Skull

Sutures

The skull is composed of several bones joined together by immovable joints called sutures. These sutures allow for growth during development and fuse with age.

• Coronal Suture: Separates the frontal bone from the parietal bones.

• Sagittal Suture: Runs along the midline, separating the two parietal bones.

• Squamous Suture: Separates the temporal bone from the parietal bone.

• Lambdoid Suture: Separates the occipital bone from the parietal bones.

Cranium Bones

The cranium protects the brain and forms the structure of the head. It consists of eight bones:

• Frontal Bone: Forms the forehead and superior part of the orbits.

  • Supraorbital Foramen: Passage for nerves and blood vessels above the orbit.

• Parietal Bones (2): Form the superior and lateral aspects of the skull.

• Occipital Bone: Forms the posterior base of the skull.

  • Superior Nuchal Line: Ridge for muscle attachment.

  • External Occipital Protuberance: Prominent projection at the back of the skull.

  • Foramen Magnum: Large opening for the spinal cord.

  • Occipital Condyles: Articulate with the first cervical vertebra (atlas).

  • Hypoglossal Canal: Passage for hypoglossal nerve.

• Temporal Bones (2): Form the sides and base of the skull.

  • External & Internal Acoustic Meatus: Ear canal openings.

  • Styloid Process: Attachment for muscles and ligaments of the tongue and neck.

  • Mastoid Process: Attachment for neck muscles.

  • Stylomastoid Foramen: Passage for facial nerve.

  • Jugular Foramen: Passage for jugular vein and cranial nerves.

  • Mandibular Fossa: Articulates with the mandible.

• Sphenoid Bone: Forms part of the base of the skull and orbits.

  • Greater & Lesser Wings: Contribute to the cranial floor and orbits.

  • Sella Turcica: Houses the pituitary gland.

  • Foramen Rotundum, Ovale, Spinosum, Lacerum: Passageways for nerves and vessels.

  • Carotid Canal: Passage for the internal carotid artery.

  • Pterygoid Processes: Attachment for jaw muscles.

  • Superior & Inferior Orbital Fissure, Optic Canal: Openings for nerves and vessels to the orbit.

• Ethmoid Bone: Forms part of the nasal cavity and orbits.

  • Crista Galli: Attachment for brain membranes.

  • Cribriform Plate: Passage for olfactory nerves.

  • Superior & Middle Nasal Conchae: Increase surface area in the nasal cavity.

  • Perpendicular Plate: Forms part of the nasal septum.

Facial Bones

The facial skeleton supports the face and forms cavities for the sense organs.

• Nasal Bones (2): Form the bridge of the nose.

• Maxillary Bones (2): Form the upper jaw and part of the hard palate.

  • Infraorbital Foramen: Passage for nerves and vessels.

  • Palatine Process: Forms the anterior hard palate.

• Lacrimal Bones (2): Form part of the medial orbit wall.

• Zygomatic Bones (2): Form the cheeks and part of the orbit.

  • Zygomatic Arch: Cheekbone structure.

• Vomer: Forms part of the nasal septum.

• Inferior Nasal Conchae (2): Form part of the lateral walls of the nasal cavity.

• Palatine Bones (2): Form the posterior hard palate.

• Mandible: Lower jawbone, only movable skull bone.

  • Condylar Process: Articulates with the temporal bone.

  • Mandibular Notch: Depression between processes.

  • Coronoid Process: Muscle attachment.

  • Mandibular Foramen: Passage for nerves.

  • Mental Foramen: Passage for nerves and vessels.

Rest of Axial Skeleton

Hyoid Bone

The hyoid bone is a U-shaped bone in the neck that supports the tongue and is not directly articulated with any other bone.

Vertebrae

The vertebral column consists of 33 vertebrae, classified by region and structure.

• General Characteristics:

  • Body: Weight-bearing portion.

  • Superior & Inferior Articular Facet/Process: Articulation points between vertebrae.

  • Lamina & Pedicle: Form the vertebral arch.

  • Spinous & Transverse Processes: Muscle and ligament attachment.

  • Vertebral Foramen: Canal for the spinal cord.

• Cervical Vertebrae (7):

  • Transverse Foramen: Passage for vertebral arteries.

  • Atlas (C1): Supports the skull; has anterior and posterior tubercles.

  • Axis (C2): Has the dens (odontoid process) for rotation of the head.

• Thoracic Vertebrae (12):

  • Transverse Costal Facets & Demifacets: Articulate with ribs.

• Lumbar Vertebrae (5): Large, robust bodies for weight bearing.

Sacrum and Coccyx

• Sacrum: Five fused vertebrae forming the posterior pelvis.

  • Sacral Promontory, Transverse Ridges, Ala, Sacral Foramina, Median Sacral Crest, Sacral Canal, Sacral Hiatus, Superior Articular Facet & Process: Features for articulation, nerve passage, and muscle attachment.

• Coccyx: Four fused vertebrae forming the tailbone.

Ribs and Sternum

• Ribs (12 pairs):

  • True Ribs (1-7): Attach directly to the sternum via costal cartilage.

  • False Ribs (8-12): Attach indirectly or not at all to the sternum.

  • Head & Neck, Tubercle, Shaft, Costal Cartilage: Key anatomical features.

• Sternum:

  • Manubrium, Sternal Angle, Body, Xiphoid Process: Components of the breastbone.

Upper Appendicular Skeleton

Clavicle and Scapula

• Clavicle: S-shaped bone with sternal (medial) and acromial (lateral) ends; acts as a strut between sternum and scapula.

• Scapula: Shoulder blade with several important features:

  • Coracoid Process, Subscapular Fossa, Spine, Acromion, Supraspinous & Infraspinous Fossa, Glenoid Cavity, Supraglenoid & Infraglenoid Tubercle: Sites for muscle attachment and articulation with the humerus.

Humerus

• Greater & Lesser Tubercle, Head, Anatomical & Surgical Neck, Intertubercular Sulcus, Deltoid Tuberosity, Olecranon Fossa, Capitulum, Trochlea, Medial & Lateral Epicondyles: Features for muscle attachment and articulation with the scapula, radius, and ulna.

Ulna and Radius

• Ulna: Medial bone of the forearm.

  • Radial Notch, Olecranon Process, Trochlear Notch, Coronoid Process, Head, Ulnar Styloid Process: Articulate with humerus and radius.

• Radius: Lateral bone of the forearm.

  • Head & Neck, Radial Tuberosity, Radial Styloid Process: Articulate with humerus, ulna, and carpal bones.

Hand

• Carpal Bones (8): Scaphoid, Lunate, Triquetrum, Pisiform, Trapezium, Trapezoid, Capitate, Hamate.

• Metacarpals I-V: Form the palm.

• Phalanges I-V: Each finger has proximal, middle, and distal phalanges (thumb lacks middle phalanx).

Lower Appendicular Skeleton

Coxal (Hip) Bone and Pelvis

• Coxal Bone: Formed by fusion of ilium, ischium, and pubis.

  • True vs False Pelvis: True pelvis is the bony passageway for childbirth; false pelvis supports abdominal organs.

  • Male vs Female Pelvis: Female pelvis is wider and shallower for childbirth.

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

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

• Pubis: Pubic tubercle, obturator foramen, pubic symphysis, pelvic brim.

Femur

• Head & Neck, Fovea Capitis, Greater & Lesser Trochanter, Gluteal Tuberosity, Linea Aspera, Medial & Lateral Condyle, Medial & Lateral Epicondyle, Adductor Tubercle, Intercondylar Fossa, Patellar Surface: Features for articulation and muscle attachment.

Patella, Tibia, and Fibula

• Patella: Kneecap; protects the knee joint.

• Tibia: Medial, weight-bearing bone of the leg.

  • Intercondylar Eminence, Medial & Lateral Condyle, Tibial Tuberosity, Medial Malleolus: Articulation and muscle attachment sites.

• Fibula: Lateral, slender bone of the leg.

  • Head, Lateral Malleolus: Stabilizes the ankle.

Foot

• Tarsal Bones (7): Calcaneus, Talus, Navicular, Cuboid, Lateral/Intermediate/Medial Cuneiforms.

• Metatarsals I-V: Form the arch of the foot.

• Phalanges I-V: Each toe has proximal, middle, and distal phalanges (big toe lacks middle phalanx).

Selected Joints

Vertebral Column Joints

• Intervertebral Discs: Pads of fibrocartilage between vertebrae.

  • Anulus Fibrosus: Tough outer ring of the disc.

  • Nucleus Pulposus: Gel-like center that absorbs shock.

Knee Joint

• Fibular & Tibial Collateral Ligaments: Stabilize the sides of the knee.

• Anterior & Posterior Cruciate Ligaments (ACL & PCL): Prevent excessive forward and backward movement of the tibia.

• Medial & Lateral Meniscus: Crescent-shaped cartilage pads that cushion and stabilize the joint.

• Patellar Ligament: Connects the patella to the tibia.

Table: Classification of Ribs

Table: Comparison of Male and Female Pelvis

Additional info: This guide expands on the original outline by providing definitions, anatomical context, and functional significance for each structure. Tables have been added for rib and pelvis classification to aid comparison and understanding.