A&P I Unit 3 topic 4 PDF

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Anatomy and physiology notes on axial skeleton, skull, vertebral column, and thoracic cage...

Description

Topic 4: Axial Skeleton: Skull, Vertebral Column, Thoracic cage -

80 bones o 22 bones in the skull, and 7 additional o 24 bones in the vertebrae o 12 ribs and sternum in the thoracic cage

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126 bones in the appendicular skeleton

The skull Orbit – The bony socket that houses the eyeball and muscles that move the eyeball or open the upper eyelid Supraorbital margin – The upper margin of the anterior orbit Supraorbital foramen – Small opening near the midpoint of the supraorbital margin. Passage of a sensory nerve to the skin of the forehead Infraorbital foramen – Point of emergence for a sensory nerve that supplies the anterior face below the orbit Nasal cavity Nasal Septum - Nasal cavity divided into half by Perpendicular plate of the ethmoid bone – What the upper portion of the nasal septum is formed by Vomer bone – What the lower portion of the nasal septum is formed by Inferior nasal concha – Lager bony plate projecting from lateral wall Middle nasal concha – Just above the inferior concha, part of ethmoid bone Superior nasal concha – Third bony plate, part of ethmoid bone. Lateral to the perpendicular plate

Zygomatic arch – Bony arch on the side of the skull that spans from the area of the cheek to just above the ear canal. Formed by the junction of: o Temporal process of the zygomatic bone (cheekbone) – Short anterior component o Zygomatic process of the temporal bone – longer posterior portion Temporal fossa – A shallow space above the level of the zygomatic arch Infratemporal fossa – A space below the level of the zygomatic arch and deep to the vertical portion of the mandible Bones of the Brain Case Calvaria (skullcap) – Rounded top of the skull -

Bones that form the top and sides of the brain case are referred to as “flat” bones

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The floor of the brain case is referred to as the base of the skull

Parietal bone – Forms most of the upper lateral side of the skull Temporal bone – Forms the lower lateral side of the skull o Mastoid process – Muscle attachment site. Just behind the earlobe. o Petrous ridge – Interior of the skull, formed by the petrous portion of each temporal bone o External acoustic meatus (ear canal)—This is the large opening on the lateral side of the skull that is associated with the ear. o Internal acoustic meatus—This opening is located inside the cranial cavity, on the medial side of the petrous ridge. It connects to the middle and inner ear cavities of the temporal bone. o Mandibular fossa—This is the deep, oval-shaped depression located on the external base of the skull, just in front of the external acoustic meatus.

o Articular tubercle—The smooth ridge located immediately anterior to the mandibular fossa.

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Contributes to the temporomandibular joint, the joint that provides the movements between the temporal bone of the skull and the mandible

o Styloid process—Posterior to the mandibular fossa on the external base of the skull is an elongated, downward bony projection. Serves as an attachment site for several small muscles and for ligaments that support the hyoid bone of the neck

o Stylomastoid foramen—This small opening is located between the styloid process and mastoid process. This is the point of exit for the cranial nerve that supplies the facial muscles. o Carotid canal—The carotid canal is a zig-zag shaped tunnel that provides passage through the base of the skull for one of the major arteries that supplies the brain.

Frontal bone – Forms the forehead o Glabella – Slight depression at its anterior midline, between the eyebrows Occipital bone – Forms the posterior skull and posterior base of the cranial cavity o External occipital protuberance - On its outside surface, at the posterior midline, is a small protrusion, which serves as an attachment site for a ligament of the posterior neck

o Superior nuchal line - Lateral to either side of this bump is a o Foramen magnum - Large opening, which allows for passage of the spinal cord as it exits the skull

o Occipital condyle - On either side of the foramen magnum is an oval-shaped. These condyles form joints with the first cervical vertebra and thus support the skull on top of the vertebral column.

Sphenoid Bone – A single midline bone that forms the anterior walls and floor of the middle cranial fossa o Lesser wings of the sphenoid bone - form the lip of a prominent ridge that marks the boundary between the anterior and middle cranial fossae

o sella turcica - is located at the midline of the middle cranial fossa.

o Hypophyseal (pituitary) fossa - houses the pituitary gland o Greater wings of the sphenoid bone - extend laterally to either side away from the sella turcica, where they form the anterior floor of the middle cranial fossa

o Medial pterygoid plate and lateral pterygoid plate - sites for chewing muscles Ethmoid Bone – A single midline bone that forms the roof and lateral walls of the upper nasal cavity, the upper portion of the nasal septum and contributes to the medial wall of the orbit o

Crista galli – Small upward bony projection located at the midline. It functions as an anterior attachment point for one of the covering layers of the brain

o Cribriform plate – At either side of the crista galli. A small, flattened area with numerous small openings. Sutures of the Skull -

Immobile joint between adjacent bones of the skull

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Dense, fibrous connective tissue

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Coronal suture – Runs from side to side across the skull. Joins the frontal bone to the right and left parietal bones.

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Sagittal suture - Extends posteriorly from the coronal suture, running along the midline at the top of the skull. Unites the right and left parietal bones

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Lambdoid suture – Extends downward and laterally to either side away from its junction with the sagittal suture. Joins the occipital bone to the right and left parietal and temporal bones.

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Squamous suture – Located of the lateral skull. Unites the squamous portion of the temporal bone with the parietal bone.

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Pterion – Small, capital-H shaped suture line at the intersection of the four bones

Facial Bones of the Skull -

Maxillary bone – Forms the upper jaw and supports the upper teeth o Alveolar process of the maxilla – Contains the upper teeth

o Palatine process – Joins together at the midline to form the anterior threequarters of the hard palate o Hard palate – Bony plate that forms the roof of the mouth and floor of the nasal cavity -

Palatine bone – One of a pair of irregularly shaped bones that contribute small areas to the lateral walls of the nasal cavity and the medial wall of each orbit

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Zygomatic – Cheekbone

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Nasal – Two small bones that join to form the bridge of the nose

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Lacrimal – Small, rectangular bone that forms the anterior, medial wall of the orbit o Lacrimal fossa - The anterior portion of the lacrimal bone forms a shallow depression

o Nasolacrimal canal – Duct that drains the tears of the eyes -

Inferior Nasal conchae – Form a curved bony pate that projects into the nasal cavity space from the lower lateral wall

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Vomer – Triangular-shaped and forms the posterior-inferior part of the nasal septum.

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Mandible – Forms the lower jaw and is the only moveable bone of the skull o Alveolar process of the mandible—This is the upper border of the mandibular body and serves to anchor the lower teeth. o Mental protuberance—The forward projection from the inferior margin of the anterior mandible that forms the chin

o Mental foramen—The opening located on each side of the anterior-lateral mandible, which is the exit site for a sensory nerve that supplies the chin. o Mylohyoid line—This bony ridge extends along the inner aspect of the mandibular body. The muscle that forms the floor of the oral cavity attaches to the mylohyoid lines on both sides of the mandible. o Mandibular foramen—This opening is located on the medial side of the ramus of the mandible. The opening leads into a tunnel that runs down the length of the mandibular body.

o Lingula—This small flap of bone. It is located immediately next to the mandibular foramen, on the medial side of the ramus. A ligament that anchors the mandible during opening and closing of the mouth extends down from the base of the skull and attaches to the lingula.

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Orbit – Bony socket that houses the eyeball and contains the muscles that move the eyeball or open the upper eyelid

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Cranial Fossae – Inside the skull, the base is subdivided into three large spaces: anterior cranial fossa, middle cranial fossa, and posterior cranial fossa. o Increase in depth from anterior to posterior

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Paranasal Sinuses – Hollow, air-filled spaces located within certain bones of the skull o Frontal sinus – located just above the eyebrows o Maxillary sinus – Right and left maxillary bones o Sphenoid sinus – In the body of the sphenoid bone

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Hyoid – Small “U” shaped bone located in the upper neck

Structure of a Vertebra -

Body, vertebral arch, and seven processes

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Intervertebral disc – Separates vertebrae, provides padding, and allows for movement

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Vertebral arch – Forms the posterior portion of each vertebra

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Pedicle – Forms one of the lateral sides of the vertebral arch

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Lamina – Forms part of the posterior roof of the vertebral arch

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Vertebral foramen – Large opening between the vertebral arch and the body

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Vertebral canal – Serves as the bony protection and passageway for the spinal cord down the back

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Intervertebral foramen – Opening through which a spinal nerve exits from the vertebral column

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Transverse process – Projects laterally and arises from the junction point between the pedicle and lamina

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Spinous process – Single. Projects posteriorly at the midline of the back

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Superior articular process – Extends and faces upward

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Inferior articular process – Faces or projects downward on each side of vertebrae

Regional

Cervical Vertebrae -

C1-C7

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Transverse foramen – Opening in transverse process. Important artery that supplies the brain ascends up the neck by passes through

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Atlas – First vertical vertebra. Supports the skull

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Anterior arch and Posterior arch – What the C1 vertebra has instead of a body or spinous process

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Axis – Second cervical vertebra. Serves as axis for rotation when turning the head

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Dens – A bony projection that extends upward from the vertebral body

Thoracic Vertebrae -

T1-T12

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Larger

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Facet – Where rib is attached

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Costal facet – Two facets located on the lateral sides of the body. For articulation with the head of the rib

Lumbar Vertebrae -

L1-L5

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Carry the greatest amount of body weight

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Short transverse processes and a short, blunt spinous process that projects posteriorly

Sacrum and Coccyx -

5 sacral vertebrae

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Medial sacral crest – Posterior surface, running down the midline. A bumpy ridge that is the remnant of the fused spinous processes

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Lateral sacral crest – Fused transverse processes of the sacral vertebrae

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Sacral promontory – Anterior lip of the superior base of the sacrum

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Sacral Canal – Tunnel that passes inferiorly through the sacrum

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Sacral Hiatus – Near the inferior tip of the sacrum

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Sacral foramina – Paired openings

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Coccyx is made of 4 small coccygeal vertebrae

Ligaments of the Vertebral Column -

Anterior longitudinal ligament – Runs down the anterior side of the entire vertebral column, uniting the vertebral bodies. Resists excess backward bending

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Supraspinous ligament – Located on the posterior side of the vertebral column, where is interconnects the spinous processes of the thoracic and lumbar vertebrae. Supports the vertebral column during forward bending motions

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Nuchal ligament – Attached to the cervical spinous processes and extends upward and posteriorly to attach to the midline base of the skull, out to the external occipital protuberance. Supports the skull and prevents it from falling forward

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Posterior longitudinal ligament – Found anterior to the spinal cord, where it is attached to the posterior sides of the vertebral bodies

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Ligamentum flavum – Posterior to the spinal column

The Thoracic Cage -

Sternum and 12 ribs

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Ribs 1-7 are true ribs, tibs 8-12 are false ribs, and ribs 11-12 are floating ribs

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Manubrium – Wider superior portion of the sternum

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Jugular notch – Shallow, U-shaped border at the top of the manubrium

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Clavicular notch – The shallow depression located on either side at the superior-lateral margins of the manubrium

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Sternal angle – The manubrium and body join together at

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Xiphoid process – Inferior tip of the sternum

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Head of the rib – Posterior end of a rib

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Neck of the rib – Lateral to the head

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Body of the rib – Remainder of the rib

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Angle of the rib – The point at which the rib has its greatest degree of curvature

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Costal groove – Passage of blood vessels and a nerve...