---
title: "Infraglenoid Tubercle | Anatomy and Physiology I"
description: "The infraglenoid tubercle is the scapular bump below the glenoid cavity where the long head of the triceps brachii attaches in Anatomy and Physiology I."
canonical: "https://fiveable.me/anatomy-physiology/key-terms/infraglenoid-tubercle"
type: "key-term"
subject: "Anatomy and Physiology I"
unit: "Unit 8"
---

# Infraglenoid Tubercle | Anatomy and Physiology I

## Definition

The infraglenoid tubercle is a small bony projection on the scapula just below the glenoid cavity. In Anatomy and Physiology I, you learn it as the attachment site for the long head of the triceps brachii.

## What It Is

The infraglenoid tubercle is a roughened bony landmark on the scapula, located just below the glenoid cavity. In Anatomy and Physiology I, it shows up as one of the shoulder girdle features you need to identify on a bone model, diagram, or lab practical.

Its main job is to give the long head of the triceps brachii a place to attach. That matters because muscle attachment points are where force gets transferred from the muscle to the skeleton. The tubercle itself does not move, but the pull from the triceps uses it as a fixed anchor during elbow extension and other upper limb movements.

Because it sits on the scapula near the shoulder joint, the infraglenoid tubercle is part of the anatomy that ties together the pectoral girdle and the arm. The scapula is not just a flat bone in the back. It is packed with landmarks, ridges, processes, and cavities that serve as attachment sites for muscles and ligaments, and the infraglenoid tubercle is one of the smaller ones worth knowing.

It is easy to mix up the infraglenoid tubercle with other scapular features because many of them sound similar. The glenoid cavity is the socket for the humeral head, while the infraglenoid tubercle sits just below that socket and gives the long head of triceps a place to begin. So if you are looking at a shoulder bone image, think location first: below the glenoid, on the lateral border region of the scapula.

A good way to picture it is as the triceps starting point on the shoulder blade. When you extend your elbow, the triceps contracts and pulls on its attachment sites, including the infraglenoid tubercle for the long head. That makes the tubercle part of a bigger structure-function story, where bone shape and muscle action fit together.

## Why It Matters

The infraglenoid tubercle matters because Anatomy and Physiology I is full of bone landmarks, and many of them are only useful if you can connect them to movement. This term links the scapula to the triceps brachii, so it helps you see how the pectoral girdle supports upper limb motion instead of just sitting there as a list of names.

It also helps you separate shape from function. The scapula is not a smooth triangle, it has attachment points all over it. When you know that the infraglenoid tubercle anchors the long head of the triceps, you can explain why that muscle has a shoulder connection and why the shoulder girdle has to provide stable attachment sites for both movement and posture.

In lab, this kind of term shows up when you identify bones on a model or match labeled structures to their roles. In lecture or homework, it often appears in questions about muscle origins, shoulder anatomy, or the way the upper limb is suspended from the trunk. If you can place the infraglenoid tubercle correctly, you are also practicing the bigger skill of reading bone landmarks as functional anatomy.

## Connections

### Scapula

The infraglenoid tubercle is one feature on the scapula, so you need to know the bone first before the landmark makes sense. The scapula gives the shoulder its broad attachment surface, and the tubercle is one of several spots that muscles use for anchoring. On a model or diagram, it sits on the lateral side of the scapula near the glenoid region.

### [Glenoid Cavity](/anatomy-physiology/key-terms/glenoid-cavity)

The glenoid cavity and the infraglenoid tubercle are close neighbors, but they do different jobs. The glenoid cavity is the socket that helps form the shoulder joint, while the infraglenoid tubercle is a rough bump below it for muscle attachment. If you confuse the two, check whether the question is about articulation or origin site.

### Triceps Brachii Muscle

The long head of the triceps brachii attaches to the infraglenoid tubercle, so this muscle is the main reason the landmark matters. Knowing the attachment helps you understand why the long head crosses the shoulder joint as well as the elbow. That extra path affects how the triceps contributes to extension and shoulder stability.

### [Acromion Process](/anatomy-physiology/key-terms/acromion-process)

The acromion process is another scapular landmark, but it is more about the top of the shoulder and the acromioclavicular region. The infraglenoid tubercle is lower and closer to the glenoid cavity. Comparing the two helps you build a mental map of the scapula instead of memorizing isolated labels.

## On the AP Exam

A lab practical may show you a scapula model and ask you to label the infraglenoid tubercle, or a quiz may ask which muscle attaches there. When you see a shoulder anatomy question, the move is simple: locate the landmark below the glenoid cavity and connect it to the long head of the triceps brachii. If a question asks about movement, remember that this attachment helps the triceps act on the elbow while also crossing the shoulder. In image-based questions, do not confuse it with the glenoid cavity or with the acromion at the top of the scapula.

## infraglenoid tubercle vs Glenoid Cavity

These two structures are close together on the scapula, but they are not the same. The glenoid cavity is the articular socket for the humeral head, while the infraglenoid tubercle is the bony prominence just below it where the long head of triceps attaches. If a question asks about the shoulder joint surface, choose the glenoid cavity. If it asks about a muscle attachment site below that socket, choose the infraglenoid tubercle.

## Key Takeaways

- The infraglenoid tubercle is a small bony landmark on the scapula just below the glenoid cavity.
- Its main function is to serve as the attachment site for the long head of the triceps brachii.
- This landmark matters because it connects shoulder anatomy to upper limb movement, especially elbow extension.
- On diagrams and lab models, place it below the glenoid cavity, not at the socket itself.
- It is one of the scapular features you learn as part of the pectoral girdle’s structure and function.

## FAQs

### What is the infraglenoid tubercle in Anatomy and Physiology I?

It is a bony projection on the scapula located just below the glenoid cavity. In Anatomy and Physiology I, it is best known as the attachment site for the long head of the triceps brachii. That makes it a muscle landmark, not a joint surface.

### Where is the infraglenoid tubercle located?

You find it on the scapula near the shoulder joint, below the glenoid cavity. It sits on the lateral part of the scapula, close to the socket where the humerus articulates. On a model, look for the roughened area just inferior to the glenoid region.

### What attaches to the infraglenoid tubercle?

The long head of the triceps brachii attaches there. That attachment is why the long head is the only head of the triceps that crosses the shoulder joint. If you are studying muscle origins and insertions, this is the detail to connect to the scapula.

### How is the infraglenoid tubercle different from the glenoid cavity?

The glenoid cavity is the socket that forms part of the shoulder joint, while the infraglenoid tubercle is a nearby projection used for muscle attachment. A common mistake is to treat them as the same because they are adjacent. One is for articulation, the other is for anchoring a muscle.

## Related Study Guides

- [8.1 The Pectoral Girdle ](/anatomy-physiology/unit-8/1-pectoral-girdle/study-guide/hwZwgwoEDxiyRWoU)

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