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    Related Topics

    From Musculoskeletal System

    Coccyx
    Tailbone, the remnant of the tail in humans.
    Extensor Tendons
    Tendons that help extend the fingers and toes.
    Patella
    Knee cap, protecting the knee joint.
    Sternum
    Breastbone located in the center of the chest.
    Buccinator
    Muscle that helps with chewing and blowing air out.
    Saddle Joints
    e.g., thumb joint
    Rectus Abdominis
    Abs muscle that flexes the trunk.
    Cervical Vertebrae (C1 - C7)
    Vertebrae in the neck region (C1-C7).
    Adductors
    Muscles that bring the thighs toward the midline.
    Cranial Bones
    Bones of the skull that protect the brain.
    Hinge Joints
    e.g., elbow, knee
    Ribs (12 Pairs)
    12 pairs of bones that form the sides of the thoracic cage.
    Temporal Bones
    Bones forming the lower sides of the skull and housing the ears.
    Pivot Joints
    e.g., atlanto-axial joint
    Gomphoses
    Fibrous joints where a peg fits into a socket (e.g., teeth in jaw).
    Ulna
    Forearm bone on the pinky side.
    Zygomatic Bones
    Cheekbones that form part of the orbit.
    Gastrocnemius
    Calf muscle responsible for plantarflexion of the foot.
    Triceps Brachii
    Muscle responsible for elbow extension.
    Femur
    Thigh bone, the longest and strongest bone in the body.
    Soleus
    Calf muscle responsible for plantarflexion of the foot.
    Biceps Tendon
    Tendon that attaches the biceps muscle to the bone.
    Sacrum
    Triangular bone at the base of the spine.
    Ellipsoidal (Condyloid) Joints
    e.g., wrist
    Scapula
    Shoulder blade providing attachment for muscles of the upper limb.

    Skull

    Reviewed by our medical team

    Bony structure of the head that encases the brain.

    1. Overview

    The skull is a complex bony structure that forms the head's skeleton. It encases and protects the brain, supports the sensory organs, and forms the framework for the face. The skull is composed of 22 bones, most of which are fused in adults. It is divided anatomically into two main parts: the neurocranium (braincase) and the viscerocranium (facial skeleton).

    2. Location

    The skull is located at the superior end of the axial skeleton:

    • Superior to: The cervical vertebrae (begins at the foramen magnum and sits on the first cervical vertebra, the atlas).

    • Anterior to: The vertebral column and posterior neck structures.

    • Encases: The brain and forms the upper part of the respiratory and digestive tracts.

    3. Structure

    The skull is composed of 22 bones, most of which are joined by immovable fibrous joints called sutures:

    • Neurocranium (8 bones):

      • Frontal

      • Occipital

      • Two parietal

      • Two temporal

      • Sphenoid

      • Ethmoid

    • Viscerocranium (14 bones):

      • Mandible

      • Maxillae (2)

      • Zygomatic (2)

      • Nasal (2)

      • Lacrimal (2)

      • Palatine (2)

      • Inferior nasal conchae (2)

      • Vomer

    Other important skull components include:

    • Sutures: Coronal, sagittal, lambdoid, and squamous sutures connect cranial bones.

    • Foramina: Openings for nerves and blood vessels (e.g., foramen magnum, optic canal, jugular foramen).

    • Sinuses: Air-filled cavities in the frontal, sphenoid, ethmoid, and maxillary bones that lighten the skull and enhance voice resonance.

    4. Function

    The skull performs multiple critical functions:

    • Protects the brain: The neurocranium forms a rigid case for the brain and meninges.

    • Supports sensory organs: Houses the structures of vision, hearing, balance, smell, and taste.

    • Facilitates speech and mastication: Provides the framework for the oral cavity, jaws, and muscles of facial expression.

    • Attachment for muscles: Serves as the origin and insertion for muscles involved in head movement, mastication, and facial expression.

    5. Physiological role(s)

    The skull also plays roles beyond protection and structure:

    • Encloses cranial nerves: Contains foramina for the passage of all 12 cranial nerves.

    • Hematopoiesis (in infancy): Some cranial bones contain red bone marrow, active in early hematopoiesis.

    • Growth and development: Skull growth accommodates rapid brain expansion in infancy and childhood.

    • Resonance and phonation: Paranasal sinuses and the oral cavity contribute to voice quality and sound resonance.

    6. Clinical Significance

    The skull is involved in numerous medical and anatomical conditions:

    • Fractures:

      • Can occur from blunt trauma, falls, or accidents; may involve cranial vault or base of skull and risk damage to brain or vessels.

    • Craniosynostosis:

      • Premature fusion of sutures in infants, leading to abnormal skull shape and potential intracranial pressure increase.

    • Temporomandibular joint (TMJ) dysfunction:

      • Involves the articulation between the temporal bone and mandible; can cause jaw pain, clicking, and difficulty chewing.

    • Sinus infections and tumors:

      • Paranasal sinuses may become infected or obstructed; neoplastic growths may affect bone integrity.

    • Skull base tumors:

      • Lesions in the cranial base (e.g., meningiomas, chordomas) may compress cranial nerves and brainstem structures.

    • Deformities and trauma in childbirth:

      • Fontanelles and sutures allow for flexibility during passage through the birth canal but may be sites of pathology.

    Did you know? The smallest joint in the body is the stapes in the ear.