Overview of the Human Skeleton

The human skeleton is a complex framework of bones that provides structure, protection, and support for the body. It is divided into two main parts: the axial skeleton (skull, vertebral column, and thoracic cage) and the appendicular skeleton (limbs and girdles).

Cranial Bones

Definition and Function

Cranial bones are the bones that form the cranium, which encases and protects the brain. There are eight cranial bones in total.

• Key Cranial Bones: Frontal, Parietal, Temporal, Occipital, Sphenoid, Ethmoid

• Function: Protection of the brain, attachment for head and neck muscles

Identification of Cranial Bones

• Not a Cranial Bone: Maxilla (Maxilla is a facial bone, not a cranial bone)

• Example: The sphenoid and ethmoid are cranial bones, while the maxilla is not.

Sutures of the Skull

Sutures are immovable joints that connect the bones of the skull.

• Squamous Suture: The suture between the parietal and temporal bones.

• Other Sutures: Coronal (frontal and parietal), Lambdoid (parietal and occipital), Sagittal (between parietal bones)

Processes and Canals

• Mastoid Process: Belongs to the temporal bone. It serves as an attachment point for neck muscles.

• Carotid Canal: Passes through the temporal bone. It transmits the internal carotid artery to the brain.

Bones Forming the Nasal Septum

• Ethmoid Bone: Helps to form the nasal septum, which divides the nasal cavity into left and right sides.

Facial Bones

Definition and Function

Facial bones form the structure of the face and support the teeth and nasal cavities. There are fourteen facial bones.

• Key Facial Bones: Maxilla, Mandible, Zygomatic, Nasal, Lacrimal, Palatine, Inferior nasal concha, Vomer

• Function: Form the face, house the teeth, anchor facial muscles

Identification of Facial Bones

• Not a Facial Bone: Hyoid (The hyoid bone is unique; it does not articulate with any other bone and is not considered a facial bone.)

Bones Forming the Nasal Septum

• Vomer: A facial bone that helps form the nasal septum.

Bones Forming the Hard Palate

• Maxilla: The maxilla forms the anterior part of the hard palate.

• Palatine Bone: Forms the posterior part of the hard palate. Additional info: Palatine bone is not listed in the questions but is relevant.

Vertebrae and Thorax

Vertebral Column Structure

The vertebral column consists of cervical, thoracic, lumbar, sacral, and coccygeal vertebrae.

• Atlas (C1): The first cervical vertebra; it has no body.

• Axis (C2): The second cervical vertebra; has the dens.

• Transverse Foramen: Found in cervical vertebrae; allows passage of vertebral arteries.

• Costal Facets: Characteristic of thoracic vertebrae; articulate with ribs.

Thoracic Cage

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

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

• Floating Ribs: Ribs 11 and 12; do not attach to the sternum.

• Sternum: The superior portion is the manubrium.

Upper Limb

Pectoral Girdle

• Composed of: Clavicle and scapula.

• Function: Attaches the upper limb to the axial skeleton.

Key Bones and Features

• Humerus: Contains the radial groove.

• Scapula: Contains the glenoid cavity, which articulates with the humerus.

• Radius: The head is found at the proximal end.

• Ulna: The olecranon process is the point of the elbow.

Important Foramina

• Mandibular Foramen: Dentists inject lidocaine here to numb lower teeth.

Lower Limb

Pelvic Girdle

• Composed of: Ilium, ischium, and pubis.

• Not Part of Pelvic Girdle: Sacrum (though it articulates with the pelvic bones, it is not part of the girdle itself).

Key Bones and Features

• Femur: Contains the lesser trochanter.

• Fibula: Contains the lateral malleolus (outer ankle).

• Calcaneus: The heel bone.

• Talus: Keystone of the medial longitudinal arch of the foot.

Unique Bones

• Hyoid Bone: Does not articulate with any other bone; supports the tongue.

• Patella: The kneecap; a sesamoid bone in the quadriceps tendon.

Summary Table: Cranial vs. Facial Bones

Key Terms and Definitions

• Suture: An immovable joint between skull bones.

• Process: A projection or outgrowth of bone for muscle attachment.

• Foramen: An opening in bone for nerves and blood vessels.

• Trochanter: Large, rough projection on the femur for muscle attachment.

• Malleolus: Rounded bony prominence on either side of the ankle.

Additional Info

• The palatine bone also contributes to the hard palate but was not listed in the questions.

• The hyoid bone is unique in that it does not articulate with any other bone.