins at the supraorbital margin, the ridge at the superior border of the eye socket (orbit). a. A hole or notch in the margin is called the supraorbital foramen or notch, respectively.

o The orbital part makes the roof of the orbit and is horizontal. o Glabellar-space area between the eyebrows and above the nose Glabellar-Reflex “Tap forehead” There is blinking at first then it should stop – if there is persistent blinking this is called Meyerson’s sign and is diagnostic for Parkinson’s disease_ 4. The paired Temporal Bones make up the lateral walls of the skull. a. The temporal bones are the only bones to articulate with the mandible (lower jaw).

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Human Anatomy, Fifth Edition, Martini/Timmons/Tallitsch

The Skeletal System – Axial Division b. The temporal bones house the sense organs for hearing and balance in the inner ear. c. The temporal bone is divided into three parts: o 1. The squamous part is vertical and makes up the lateral wall of the skull. 

2. The inferior most part of the squamous portion is the large zygomatic process. a. The zygomatic process of the temporal bone articulates with the temporal process of the zygomatic bone to form the zygomatic arch. (this is labeled on the bone exam by the way.. so look it over b. At the base of the zygomatic process is a depression called the mandibular fossa, and a small bump called the articular tubercle that articulate with the mandible.

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3. The lateral part is the large bulge called the mastoid process. a. The mastoid process is the attachment site for muscles that rotate the head. b. The mastoid process has many hollow mastoidal air cells. Mastoiditis – inflammation and infection of the mastoid caused by the Streptococcus pneumonia bacterial – stems from from ear infections. Medial to the mastoid process on the inferior surface is the long, pointy styloid process, an attachment site for many muscles.

5. The sphenoid bone - best seen looking into skull cavaty. a. The sphenoid spans across the floor of the cranium uniting the skull together. b. The general shape of the sphenoid is that of a bat or owl flying with wings spread and hind limbs extended. 6. The ethmoid bone is the most irregularly shaped cranial bone.

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Human Anatomy, Fifth Edition, Martini/Timmons/Tallitsch

The Skeletal System – Axial Division a. It makes up the anteromedial floor of the cranium, the roof of the nasal cavity, and part of the nasal septum.

• Pterion and Trauma - Known as the weakest part of the skull. and marks the • • •

junction of four bones: - (called our Temple region in layman’s terms…. Parietal bone, temporal bone, sphenoid bone , & frontal bone. The anterior division of the middle meningeal artery runs underneath the pterion. Consequently, a traumatic blow to the pterion may rupture the middle meningeal artery causing an epidural hematoma – bruise due to arterial rupture. The pterion may also be fractured indirectly by blows to the top or back of the head that place sufficient force on the skull to fracture the pterion

• Bones of the Face (14) ● The skull contains 14 total facial bones, which protect the entrances to the digestive and respiratory tract. 1. The Maxillae (2) are the largest facial bones and make up the upper jaw. a. The maxillae articulate with every other facial bone except the mandible. 2. The Palatine Bones are L-shaped bones posterior to the maxillae.(we did not cover this in lab!) 3. The Nasal Bones articulate with the frontal bones, at the frontonasal suture, and the maxillae laterally. a. Cartilage extends from the nasal bones forming the circular external nares. 4. The Inferior Nasal Conchae are similar in structure to the superior and middle nasal conchae of the ethmoid, however they are separate bones. (We did not cover this in lab!) a. The inferior nasal conchae are found bilateral to the nasal septum making up the lateral walls of the nasal cavity. 5. The Zygomatic Bones, or cheekbones, articulate with the temporal bone to form the zygomatic arch. 6. The Lacrimal Bones are found posterior to the frontal processes of the maxillae.- and are adjacent to the tear glands in the eye - Lacrimal a. These are the smallest of the skull bones. 7. The Vomer makes up the inferior portion of the nasal septum, which divides the nasal cavity into right and left cavities. (Did not cover in lab) 4of 10

Human Anatomy, Fifth Edition, Martini/Timmons/Tallitsch

The Skeletal System – Axial Division 8. The Mandible, or lower jaw, articulates only with the temporal bone at the temporomandibular joint (TMJ). a. The bone is divided into two portions: o The U-shaped horizontal body contains the alveolar processes for the lower teeth. The entire area where teeth attach is called the alveolar part.

● The Hyoid Bone is a U-shaped bone that lies inferior to the mandible in the anterior neck. 1. The hyoid bone does not have direct contact with any other bone. 2. The body of the bone is a muscle and ligament attachment site and makes up the midpiece of the bone. Big time muscle attachment!!!!!!!!!!!! The Vertebral Column ● The adult vertebral column 1. cervical (7) 2. thoracic (12) 3. Lumbar (5) 4. Sacral (1) 5 fused vertebrae 5. Coccygeal (1) 3-5 fused vertebrae ● The vertebral column performs several functions: • Protects the spinal cord • Supports head aids in uprightness • Transfers weight to lower regions ● Spinal Curves are weight transferring anterior and posterior curves of the vertebral column that are best viewed laterally. 2 major types…. 1. Primary curves or accommodation curves …..are the posteriorly sweeping curves of the thoracic and sacral regions. o These curves develop before birth to allow for:? Allow for abdominopelvic development /fetal development Kyphosis - Abnormal accentuation of the primary thoracic curve.

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Human Anatomy, Fifth Edition, Martini/Timmons/Tallitsch

The Skeletal System – Axial Division Scheuermann’s Disease_(genetic disorder – where blood supply is cut off from the epiphysis (the growth plate of the vertebra. Usually occurs at the level of the 7th and tenth thoracic vertebrae. Vertebrae grow unevenly with respect to the Sagittal plane. Anterior angle is often sharper than the posterior. So we see wedging of segments. Spinal curve #2: 2. _Secondary curves or compensation curves (Lordotic and cervical) - develop in the infant and toddler as anteriorly sweeping curve of the cervical and lumbar regions. a. These curves develop as the infant learns to hold up their head (cervical) and begins to walk (lumbar). b. They form secondarily to compensate for changes in the body position from horizontal to vertical, hence their names. 3. The spinal curves complete development by age 10, but may flex more or less based on lifestyle and body weight distribution. a. For example, a pregnant woman will have an “exaggerated lumbar curve” (lordosis) due to the excess weight of the offspring in the abdominopelvic cavity. Anterior Pelvic Tilt – what is it and what muscle are involved? Weak Hamstrings Weak Gluteals Tight Erector Spinae group Tight Hip Flexors Scoliosis - is a medical condition in which a person's spinal axis has a threedimensions. Viewed from the rear, the spine of an individual with scoliosis can resemble an "S" or a "C", rather than a straight line. --there is congenital or idiopathic (cause unknown and accounts for 65% of all cases). Vertebral Anatomy -a quick review from lab!!!!!!!!!!!!!!!!!!!!!!!!! We are going to go through this quickly because it has already been seen in lab The Vertebral Body is the anterior mass of bone that transfers weight down the vertebral column. b. The bodies superiorly are relatively small and get proportionately larger at you go inferiorly down the vertebral column. c. The 1st vertebra does not have a body, and the second has an atypical body. (described later)

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Human Anatomy, Fifth Edition, Martini/Timmons/Tallitsch

The Skeletal System – Axial Division The Vertebral Arch, or neural arch, is the lateral and posterior arch of bone that connects to the posterior body.

Let’s talk about the cushions between the vertebrae (more later) Vertebral Bodies are attached by ligaments and separated by the fibrocartilage pads called intervertebral discs. 1. Cervical Vertebrae are 7 in total and are the smallest, most superior vertebrae. o Transverse foramina result from the hole between the costal process and the transverse process. 

The vertebral artery that brings blood to the brain runs through the adjacent transverse foramina.

b. The cervical region most flexible region. c. Three of the cervical vertebrae are unique: o The Atlas (C1) is the 1st cervical vertebra. (from lab again) 

The atlas has no body and articulates cranially with the occipital condyles.

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The atlas has two arches, the anterior and posterior vertebral arches.

The articulations with the occipital condyles allow one to shake their head as if to say the word “Yes” Hangman’s Fracture (C2) & Jefferson fracture C1 –a deceleration injury. Occurs when there is an axial force on the spine or due to hyperextension and C1 or C2 fractures and shatters. Usually a four-part break on both pedicles or pars interarticularis. Can happen due to pulling forces hanging and hitting chin on steering wheel or compressive forces such as - diving into shallow water or an Impact against the roof of a vehicle. The Axis (C2) is the second cervical vertebra. 

The body of the atlas (above) fuses with the body of the axis during development to form a large superior projection of the body called the dens (odontoid process).

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Because of the dens, there is no intervertebral disc.

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Human Anatomy, Fifth Edition, Martini/Timmons/Tallitsch

The Skeletal System – Axial Division 

The articulation between the atlas and axis allow one to shake their head as if to say “ No”

o Vertebra Prominens (C 7) is the last cervical vertebrae, and therefore resembles the thoracic vertebra is structure. (from lab again). 

This vertebra has a long, slender spinous process, and enlarged transverse processes that may or may not contain a transverse foramen.

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An elastic ligament called the Ligamentum nuchae (Nuchal Ligament extends from the spinous process cranially to the occipital crest. Damage to the ligamentum nuchae is called? Whiplash AKA Acceleration flexion-extension neck injury or "Cervical acceleration-deceleration" (CAD) or Soft tissue cervical hyperextension injury Anterior longitudinal ligament is also strained in this as well! 2. Thoracic Vertebrae are 12 in total and make up the posterior of the rib cage. a. The spinous process is long and slender and points on a posterocaudal angle.

b. The thoracic vertebrae articulate with ribs and therefore contain extra facets. 3. Lumbar Vertebrae are 5 in total, are the largest vertebrae, and make up the lower back region. a. The body of lumbar vertebrae is very thick and oval shaped. b. The relatively small vertebral foramen is triangular. c. The transverse processes point more laterally than the thoracic vertebrae. d. The spinous process resembles a tail fin of a fish, stumpy and flattened.

Lumbarization – is a nonfusion of the first and second segments of the sacrum. Lumbar spine appears to have six vertebrae. It is a congenital Anomaly

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Human Anatomy, Fifth Edition, Martini/Timmons/Tallitsch

The Skeletal System – Axial Division •

Spondylolisthesis_ - Slippage of one vertebra over the top of the inferior vertebra. Spondylo means– “bones of the spine” Causes: Congenital Childhood injury. Disc and facet degeneration Pars interarticularis fracture pondylolysis African Americans more often than in whites. Symptoms An ache in the low back and buttock areas usually, worse when standing, Spasm low back muscles. Tight hamstring muscles. Mechanical pain Wear and tear on disc and facet joints. Nerve compression 4.

The Sacrum is 5 fused vertebrae. o The vertebrae do not complete fusion until 25-30 years of age. o The sacrum attaches the axial skeleton to the appendicular skeleton by forming the sacroiliac joint with the pelvic girdle. o Together the sacrum and pelvic girdle make up the pelvis. o The auricular surface is the lateral area of the sacrum that forms the sacroiliac joint. o •

Sacralization - L5 fuses to sacrum (more sacrum)

5. The Coccyx, or tailbone, is the result of the fusion of 3-5 small vertebrae. a. The fusion occurs in the late 20’s as with the sacrum. The Thoracic Cage – Manubrium, Sternum and Xyhoid process and Ribs – not on the slides in class ● The Sternum, or breastbone, is a flat bone just under the skin of the chest in the midline of the body. It has three parts: 1. The Manubrium is the triangular, or home plate, shaped portion that articulates with the clavicles and the first pair of ribs.

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Human Anatomy, Fifth Edition, Martini/Timmons/Tallitsch

The Skeletal System – Axial Division 2. The Body of the sternum is elongated and extends caudally from its attachment with the manubrium. a. Ribs 2-10 are attached to this portion of the sternum. 3. The Xiphoid process is the inferior tip of the sternum. a. The diaphragm and rectus abdominis muscles attach to the process.

● The Ribs, or costae, are long, curved, flat bones that originate on or between thoracic vertebrae and end in the wall of the thoracic cavity. ● There are twelve pairs of ribs: 1. True ribs (vertebrosternal) are the first 7 pairs.

2. False ribs (vertebrochondral) are pairs 8-12. 3. Floating = 11 & 12

Ribs have two ends, a vertebral end and a sternal end separated by a body. ● Cervical Rib Is a supernumerary rib (additional member or extra). 1. Arises from the 7th cervical vertebra and is located above the normal first rib. 2. Does not attach directly to sternum. 3. Congenital abnormality or anomaly (deformation of an anatomical structure) 4. Occurs in 1 in 500 (0.2%) of people; rarer cases two cervical ribs can be present

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