BIO 231 Exam 5 Study Guide: The Skeletal System and Anatomical Terminology

Introduction to the Skeletal System and Anatomical Terminology

Anatomical Position and Directional Terms

The anatomical position is a standardized posture used as a reference in anatomy. The body stands upright, facing forward, with arms at the sides and palms facing forward. Directional terms describe the locations of structures relative to other structures or locations in the body.

• Superior: Toward the head or upper part of a structure; Inferior: Away from the head or toward the lower part.

• Anterior (Ventral): Toward the front; Posterior (Dorsal): Toward the back.

• Medial: Toward the midline; Lateral: Away from the midline.

• Proximal: Closer to the point of attachment or origin; Distal: Farther from the point of attachment or origin.

• Superficial (External): Toward or at the body surface; Deep (Internal): Away from the body surface.

Example: The heart is medial to the lungs. The wrist is distal to the elbow.

Surface Anatomy and Body Regions

Surface anatomy refers to the study of external features of the body. Body regions are specific areas such as the thoracic (chest), abdominal, pelvic, and cranial regions.

• Major regions include: head, neck, trunk, upper limbs, and lower limbs.

Body Cavities and Membranes

The body contains several cavities that house organs. Membranes line these cavities and cover organs.

• Dorsal cavity: Cranial cavity (brain) and vertebral cavity (spinal cord).

• Ventral cavity: Thoracic cavity (heart, lungs) and abdominopelvic cavity (digestive, urinary, reproductive organs).

• Serous membranes (e.g., pleura, pericardium, peritoneum) line cavities and reduce friction.

Body Planes

Body planes are imaginary lines used to divide the body for anatomical study.

• Sagittal plane: Divides the body into right and left parts.

• Frontal (coronal) plane: Divides the body into anterior and posterior parts.

• Transverse (horizontal) plane: Divides the body into superior and inferior parts.

Bone Markings and the Skeletal System

Definitions of Bone Markings

Bones have specific markings that serve as attachment points for muscles, passageways for nerves and blood vessels, and articulation surfaces for joints.

• Suture: Immovable joint between skull bones.

• Process: Any bony prominence.

• Head: Rounded, articular projection supported on a neck.

• Condyle: Rounded articular projection.

• Epicondyle: Raised area above a condyle.

• Tubercle: Small, rounded projection.

• Tuberosity: Large, roughened projection.

• Facet: Smooth, flat articular surface.

• Fossa: Shallow depression.

• Foramen: Round or oval opening through a bone.

• Canal: Tubelike passageway.

• Trochanter: Large, blunt, irregular surface (found only on femur).

• Spine: Sharp, slender projection.

Axial vs. Appendicular Skeleton

The human skeleton is divided into two main parts:

• Axial skeleton: Skull, vertebral column, and thoracic cage (ribs and sternum).

• Appendicular skeleton: Limbs and girdles (pectoral and pelvic girdles).

Example: The femur is part of the appendicular skeleton; the sternum is part of the axial skeleton.

The Skull

Skull Bones

The skull consists of 22 bones, some paired and some single. The following table summarizes the 14 facial bones and their paired status:

Bone	Paired?
Frontal	No
Parietal	Yes
Occipital	No
Temporal	Yes
Zygomatic	Yes
Sphenoid	No
Ethmoid	No
Vomer	No
Inferior Nasal Concha	Yes
Lacrimal	Yes
Nasal	Yes
Maxilla	Yes
Palatine	Yes
Mandible	No

Paranasal Sinuses

Sinuses are air-filled cavities within certain skull bones. The paranasal sinuses are located in the frontal, maxillary, sphenoidal, and ethmoidal bones. They drain into the nasal cavity and help lighten the skull and resonate sound.

• Frontal sinuses: In the frontal bone above the eyes.

• Maxillary sinuses: In the maxilla, largest sinuses.

• Sphenoidal sinuses: In the sphenoid bone.

• Ethmoidal sinuses: In the ethmoid bone.

Fontanels

Fontanels are soft spots on a fetal skull where bone formation is incomplete. They allow for growth of the brain and skull during infancy.

• Anterior fontanel: Largest, between frontal and parietal bones.

• Posterior fontanel: Between parietal and occipital bones.

• Anterolateral (sphenoid) fontanel: At the junction of frontal, parietal, temporal, and sphenoid bones.

• Posterolateral (mastoid) fontanel: At the junction of parietal, occipital, and temporal bones.

Key Skull Bone Markings

• Parietal bone: Coronal, sagittal, lambdoid, and squamous sutures.

• Occipital bone: Foramen magnum, occipital condyles.

• Temporal bone: External/internal auditory canal, mandibular fossa, zygomatic process, mastoid process, styloid process, carotid canal, jugular foramen.

• Sphenoid bone: Greater/lesser wings, sella turcica, optic foramen, pterygoid process.

• Ethmoid bone: Crista galli, cribriform plate with olfactory foramina, perpendicular plate, superior and middle nasal conchae.

• Lacrimal bone: Lacrimal fossa.

• Maxilla: Alveolar process, palatine process, intermaxillary suture.

• Mandible: Body, ramus, angle, mandibular condyle, coronoid process, mandibular foramen, alveolar process, mental foramen.

Vertebral Column and Thoracic Cage

Vertebrae Types and Features

The vertebral column consists of 33 vertebrae, classified as follows:

Type	Number	Key Features
Cervical	7	Transverse foramina (for vertebral arteries)
Thoracic	12	Facets for rib articulation, long spinous process
Lumbar	5	Largest body, short thick spinous process
Sacral	5 (fused)	Forms sacrum
Coccygeal	~4 (fused)	Forms coccyx

• All vertebrae have a body, vertebral foramen, spinous process, transverse processes, laminae, superior/inferior articular processes and facets.

• C1 (atlas) and C2 (axis) are specialized cervical vertebrae; the axis has the dens (odontoid process).

• The sacrum has a superior articular process, auricular surface, and sacral canal.

• Intervertebral discs are located between vertebral bodies; intervertebral foramina are passageways for spinal nerves.

Sternum and Ribs

• Sternum: Consists of manubrium, body, and xiphoid process.

• Ribs:

  • Vertebrosternal (true) ribs: 1-7, attach directly to sternum.

  • Vertebrochondral (false) ribs: 8-10, attach to sternum via cartilage.

  • Vertebral (floating) ribs: 11-12, do not attach to sternum.

Appendicular Skeleton: Pectoral Girdle and Upper Limb

Pectoral Girdle

• Clavicle: Collarbone.

• Scapula: Shoulder blade; features include spine, acromion, coracoid process, glenoid cavity, supraspinous fossa, infraspinous fossa, subscapular fossa.

Upper Limb Bones and Markings

• Humerus: Head, greater/lesser tubercle, deltoid tuberosity, medial/lateral epicondyle, trochlea, capitulum, olecranon fossa.

• Radius: Head, radial tuberosity, styloid process.

• Ulna: Olecranon, trochlear notch, coronoid process, head, styloid process.

• Hand:

  • Carpals (8): Scaphoid, lunate, triquetrum, pisiform, hamate, capitate, trapezoid, trapezium.

  • Metacarpals (5)

  • Phalanges (14): Proximal, middle, distal (thumb has no middle phalanx).

Appendicular Skeleton: Pelvic Girdle and Lower Limb

Pelvic Girdle

Each pelvic bone is formed by the fusion of the ilium, ischium, and pubis.

• Ilium: Iliac crest, anterior/posterior superior/inferior iliac spines, greater sciatic notch, auricular surface.

• Ischium: Ischial spine, lesser sciatic notch, ischial tuberosity.

• Pubis: Contains pubic symphysis.

• Acetabulum: Socket for femur head.

• Obturator foramen: Large opening for nerves and vessels.

Lower Limb Bones and Markings

• Femur: Head, neck, greater/lesser trochanter, lateral/medial condyle.

• Patella: Kneecap.

• Tibia: Lateral/medial condyle, tibial tuberosity, medial malleolus.

• Fibula: Head, lateral malleolus.

• Foot:

  • Tarsals (7): Talus, calcaneus, cuboid, navicular, cuneiforms (medial, intermediate, lateral).

  • Metatarsals (5)

  • Phalanges (14): Proximal, middle, distal (big toe has no middle phalanx).

Articulations and Sidedness

• Bones articulate (form joints) with specific other bones. For example, the humerus articulates with the scapula, radius, and ulna.

• Determining right vs. left bones involves identifying anatomical landmarks and orientation.

Root Words 77-95

Understanding root words helps in deciphering anatomical and medical terminology.

Root	Meaning	Example
mal-	bad	malformation
medi-, meso-	middle	medial, mesoderm
mega-	large	megakaryocyte
micro-	small	microscope
mono-	one	monocyte
myo-	muscle	myofibril
nephro-	kidney	nephron
neo-	new	neoplasm
neuro-	nerve	neuron
oculo-	eye	oculomotor
-ology	study of	biology
onco-	tumor	oncology
ophthalm-	eye	ophthalmology
ortho-	straight, correct	orthopedics
osteo-	bone	osteocyte
para-	beside, near	parathyroid
patho-, path-	disease	pathology
peri-	around	pericardium
phag-	eat	phagocyte

Additional info: For exam preparation, students should be able to identify bones and markings on models, understand the relationships between bones, and apply anatomical terminology to describe locations and orientations. Practice with diagrams and models is highly recommended.