The Cervix

Anatomical Structure

The cervix is comprised of two main regions—ectocervix and endocervical canal—and contains two openings: the external os and the internal os.

• Ectocervix – the portion that projects into the vaginal lumen. It is lined by non-keratinised stratified squamous epithelium. The central opening, called the external os, leads into the endocervical canal.
• Endocervix (endocervical canal) – the inner canal that extends from the external os to the internal os, where it opens into the uterine cavity. It is lined by mucus-secreting simple columnar epithelium.

By TeachMeSeries Ltd (2026)

Fig 2
The ectocervix, endocervical canal, and their openings.

Pro Feature - Dissection Atlas

You've Discovered a Pro Feature

Access our Dissection Image Library

Enhance your understanding with high-resolution dissection images showcasing real-life anatomy.

Learn More

Functions

The cervix serves two main functions:

• Sperm entry – permits the entry of sperm into the uterus, particularly during ovulation when cervical mucus becomes thinner and more receptive.
• Barrier function – forms a physical and immunological barrier that helps maintain sterility in the uterus. This is achieved through tight cervical closure and thick mucus within the endocervical canal.

By TeachMeSeries Ltd (2026)

Fig 3
The ectocervix, visible via a speculum inserted into the vagina. The external os is marked with an arrow.

Neurovascular Supply

Blood Supply

The cervix receives its arterial supply primarily from the uterine artery, with contributions from the vaginal artery. Both vessels are branches of the internal iliac artery.

Venous drainage is via the uterine venous plexus, which drains into the uterine veins and then into the internal iliac veins.

Innervation

The cervix recieves visceral sensory, sympathetic and parasympathetic innervation:

• Visceral sensory – transmit pain, stretch, and inflammatory stimuli. These fibres travel via autonomic pathways rather than somatic nerves.
• Sympathetic – fibres arising from T10–L2 via the hypogastric nerves contribute to visceral pain transmission and vascular tone.
• Parasympathetic – fibres from S2–S4 via the pelvic splanchnic nerves contribute to secretory activity, reflex motor responses, and also carry visceral afferent input.

The cervix has minimal somatic sensory innervation compared with the vagina and vulva. However, pain fibres are present, and cervical instrumentation may be painful, with marked inter-individual variation.

By TeachMeSeries Ltd (2026)

Fig 4
Posterior view of the arterial supply to the female reproductive tract.

Lymphatic Drainage

Lymph from the cervix drains to the iliac, sacral, aortic, and inguinal lymph nodes.